JP2022030998A - White interference microscope - Google Patents

Abstract

To easily correct the inclination of a measurement object without using an electrically-driven tilt stage.SOLUTION: A white interference microscope 1 comprises: a white light source 51; an adjustment member 25 which can be operated so as to adjust an angle θ formed by a direction A4 orthogonal to an upper surface 25a of a stage 23 and a direction along an optical axis A3 of an objective lens 54; an imaging unit 58 which images an interference image; an inclination calculation unit 8h which captures the plurality of interference images in which the relative height position of the stage 23 is made to be different and calculates the inclination of a sample SP with respect to the optical axis A3 of the objective lens 54 on the basis of the plurality of interference images; an operation amount conversion unit 8i which calculates an operation amount of the adjustment member 25 for correcting the inclination on the basis of the inclination calculated by the inclination calculation unit 8h; and a display control unit 8b which performs control so as to display the operation amount calculated by the operation amount conversion unit 8i.SELECTED DRAWING: Figure 13

Description

The technique disclosed herein relates to a white interference microscope.

For example, Patent Document 1 discloses a shape measuring device using the principle of white interference. Specifically, the shape measuring device disclosed in Patent Document 1 has an interference unit that generates interference light by branching white light into measurement light and reference light and then interfering with each of the branched lights. , A surface shape acquisition unit for acquiring surface shape data of an object to be measured based on the interference fringes caused by the interference light.

When measuring using the principle of white interference, if the object to be measured is tilted, the obtained interference fringes become dense and the measurement accuracy deteriorates, or the number of movements in the Z-axis direction increases and the measurement time becomes long. There is a problem of becoming. Therefore, it is generally performed to correct the inclination of the object to be measured before performing the measurement using the principle of white interference.

Japanese Unexamined Patent Publication No. 2018-146496

In order to automatically correct the tilt of the object to be measured, an electric tilt stage that detects the tilt of the object to be measured and electrically tilts the stage is required. However, the electric tilt stage is more expensive than a general electric stage (for example, one that moves electrically in the XYZ direction), and the drive mechanism is also complicated. On the other hand, it is conceivable that the user manually operates the stage movement in the tilting direction while viewing the interference fringe image, but in which direction and how much operation should be performed to eliminate the tilt, from the interference fringe image. It is difficult to judge.

The technique disclosed herein has been made in view of this point, and an object thereof is to make it possible to easily correct the inclination of the object to be measured without using an electric inclination stage.

The first aspect of the present disclosure relates to a white interference microscope that measures the surface shape of an object to be measured by using a white interferometry method. This white interference microscope includes a stage for mounting the measurement object, a white light source for irradiating the measurement object placed on the stage with white light through an objective lens, and the stage. An adjusting member that can be operated to adjust the angle formed by the direction orthogonal to the upper surface and the direction along the optical axis of the objective lens, and the white light emitted from the white light source toward a predetermined reference surface. A branching optical system that branches into a reference light, a measurement light directed to the measurement object via the objective lens, a reference light reflected by the reference surface, and a measurement light reflected by the measurement object. By controlling the image pickup unit that receives light and captures an interference image, the drive unit that changes the relative height position of the stage with respect to the objective lens, and the drive unit and the image pickup unit, the stage A tilt calculation unit that captures a plurality of interference images having different relative height positions and calculates the tilt of the measurement object with respect to the optical axis of the objective lens based on the plurality of interference images. The operation amount conversion unit that calculates the operation amount of the adjusting member for correcting the inclination based on the inclination calculated by the inclination calculation unit and the operation amount calculated by the operation amount conversion unit are displayed. It is provided with a display control unit for controlling the light.

Here, the term "tilt of the object to be measured" refers to a concept that collectively refers to the direction of inclination (direction of inclination angle) and the magnitude of inclination (magnitude of inclination angle).

According to the first aspect, the white interference microscope captures an interference image reflecting the interference between the reference light and the interference light, and is based on the principle of white interference (white interference method) on the surface of the object to be measured. The shape can be measured.

Here, although the measurement using the white interferometry is required to correct the inclination of the object to be measured as much as possible, there are disadvantages in both the automatic correction configuration and the manual correction configuration. ..

On the other hand, the white interference microscope according to the first aspect includes an adjusting member that can be operated from the outside in order to correct the inclination of the object to be measured. This white interference microscope also calculates the inclination of the object to be measured by using the interference image, and also calculates the amount of operation to be performed on the adjusting member so that the inclination is corrected. The operation amount calculated in this way is displayed on a display or the like by the display control unit. The user can operate the adjusting member to correct the inclination by visually recognizing the displayed operation amount.

Therefore, according to the first aspect, the white interference microscope automatically calculates the inclination of the object to be measured and the operation amount corresponding to the inclination. As a result, it is possible to realize a correction having excellent work efficiency, accuracy, and the like, as in the case of automatic correction.

On the other hand, by making the user visually recognize the calculated operation amount, the user himself / herself will perform the operation on the adjusting member. As a result, it is possible to realize an inexpensive and compact configuration as compared with the above-mentioned electric tilting stage. The term "manual" here includes operations using various tools such as operations using a wrench.

In this way, the inventors of the present application have newly created a configuration that realizes "semi-automatic" correction by combining the elements of automatic correction and manual correction. This makes it possible to achieve both the advantages of the configuration that manually corrects the tilt of the stage, which has been considered to be contradictory, and the advantages of the configuration that automatically corrects the tilt. According to the present disclosure, the tilt of the object to be measured can be easily corrected without using the electric tilt stage.

Further, according to the second aspect of the present disclosure, the white interference microscope changes the relative height position of the stage to a plurality of different height positions by controlling the driving unit, and changes the height position. When a measuring unit for measuring the surface shape of the object to be measured is provided based on a plurality of interference images captured by the imaging unit at each height position, and the relative height position of the stage is changed. The distance between the height positions of the above is set wider when the inclination calculation unit calculates the inclination of the measurement object than when the measurement unit measures the surface shape of the measurement object. May be.

When calculating the inclination of the object to be measured, it is permissible to make the distance between the height positions used for measurement (pitch width in the height direction) relatively wider than when measuring the surface shape. It is thought that it will be done.

According to the second aspect, when the inclination is calculated by using the white interferometry, the pitch in the height direction is set relatively coarse as compared with the case where the surface shape is measured. By setting in this way, the inclination of the object to be measured can be calculated at a higher speed.

Further, according to the third aspect of the present disclosure, the size of the region of the surface region of the measurement object that is imaged by the imaging unit to form the interference image is such that the inclination calculation unit determines the measurement object. In the case of calculating the inclination of, the measuring unit may be set to be smaller than in the case of measuring the surface shape of the object to be measured.

According to the third aspect, when the inclination is calculated by using the white interferometry, the size of the interference image is set to be relatively small as compared with the case where the surface shape is measured. By setting in this way, the inclination of the object to be measured can be calculated at a higher speed.

Further, according to the fourth aspect of the present disclosure, the inclination calculation unit measures the surface shape of the object to be measured based on the plurality of interference images, and the tilt calculation unit of the objective lens is based on the surface shape. The inclination of the object to be measured with respect to the optical axis may be calculated.

According to the fourth aspect, the inclination calculation unit measures the surface shape via the measurement unit or the like, and calculates the inclination based on the measurement result. In this way, by diverting the basic function as a white interference microscope, it becomes possible to appropriately calculate the inclination without unnecessarily increasing the number of parts.

Further, according to the fifth aspect of the present disclosure, the inclination calculation unit determines the morphological change of the interference fringes in each interference image based on the plurality of interference images, and the determination is made. Based on the result, the inclination of the object to be measured with respect to the optical axis of the objective lens may be calculated.

Here, the term "morphological change of interference fringes" includes a change in the number of stripe patterns of interference fringes, a change in the direction of each fringe pattern, a movement direction of each fringe pattern, and the like.

According to the fifth aspect, the inclination calculation unit calculates the inclination of the object to be measured based on the moving direction of the striped pattern and the like. According to this configuration, the inclination can be calculated more quickly without calculating the surface shape of the object to be measured.

Further, according to the sixth aspect of the present disclosure, the white interference microscope includes a storage unit that stores a correspondence relationship between the inclination calculated by the inclination calculation unit and the operation amount of the adjustment member.
The operation amount conversion unit may calculate the operation amount of the adjustment member based on the storage content in the storage unit.

Here, the storage unit may directly associate the inclination with the manipulated variable on a one-to-one basis and store it, or may indirectly associate and store the inclination and the manipulated variable via other parameters.

According to the sixth aspect, by storing the operation amount corresponding to the calculation result of the inclination calculation unit in advance, the operation amount can be calculated more quickly.

Further, according to the seventh aspect of the present disclosure, the adjusting member includes a first adjusting knob that rotates the upper surface of the stage around a first rotation axis extending along the upper surface, and an upper surface of the stage. The operation amount conversion unit has an operation amount of the adjustment member. The operation amount of each of the first and second adjustment knobs may be calculated.

According to the seventh aspect, by changing the posture of the upper surface of the stage, the inclination of the measurement object placed on the upper surface can be corrected. Here, since the inclination of the object to be measured has a two-degree-of-freedom system, the inclination of the object to be measured can be reliably corrected by providing the first adjustment knob and the second adjustment knob.

As described above, according to the present disclosure, the inclination of the object to be measured can be easily corrected without using the electric inclination stage.

FIG. 1 is a schematic diagram illustrating a system configuration of a white interference microscope. FIG. 2 is a perspective view of the observation unit. FIG. 3A is a schematic diagram illustrating the white optical system of the observation unit. FIG. 3B is a schematic diagram illustrating the laser optical system of the observation unit. FIG. 4 is a block diagram illustrating the configuration of a white interference microscope. FIG. 5 is a block diagram illustrating the configuration of the unit control system. FIG. 6A is a diagram illustrating the relationship between the relative position of the sample in the Z direction and the light receiving intensity due to the interference light of the white light in one pixel. FIG. 6B is a diagram illustrating the relationship between the relative position of the sample in the Z direction and the light receiving intensity due to the reflected light of the laser light in one pixel. FIG. 6C is a diagram illustrating the size of the second pitch. FIG. 6D is a diagram comparing the sizes of the fourth pitch and the first pitch. FIG. 6E is a diagram comparing the sizes of the third pitch and the fourth pitch. FIG. 6F is a diagram comparing the sizes of the third pitch and the fourth pitch. FIG. 7 is a diagram illustrating a procedure for setting a height range. FIG. 8 is a perspective view illustrating the configuration of the adjusting member. FIG. 9 is a flowchart illustrating a basic procedure for using a white interference microscope. FIG. 10 is a flowchart illustrating a procedure for setting parameters using a white interference microscope. FIG. 11 is a flowchart illustrating the procedure for executing autofocus using a white interference microscope. FIG. 12 is a flowchart illustrating a procedure for measuring a surface shape using a white interference microscope. FIG. 13 is a flowchart illustrating a procedure for correcting the inclination of the sample. FIG. 14 is a flowchart illustrating a procedure for measuring the inclination of the sample. FIG. 15 is a flowchart showing another example of the procedure for measuring the inclination of the sample. FIG. 16 is a diagram illustrating a display screen at the time of simple setting. FIG. 17 is a diagram illustrating a display screen at the time of measurement by the white interferometry. FIG. 18 is a user interface for guiding the tilt correction. FIG. 19 is a user interface for guiding the tilt correction. FIG. 20 is a user interface for guiding the tilt correction. FIG. 21 is a diagram illustrating the inclination of the sample surface.

The following is a schematic diagram illustrating the system configuration of the white interference microscope 1 according to the embodiment of the present disclosure. The white interference microscope 1 exemplified in FIG. 1 is an apparatus for enlarging and observing an observation object and a sample SP as a measurement object, and for measuring the surface shape (three-dimensional shape) of the sample SP. Is.

The white interference microscope 1 is configured as a two-luminous flux interferometer using white light. That is, this white interference microscope 1 can carry out a white interference method utilizing the two light beam interferences of white light when measuring the surface shape of the sample SP. In particular, the white interference microscope 1 according to the present embodiment uses white light as coaxial epi-illumination, and this can also be used for observing the sample SP.

The white interference microscope 1 can also carry out a laser cofocal method using a laser beam when measuring the sample SP, and depending on the user's needs, the measurement by the white interferometry and the measurement by the laser cofocal method can be performed. , Can be used properly.

When focusing on its observation function, the white interference microscope 1 can be called a magnifying observation device, simply called a microscope, or a digital microscope, while when focusing on its measurement function, it can be called. It can also be called a three-dimensional shape measuring device or a surface shape measuring device. The white interferometer 1 can also be referred to as a white interferometer or a laser confocal microscope when focusing on its measurement principle.

As shown in FIG. 1, the white interference microscope 1 according to the present embodiment includes an observation unit 2 and an external unit 3. The observation unit 2 is formed by unitizing optical components for performing observation and measurement by white interference. On the other hand, the external unit 3 is a unit for realizing a communication function, a power supply function, and the like. It is also possible to incorporate the external unit 3 into the observation unit 2 and integrate it. When the white interference microscope 1 is configured by the observation unit 2 and the external unit 3 as shown in the illustrated example, the external unit 3 can be provided with a power supply device 3a for supplying electric power to the observation unit 2. The observation unit 2 and the external unit 3 are connected by wiring 2a.

Further, the operation terminal 4 can be connected to the white interference microscope 1. The communication unit 3b (see FIG. 4) built into the external unit 3 enables the connection of the operation terminal 4. Instead of connecting the operation terminal 4 and the external unit 3, or in addition to the connection between the operation terminal 4 and the external unit 3, the operation terminal 4 and the observation unit 2 can be connected. In that case, the observation unit 2 has a built-in device corresponding to the communication unit 3b.

As shown in FIG. 1, the operation terminal 4 according to the present embodiment includes a display unit 41, a keyboard 42, a mouse 43, and a storage device 44. The operation terminal 4 can be a constituent member of the white interference microscope 1 by incorporating it into the observation unit 2 or the external unit 3 and integrating it. In this case, the operation terminal 4 can be called a control unit or the like instead of the “operation terminal”, but in this embodiment, the case where the observation unit 2 and the external unit 3 are separate from each other is illustrated. ..

Further, one or more of the display unit 41, the keyboard 42, the mouse 43, and the storage device 44 are also incorporated into the observation unit 2, the external unit 3, and the like to be integrated into the white interference microscope 1. be able to. That is, the entire operation terminal 4 or each component of the operation terminal 4 can be a part of the white interference microscope 1. For example, a white interference microscope 1 with a display unit 41 and a white interference microscope 1 with a keyboard 42 and a mouse 43 (operation unit) can be used.

The keyboard 42 and the mouse 43 are well-known computer operation devices, and form an operation unit for operating the operation terminal 4. By receiving the operation input by the user and inputting the signal corresponding to the operation input to the operation terminal 4, the white interference microscope 1 can be operated via the operation terminal 4. Specifically, by operating the keyboard 42 and the mouse 43, various information can be input, a selection operation, an image selection operation, an area designation, a position designation, and the like can be performed.

The keyboard 42 and the mouse 43 are merely examples of the operation unit. Instead of the keyboard 42 and the mouse 43, or in addition to the keyboard 42 and the mouse 43, for example, various pointing devices, voice input devices, touch panels, and other devices can be used.

The display unit 41 is composed of, for example, a liquid crystal display or an organic EL panel. The display unit 41 can display information to the user, such as the stored contents in the storage device 44. A touch panel as an operation unit may be incorporated in the display unit 41.

Further, each member, means, element, unit and the like described later may be provided in any of the observation unit 2, the external unit 3 and the operation terminal 4.

In addition to the above-mentioned devices and devices, the white interference microscope 1 includes devices for performing various operations and controls, printers, computers for performing various other processes, storage devices, peripheral devices, and the like by wire or wirelessly. You can also connect.

<Overall configuration of observation unit 2>
FIG. 2 is a perspective view of the observation unit 2. The external shape of the observation unit 2 is as shown in FIG. The observation unit 2 measures the base 20 placed on a workbench or the like, the support portion 21 extending upward from the back side portion of the base 20, and the head portion 22 provided on the upper portion of the support portion 21. A stage 23 for mounting the sample SP as an object is provided.

The front side of the observation unit 2 refers to one side close to the user when the user faces the observation unit 2 in a normal operating posture. On the other hand, the back side of the observation unit 2 refers to the other side that is separated from the user when the user faces the observation unit 2 in a normal operating posture. These are defined only for convenience of explanation and do not limit the actual usage state.

In the following description, the depth direction (longitudinal direction of the head portion 22) connecting the front side and the back side of the observation unit 2 is referred to as "X direction", and the left-right direction of the observation unit 2 (short side of the head portion 22). Direction) is referred to as "Y direction". The direction along both the X direction and the Y direction is referred to as a "horizontal direction", and the plane along the horizontal direction is referred to as a "horizontal plane".

Further, the height direction of the observation unit 2 is referred to as "Z direction". This Z direction is orthogonal to both the X direction and the Y direction. The "height position" in the following description refers to a position when viewed on a coordinate axis (Z axis) along the Z direction. The height position may also be referred to as the "Z position".

Of course, the present disclosure is not limited to these definitions, and the definitions of the X direction, the Y direction, the Z direction, and the like can be arbitrarily changed.

Among the members constituting the observation unit 2, the stage 23 is configured as an electric mounting table. The stage 23 can be moved in the Z direction by rotating the elevating dial 23a shown in FIGS. 1 and 2 and the like. Further, the upper surface of the stage 23 is composed of the upper surface 25a of the adjusting member 25. The adjusting member 25 will be described later.

The observation unit 2 includes a white optical system 5 which is a set of parts related to observation and measurement using white light, in addition to members related to the appearance shape of the observation unit 2 such as the base 20, and measurement using laser light. A unit that executes various processes via a laser optical system 6, which is a set of parts related to the above, a unit drive system 7 that drives a stage 23, etc., a white optical system 5, a laser optical system 6, and a unit drive system 7. A control system 8 is provided.

The white optical system 5 is an observation optical system (non-confocal observation optical system) that uses white light as an illumination for observation or a generation source of interference light, and can observe a sample SP illuminated by white light or a sample SP. It is an optical system for generating an interference image that characterizes the surface shape of the light. The term "optical system" used here is used in a broad sense. That is, the white optical system 5 is defined as a system that includes a light source, an image pickup device, and the like in addition to optical components such as a lens. The same applies to the laser optical system 6.

The laser optical system 6 is an observation optical system (cofocal observation optical system) that uses a so-called laser cofocal method, and laser light is obtained by scanning the laser light in two dimensions or irradiating the laser light in a focused state. It is a system for generating an image based on the reflected light of the above (hereinafter referred to as "laser image").

The unit drive system 7 is composed of a Z-direction drive unit 71 that operates the stage 23, an electric revolver (electric scaling mechanism) 74 that switches the objective lens in the first and laser optical systems 5 and 6, and the like. The unit drive system 7 operates various members constituting the white interference microscope 1 based on an electric signal input from the unit control system 8.

The unit control system 8 is connected to the white optical system 5, the laser optical system 6, and the unit drive system 7 so as to be able to transmit and receive electric signals, and can display an interference image, a laser image, or the like on the display unit 41, or can display a laser image. The autofocus of the white interference microscope 1 can be performed based on the above, and the surface shape of the sample SP can be measured based on at least one of the interference image and the laser image.

Specifically, the unit control system 8 according to the present embodiment has, as main components, a scanning control unit 8a that controls two-dimensional scanning of laser light, and a sample SP based on an interference image generated by the white optical system 5. It has a first measuring unit 8k for measuring the surface shape of the sample SP and a second measuring unit 8l for measuring the surface shape of the sample SP based on the laser image generated by the laser optical system 6. Here, the first measurement unit 8k is an example of the “measurement unit” in the present embodiment.

As illustrated in FIG. 4, the unit control system 8 according to the present embodiment is configured to be shared by the white optical system 5, the laser optical system 6, and the unit drive system 7. Not limited to. For example, a dedicated control system may be connected to each of the white optical system 5, the laser optical system 6, and the unit drive system 7.

Further, the classifications of the white optical system 5, the laser optical system 6, the unit drive system 7, and the unit control system 8 are merely classifications for convenience for systematic explanation, and do not limit the configuration of the present disclosure. .. The white interference microscope 1 according to the present embodiment has components shared by the white optical system 5 and the laser optical system 6, such as the first beam splitter 57.

(White optical system 5)
FIG. 3A is a schematic diagram illustrating, among the optical systems of the observation unit 2, a white optical system 5 in particular. The white optical system 5 of the observation unit 2 can be configured in the same manner as the optical system conventionally used for the white interferometer, and uses the white light source 51 described later as a light source for observation and measurement. .. The white optical system 5 is configured to irradiate the sample SP with white light emitted from the white light source 51 and condense the reflected light on the image pickup unit 58.

Specifically, the white optical system 5 includes a white light source 51, a first mirror 52, a first half mirror 53, an objective lens 54, and a branch optical system 55 that constitutes an interference objective lens Oct together with the objective lens 54. , A first lens 56, a first beam splitter 57, and an image pickup unit 58 having an image pickup element 58a. Of these, the image pickup unit 58 is electrically connected to the first measurement unit 8k, which is an element of the unit control system 8. In the example shown in FIG. 3A, the branching optical system 55 is configured to be built in the interference objective lens Oct, but the present disclosure is not limited to such a configuration. As will be described later, the branched optical system 55 and the objective lens 54 can be laid out as independent members, and the branched optical system 55 can be configured to operate as needed.

-White light source 51-
The white light source 51 irradiates the sample SP mounted on the stage 23 with white light via the objective lens 54 (interference objective lens Oct when the white interference method is used) (see reference numeral L1 in FIG. 3A). When the white light source 51 is used as illumination for observation, it functions as coaxial epi-illumination that is coaxial with the optical axis of the image pickup unit 58 (particularly, the optical axis of the image pickup element 58a).

Specifically, the white light source 51 according to the present embodiment is incident with, for example, a light emitting body 51a that can be configured by a halogen lamp or a white LED (Light Emitting Diode) and white light emitted from the light emitting body 51a. It has an optical component (not shown).

The white light emitted from the white light source 51 is reflected by the first mirror 52 and the first half mirror 53, and then irradiates the sample SP via the objective lens 54 and the branch optical system 55.

-First mirror 52-
The first mirror 52 is arranged so as to face the light emitting body (not shown) of the white light source 51 in a state where the mirror surface of the first mirror 52 is tilted. The first mirror 52 reflects the white light emitted from the white light source 51 and causes it to be incident on the first half mirror 53.

-First half mirror 53-
The first half mirror 53 is arranged on the optical axis of the image pickup device 58a. The first half mirror 53 re-reflects the white light reflected by the first mirror 52, so that the optical axis of the white light and the optical axis of the image pickup element 58a are coaxialized. The white light thus coaxialized is applied to the sample SP via the objective lens 54.

The white light reflected by the sample SP returns to the first half mirror 53 via the objective lens 54. The first half mirror 53 transmits the reflected white light and guides the reflected white light to the imaging unit 58 via the first lens 56 and the first beam splitter 57.

-Objective lens 54 and branch optical system 55-
The objective lens 54 is configured as an interference objective lens Oct integrated with the branch optical system 55. This interference objective lens Oct can be configured as an objective lens for two-luminous flux interference.

That is, the interference objective lens Oct divides the light for condensing the objective lens 54 and the light (white light or laser light) that has passed through the objective lens 54 into two light beams (reference light and measurement light), and divides the light into two. A branch optical system 55 that overlaps the two light beams with different optical path lengths is provided.

In particular, the interference objective lens Oct according to the present embodiment is configured as a Mirau-type interference objective lens Oct as illustrated in FIG. 3A, among the objective lenses classified as the objective lens for two-beam interference. Can be done.

Specifically, the branching optical system 55 includes an interference beam splitter 55a and a reference mirror 55b. When configured as a Mirau-type interference objective lens Oct, the interference beam splitter 55a and the reference mirror 55b are both arranged coaxially with respect to the optical axis of the objective lens 54, as illustrated in FIG. 3A.

More specifically, the interference beam splitter 55a directs the white light emitted from the white light source 51 and passing through the objective lens 54 toward a predetermined reference surface (in the present embodiment, the mirror surface of the reference mirror 55b) (FIG. (Refer to the reference numeral Lr of 3A) and the measurement light directed to the sample SP as the measurement target. The latter measurement light is reflected by the sample SP and then re-incidents into the interference beam splitter 55a (see reference numeral L2 in FIG. 3A). On the other hand, the reference mirror 55b reflects the reference light generated by the interference beam splitter 55a and propagates it toward the interference beam splitter 55a.

Therefore, the reflected light of the measurement light (measurement light reflected by the sample SP) merges with the reference light reflected by the reference mirror 55b and propagates in a state where both are overlapped. Hereinafter, the reflected light of each of the reference light and the measurement light propagating in a state of being overlapped with each other may be collectively referred to as “interference light”. The interference light thus formed passes through the objective lens 54, the first half mirror 53, the first lens 56, and the first beam splitter 57 in sequence, and reaches the imaging unit 58.

The interference objective lens Oct is not limited to the Mirau type as described above. For example, a Michaelson type interference objective lens can also be used. In that case, the reference mirror 55b is arranged at a position off the optical axis of the objective lens 54 (a position non-coaxial with the optical axis of the objective lens 54).

Further, the interference objective lens Oct is not essential when the white light source 51 is used as mere illumination. In that case, the objective lens 54 can be used alone as illustrated in FIG. 3 instead of the interference objective lens Oct having the branched optical system 55. Hereinafter, the objective lens 54 that does not include the branched optical system 55 may be referred to as a “normal objective lens”.

Further, the interference objective lens Oct is not essential when the laser beam is used for various processes. In that case, the normal objective lens 54 is basically used, but the interference objective lens Oct can be used even in the process using the laser beam as in the autofocus described later.

Further, although details are omitted, as schematically illustrated in FIG. 3B, a ring illumination 54a can be attached to the objective lens 54, and the ring illumination 54a can be used as illumination for observation (non-coaxial epi-illumination). ..

-First lens 56-
The first lens 56 is arranged so as to be coaxial with the optical axis of the image pickup device 58a. The first lens 56 collects the white light reflected by the sample SP and causes it to enter the image pickup device 58a via the first beam splitter 57.

-First beam splitter 57-
The first beam splitter 57 is arranged on the optical axis of the image pickup device 58a. The first beam splitter 57 is configured as, for example, a cube mirror, and reflects light that falls within a specific wavelength range, particularly laser light used in the laser optical system 6.

As illustrated in FIG. 3A, the first beam splitter 57 transmits white light or the like focused by the first lens 56 and guides it to the image pickup unit 58. As illustrated in FIG. 3B, the first beam splitter 57 also has a laser beam emitted from the laser light source 61 (see reference numeral L3 in FIG. 3B) and a reflected light of the laser beam from the sample SP (reference numeral in FIG. 3B). L4) and are reflected respectively.

-Image pickup unit 58-
The image pickup unit 58 receives the reference light reflected by the mirror surface (reference surface) of the reference mirror 55b and the measurement light reflected by the sample SP as a measurement object, and causes interference between the reference light and the measurement light. Image the reflected interference image. The image pickup unit 58 also functions as a camera for capturing the surface of the sample SP when the white light source 51 is used as a mere illumination.

Specifically, the image pickup unit 58 has an image pickup element 58a for receiving light collected by the first lens 56, such as white light. The image pickup device 58a photoelectrically converts the intensity of light incident through the first lens 56 or the like by a plurality of pixels arranged on the light receiving surface thereof, and converts it into an electric signal corresponding to the optical image of the subject.

The image pickup element 58a may have a plurality of light receiving elements arranged along the light receiving surface. In this case, each light receiving element corresponds to a pixel. Specifically, the image pickup device 58a according to the present embodiment is configured by an image sensor made of CMOS (Complementary Metal Oxide Semiconductor), but is not limited to this configuration. As the image pickup device 58a, for example, an image sensor made of a CCD (Charged-Coupled Device) can be used.

Then, the image pickup unit 58 generates an image corresponding to the optical image of the subject based on the electric signal converted by the image pickup element 58a, and inputs this to the unit control system 8 or the like. Among the images (camera images) generated by the image pickup unit 58, those obtained by capturing the interference fringes used in the white interferometry correspond to the above-mentioned "interference image". Of course, the image generated by the image pickup unit 58 also includes an image for observing the surface of the sample SP.

-About the basic principle of white interferometry-
As described above, the image pickup unit 58 receives the reference light reflected by the mirror surface (reference surface) of the reference mirror 55b and the measurement light reflected by the sample SP as the measurement object. Here, the reflected light of the reference light and the measurement light propagates in the same optical path after being emitted from the interference objective lens Oct, but overlaps with each other because the optical path lengths differ when passing through the branched optical system 55. Interference occurs when

Here, when the phases of the reference light and the measurement light are in agreement, both are strengthened by interference. In this case, the amount of light received by the image sensor 58a (the amount of light received) is larger than that in the case where the phases do not match, so that the light receiving intensity, that is, the luminance value detected by each pixel is large.

On the other hand, when the phases of the reference light and the measurement light do not match, and particularly when they are deviated by half a wavelength, the two are weakened by interference. In this case, the light receiving amount of the image pickup device 58a is smaller than that when the phases match, so that the light receiving intensity, that is, the luminance value detected by each pixel is small.

Therefore, in the white light irradiation region through the interference objective lens Oct, the portion where the phase of the reference light and the measurement light are in phase is bright, and the portion where the phase is not, is darkened, and a bright and dark fringe pattern (interference fringe) is formed. Will be done. The image pickup unit 58 captures the interference fringes to capture an interference image that reflects the lightness and darkness.

Here, the phase difference between the reference light and the measurement light is derived from the difference in the optical path lengths of the two. Therefore, the contrast of the interference fringes and the arrangement of light and dark will change depending on the distance between the sample SP and the interference objective lens Oct.

Therefore, while changing the relative height position of the interference objective lens Oct with respect to the sample SP, the interference image is imaged at each height position, and how the interference fringes change between the interference images is analyzed. This makes it possible to measure the surface shape of the sample SP, such as the uneven shape.

In order to perform such measurement, the image pickup unit 58 inputs an electric signal indicating an interference image captured at each height position to the first measurement unit 8k described above. The first measuring unit 8k is configured to measure the surface shape of the sample SP based on a plurality of interference images corresponding to the input electric signals.

As described above, the white optical system 5 is an optical system capable of performing shape measurement by the white interferometry method. The distance between the light and dark of the interference fringes and the peak width of the light receiving intensity corresponding to each light and dark are narrowed to the order of nanometers as well as micrometer. Further, since these intervals and the magnitude of the peak width are derived from the difference in the optical path length, they are constant regardless of the magnification of the objective lens 54 or the like. Therefore, this method can measure on the order of several nanometers in height regardless of the performance of the objective lens 54 or the like, and is compared with the methods such as focus synthesis and laser confocal, in the height direction (Z). It is possible to make extremely good measurements with respect to the accuracy of the direction) and the resolution in the same direction.

(Laser optical system 6)
FIG. 3B is a schematic diagram illustrating the laser optical system of the observation unit 2. The laser optical system 6 can be configured in the same manner as the optical system conventionally used in a confocal microscope, and uses the laser light source 61 described later as a light source for measurement. The laser optical system 6 is configured to irradiate the sample SP with the laser light emitted from the laser light source 61 and condense the reflected light on the light receiving unit 66.

Specifically, the laser optical system 6 includes a laser light source 61, a second beam splitter 62, a laser light scanning unit 63, a first beam splitter 57, a first lens 56, a first half mirror 53, and an objective. It includes a lens 54 or an interference objective lens Oct, a second lens 64, a pinhole plate 65 on which a pinhole 65a is formed, and a light receiving portion 66 having a light receiving element 66a. Of these, the light receiving unit 66 is electrically connected to the second measuring unit 8l, which is one element of the unit control system 8. The laser optical system 6 is an example of the “cofocal optical system” in the present embodiment.

That is, the laser optical system 6 as a cofocal optical system is laid out so that when the laser light is focused on the surface of the sample SP, the reflected light of the laser light is focused in the vicinity of the pinhole 65a or the light receiving element 66a. (More specifically, the pinhole 65a is laid out at a position "conjugated" with the focal plane of the objective lens 54).

-Laser light source 61-
The laser light source 61 irradiates the sample SP mounted on the stage 23 with the laser beam through the same or different objective lens 54 as the interference objective lens Oct. That is, as illustrated in FIG. 3AA, laser light may be irradiated through the objective lens 54 and the branched optical system 55, or as illustrated in FIG. 3B, the branched optical system 55 is not interposed. , The laser beam may be irradiated only through the objective lens 54. In the following description, for the sake of simplicity, a case where the laser beam is irradiated without intervening the branched optical system 55 will be described. The laser light source 61 functions as a so-called point light source.

Further, as the laser light source 61, for example, a He-Ne gas laser, a semiconductor laser, or the like can be used. Further, instead of the laser light source 61, various light sources capable of generating a point light source can be used, and in that case, for example, a combination of a high-luminance lamp and a slit may be used.

The laser light output from the laser light source 61 passes through the second beam splitter 62 and reaches the laser light scanning unit 63, from the laser light scanning unit 63 to the first beam splitter 57, the first lens 56, and the first half. The sample SP is irradiated through the mirror 53 and the objective lens 54.

-Second beam splitter 62-
The second beam splitter 62 is arranged on the optical axis of the laser light source 61, and is located between the laser light source 61 and the laser light scanning unit 63. The second beam splitter 62 transmits the laser light output from the laser light source 61 and guides the laser light to the laser light scanning unit 63. The second beam splitter 62 also reflects the laser beam reflected by the sample SP and guides it to the light receiving unit 66. As the second beam splitter 62, a well-known beam splitter can be used.

-Laser light scanning unit 63-
The laser light scanning unit 63 can two-dimensionally scan the laser light emitted from the laser light source 61 on the surface of the sample SP. The term "two-dimensional scanning" as used herein refers to a two-dimensional operation of scanning the irradiation position of the laser beam on the surface of the sample SP.

As shown in FIG. 3B and the like, the laser light scanning unit 63 is configured as a so-called biaxial galvano scanner, and is arranged between the second beam splitter 62 and the first beam splitter 57.

The laser light scanning unit 63 can scan the laser light along at least one of a predetermined first direction and a second direction orthogonal to the one direction (both in the figure). Specifically, the laser light scanning unit 63 according to the present embodiment is scanned by the first scanner 63a for scanning the laser light incident from the second beam splitter 62 in the first direction and the first scanner 63a. It has a second scanner 63b that scans the laser beam in the second direction and reflects it toward the first beam splitter 57.

In the present embodiment, the "first direction" corresponds to the X direction defined as described above. Further, the "second direction" corresponds to the defined Y direction as well as the X direction. Of course, the definition is not limited to these, and the definitions of the first direction and the second direction can be arbitrarily changed.

Further, the laser light scanning unit 63 may be a unit configured to be able to scan the laser light two-dimensionally on the surface of the sample SP, and is not limited to the two-axis type galvano scanner as described above. For example, by adhering a piezoelectric element to an acoustic optical medium made of glass and inputting an electric signal to the piezoelectric element to generate ultrasonic waves, light that diffracts laser light passing through the acoustic optical medium and deflects the light. By using the acoustic element method (resonant method) or by rotating a disk having one or many rows of pinholes in a spiral shape, the light passing through the pinholes scans the surface of the sample SP two-dimensionally. The Nipo disk method configured as described above may be used.

The laser light that has passed through the laser light scanning unit 63 is reflected by the first beam splitter 57 and is applied to the sample SP via the first lens 56, the first half mirror 53, and the objective lens 54.

The laser beam irradiated to the sample SP is reflected by the sample SP and returns to the observation unit 2. Specifically, the reflected light of the laser beam from the sample SP passes through the objective lens 54, the first half mirror 53, the first lens 56, and the laser beam scanning unit 63, and then is reflected by the second beam splitter 62. 2 lenses up to 64.

Further, the laser light scanning unit 63 is operated by the scanning control unit 8a described above. Specifically, the laser light scanning unit 63 is electrically connected to the scanning control unit 8a, and is configured to operate by receiving an electric signal input from the scanning control unit 8a.

-Second lens 64-
The second lens 64 is arranged so as to be coaxial with the optical axis of the light receiving element 66a in the light receiving unit 66, and is located between the second beam splitter 62 and the pinhole plate 65. The second lens 64 collects the reflected light of the laser light from the second beam splitter 62 and causes it to enter the light receiving element 66a via the pinhole plate 65.

-Pinhole plate 65-
The pinhole plate 65 is a plate-shaped member arranged so as to be orthogonal to the optical axis of the light receiving element 66a, and has a pinhole 65a penetrating the plate-shaped member in the plate thickness direction. The pinhole plate 65 is arranged between the second lens 64 and the light receiving unit 66. The reflected light of the laser beam focused by the second lens 64 passes through the pinhole 65a and is incident on the light receiving element 66a.

As described above, the pinhole 65a is arranged at a position conjugate with the focal plane of the objective lens 54, and the laser optical system 6 can function as a cofocal optical system.

-Light receiving unit 66-
The light receiving unit 66 receives the reflected light of the laser light from the sample SP through the pinhole 65a in the confocal optical system (laser optical system 6), and generates a light receiving signal according to the light receiving intensity of the reflected light. do.

Specifically, the light receiving unit 66 has a light receiving element 66a for receiving the reflected light collected by the second lens 64. The light receiving element 66a photoelectrically converts the light incident through the pinhole 65a by the photoelectric surface formed on the incident window, and converts it into an electric signal corresponding to the light receiving intensity.

It is preferable that the light receiving element 66a has a higher frame rate than the image pickup element 58a. More preferably, the light receiving element 66a may have higher sensitivity than the image pickup element 58a. Specifically, the light receiving element 66a according to the present embodiment is configured by an optical sensor made of a PMT (PhotoMultiplier Tube), but is not limited to this configuration. As the light receiving element 66a, the image sensor 58a as described above can be used, or for example, a photodetector such as an HPD (Hybrid Photo Dector) or MPPC (Multi-Pixel Photon Counter) using an avalanche diode is used. You can also do it.

Then, the light receiving unit 66 generates an image corresponding to the optical image of the subject by associating the electric signal converted by the light receiving element 66a with the irradiation position of the laser beam, and transfers this to the unit control system 8 or the like. input. The image (laser image) generated by the light receiving unit 66 can be used for shape measurement by the laser confocal method or for observing the surface of the sample SP.

-About the basic principle of the laser confocal method-
As described above, the pinhole 65a is arranged at a position conjugate with the focal plane of the objective lens 54. Therefore, when the laser light emitted from the laser light source 61 focuses on the surface of the sample SP, the reflected light from the surface converges near the pinhole 65a and focuses on the light receiving element 66a. In this case (at the time of focusing), the amount of light received by the light receiving element 66a (the amount of light received) is significantly larger than that at the time of non-focusing, so that the light receiving intensity, that is, the luminance value detected by each pixel is increased.

On the other hand, when the laser beam is not focused on the sample SP (when out of focus), the reflected light from the surface of the sample SP is diffused without converging near the pinhole 65a, and is mostly diffused by the pinhole plate 65. Is shaded. In this case, the amount of light received by the light receiving element 66a (light receiving amount) is significantly smaller than that at the time of focusing, so that the light receiving intensity, that is, the luminance value detected by each pixel is reduced.

Therefore, in the scanning region of the laser beam realized by the scanning control unit 8a operating the laser light scanning unit 63, the focused portion on the surface of the sample SP is bright, while the other heights. It gets dark about. Therefore, it is possible to measure the surface shape of the sample SP (particularly, the information that characterizes the height of the sample SP) based on the brightness of the reflected light of the laser beam.

In order to perform such measurement, the light receiving unit 66 transmits an electric signal indicating the light receiving intensity of the reflected light of the laser light two-dimensionally scanned by the scanning control unit 8a and the laser light scanning unit 63 to the second measuring unit 8l described above. Enter in. The second measuring unit 8l measures the surface shape of the sample SP based on the light receiving intensity (specifically, the brightness and darkness of the reflected light) indicated by the input electric signal.

As described above, the laser optical system 6 is an optical system capable of performing shape measurement by the laser confocal method, and detects only substantially focused light, so that it is not as good as the white interference method. It is possible to provide brightness information having excellent accuracy in the height direction (Z direction) and resolution in the same direction as compared with other methods such as focus composition.

Further, since the shape measurement by the laser cofocal method is performed by two-dimensionally scanning the laser beam irradiated in a spot shape, it provides brightness information having superior resolution in the horizontal direction as compared with the white interferometry method. can do.

(Unit drive system 7)
FIG. 4 is a block diagram illustrating the configuration of the white interference microscope 1. The unit drive system 7 drives each part of the white interference microscope 1, changes the objective lens 54, adjusts the height position of the stage 23 with respect to the objective lens 54, and moves the stage 23 along the horizontal direction. It is configured as a system that can be moved. Each component of the unit drive system 7 is electrically connected to the unit control system 8, and operates by receiving an electric signal input from the unit control system 8.

Specifically, as illustrated in FIGS. 1, 2, 4, 4 and the like, the unit drive system 7 includes a Z-direction drive unit 71, a height position detection unit 72, an XY-direction drive unit 73, and an electric revolver. 74 and. The Z-direction drive unit 71 is an example of the “drive unit” in the present embodiment.

-Z direction drive unit 71-
The Z-direction drive unit 71 changes the height position of the stage 23 relative to the objective lens 54. Specifically, the Z-direction drive unit 71 has, for example, a stepping motor and a motion conversion mechanism that converts the rotational motion of the output shaft in the stepping motor into a linear motion in the vertical direction (Z direction). The Z-direction drive unit 71 is built in the head unit 22.

By rotating the stepping motor of the Z-direction drive unit 71, the electric revolver 74 and the objective lens 54 mounted on the electric revolver 74 move integrally along the Z direction.

For example, by moving the objective lens 54 in the Z direction while the stage 23 is fixed, the height position of the stage 23 with respect to the objective lens 54 can be changed relative to the objective lens 54 as a result. The stage 23 may be configured to move in the Z direction with the objective lens 54 fixed.

The Z-direction drive unit 71 determines the relative height position of the stage 23 with respect to the objective lens 54 (hereinafter, referred to as “relative distance” or simply referred to as “height position”). The pitch size can be adjusted to a minimum of about 1 nm.

-Height position detector 72-
The height position detection unit 72 can detect the relative distance between the objective lens 54 and the stage 23, and output an electric signal corresponding to the relative distance. This electric signal is input to the unit control system 8.

Specifically, the height position detection unit 72 can be configured by, for example, a linear scale (linear encoder) or the like. The height position detecting unit 72 can detect even if the change in the relative distance between the objective lens 54 and the stage 23 is about 1 nm.

In the present embodiment, the above-mentioned relative distance is changed by moving the objective lens 54 in the Z direction while the stage 23 is fixed. By detecting the amount of movement at that time on a linear scale, the relative height position of the stage 23 with respect to the objective lens 54 can be detected. Similarly, even when the stage 23 is moved in the Z direction with the objective lens 54 fixed, the height position can be detected in the same manner.

-XY direction drive unit 73-
The XY direction drive unit 73 is a mechanism for moving the stage 23 in the horizontal direction. That is, the stage 23 is separate from the stage support member 24 exemplified in FIG. 1, and is supported so as to be movable in the horizontal direction with respect to the stage support member 24.

Specifically, the XY direction drive unit 73 can be configured by an actuator such as a linear motor. This actuator can move the relative position of the stage 23 with respect to the stage support member 24 within a predetermined range along the X and Y directions.

-Electric Revolver 74-
The electric revolver 74 is configured as an electric scaling mechanism and rotates around a predetermined central axis Ar. The electric revolver 74 is configured to have a plurality of objective lenses 54 detachably attached so as to surround the central axis Ar. Here, the objective lens 54 that can be attached to the electric revolver 74 is integrated with the objective lens 54 equipped with the ring illumination 54a, the objective lens 54 without the ring illumination 54a attached, and the branch optical system 55. The objective lens 54 constituting the interference objective lens Oct and the like are included.

By rotating the electric revolver 74, one of the plurality of objective lenses 54 can be selected and confronted with the sample SP mounted on the stage 23. Information indicating which objective lens 54 is selected from the plurality of objective lenses 54 is stored in the storage device 82 of the unit control system 8.

By controlling the electric revolver 74, the magnifications of the white optical system 5 and the laser optical system 6 can be changed, and the interference objective lens Oct required for the white interferometry can be confronted with the sample SP. In addition to the electric revolver 74, or in place of the electric revolver 74, a single-lens type objective lens (not shown) composed of an electric zoom lens may be used.

The electric revolver 74 can be operated via a screen displayed on the display unit 41 (see FIGS. 16 to 18 described later), or can be operated via a switch provided on the observation unit 2 or the like. You can also.

(Other hardware configurations)
FIG. 8 is a perspective view illustrating the configuration of the adjusting member 25. The adjusting member 25 not only functions as the upper surface of the stage 23, but can also adjust the inclination of the upper surface thereof. This makes it possible to correct the inclination of the sample SP via the adjusting member 25.

Specifically, the adjusting member 25 according to the present embodiment can be operated so as to adjust the angle θ formed by the direction A4 orthogonal to the upper surface of the stage 23 and the direction along the optical axis A3 of the objective lens 54. ing. The angle θ is as shown in FIG.

The adjusting member 25 is configured separately from the stage 23. The adjusting member 25 has a mounting surface 25a that functions as an upper surface of the stage 23, a first adjusting knob 25b, and a second adjusting knob 25c.

More specifically, the adjusting member 25 has a cylindrical shape extending along the Z direction, and its top surface forms the previously described mounting surface 25a. Of the side surfaces of the adjusting member 25, the side surface arranged on the front side (Y direction side) of the stage 23 has a first adjusting knob 25b and a second adjusting knob 25c so as to project from the side surface. Is placed. Both the first and second adjustment knobs 25b and 25c project toward the front side, and are arranged in a state of being arranged side by side in the X direction with each other.

Here, the first adjustment knob 25b rotates the mounting surface 25a, which functions as the upper surface of the stage 23, around the first rotation axis (X-axis in the present embodiment) extending along the mounting surface 25a. .. That is, by operating the first adjustment knob 25b, the mounting surface 25a rotates about the X axis.

Further, the first adjustment knob 25b is configured to be operated by turning it. The operation amount of the first adjustment knob 25b includes the rotation direction and the rotation amount. For example, by changing the rotation direction of the first adjustment knob 25b, the mounting surface 25a rotates in the clockwise direction about the X axis or in the counterclockwise direction. The amount of rotation of the first adjustment knob 25b corresponds to the magnitude of the rotation angle of the mounting surface 25a.

On the other hand, the second adjustment knob 25c extends the previously described mounting surface 25a along the mounting surface 25a and is around a second rotation axis (Y axis in the present embodiment) orthogonal to the first rotation axis. Rotate to. That is, by operating the second adjustment knob 25c, the mounting surface 25a rotates about the Y axis.

Further, the second adjustment knob 25c is configured to be operated by turning it. The operation amount of the second adjustment knob 25c includes the rotation direction and the rotation amount. For example, by changing the rotation direction of the second adjustment knob 25c, the mounting surface 25a rotates in the clockwise direction about the Y axis or in the counterclockwise direction. The amount of rotation of the second adjustment knob 25c corresponds to the magnitude of the rotation angle of the mounting surface 25a.

The relationship between the rotation direction and the amount of rotation of the first and second adjustment knobs 25b and 25c and the size of the rotation direction and the rotation angle of the mounting surface 25a is stored in advance by the storage device 82 described later. It has become like.

(Unit control system 8)
FIG. 5 is a block diagram illustrating the configuration of the unit control system 8. The unit control system 8 outputs control signals to each part of the white optical system 5, the laser optical system 6 and the unit drive system 7 in the observation unit 2, controls their operations, and receives detection signals from each part. The surface shape of the sample SP is measured.

The unit control system 8 is also electrically connected to the operation terminal 4 in addition to the observation unit 2, and displays the measurement result of the surface shape on the display unit 41, while the keyboard 42, the mouse 43, and the like are displayed. It is also possible to generate a control signal to be input to each part of the observation unit 2 based on the operation input.

In the example shown in FIG. 4, the unit control system 8 is provided in the observation unit 2, but the configuration is not limited to the observation unit 2. The unit control system 8 may be provided in the external unit 3 or the operation terminal 4.

Specifically, the unit control system 8 according to the present embodiment includes a processing device 81 composed of a CPU, a system LSI, a DSP, and the like, a storage device 82 composed of a volatile memory, a non-volatile memory, and the like, an input / output bus 83, and the like. Has. Further, the unit control system 8 may be realized by a logic circuit or may be realized by executing software. The storage device 82 is an example of the “storage unit” in the present embodiment.

Specifically, as illustrated in FIG. 4, the unit control system 8 includes at least a white light source 51, a ring illumination 54a, an image pickup element 58a, a laser light source 61, a laser light scanning unit 63, a light receiving element 66a, and a Z-direction drive. The unit 71, the height position detection unit 72, the XY direction drive unit 73, and the electric revolver 74 are electrically connected. The unit control system 8 controls the white light source 51, the ring illumination 54a, the laser light source 61, the laser light scanning unit 63, the Z direction drive unit 71, the XY direction drive unit 73, and the electric revolver 74. Further, the output signals of the image pickup element 58a, the light receiving element 66a, and the height position detection unit 72 are input to the unit control system 8.

Specifically, as illustrated in FIG. 5, the unit control system 8 according to the present embodiment has a scanning control unit 8a, a drive control unit 8b, a display control unit 8c, and a mode switching unit as main components. 8d, focusing calculation unit 8e, focus adjustment unit 8f, brightness adjustment unit 8g, tilt calculation unit 8h, operation amount conversion unit 8i, measurement range setting unit 8j, first measurement unit 8k, and so on. It has a second measuring unit 8l and.

-Scanning control unit 8a-
The scanning control unit 8a is electrically connected to the laser light scanning unit 63 as described above, and controls its operation. The laser light scanning unit 63 can scan two-dimensionally or one-dimensionally within the scanning range defined on the surface of the sample SP according to the control signal input from the scanning control unit 8a. The setting of the scanning range can be appropriately changed according to the function performed by the white interference microscope 1.

-Drive control unit 8b-
The drive control unit 8b controls each unit of the unit drive system 7. Specifically, the drive control unit 8b changes the height position of the stage 23 by controlling the Z-direction drive unit 71, or changes the horizontal position of the stage 23 by controlling the XY-direction drive unit 73. The objective lens 54 can be switched by controlling the electric revolver 74.

-Display control unit 8c-
The display control unit 8c is electrically connected to the display unit 41 of the operation terminal 4 and controls the display mode on the display unit 41. Specifically, the display control unit 8c according to the present embodiment displays the measurement results by the first measurement unit 8k, the second measurement unit 8l, etc., displays the camera image generated by the image pickup unit 58, and the like. , Various interfaces can be displayed.

Further, the display control unit 8c according to the present embodiment can also display the operation amount (operation amount of the adjusting member 25) calculated by the operation amount conversion unit 8i. This point will be described later.

-Mode switching unit 8d-
As described above, the white interference microscope 1 mainly performs observation of a sample SP using a laser beam or white light as a light source, measurement of a sample SP using a laser cofocal method or a white interference method, and the like. can do.

The mode switching unit 8d can properly use these functions based on the user's operation input via the keyboard 42 and the mouse 43. Specifically, the mode switching unit 8d according to the present embodiment has, for example, a first mode for measuring the surface shape of the sample SP and a second mode for measuring the film thickness of the sample SP based on the operation input of the user. One mode can be selected from the mode group including (details omitted) and the third mode for observing the sample SP, and this can be executed. As will be described later, the user's operation input is performed via the interface displayed on the display unit 41. Of the three operation modes, the second mode and the third mode are not essential. The white interference microscope 1 may be configured so that at least the first mode can be executed.

-Focus calculation unit 8e-
The focusing calculation unit 8e uses the laser confocal method by the laser optical system 6 to bring the focus of the objective lens 54 onto the surface of the sample SP (in other words, "autofocus" by the laser confocal method. Execute). The focus adjusted by the laser cofocal method is used for both the measurement of the surface shape by the laser cofocal method and the measurement of the surface shape by the white interferometry.

That is, the white interference microscope 1 according to the present embodiment is configured to focus by using the laser confocal method even when the surface shape of the sample SP is measured by using the white interferometry.

When focusing, an interference objective lens Oct (first objective lens) for white interference may be used as the objective lens 54, or an objective for non-white interference different from the interference objective lens Occ. The lens 54 may be used.

Specifically, the focusing calculation unit 8e according to the present embodiment is the objective lens 54 based on the light receiving signal generated by the light receiving unit 66 of the laser optical system 6 at each height position of the stage 23 or the objective lens 54. The in-focus position where the focal point of is aligned with the surface of the sample SP is calculated. The focusing calculation unit 8e is an example of the “calculation unit” in the present embodiment.

Here, "each height position of the stage 23 or the objective lens 54" refers to the relative height position of the stage 23 with respect to the objective lens 54, which can be detected by the height position detecting unit 72. This height position can be a distance between the tip surface of the objective lens 54 (the tip surface in the Z direction) and the upper surface of the stage 23 (specifically, the mounting surface 25a of the adjusting member 25). However, the distance is not limited to this, and the distance between the predetermined portion of the objective lens 54 and the predetermined portion of the stage 23 in the Z direction can be set. As mentioned above, the height position is also referred to as the "Z position".

Further, in the following description, "distance between height positions (Z pitch)" refers to white optics such as autofocus, brightness adjustment, setting of height range (measurement range) at the time of measurement, measurement of surface shape, etc. It refers to the interval between height positions (moving interval of the objective lens 54 or stage 23 in the Z direction) when the interference image is generated in the system 5 and when the laser optical system 6 receives the laser beam.

Further, in the following description, "moving the Z position upward" means moving the objective lens 54 upward with respect to the stage 23 and the sample SP, or moving the objective lens 54 upward with respect to the objective lens 54, or the stage 23 and the sample SP with respect to the objective lens 54. That is, moving the stage 23 and the sample SP downward, that is, separating the objective lens 54 from the stage 23 in the Z direction.

Similarly, "moving the Z position downward" means moving the objective lens 54 downward with respect to the stage 23 and the sample SP, or moving the stage 23 and the sample SP upward with respect to the objective lens 54. That is, to bring the stage 23 and the sample SP closer to each other in the Z direction.

Specifically, the focusing calculation unit 8e irradiates the laser beam at each height position while changing the height position via the drive control unit 8b to acquire a light receiving signal. As described above, when the laser beam is focused on the surface of the sample SP, the amount of light received by the light receiving element 66a (light receiving amount) becomes significantly larger than that at the time of out-of-focus, and the light receiving intensity is relatively large. growing.

Therefore, as illustrated in FIG. 6B, the focusing calculation unit 8e monitors a curve (hereinafter, referred to as “Z—I curve”) indicating a change in the light receiving intensity with respect to the height position (Z position). Search for the height position where the light receiving intensity reaches its peak. Such a searched height position is determined as the in-focus position Zp. The focusing position Zp is temporarily or continuously stored in the storage device 82 and input to the focus adjusting unit 8f.

Further, the height position used for searching the in-focus position Zp is discrete. The distance (Z pitch) between the height positions is set according to the full width at half maximum of the Z—I curve. Specifically, when the half width of the Z-I curve is assumed to be narrow, the Z pitch is set narrower than when it is assumed to be wide. Here, the full width at half maximum of the ZI curve becomes narrower when the numerical aperture of the objective lens 54 is large, as compared with when it is small. The numerical aperture of the objective lens 54 generally increases as the lens magnification increases.

Based on the above findings, the focusing calculation unit 8e according to the present embodiment is configured to set the Z pitch defined as described above to be narrower as the magnification of the objective lens 54 increases. Specifically, the focusing calculation unit 8e narrows the height position when adjusting the height position of the stage or the objective lens 54 by operating the Z-direction drive unit 71 via the drive control unit 8b. The light receiving signal is acquired at each height position by changing the Z pitch. In this way, the Z pitch at which the received light signal is acquired can be changed according to the magnification of the objective lens 54.

As a result of further studies on the Z pitch, the inventors of the present application have newly found that the magnitude of the Z pitch is adjusted according to the function performed by the white interference microscope 1.

Specifically, in the present embodiment, the distance (Z pitch) between the height positions of the stage 23 is set by the second measuring unit 8l together with the laser when the focusing calculation unit 8e calculates the focusing position Zp. It is set to be wider than when the surface shape of the sample SP is measured by using the focal method.

That is, when the focusing calculation unit 8e searches for the focusing position Zp, the measurement accuracy of the light receiving intensity is not required as much as when the second measuring unit 8l measures the surface shape. Therefore, as illustrated in FIG. 6D, when the focusing position Zp is searched (when the focusing calculation unit 8e searches for the focusing position Zp), the surface shape is measured (first measurement). It is permissible to set the Z pitch coarser than when the unit 8k or the second measuring unit 8l measures the surface shape of the sample SP). Hereinafter, the Z pitch used when the in-focus position Zp is searched for may be referred to as a "first pitch".

For example, in FIG. 6D, the black-filled plot refers to the height position used when the in-focus position Zp is searched (during autofocus), and the cross-shaped plot refers to the height position used when measuring the surface shape. Point to. As shown in FIG. 6D, the first pitch according to the present embodiment can be set coarser (wider) than the fourth pitch described later, which is the Z pitch used when the surface shape is measured. ..

Further, the search for the in-focus position Zp can be executed by fitting the light receiving intensity measured at each height position by a parabola, a Gaussian function, or the like. The details of fitting are omitted.

Further, as described above, when searching for the in-focus position Zp, the laser beam is emitted at each height position. The scanning range of the laser beam at that time can be set to a range suitable for searching for the in-focus position Zp.

Specifically, the scanning control unit 8a scans the laser light when the focusing calculation unit 8e calculates the focusing position Zp by operating the laser light scanning unit 63 at each height position of the stage 23. At that time, the scanning range of the laser beam is larger when the focusing calculation unit 8e calculates the focusing position Zp than when the second measuring unit 8l measures the surface shape based on the laser confocal method. It can be set narrowly.

Specifically, the scanning range of the laser beam is the first and second directions when the focusing calculation unit 8e calculates the focusing position Zp, as compared with the case where the second measuring unit 8l measures the surface shape. The dimension in one of them can be set short.

More specifically, in the present embodiment, when the focusing calculation unit 8e calculates the focusing position Zp, the scanning control unit 8a scans the laser beam in a line along the X direction as the first direction. In this case, the scanning range is set so that the dimension in the Y direction as the second direction is shortened. Here, the laser beam may be scanned over several sequences arranged parallel to each other.

Alternatively, instead of implementing the above configuration, the laser light scan interval (distance between the laser beam irradiation positions Ps) is the second measurement unit when the focusing calculation unit 8e calculates the focusing position Zp. It is also possible to set 8 liters to be wider than when measuring the surface shape (thinning scan). As a result, autofocus can be performed at high speed.

-Focus adjustment unit 8f-
The focus adjustment unit 8f calculates the height position by the focusing calculation unit 8e by operating the Z-direction drive unit 71 via the drive control unit 8b to adjust the height position of the stage 23 or the objective lens 54. It matches the focused position Zp.

By adjusting the height position of the focus adjusting unit 8f, the focus of the objective lens 54 can be adjusted on the sample SP, and a state suitable for the measurement of the sample SP is realized.

The height position is adjusted by the focus adjusting unit 8f by observing with a laser image or a camera image and by the brightness adjusting unit 8g described later, in addition to measuring the surface shape by the first measuring unit 8k or the second measuring unit 8l. It is executed when adjusting the brightness, calculating the inclination by the inclination calculation unit 8h, setting the height range by the measurement range setting unit 8j, and the like. As a result, various processes can be started from the focused state, and the speed can be increased.

-Brightness adjustment unit 8g-
Since the processing by the focusing calculation unit 8e and the focusing unit 8f is a processing using a laser beam, the setting of white light such as an appropriate exposure time is unknown at the time when the focusing unit 8f focuses. .. In order to smoothly combine the autofocus by the laser confocal method and the shape measurement by the white interferometry, it is necessary to set the white light after the autofocus.

Therefore, the brightness adjusting unit 8g adjusts the brightness of the white light emitted from the white light source 51 in a state where the height position is adjusted by the focus adjusting unit 8f. The adjustment target here includes, in addition to the control parameters of the white light source 51 itself, parameters that characterize the image pickup device 58a for receiving white light. For example, the brightness adjusting unit 8g can adjust at least one of the exposure time and the gain of the image pickup device 58a in order to adjust the brightness of the white light.

Specifically, the brightness adjusting unit 8g according to the present embodiment sets the focusing position Zp calculated by the focusing calculation unit 8e as the starting position. The brightness adjusting unit 8g changes the height position of the stage 23 or the objective lens 54 at a predetermined pitch (hereinafter, also referred to as “second pitch”), and irradiates white light from the white light source 51 at each height position. .. The size of the second pitch at that time does not depend on the numerical aperture of the objective lens 54 or the like, and is determined based on the wavelength of white light.

For example, in FIG. 6C, the plot filled with black indicates the height position used when the brightness adjusting unit 8g adjusts the brightness of the white light (during the brightness adjustment). As shown in FIG. 6C, the height position used at the time of brightness adjustment can be set within a predetermined range including the in-focus position Zp.

The brightness adjusting unit 8g adjusts the brightness of the white light based on a plurality of interference images generated in a state where the height positions are different. Specifically, the brightness adjusting unit 8g selects an interference image including relatively bright pixels (particularly, the brightest pixel in the present embodiment) among the interference images generated via the imaging unit 58. The interference image can be selected, for example, by comparing the light receiving intensities used for generating each interference image for each pixel.

The brightness adjusting unit 8g adjusts the brightness of the white light source 51 within a range in which each pixel in the selected interference image (brightest interference image) becomes unsaturated. Specifically, the brightness adjusting unit 8g adjusts the exposure time and gain of the image pickup device 58a so that the interference image becomes as bright as possible within the range where each pixel in the selected interference image is below a predetermined upper limit value. , Determine the optimal parameters. The determined parameters are input to the storage device 82 and the like, and are temporarily or continuously stored.

-Inclination calculation unit 8h-
The inclination calculation unit 8h calculates the inclination of the stage 23. Specifically, the tilt calculation unit 8h according to the present embodiment captures a plurality of interference images in which the relative height positions of the stages 23 are different from each other by controlling the Z-direction drive unit 71 and the image pickup unit 58. At the same time, the inclination of the sample SP with respect to the optical axis A3 of the objective lens 54 is calculated based on the plurality of interference images.

For convenience of explanation, in the following description, it is assumed that the surface of the sample SP and the upper surface (mounting surface 25a) of the stage 23 are parallel to each other (see FIGS. 3A and 3B). In this case, the tilt angle of the sample SP coincides with the angle θ formed by the direction A4 orthogonal to the upper surface of the stage 23 and the direction along the optical axis A3 of the objective lens 54.

Specifically, in the tilt calculation unit 8h, after the focusing position Zp is calculated by the focusing calculation unit 8e, the relative height position of the stage 23 is adjusted by the focus adjustment unit 8f (the height position is). In the state adjusted to the in-focus position Zp), the calculation of the inclination based on the interference image is started.

The inclination calculated by the inclination calculation unit 8h may be performed prior to the processing by the brightness adjusting unit 8g, or may be performed after the processing. Further, apart from the autofocus performed prior to the processing by the brightness adjusting unit 8g, the autofocus may be performed independently immediately before the calculation of the inclination. Similarly, the timing for calculating the inclination may be before or after the measurement of the height range by the measurement range setting unit 8j.

First, the tilt calculation unit 8h moves the stage 23 or the objective lens 54 upward or downward at a predetermined Z pitch (fifth pitch) from the start position set with reference to the in-focus position Zp. The inclination calculation unit 8h irradiates white light from the white light source 51 at each height position thus moved. As a result, a plurality of interference images having different height positions are generated.

The tilt calculation unit 8h according to the present embodiment is configured to set the in-focus position Zp as the start position, but is not limited to this configuration. For example, the height position displaced upward or downward from the in-focus position Zp is set as the start position, and the stage 23 or the objective lens 54 is moved downward or upward at the fifth pitch from the start position to obtain the height position. May be changed.

Further, the moving range of the stage 23 or the objective lens 54 may be defined as a position where the interference fringes disappear from the interference image. For example, the tilt calculation unit 8h determines the presence or absence of interference fringes based on the brightness in the interference image, and if interference fringes are present, the stage 23 or the objective lens 54 is continuously moved upward or downward, while the interference fringes are present. If it does not exist, the movement of the stage 23 or the objective lens 54 may be stopped.

Further, in the present embodiment, the distance (fifth pitch) between the height positions when the relative height position of the stage 23 is changed is determined when the inclination calculation unit 8h calculates the inclination of the sample SP. The first measuring unit 8k as a measuring unit is set wider than when measuring the surface shape of the sample SP.

That is, when the inclination calculation unit 8h calculates the inclination, an interference image having excellent image quality is not required as much as when the first measurement unit 8k measures the surface shape. Therefore, when the inclination of the sample SP is calculated, it is permissible to set the Z pitch coarser than when the surface shape is measured. Therefore, the fifth pitch can be roughly set in the same manner as the first pitch.

Then, the inclination calculation unit 8h measures the surface shape of the sample SP based on a plurality of interference images having different height positions, and based on the surface shape, the tilt calculation unit 8h of the sample SP with respect to the optical axis A3 of the objective lens 54. Calculate the slope. As a method for measuring the surface shape, the white interferometry can be used in the same manner as in the first measuring unit 8k. This will be described in detail when the first measuring unit 8k is described.

Specifically, the inclination calculation unit 8h acquires height information of the sample SP (data indicating the height of the sample SP for each pixel of the interference image, as described later) based on the surface shape of the sample SP. Then, the slope of the sample SP is calculated based on the amount of change in the height information in the X direction and the Y direction.

Further, the size of the region (the size of the interference image) imaged by the imaging unit 58 in the surface region of the sample SP to form an interference image is measured when the inclination calculation unit 8h calculates the inclination of the sample SP. The first measuring unit 8k as a unit is set smaller than when measuring the surface shape of the sample SP.

That is, when the inclination calculation unit 8h calculates the inclination, the interference image captured in a wider range is not required as much as when the first measurement unit 8k measures the surface shape. Therefore, when the inclination of the sample SP is calculated, it is permissible to make the interference image relatively smaller than when the surface shape is measured.

Further, as shown in the modification described later, the inclination calculation unit 8h can also calculate the inclination of the sample SP based on an index other than the surface shape of the sample SP.

The inclination calculated by the inclination calculation unit 8h is acquired in a state where the inclination angle θx around the X axis and the inclination angle θy around the Y axis are combined. When the information indicating this inclination is called the first inclination data (θx, θy), the first inclination data is output to the manipulated variable conversion unit 8i, and at the same time, is temporarily stored in the storage device 82 as needed. Or it is designed to be memorized over time.

-Operation amount conversion unit 8i-
The operation amount conversion unit 8i calculates the operation amount of the adjusting member 25 for correcting the inclination based on the inclination calculated by the inclination calculation unit 8h. The "operation amount" referred to here refers to the operation amount of each of the first adjustment knob 25b and the second adjustment knob 25c.

For example, in order to correct the inclination of the sample SP so as to cancel it, the adjusting member 25 is operated to rotate the mounting surface 25a around the X axis by an angle −θx, and at the same time, rotate the mounting surface 25a by an angle −θx, and at the same time, rotate the mounting surface 25a around the Y axis by an angle −θx. It is required to rotate by −θy.

Therefore, the operation amount conversion unit 8i converts the first inclination data input from the inclination calculation unit 8h, and the second inclination data (−θx, −θy) indicating the correction amount (rotation angle) to be applied to the sample SP. ) Is generated. The conversion by the manipulated variable conversion unit 8i is executed by inverting the sign of the first tilt data.

Here, the user cannot accurately grasp the operation amount of the adjusting member 25 simply by generating the second inclination data. In order to improve usability, it is necessary to replace information such as the rotation angle with information that can be intuitively understood by the user.

Therefore, the storage device 82 of the unit control system 8 stores the correspondence between the inclination calculated by the inclination calculation unit 8h and the operation amount of the adjusting member 25. Specifically, the storage device 82 stores in advance the correspondence between the second tilt data generated by converting the first tilt data and the operation amount of the adjusting member 25. This correspondence relationship is determined according to the use, design, etc. of the adjusting member 25, and is a relationship that can be determined in advance.

The operation amount conversion unit 8i calculates the operation amount of the adjusting member 25 based on the storage contents in the storage device 82. Here, the operation amount conversion unit 8i determines the operation amount corresponding to the second inclination data by referring to the correspondence relationship. The operation amount determined by the operation amount conversion unit 8i is composed of the rotation direction and the rotation amount of the first adjustment knob 25b and the rotation direction and the rotation amount of the second adjustment knob 25c.

The operation amount calculated by the operation amount conversion unit 8i is input to the display control unit 8c described above. The display control unit 8c controls the display unit 41 so as to display the operation amount calculated by the operation amount conversion unit 8i.

-Measurement range setting unit 8j-
FIG. 7 is obtained by dividing the height range setting procedure using the in-focus position Zp and the start position set with the in-focus position Zp as a reference, and the height range thus set. It is a figure which simplifies the relationship with the 4th pitch.

The surface shape can be measured by changing the height position of the stage 23 or the objective lens 54 around the in-focus position Zp. The range of height positions used at this time (hereinafter referred to as "height range") can be set by using either the white interferometry method or the laser confocal method.

The white interference microscope 1 according to the present embodiment includes a measurement range setting unit 8j for setting a height range using a white interferometry method. In addition to or in place of the measurement range setting unit 8j, a second measurement range setting unit capable of setting the height range by using the laser confocal method may be provided.

Here, as shown in FIG. 7, the height range set by the measurement range setting unit 8j is set to include at least the in-focus position Zp. That is, the height range is set as a range partitioned by an upper limit position set to be equal to or higher than the focusing position Zp and a lower limit position set to be equal to or lower than the focusing position Zp.

In the present embodiment, the measurement range setting unit 8j sets the upper limit position after setting the lower limit position, but is not limited to the setting. The lower limit position may be set after setting the upper limit position.

Further, the measurement range setting unit 8j according to the present embodiment divides the interval between the upper limit position and the lower limit position at equal intervals in a state where the upper limit position and the lower limit position are set, so that the first measurement unit 8k or When the second measuring unit 8l measures the surface shape of the sample SP, each height position of the stage 23 is set.

Specifically, in the measurement range setting unit 8j, after the focusing position Zp is calculated by the focusing calculation unit 8e, the relative height position of the stage 23 is adjusted by the focus adjustment unit 8f (height position). Is adjusted to the in-focus position Zp), and the setting of the height range based on the interference image captured by the image pickup unit 58 is started.

Here, the measurement range setting unit 8j generates an interference image via the image pickup unit 58 in a state where the height position of the stage 23 or the objective lens 54 is changed, and from the interference image generated at each height position. The peak position of the interference fringe is calculated, and it is determined whether or not the number of pixels for which the calculation of the peak position is successful exceeds a predetermined first threshold value in the screen. Then, the first measurement range setting unit 8i sets the height range as a range exceeding the first threshold value (particularly, a range along the Z direction).

That is, even if interference fringes are found in the interference image, if the peak position of the interference fringes occupies a very small part of the screen, it is considered inconvenient to perform the measurement by the white interferometry. .. Therefore, by making a setting based on the number of pixels that have succeeded in calculating the peak position of the interference fringe, the height range can be set more appropriately.

The number of pixels constituting the interference image may be reduced when setting the height range as compared with when measuring the surface shape. This makes it possible to set the height range at high speed. Further, although the first threshold value as an index of determination is basically stored in the storage device 82, it can be appropriately changed based on an operation input from the outside or the like.

Further, as shown in FIG. 7, when the measurement range setting unit 8j changes the height position of the stage 23 or the objective lens 54 when setting the height range, the focusing position calculated by the focusing calculation unit 8e A start position is set with reference to Zp, and the stage 23 or the objective lens 54 is moved upward or downward at a predetermined Z pitch (third pitch) from the start position.

As shown in the central view of FIG. 7, the measurement range setting unit 8j according to the present embodiment is configured to set the in-focus position Zp at the start position. However, the present disclosure is not limited to such configurations. For example, the height position displaced upward or downward along the Z direction from the in-focus position Zp is set as the start position (in this case, the start position ≠ the in-focus position Zp), and the stage 23 or the objective lens is set from the start position. The height position may be changed by moving the 54 downward or upward at the third pitch.

Further, the distance between the height positions of the stage 23 is wider when the measurement range setting unit 8j sets the height range than when the first measurement unit 8k measures the surface shape of the sample SP. Can be set to be. That is, as shown in FIG. 7, when the height range is set (when the measurement range setting unit 8j sets the height range), when the surface shape is measured (the first measurement unit 8k or It is permissible to set the Z pitch (third pitch) coarser than when the second measuring unit 8l measures the surface shape of the sample SP). The third pitch, which is the Z pitch used when setting the height range, can be roughly set in the same manner as the first pitch.

For example, in FIG. 6E, the white circle-shaped plot refers to the height position used when setting the height range, and the cross-shaped plot refers to the height position used when measuring the surface shape as described above. As shown in FIG. 6E, the third pitch according to the present embodiment is coarser than the Z pitch (fourth pitch) used when the surface shape is measured, similar to the first pitch described above. Can be set widely).

The height range set by the measurement range setting unit 8j and each height position obtained by dividing the height range are input to the first measurement unit 8k or the second measurement unit 8l.

-First measuring unit 8k-
FIG. 6A is a diagram illustrating the relationship between the relative position of the sample SP in the Z direction and the light receiving intensity due to the interference light of white light in one pixel. The first measuring unit 8k measures the surface shape of the sample SP by using the white interferometry as described above. Specifically, the first measuring unit 8k is the surface of the sample SP based on a plurality of interference images captured by the imaging unit 58 at a plurality of height positions defined within the height range including the focusing position Zp. Measure the shape.

The surface shape of the sample SP can also be referred to as a three-dimensional shape or texture of the sample SP. This also applies to the surface shape measured by the second measuring unit 8l.

Specifically, the first measurement unit 8k acquires an interference image (first image data) capable of grasping the surface shape of the sample SP by using the principle of white interference. This first image data is acquired for each image pickup range by the image pickup unit 58. This imaging range is determined according to the magnification of the objective lens 54 and the like.

First, white light is irradiated within the imaging range with the height position of the stage 23 and the sample SP fixed. This white light is branched into the reference light reflected by the reference mirror 55b and the measurement light reflected by the sample SP in the branch optical system 55 provided in the interference objective lens Oct. Of these, the reflected light of the measurement light is irradiated to the image pickup unit 58 together with the reference light, and is received by the image pickup element 58a. The measurement light and the reference light received by the image pickup device 58a overlap each other to generate an interference image. At this time, the light receiving intensity corresponding to the interference image is acquired, and the light receiving intensity is acquired for each pixel of the interference image.

Next, the Z-direction drive unit 71 changes the height position of the interference objective lens Oct at a predetermined fourth pitch. As a result, the height position of the interference objective lens Occ is different from the previous state, and the sample SP is irradiated with white light in a state where the height position is different from the previous time. As a result, interference images with different height positions are generated. The light receiving intensity is monitored for each pixel of the interference image. This is repeated for each height position.

At this time, the moving range of the interference objective lens Oct in the Z direction is equal to the height range set by the measurement range setting unit 8j, and the fourth pitch, which is the change width of the height position, has the height range at equal intervals. Equal to a split (see Figure 7). As described with reference to FIGS. 6D and 6E, the fourth pitch is the Z pitch used at the time of autofocus, the first pitch, and the third pitch, which is the Z pitch used at the time of setting the height range. It can be set finer (narrower) than both.

The number of pixels of the interference image is determined by the number of pixels arranged on the light receiving surface of the image pickup element 58a, but it is not necessary to match the numbers of both. From the viewpoint of the presence / absence of digital zoom, reduction of data capacity, and the like, a part of the pixels constituting the image pickup device 58a may be used to generate an interference image.

Further, when an interference image captured over a wider range than the angle of view of the image pickup unit 58 is desired, the drive control unit 8b controls the XY direction drive unit 73 to move the stage 23 in the X direction or the Y direction. .. Then, white light is irradiated to an imaging range different from the previous one, and an interference image corresponding to the imaging range is captured. This process is executed at each height position, and the obtained interference images are spliced together to generate an integrated first image data.

Here, as illustrated in FIG. 6A, when the surface of the sample SP coincides with the focal point of the interference objective lens Oct (when it is in the in-focus position Zp), the measurement light reflected by the surface and the reference mirror 55b The reflected reference light is incident on the image pickup device 58a in a state of intensifying each other. As a result, the light receiving intensity in the image pickup device 58a is maximized.

On the other hand, when the surface of the sample SP does not match the focal point of the interference objective lens Occ (when it is in the out-of-focus position), the light-receiving intensity in the image sensor 58a gradually increases and decreases as it moves away from the in-focus position Zp. Decays to. As a result, the bright and dark patterns showing the interference fringes disappear from the interference image. In other words, the interference fringes appear in the interference image only in the vicinity of the in-focus position Zp.

As described above, when the surface of the sample SP coincides with the focal point of the interference objective lens Oct, the light receiving intensity distribution of the image pickup device 58a reaches its peak (see the intensity Ip in FIG. 6A). The light receiving intensity distribution also converges to the value due to the reference light as a flare component as it moves away from the in-focus position (see intensity Ib in FIG. 6A). Based on the interference image as the second image data, a curve (ZI curve) showing the change in the light receiving intensity in the Z direction can be obtained for each pixel.

Information (height information) indicating the distance between the surface of the sample SP and the interference objective lens Oct by acquiring data indicating the peak position (position in the Z direction, Z coordinate) of the light receiving intensity for each pixel. Can be acquired for each pixel. Based on this height information, the surface shape of the sample SP can be measured.

Here, "when the focal points do not match" means that the luminance difference between adjacent pixels disappears (the luminance ratio approaches 1), and conversely, "when the focal points match" means that the luminance ratio approaches 1. In other words, the luminance difference (luminance ratio) between adjacent pixels is larger than when it is out of focus.

In the actual measurement, the interference objective lens Oct is moved in the Z direction, and the contrast change, phase change, etc. of the interference fringes appearing at that time are analyzed to acquire data indicating the unevenness of the sample SP surface. can do.

The first image data generated by the first measurement unit 8k is displayed on the display unit 41 by the display control unit 8c. The user can grasp the surface shape of the sample SP by visually observing the displayed first image data.

-Second measuring unit 8l-
FIG. 6B is a diagram illustrating the relationship between the relative position of the sample SP in the Z direction and the light receiving intensity due to the reflected light of the laser light in one pixel. The second measuring unit 8l measures the surface shape of the sample SP by using the laser confocal method as described above. Specifically, the second measuring unit 8l measures the surface shape of the sample SP based on the received intensity of the reflected light of the laser light scanned by the scanning control unit 8a controlling the laser light scanning unit 63.

Specifically, the second measuring unit 8l acquires a laser image (second image data) capable of grasping the surface shape of the sample SP by using the principle of laser confocal. This second image data is acquired for each unit area on the sample SP. This unit area is determined according to the magnification of the objective lens 54 and the like. The second image data for each unit area is generated based on the pixel data described later.

First, with the height position of the stage 23 and thus the sample SP fixed, the laser light scanning unit 63 scans the laser light in the X direction within the unit region. When the scanning in the X direction is completed, the irradiation position of the laser beam is moved by the laser beam scanning unit 63 in the Y direction by a certain interval. After that movement, the laser beam is scanned in the X direction. By repeating the scanning of the laser beam in the X direction and the movement in the Y direction in the unit region, the scanning in the X direction and the Y direction of the unit region is completed.

At that time, the reflected light of the laser beam scanned two-dimensionally is applied to the light receiving unit 66 via the confocal optical system (laser optical system 6) composed of pinholes 65a and the like, and is received by the light receiving element 66a. Ru.

Next, the height position of the objective lens 54 is changed by the Z-direction drive unit 71. As a result, the height position of the objective lens 54 is different from the previous state, and the unit region is scanned in the X direction and the Y direction in a state where the height position is different from the previous time. After that, the height position of the objective lens 54 is moved at a predetermined pitch (fourth pitch), and scanning in the X direction and the Y direction of the unit region is performed. This is repeated for each unit area. As described above, the fourth pitch is set more finely (narrowly) than the Z pitch (first pitch) used at the time of autofocus and the Z pitch (third pitch) used at the time of setting the height range. Can be done (see FIGS. 6D-6E).

The number of pixels in the X direction of the second image data is determined by the scanning speed of the laser light in the X direction by the laser light scanning unit 63 and the sampling period. The number of samplings in one scan in the X direction (one scanning line) is the number of pixels in the X direction. Further, the number of pixels in the Y direction is determined by the amount of change in the laser light in the Y direction by the laser light scanning unit 63 at each end of scanning in the X direction. The number of scanning lines in the Y direction is the number of pixels in the Y direction.

When the scanning in the X direction and the Y direction of the unit region is completed, the drive control unit 8b controls the XY direction drive unit 73 to move the stage 23 in the X direction or the Y direction. Then, in another unit area different from the previous one, scanning in the X direction and the Y direction is performed in the same manner. This is repeated to scan a plurality of unit regions in the X direction and the Y direction. By concatenating the obtained second image data of each unit area, it is possible to obtain an integrated second image data.

Here, as described with reference to FIG. 6B, when the surface of the sample SP coincides with the focal point of the objective lens 54 (when it is in the in-focus position Zp), the reflected light reflected by the surface is a pinhole. It is incident on the light receiving element 66a in a converged state near 65a. As a result, the light receiving intensity in the light receiving element 66a is maximized.

On the other hand, when the surface of the sample SP does not match the focal point of the objective lens 54 (when it is in the out-of-focus position), the reflected light reflected by the surface is received in a state where most of the reflected light is shielded by the pinhole 65a. It is incident on the element 66a. As a result, the light receiving intensity of the light receiving element 66a is significantly smaller than that of the focusing position Zp.

As described above, when the surface of the sample SP coincides with the focal point of the objective lens 54, a steep peak appears in the light receiving intensity distribution of the light receiving element 66a (see the intensity Ip in FIG. 6B). Based on the first image data in each unit region, a curve (ZI curve) showing a change in light receiving intensity in the Z direction can be obtained for each pixel.

By acquiring data indicating the peak position of the light receiving intensity (position in the Z direction, Z coordinate) for each pixel, information (height information) indicating the distance between the surface of the sample SP and the objective lens 54 can be obtained. It will be possible to acquire each pixel. By arranging the height information according to the arrangement of each pixel, the second image data capable of grasping the surface shape of the sample SP is generated.

The second image data generated by the second measurement unit 8l is displayed on the display unit 41 by the display control unit 8c. The user can grasp the surface shape of the sample SP by visually observing the displayed second image data.

<Specific example of measurement procedure>
-Basic flow-
FIG. 9 is a flowchart illustrating the measurement procedure of the sample SP by the white interference microscope 1. First, when the white interference microscope 1 is activated, in step S1, the operation content (operation mode) of the white interference microscope 1 and the principle of use used during the operation are selected.

Here, the operation modes are, as described above, a first mode for measuring the surface shape of the sample SP, a second mode for measuring the film thickness of the sample SP (details omitted), and for observing the sample SP. Corresponds to the third mode of. The user selects the operation content to be executed by the white interference microscope 1 by performing a click operation or the like on the screen displayed on the display unit 41. The mode switching unit 8d displays a screen corresponding to the operation content selected by the user on the display unit 41.

As will be described later, the screen displayed on the display unit 41 conveys various information to the user such as laser images, interference images, surface shape measurement results, etc., while accepting operation inputs of the keyboard 42, mouse 43, etc. Functions as (User Interface: UI). This UI will be described later.

Further, the usage principle that can be selected in step S1 includes at least a white interferometry method and a laser confocal method. In addition, the user may be allowed to select another principle such as focus stacking.

In the following step S2, the user operates the screen described above to select the parameter setting mode used for each operation mode. The white interference microscope 1 according to the present embodiment has an automatic setting mode (also referred to as "easy setting") in which the unit control system 8 automatically sets parameters as a parameter setting mode, and the user himself / herself operates the keyboard 42 and the like. You can execute the manual setting mode (also called "basic setting") to set the parameters. The mode switching unit 8d displays information corresponding to the setting mode selected by the user on the display unit 41.

In the following step S3, the objective lens 54 having the lowest magnification among the plurality of objective lenses 54 mounted on the electric revolver 74 is switched. This switching may be automatically performed by the drive control unit 8b as soon as the setting mode is selected, or may be manually performed by the user.

In the following step S4, the sample SP is placed on the stage 23.

The order of steps S1 to S4 is not limited to the above-mentioned flow. For example, the order of step S1 and step S2 may be exchanged, or step S4 may be executed at a timing earlier than step S1. The flow shown in FIG. 9 is merely an example.

In the following step S5, the measurement point on the sample SP is searched, and the measurement point is focused on the measurement point. This focus may be manually performed by the user, or may be automatically performed by the focus adjustment unit 8f or the like.

In the following step S6, the objective lens 54 used for the measurement is selected. This selection is manually made by the user via the UI displayed on the display unit 41.

Here, when the white interferometry method is selected in step S1, the interferometric objective lens Oct, which is a combination of the objective lens 54 and the branch optical system 55, is selected as the objective lens 54. However, the present disclosure is not limited to such configurations. As described above, even when the measurement is performed by the white interferometry, the autofocus using the laser confocal method is executed prior to the measurement. Therefore, even when the white interferometry method is selected, the normal objective lens 54 without the branched optical system 55 may be temporarily selected.

On the other hand, when the laser confocal method is selected in step S1, a normal objective lens 54 without the branch optical system 55 is selected as the objective lens 54 in step S6.

When the objective lens 54 is selected in step S6, the drive control unit 8b operates the electric revolver 74 to confront the tip surface of the selected objective lens 54 with respect to the measurement point on the sample SP.

In the following step S7, the unit control system 8 determines whether or not the white interferometry method is selected as the principle of use. When it is determined that the white interferometry method is selected (step S7: YES), the control process proceeds to step S8, and the inclination calculation unit 8h and the operation amount conversion unit 8i execute the process related to the inclination correction of the sample SP. do. Step S8 is a process including a plurality of steps, the details of which will be described later.

On the other hand, when it is determined that the laser confocal method is selected (step S7: NO), the control process skips step S8 and proceeds to step S9. Even when the laser confocal method is selected, the inclination may be adjusted by using the inclination calculation unit 8h or the like.

In the following step S9, various parameters are set, the surface shape of the sample SP is measured, and the like are executed based on the selections made in steps S1 and S2. Hereinafter, only the case where the first mode (operation mode for measuring the surface shape of the sample SP) is selected will be described.

-Specific example of user interface-
16 and 17 are diagrams showing specific examples of the UI displayed on the display unit 41.

Specifically, FIG. 16 is a diagram illustrating a display screen at the time of simple setting of various parameters. Further, FIG. 17 is a diagram illustrating a display screen at the time of measurement by the white interferometry.

Here, the first display area R1 is an area for partially enlarging and displaying the surface (observation surface) of the sample SP, and the second display area R2 is a bird's-eye view of the entire surface of the sample SP. This is an area for display.

Further, the rectangular frame Rg displayed in the second display area R2 is a frame for showing the area enlarged and displayed as the first display area R1. In the example shown in FIG. 16 and the like, a part of the marking pattern Pt (particularly, the corner portion of the rectangular portion) is displayed in the first display area R1.

Here, the button B2 is a UI for selecting a means for acquiring an image displayed on the screen. By clicking this button B2, the camera image captured by the imaging unit 58 can be displayed in the first and second display areas R1 and R2 (camera), or the laser beam can be scanned on the surface of the sample SP. The laser image generated in the above can be displayed (laser) in the first and second display areas R1 and R2. In the illustrated example, the former "camera" is displayed.

Further, around the button B2, there is a UI for allowing the user to select whether to use the white light emitted from the white light source 51 or the light emitted from the ring illumination 54a described above when generating the camera image. It may be displayed, or a UI for adjusting the brightness of each light source may be displayed. In the illustrated example, the former white light source 51 is in the selected state (indicated as "coaxial" in the figure).

When the white interference microscope 1 is activated and the first mode is selected as the operation mode, the screen illustrated in FIG. 16 is displayed. Here, the tabs T1 to T3 are UIs for switching the operation mode of the white interference microscope 1.

For example, clicking the tab T1 selects the third mode (operation mode for observing the sample SP), clicking the tab T2 selects the first mode, and clicking the tab T3 selects the second mode (sample). The operation mode for measuring the film thickness of the SP) is selected. In both FIGS. 16 and 17, the first mode is selected.

Further, the button B3 is a UI for selecting a setting mode of various parameters. In the illustrated example, one of the above-mentioned automatic setting mode (simple setting) and manual setting mode (basic setting) can be selected by clicking the button B3. Note that FIG. 16 illustrates a state in which the automatic setting mode is selected.

Further, the button B1 is a UI for selecting the usage principle used for the measurement. Button B1 is displayed both when the automatic setting mode is selected and when the manual setting mode is selected (not shown). By clicking the button B1, one of the laser confocal method and the white interferometry can be selected. When other principles such as focus stacking are configured to be executable, a button for selecting another principle is additionally displayed around the button B1. In the illustrated example, the white interferometry is selected.

Further, the button B4 is a UI for selecting the objective lens 54 facing the sample SP from the plurality of objective lenses 54. In the illustrated example, five objective lenses 54 suitable for the laser confocal method and one interference objective lens Oct suitable for the white interferometry method are displayed side by side. The objective lens 54 is selected by clicking and operating any one of them. In the illustrated example, the interference objective lens Oct is in the selected state.

In addition, when the automatic setting mode is selected, the button B5 for guiding how to adjust the field of view and the button B6 for guiding the tilt adjustment are displayed on the screen, and the manual setting mode is selected. If so, the button group B8 for manually adjusting various parameters is displayed on the screen.

The process according to step S8 in FIG. 9 (process related to the tilt correction of the sample SP) may be configured to be executed only when the button B6 is pressed, and whether or not the button B6 is pressed. It may be configured to start automatically regardless of.

Further, when the measurement start button Bs arranged at the lower right of the screens of FIGS. 16 and 17 is pressed, the measurement of the surface shape of the sample SP is started. The timing at which the measurement start button Bs is pressed will be described later.

-Specific examples of various processes-
Hereinafter, the processing related to the setting of various parameters and the processing related to the measurement based on the set parameters will be described in order. FIG. 10 is a flowchart illustrating a procedure for setting parameters using a white interference microscope. Steps S11 to S18 shown in FIG. 10 exemplify the details of the process shown in step S9 of FIG.

First, in step S11 of FIG. 10, it is determined whether or not the automatic setting mode is selected as the parameter setting mode. This determination is performed, for example, by the mode switching unit 8d.

If it is determined that the automatic setting mode is selected (step S11: YES), the control process proceeds from step S11 to step S12. In this case, as soon as the measurement start button Bs illustrated in FIG. 16 or the like is pressed, the unit control system 8 continuously executes automatic setting of various parameters and measurement based on the automatically set parameters.

On the other hand, when it is determined that the automatic setting mode is not selected (step S11: NO), the control process proceeds from step S11 to step S17. In this case, in step S17, the button group for basic setting is operated by the user, and various parameters are manually set. Subsequently, when the measurement start button Bs is pressed in step S18, the surface shape measurement using the white interferometry or the laser confocal method is executed and returns in step S16.

Returning to step S12, when the measurement start button Bs is pressed in the same step, the control process proceeds from step S12 to step S13. In step S13, autofocus (automatic focusing) using the laser confocal method is executed regardless of the principle used for measuring the surface shape.

FIG. 10 is a diagram illustrating a specific process performed in step S13 of FIG. That is, FIG. 10 is a flowchart illustrating the procedure for executing autofocus by the white interference microscope 1.

First, in step S101 of FIG. 10, the gain of the light receiving element 66a is temporarily increased. This makes it possible to more reliably capture the reflected light corresponding to the in-focus position Zp when the sample SP is irradiated with the laser beam. In the case of autofocus using the laser confocal method, it is permissible to significantly increase the gain of the light receiving element 66a even when the focus position is out of Zp.

In the subsequent step S102, the drive control unit 8b controls the Z-direction drive unit 71, so that the relative height position (Z position) of the stage 23 with respect to the objective lens 54 changes at a predetermined first pitch. Then, the unit control system 8 controls the laser light source 61 to irradiate the sample SP with the laser beam at each Z position. As described above, this first pitch is set coarser than the Z pitch (fourth pitch) used in the measurement by the laser confocal method (see FIG. 6D).

In the subsequent step S103, the scanning control unit 8a controls the laser light scanning unit 63 to linearly scan the laser light for several rows along the X direction. That is, while scanning is performed over substantially the entire area in the X direction, only a few pixels are scanned in the Y direction. The reflected light of the laser beam scanned in this way is directed to the light receiving element 66a via the laser optical system 6 (cofocal optical system) including the pinhole 65a and the like. As described above, when the focal point of the objective lens 54 coincides with the surface of the sample SP, it reaches the light receiving element 66a, but when it does not coincide, it is blocked by the pinhole 65a.

In the following step S104, the storage device 82 stores the light receiving intensity for each Z position.

In the following step S105, the focusing calculation unit 8e searches for the Z position (focusing position Zp) at which the light receiving intensity is maximum from among the plurality of Z positions. As described above, the search for the in-focus position Zp can be performed by fitting the light receiving intensity stored in association with each Z position using a parabola, a Gaussian function, or the like.

In the following step S106, the focus adjusting unit 8f controls the Z direction driving unit 71 to adjust the height position of the stage 23 or the objective lens 54 so as to realize the focusing position Zp searched in the step S105. do. As a result, the focusing of the objective lens 54 is completed (autofocus is completed).

By the way, in the case of a known configuration, it is assumed that the autofocus using the laser confocal method is performed by using a normal objective lens 54. However, as described above, the white interference microscope 1 according to the present embodiment can perform autofocus with the interference objective lens Oct selected instead of the normal objective lens 54. Between the in-focus position Zp obtained by using the normal objective lens 54 and the in-focus position Zp obtained by using the interference objective lens Oct, the optical characteristics (specifically, chromatic aberration) of an optical component such as a lens. And, there is a deviation caused by the combination of the wavelength of the light passing through each optical component.

In other words, the deviation of the in-focus position Zp does not change with each measurement, such as the laser characteristics, the layout of the scanning region, and the unevenness of the sample SP, but only depends on the optical characteristics of the lens. Therefore, the deviation of the in-focus position Zp can be measured in advance and stored in the storage device 82 or the like. The white interference microscope 1 according to the present embodiment corrects the deviation of the in-focus position Zp based on the stored contents of the storage device 82 when the in-focus position Zp is measured by using the interference objective lens Oct. It is configured.

Specifically, in step S107 following step S106, the unit control system 8 determines whether or not the interference objective lens Oct has been used when the focusing calculation unit 8e calculates the focusing position Zp. Then, when it is determined that the interference objective lens Oct has been used (step S107: YES), the control process proceeds to step S108. In this case, the in-focus position Zp is corrected by the amount of the deviation stored in the storage device 82. On the other hand, when it is determined that the interference objective lens Oct is not used (step S107: NO), the control process skips step S108 and returns. Even when the same objective lens 54 as in the case of autofocus by the laser confocal method is used without using the interference objective lens Oct when measuring the shape by the white interference method, the deviation of the focal position due to the difference in wavelength is corrected. There is a need. In this case, the process may proceed to step S108 without determining the presence / absence of the specification of the interference objective lens Oct in step SP107.

When the flow shown in FIG. 11 is completed, the control process proceeds from step S13 to step S14 in FIG. In step S14, the brightness of the white light source 51 is automatically adjusted as a preparation for shape measurement by the white interferometry method. Step S14 is executed by the brightness adjusting unit 8g described above by using the white interferometry method. When measuring the surface shape using the laser confocal method, step S14 can be skipped. The adjustment by the brightness adjusting unit 8g may be executed by adjusting the control parameter of the white light source 51 itself, or may be executed by adjusting the exposure time of the imaging unit 58 as a camera.

In the following step S15, the height range used when measuring the surface shape is set by using the white interferometry. Step S15 is executed by the measurement range setting unit j described above by using the white interferometry method or the laser confocal method.

When the height range is set, the control process proceeds from step S15 to step S16. FIG. 12 is a diagram illustrating a specific process performed in step S16 of FIG. That is, FIG. 12 is a flowchart illustrating the procedure for measuring the surface shape by the white interference microscope 1.

First, in step S501 of FIG. 12, the drive control unit 8b controls the Z-direction drive unit 71, so that the measurement range setting unit 8j sets the relative height position (Z position) of the stage 23 with respect to the objective lens 54. Move within the set height range.

In the following step S502, the unit control system 8 determines whether or not the white interferometry method is selected as the principle of use. Here, if it is determined that the white interferometry is selected (step S502: YES), the control process proceeds from step S502 to step S503. In this case, the measurement using the white interferometry is performed.

On the other hand, when it is determined in step S502 that the white interferometry is not selected and, for example, the laser confocal method is selected (step S502: NO), the control process proceeds from step S502 to step S508. In this case, in the illustrated example, the measurement using the laser confocal method is performed.

When the process proceeds from step S502 to step S503, the first measuring unit 8k changes the Z position at the above-mentioned fourth pitch by operating the Z-direction drive unit 71 via the drive control unit 8b. Then, the first measuring unit 8k irradiates white light from the white light source 51 at each Z position moved at each fourth pitch.

In the following step S504, interference light formed by interfering the reflected light of the measurement light with the reference light is irradiated onto the image pickup element 58a, and a signal indicating the light reception intensity for each pixel is input to the first measurement unit 8k. ..

In the following step S505, an interference image is generated for each Z position based on the signal input in step S504. In this case, as shown in FIG. 17, interference fringes S1, S2, and S3 appear in the interference image. In the subsequent step S506, the first measuring unit 8k measures the surface shape of the sample SP based on the plurality of interference images having different Z positions.

On the other hand, when the process proceeds from step S502 to step S508, the second measuring unit 8l changes the Z position at the fourth pitch by operating the Z-direction drive unit 71 via the drive control unit 8b. Then, the second measuring unit 8l irradiates the laser light from the laser light source 61 at each Z position moved at each fourth pitch.

In the subsequent step S509, the laser light is two-dimensionally scanned for each unit region as described above, and the reflected light of the laser light is received through the pinhole 65a forming the cofocal optical system. As a result, the reflected light of the laser beam is irradiated onto the light receiving element 66a, and a signal indicating the light receiving intensity for each pixel is input to the second measuring unit 8l.

In the following step S510, a laser image is generated for each Z position based on the signal input in step S509. In the subsequent step S511, the second measuring unit 8l measures the surface shape of the sample SP based on the plurality of laser images having different Z positions.

Finally, in step S506 or step S507 following step S511, the display control unit 8c controls the display unit 41, so that the surface shape formed by the first measurement unit 8k or the second measurement unit 8l on the display unit 41. The measurement result of is displayed.

-Specific example of tilt correction-
Hereinafter, the description of step S8 in FIG. 9 will be returned, and the processing performed in the same step will be described in detail. FIG. 13 is a diagram illustrating a specific process performed in step S8 of FIG. 9, and is a flowchart illustrating a procedure for correcting the inclination of the sample SP. Further, FIGS. 18, 19 and 20 are user interfaces for guiding the tilt correction.

First, in step S21 of FIG. 13, a measurement point on the sample SP is set, and the focus is roughly focused on the measurement point (rough focusing). This focusing may be performed manually by the user, or may be automatically performed by the focus adjusting unit 8f or the like.

In the following step S22, the user presses the button B6 (UI displayed as "How to adjust the tilt") illustrated in FIGS. 16 and 17.

When the button B6 is pressed, the first dialog D1 as illustrated in FIG. 18 is displayed on the display unit 41. In this dialog D1, a start button Ba displayed as "start" and a stop button Bb displayed as "stop" are displayed. When the start button Ba is pressed, the process related to the tilt correction (tilt adjustment) proceeds, and when the stop button Bb is pressed, the process is interrupted.

In the following step S23, the dialog D1 is confirmed by the user, and the user presses the start button Ba.

In the following step S24, autofocus using the laser confocal is executed. Specifically, in step S24, the unit control system 8 sequentially executes steps S101 to S108 in FIG. When the autofocus is completed, the control process proceeds from step S24 to step S25.

In the following step S25, the inclination calculation unit 8h measures the inclination of the sample SP (determines the inclination state). This measurement is performed based on the interference image generated by irradiating the sample SP with white light via the interference objective lens Oct.

FIG. 14 is a diagram illustrating a specific process performed in step S25 of FIG. That is, FIG. 14 is a flowchart illustrating a procedure for measuring the inclination of the sample.

First, in step S601 of FIG. 14, the tilt calculation unit 8h controls the Z-direction drive unit 71 via the drive control unit 8b to determine the relative height position (Z position) of the stage 23 with respect to the objective lens 54. Move to the specified start position. This start position may be the focusing position Zp or another height position set based on the focusing position Zp. Here, the case where the starting position is the focusing position Zp will be illustrated.

In the following step S602, the tilt calculation unit 8h controls the Z-direction drive unit 71 via the drive control unit 8b, so that the Z position of the objective lens 54 is at a predetermined fifth pitch from the start position moved in step S601. Is moved upward (moved so that the distance between the stage 23 and the objective lens 54 is widened).

In step S603 following step S602, the tilt calculation unit 8h executes the generation of the interference image by the white optical system 5 at each Z position moved at each fifth pitch. As described above, this fifth pitch is set coarser than the Z pitch (fourth pitch) used when the first measuring unit 8k measures the surface shape of the sample SP. Further, the interference image generated in step S603 is smaller in size than the interference image generated when the surface shape is measured.

As described above, when the interference fringes are not present in the interference image, it is considered that the Z position is out of focus and is inappropriate for measuring the surface shape by the white interferometry. In other words, by generating the interference image within the range where the interference fringes are present in the interference image, the surface shape of the sample SP and the inclination of the surface can be efficiently calculated.

Specifically, in step S604, the inclination calculation unit 8h determines whether or not the interference fringes are present in the interference image generated in step S603, and if this determination is YES (when no interference fringes are present). The process proceeds to step S605, while the process returns to step S602 in the case of NO (when an interference fringe is present). In this way, the tilt calculation unit 8h repeats the change of the Z position and the generation of the interference image at the changed Z position until the interference fringes disappear from the interference image.

In the following step S605, the tilt calculation unit 8h controls the Z-direction drive unit 71 via the drive control unit 8b to return the Z position to the start position (focus position Zp).

In the following step S606, the inclination calculation unit 8h controls the Z-direction drive unit 71 via the drive control unit 8b so as to move in the direction opposite to the step S602 from the start position moved in step S605. , The Z position of the objective lens 54 is moved downward at a predetermined fifth pitch (moved so that the distance between the stage 23 and the objective lens 54 is narrowed).

In the subsequent step S607, the tilt calculation unit 8h executes the generation of the interference image by the white optical system 5 at each Z position moved at each fifth pitch, as in the step S603. The interference image generated in step S607 is smaller in size than the interference image generated when the surface shape is measured.

In the following step S608, the inclination calculation unit 8h determines whether or not the interference fringes are present in the interference image generated in step S607, and if this determination is YES (when no interference fringes are present), the step. While proceeding to S609, if NO (when interference fringes are present), the process returns to step S606.

In the following step S609, the inclination calculation unit 8h calculates height information of various parts on the surface of the sample SP based on the interference images generated in step S603 and step S607. This calculation is executed by analyzing the light receiving intensity acquired for each pixel of the interference image, and can be performed, for example, by monitoring the change in the light receiving intensity when the Z position is changed.

In the following step S610, the inclination calculation unit 8h calculates the inclination state (inclination) of the sample SP surface based on the high information calculated in step S609. This calculation can be performed based on the amount of change in height information when the position in the X direction is changed or the position in the Y direction is changed.

When the process shown in step S610 is completed, the control process proceeds from step S25 to step S26 in FIG. In this step S26, the operation amount conversion unit 8i calculates the adjustment amount of the adjustment member 25 based on the inclination calculated in step S25.

Specifically, in step S26, the manipulated variable conversion unit 8i indicates the correction amount (rotation angle) to be applied to the sample SP from the first inclination data (θx, θy) indicating the inclination of the surface of the sample SP. The second slope data (−θx, −θy) is calculated. The operation amount conversion unit 8i compares the second inclination data thus calculated with the correspondence relationship stored in the storage device 82, so that the operation amount of the adjustment member 25 (specifically, the first adjustment) The rotation amount and rotation direction of the knob 25b and the rotation amount and rotation direction of the second adjustment knob 25c) are calculated. The operation amount calculated by the operation amount conversion unit 8i is input to the display control unit 8c.

In the following step S27, the display control unit 8c displays the inclination (tilt state) calculated in step S25 and the operation amount calculated in step S26 on the display unit 41.

Specifically, in this step S27, a second dialog D2 as illustrated in FIG. 19 is displayed. In this dialog D2, "It is tilted 3 degrees toward you" is displayed in parentheses. This display corresponds to the inclination angle around the X axis in the inclination calculated by the inclination calculation unit 8h.

Dialog D2 also displays "Turn the X knob of the tilt stage 15 scales to the right" for the "tilt stage" as the adjustment member 25 and the "X knob" as the first adjustment knob 25b. Has been done. This display corresponds to the operation amount related to the first adjustment knob 25b among the operation amounts calculated by the operation amount conversion unit 8i.

The image I1 corresponding to the adjusting member 25 is also displayed in the dialog D2. In this image I1, in addition to the image showing the adjusting member 25, an image showing visually the amount of operation to be performed on the first adjusting knob 25b is displayed. As an image showing the operation amount, the image I1 has an arrow indicating the rotation direction of the first adjustment knob 25b (an arrow extending in the clockwise direction) and a numerical value indicating the rotation amount (a numerical value described as "15"). And are displayed. Since the arrow indicating the rotation direction is arranged near the first adjustment knob 25b, the user intuitively knows which of the first adjustment knob 25b and the second adjustment knob 25c is the first adjustment knob 25b. You can know.

The dialog D2 also displays a progress button Bc displayed as "Next" and a return button Bd displayed as "Back". When the progress button Bc is pressed, the display content of the dialog D2 is switched, and the transition to the third dialog D3 exemplified in FIG. 20 is performed. On the other hand, when the return button Bc is pressed, the display content of the dialog D2 is switched, and the process returns to the first dialog D1 exemplified in FIG.

In step S28 following step S27, the user operates the first adjustment knob 25b according to the second dialog D2 and presses the progress button Bc. By operating the first adjustment knob 25b, the inclination of the sample SP due to the rotation around the X axis is corrected. The user continues to correct the tilt according to the third dialog D3 that is subsequently displayed.

Specifically, in the third dialog D3, "tilted to the left by 5 degrees" is displayed in parentheses. This display corresponds to the inclination angle around the Y axis among the inclinations calculated by the inclination calculation unit 8h.

Dialog D3 also displays "Turn the X knob of the tilt stage 25 scales to the left" for the "tilt stage" as the adjustment member 25 and the "Y knob" as the second adjustment knob 25c. Has been done. This display corresponds to the operation amount related to the second adjustment knob 25c among the operation amounts calculated by the operation amount conversion unit 8i.

The image I2 corresponding to the adjusting member 25 is also displayed in the dialog D3. In this image I2, in addition to the image showing the adjusting member 25, an image showing visually the amount of operation to be performed on the second adjusting knob 25c is displayed. As an image showing the amount of operation, in the image I2, an arrow indicating the rotation direction of the second adjustment knob 25c (an arrow extending in the counterclockwise direction) and a numerical value indicating the amount of rotation (a numerical value described as "25") are shown. ) And is displayed. Since the arrow indicating the rotation direction is arranged near the second adjustment knob 25c, the user intuitively knows which of the first adjustment knob 25b and the second adjustment knob 25c is the second adjustment knob 25c. You can know.

The dialog D3 also displays a completion button Be displaying "Complete". When the completion button Be is pressed, the third dialog D3 disappears from the screen, and the process related to the tilt correction is completed.

In step S28, the user operates the second adjustment knob 25c according to the third dialog D3. By operating the second adjustment knob 25c, the inclination of the sample SP due to the rotation around the Y axis is corrected. After that, when the completion button Be is pressed, the flow shown in FIG. 13 ends, and the process proceeds from step S8 to step S9 in FIG. Subsequent processing is as described above.

<About semi-automation of tilt correction>
As described above, the white interference microscope 1 according to the present embodiment includes an adjusting member 25 that can be operated from the outside in order to correct the inclination of the sample SP, as illustrated in FIG. As illustrated in FIG. 13, the white interference microscope 1 should also be applied to the adjusting member 25 so that the inclination of the sample SP is calculated by using the interference image and the inclination is corrected. Calculate the operation amount. The operation amount calculated in this way is displayed on the display unit 41 by the display control unit 8c. The user can operate the adjusting member 25 to correct the inclination by visually recognizing the operation amount displayed on the display unit 41.

According to the present embodiment, the white interference microscope 1 automatically calculates the inclination of the sample SP and the operation amount corresponding to the inclination. As a result, it is possible to realize a correction having excellent work efficiency, accuracy, and the like, as in the case of automatic correction.

On the other hand, by making the user visually recognize the calculated operation amount, the user himself / herself will perform the operation on the adjusting member 25. As a result, it is possible to realize an inexpensive and compact configuration as compared with a well-known electric tilting stage.

In this way, the inventors of the present application have newly created a configuration that realizes "semi-automatic" correction by combining the elements of automatic correction and manual correction. This makes it possible to achieve both the advantages of the configuration in which the inclination of the stage 23 is manually corrected and the advantages of the configuration in which the tilt of the stage 23 is automatically corrected. According to this embodiment, the tilt of the sample SP can be easily corrected without using the electric tilt stage.

Further, when calculating the inclination by using the white interferometry, the pitch in the height direction is set to a relatively wide fifth pitch as compared with the case of measuring the surface shape (step S602 in FIG. 14). Etc.). By setting in this way, the inclination of the sample SP can be calculated at a higher speed.

Further, as illustrated in step S603 of FIG. 14, when the inclination is calculated by using the white interferometry, the size of the interference image is set to be relatively small as compared with the case where the surface shape is measured. do. By setting in this way, the inclination of the sample SP can be calculated at a higher speed.

Further, as illustrated in step S609 of FIG. 14, the inclination calculation unit 8h measures the surface shape via the first measurement unit 8k or the like, and calculates the inclination based on the measurement result. By diverting the basic function of the white interference microscope 1 in this way, it becomes possible to appropriately calculate the inclination without unnecessarily increasing the number of parts.

Further, by storing the operation amount corresponding to the calculation result of the inclination calculation unit 8h in the storage device 82 or the like in advance, the operation amount can be calculated more quickly.

Further, as described with reference to FIG. 8, by changing the posture of the mounting surface 25a that functions as the upper surface of the stage 23, the inclination of the sample SP mounted on the mounting surface 25a can be corrected. become able to. Here, since the inclination of the sample SP is a two-degree-of-freedom system, the inclination of the sample SP can be reliably corrected by providing the first adjustment knob 25b and the second adjustment knob 25c.

<< Other Embodiments >>
-About the deformation example related to tilt adjustment-
In the above embodiment, the surface shape of the sample SP is measured by using the white interferometry method to calculate the inclination of the sample SP, but the present disclosure is not limited to such a configuration.

Specifically, the tilt calculation unit 8h determines the morphological change of the interference fringes in each interference image based on a plurality of interference images generated at different Z positions, and the objective lens 54 is based on the determination result. It is also possible to calculate the inclination of the sample SP with respect to the optical axis A3 of.

When this method is used, an interference image generated by interfering the measurement light with the reference light is used as in the embodiment, but the embodiment is a specific example of the interference image. The usage will be different.

In this case, the inclination calculation unit 8h utilizes the arrangement of the interference fringes, the orientation of the interference fringes (the direction in which the interference fringes extend), and the number of the interference fringes as an example of the form of the interference fringes. The tilt calculation unit 8h also compares the interference images generated at different Z positions to determine how the position of each interference fringe changes, especially in which direction each interference light moves. The slope of the sample SP is calculated based on the determination result.

FIG. 15 is a diagram showing another example of the process performed in step S25 of FIG. That is, FIG. 15 is a flowchart showing another example of the procedure for measuring the inclination of the sample SP.

First, in step S701 of FIG. 15, the tilt calculation unit 8h controls the Z-direction drive unit 71 via the drive control unit 8b to determine the relative height position (Z position) of the stage 23 with respect to the objective lens 54. Move to the specified start position. This start position may be the focusing position Zp or another height position set based on the focusing position Zp. Here, the case where the starting position is the focusing position Zp will be illustrated.

In the following step S702, the tilt calculation unit 8h executes the generation of the interference image by the white optical system 5. The interference image generated in step S702 has a smaller size than the interference image generated when measuring the surface shape, similarly to the interference image generated in step S603 of FIG.

In the following step S703, the inclination calculation unit 8h confirms the arrangement, orientation, and number of interference fringes in the interference image. This confirmation result is temporarily stored in the storage device 82.

In the following step S704, the tilt calculation unit 8h controls the Z-direction drive unit 71 via the drive control unit 8b, so that the Z position of the objective lens 54 is at a predetermined fifth pitch from the start position moved in step S701. Is moved upward or downward (moved so that the distance between the stage 23 and the objective lens 54 is widened or narrowed).

In the following step S705, the tilt calculation unit 8h executes the generation of the interference image by the white optical system 5. The interference image generated in step S705 has a smaller size than the interference image generated when measuring the surface shape, similarly to the interference image generated in step S702 described above.

In the following step S706, the tilt calculation unit 8h compares the interference image generated in step S705 with the interference image generated in step S702 before changing the Z position. In the following step S707, the inclination calculation unit 8h confirms the moving direction of the interference fringes due to the change in the Z position.

In the following step S708, the inclination calculation unit 8h determines the inclination state (sample) of the sample SP surface based on the orientation and number of the interference fringes confirmed in step S703 and the movement direction of the interference fringes confirmed in step S707. Calculate the slope of SP).

When the process according to step S708 is completed, the control process proceeds from step S25 to step S26 in FIG. Subsequent processing is as described above.

In this way, the inclination calculation unit 8h can also calculate the inclination of the sample SP based on the moving direction of the striped pattern and the like. According to this configuration, the inclination can be calculated more quickly without calculating the surface shape of the sample SP.

Further, the configurations of various flowcharts such as FIG. 9 can be changed as appropriate. For example, the order of step S1 and step S2 in FIG. 9 may be exchanged, the order of step S2 and step S3 may be exchanged, or the order of step S14 and step S15 in FIG. 10 may be exchanged.

-About the modification related to the setting of the height range-
Further, in the above embodiment, the measurement range setting unit 8j is configured to set the height range shown in FIG. 7 by using white interference, but the present disclosure is not limited to such a configuration. The measurement range setting unit 8j can set the height range by using the laser confocal method instead of using the white interference or in addition to using the white interference.

In that case, the measurement range setting unit 8j generates a laser image via the light receiving unit 66 in a state where the height position of the stage 23 or the objective lens 54 is changed. Next, the measurement range setting unit 8i generates pixel data corresponding to the light receiving signal generated by the light receiving unit 66 for each of the plurality of pixels in the laser image generated at each height position. Then, the measurement range setting unit 8j sets the height range as a range in which all the values of the plurality of pixel data are below a predetermined second threshold value.

Here, the pixel data is a digital signal obtained by A / D converting the output signal (light receiving signal) of the light receiving unit 66. Therefore, the value of the pixel data increases as the gain of the light receiving element 66a increases, and decreases as the gain of the light receiving element 66a decreases. Further, the pixel data is output from an A / D converter (not shown).

Further, the second threshold value can be, for example, an upper limit value of the output range of the A / D converter (hereinafter, also referred to as an “output upper limit value”). When the peak value of the pixel data is smaller than the output upper limit value, the pixel data is not saturated with the output upper limit value. Therefore, the peak value of the pixel data can be easily detected by performing the determination based on the output upper limit value as the second threshold value.

In this case, the distance between the height positions of the stage 23 is larger when the measurement range setting unit 8j sets the height range than when the first measurement unit 8k measures the surface shape of the sample SP. Set to be wide. That is, as illustrated in FIG. 7, when the height range is set, it is permissible to set the Z pitch (third pitch) coarser than when the surface shape is measured.

For example, in FIG. 6F, the white circle-shaped plot refers to the height position used when setting the height range, and the cross-shaped plot refers to the height position used when measuring the surface shape as described above. As shown in FIG. 6F, the third pitch according to the present embodiment is coarser than the Z pitch (fourth pitch) used when the surface shape is measured, similar to the first pitch described above. Can be set widely).

The "third pitch" according to this modification has been described with the same name as the "third pitch" according to the embodiment in order to clarify its technical significance. Is only set for convenience. That is, the "third pitch" according to the white interferometry and the "third pitch" according to the laser confocal method do not need to be set to the same length and can be different from each other. The same applies to the fourth pitch.

-About a modified example of the branched optical system 55-
Further, in the above embodiment, the configuration in which the branch optical system 55 is built in the interference objective lens Oct is exemplified, but the present disclosure is not limited to such a configuration. Instead of arranging in the interference objective lens Oct, the branch optical system 55 may be arranged in the observation unit 2. When arranged in this way, the branched optical system 55 can be configured as an optical element that can be inserted and removed from the optical path connecting the optical components of the observation unit 2.

When a removable optical element is used as described above, the optical element is inserted in the optical path when the measurement by the white interferometry is performed, while the measurement by the laser cofocal method is performed. Will be evacuated from the optical path. Further, this optical element is not limited to the timing at which the measurement is executed, and can be inserted and removed as necessary when the white light source 51 is used as mere illumination or when various processes using laser light are performed.

1 White interference microscope 23 Stage 25 Adjustment member 25b First adjustment knob 25c Second adjustment knob 5 White optical system 51 White light source 54 Objective lens 55 Branch optical system 55b Reference mirror 58 Image pickup unit 6 Laser optical system (cofocal optical system) )
7 Unit drive system 71 Z-direction drive unit (drive unit)
8 Unit control system 8c Display control unit 8e Focus calculation unit (calculation unit)
8f Focus adjustment unit 8h Tilt calculation unit 8i Operation amount conversion unit 8k First measurement unit (measurement unit)
Occ Interference objective lens A3 Direction along the optical axis of the objective lens A4 Direction orthogonal to the upper surface of the stage SP sample (measurement object)
Zp focusing position

Claims (7)

In a white interference microscope that measures the surface shape of an object to be measured using the white interferometry method,
A stage for placing the object to be measured and
A white light source that irradiates the measurement object placed on the stage with white light through an objective lens, and
An adjusting member that can be operated to adjust the angle formed by the direction orthogonal to the upper surface of the stage and the direction along the optical axis of the objective lens.
A branched optical system that branches white light emitted from the white light source into reference light directed to a predetermined reference surface and measurement light directed to the measurement object via the objective lens.
An imaging unit that receives the reference light reflected by the reference surface and the measurement light reflected by the measurement object to capture an interference image.
A drive unit that changes the relative height position of the stage with respect to the objective lens,
By controlling the driving unit and the imaging unit, a plurality of interference images in which the relative height positions of the stages are different from each other are captured, and the light of the objective lens is obtained based on the plurality of interference images. A tilt calculation unit that calculates the tilt of the object to be measured with respect to the axis,
An operation amount conversion unit that calculates the operation amount of the adjusting member for correcting the inclination based on the inclination calculated by the inclination calculation unit.
A white interference microscope comprising a display control unit that controls to display the operation amount calculated by the operation amount conversion unit. In the white interference microscope according to claim 1,
By controlling the drive unit, the relative height position of the stage is changed to a plurality of different height positions, and at each changed height position, a plurality of interference images captured by the image pickup unit are displayed. Based on this, a measuring unit for measuring the surface shape of the object to be measured is provided.
When the inclination calculation unit calculates the inclination of the measurement object, the measurement unit determines the distance between the height positions when the relative height position of the stage is changed. A white interference microscope characterized by being set wider than when measuring the surface shape. In the white interference microscope according to claim 2.
Of the surface region of the measurement object, the size of the region imaged by the imaging unit to form the interference image is determined by the measurement unit when the inclination calculation unit calculates the inclination of the measurement object. A white interference microscope characterized in that it is set smaller than when measuring the surface shape of the object to be measured. In the white interference microscope according to any one of claims 1 to 3.
The inclination calculation unit measures the surface shape of the measurement object based on the plurality of interference images, and calculates the inclination of the measurement object with respect to the optical axis of the objective lens based on the surface shape. A white interference microscope characterized by. In the white interference microscope according to any one of claims 1 to 3.
The tilt calculation unit determines the morphological change of the interference fringes in each interference image based on the plurality of interference images, and based on the determination result, determines the inclination of the measurement object with respect to the optical axis of the objective lens. A white interference microscope characterized by calculation. In the white interference microscope according to any one of claims 1 to 5.
A storage unit for storing the correspondence between the inclination calculated by the inclination calculation unit and the operation amount of the adjustment member is provided.
The operation amount conversion unit is a white interference microscope characterized in that the operation amount of the adjustment member is calculated based on the storage content in the storage unit. In the white interference microscope according to any one of claims 1 to 6.
The adjusting member is
A first adjustment knob that rotates the upper surface of the stage around a first rotation axis extending along the upper surface.
The upper surface of the stage is provided with a second adjusting knob that extends along the upper surface and rotates around a second rotation axis orthogonal to the first rotation axis.
The operation amount conversion unit is a white interference microscope characterized in that the operation amount of each of the first and second adjustment knobs is calculated as the operation amount of the adjustment member.

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