JP2019168280A - Void inspection device - Google Patents

Abstract

To provide inspection means for voids on laminate interfaces.SOLUTION: Provided is a void inspection device 1 for inspecting voids latent on interfaces of a laminate, comprising: a holding unit 2 for holding the laminate; an infrared lighting unit for irradiating illumination light of infrared wavelength toward the laminate; a confocal microscope unit 4 for observing the inside of the laminate; a length measuring instrument 5 for measuring the distance between the laminate and the confocal microscope unit; a relative movement unit 6 for integrally moving the infrared lighting unit, the confocal microscope unit 4 and the length measuring instrument 5 relatively to the holding unit; and a control unit for controlling the relative movement unit. While relatively moving a slider mechanism, the control unit relatively moves a lift mechanism on the basis of the distance measured by the length measuring instrument 5 so that the working distance between the laminate and the confocal microscope unit 4 is constant. The confocal microscope unit 4 is provided with a focal distance oscillating mechanism 45 for oscillating the focal distance in a prescribed range including the interfaces of the laminate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a void inspection apparatus that inspects voids hidden in an interface of a laminate.

  A laminated body bonded with a silicon wafer or the like becomes a defective product when a void (gap) is mixed in the interface during the bonding. Therefore, after the bonding process, an inspection is performed to determine whether there is a void at the interface of the laminate by a technique called ultrasonic flaw detection (for example, Patent Document 1).

  On the other hand, in order to detect defects on the back side of mask blanks for stencil masks, a technology has been proposed that uses a confocal optical system and an autofocus mechanism to control the copying so that the back side is in focus while moving the mask blanks. (For example, Patent Document 2).

JP 2010-157585 A JP 2004-226939 A

  The technique disclosed in Patent Document 1 not only takes time to inspect, but also dries and removes water droplets and the like adhering to the surface of the laminate after inspecting the laminate by immersing it in a liquid such as water, oil, or a reagent. It is necessary to let Inspection in the air has been desired because of the occurrence of contamination due to adhesion of moisture and liquids and the loss of drying time.

Although the technique disclosed in Patent Document 2 seems to be able to inspect the laminate interface in the air, the depth of field of the confocal optical system is very shallow, so the thickness of the laminate varies. In such a case, it is difficult to make the focus of the confocal optical system follow the interface of the multilayer body only by scanning control that keeps the distance between the surface of the multilayer body and the confocal optical system constant. Even when there is little or no variation in the thickness of the laminated body, it is difficult to focus at a desired position when the laminated body has warping or undulation and the followability of the scanning control is poor. That is, even if the confocal optical system is copied and controlled, the void may be missed.
However, if the depth of field is increased in order to reduce the focus shift, it is necessary to increase the pinhole. However, if this is done, there is a problem that a minute void cannot be detected, leading to a decrease in measurement accuracy. It was. In addition, if the movement speed of the laminate and the confocal optical system is slowed to compensate for the followability of the scanning control, the time required for the inspection becomes long when the inspection has to be performed over a wide range. was there.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a means for inspecting voids hidden at the interface of a laminate at high speed and with high accuracy.

In order to solve the above problems, an aspect of the present invention is as follows.
In the void inspection device that inspects voids hidden in the interface of the laminate,
A holding unit for holding the laminate;
An infrared illumination unit that irradiates illumination light with an infrared wavelength toward the laminate;
A confocal microscope section for observing the inside of the laminate,
A length measuring device for measuring the distance between the laminate and the confocal microscope,
A relative movement unit that integrally moves the infrared illumination unit, the confocal microscope unit, and the length measuring device relative to the holding unit;
A control unit for controlling the relative movement unit,
The controller is
While relatively moving the slider mechanism, based on the distance measured by the length measuring device, the elevation mechanism is relatively moved so that the working distance between the laminate and the confocal microscope unit is constant,
In the confocal microscope section,
A focal length swing mechanism is provided that swings the focal length within a predetermined range including the interface of the laminate.

  According to the void inspection apparatus, it is possible to inspect voids hidden at the interface of the laminate at high speed and with high accuracy.

It is the schematic which shows the whole structure of an example of the form which embodies this invention. It is the schematic which shows the principal part of an example of the form which embodies this invention. It is the schematic which shows the holding | maintenance part in an example of another form which embodies this invention. It is the schematic which shows the whole structure in an example of another form which embodies this invention.

  Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. In the following description, the three axes of the orthogonal coordinate system are represented as X, Y, and Z, the horizontal direction is represented as the X direction and the Y direction, and the direction perpendicular to the XY plane (that is, the gravitational direction) is represented as the Z direction. To do. The Z direction is expressed as the direction against gravity and the direction in which gravity works as down. A direction rotating around the Z direction as a central axis is defined as a θ direction.

  FIG. 1 is a schematic diagram showing an overall configuration of an example of a form embodying the present invention. FIG. 1 shows a schematic view of a void inspection apparatus 1 according to the present invention. Here, as a specific example of the laminated body W, one in which two silicon wafers are bonded together is shown, and detailed description will be given.

  FIG. 2 is a schematic diagram showing a main part of an example of a form embodying the present invention. FIG. 2 shows a cross-sectional view of the stacked body W, and schematically shows how the voids B1 and B2 hidden in the interface of the stacked body W are detected by applying the present invention.

The void inspection apparatus 1 inspects voids hidden in the interface K of the laminate W.
Specifically, the void inspection apparatus 1 includes a holding unit 2, an infrared illumination unit 3, a confocal microscope unit 4, a length measuring device 5, a relative moving unit 6, a control unit CN, and the like.

The holding unit 2 holds the stacked body W.
Specifically, the holding unit 2 has a configuration in which an outer edge portion (also referred to as an outer peripheral edge) of the stacked body W is held and held in a predetermined posture.
More specifically, the holding unit 2 includes a plurality of gripping members 21 (four examples are illustrated in FIG. 1) arranged so as to surround the outer edge of the multilayer body W. The part in contact with the outer edge has a substantially Σ shape or a shape recessed in an arc shape. Further, the holding unit 2 includes an opening / closing mechanism (an actuator, a solenoid, etc., not shown) that moves the gripping member 21 toward the outside / inside of the outer edge of the stacked body W. The opening / closing mechanism is attached to the holding table 20.

The illumination unit 3 irradiates the laminated body W with illumination light L1.
Specifically, the illumination unit 3 irradiates a predetermined area including the inspection area F of the stacked body W with the illumination light L1 having a light amount necessary for generating the observation light L2. More specifically, the illumination unit 3 can exemplify coaxial falling illumination or transmitted illumination in addition to the reflected illumination as illustrated, and the illumination light L1 can be exemplified by infrared light including a wavelength of 1000 to 1100 nm. .

The confocal microscope unit 4 is for observing the inside of the laminate W.
Specifically, the confocal microscope unit 4 includes an imaging camera 40, a lens barrel 41, an objective lens 42, a pinhole 43, and a focal length swing mechanism 45.

  The imaging camera 40 includes an imaging element 40P and captures images of the imaging regions F (1) to F (6) set inside the stacked body W. Specifically, the imaging camera 40 includes an imaging element 40P, converts light received by the imaging element 40P into an electrical signal, and outputs the signal as an image signal (analog signal) or image data (digital signal). is there.

  The lens barrel 41 includes optical members such as a pinhole array 43, an objective lens 42, a relay lens, and an imaging lens, and these optical members and the imaging camera 40 are fixed in a predetermined posture.

  The objective lens 42 forms an image of the imaging regions F (1) to F (6) set inside the stacked body W on the imaging camera 40, and the stacked body W held by the holding unit 2 It arrange | positions so that it may oppose.

  The pinhole array 43 allows light that forms an image within the predetermined depth of field of the imaging field to pass through the light that is imaged by the image sensor 40P, and blocks the other light. Specifically, the pinhole array 43 is provided with a large number of openings in the XY directions.

  The focal distance swing mechanism 45 swings the focal distance f when the imaging camera 40 captures an image. Specifically, the focal length swing mechanism 45 includes a mechanism for swinging the focal length f of the objective lens 42 within a predetermined range while keeping the working distance WD of the confocal microscope unit 4 with respect to the stacked body W constant. ing. More specifically, the focal length swing mechanism 45 includes optical path length changing elements 46a to 46f, a turret 47, and a rotation mechanism 48.

  The optical path length changing elements 46a to 46f shift the focal lengths f of the imaging regions F (1) to F (6) set inside the stacked body W forward and backward (up and down in the drawing), respectively (also referred to as shifting). It is. Specifically, the optical path length changing elements 46a to 46f transmit the illumination light L1, are made of a material having a different refractive index from the atmosphere, and are made of parallel plates having different thicknesses. More specifically, the optical path length changing elements 46 a to 46 f are made of glass, quartz, resin, silicon compound, or the like, and are disposed between the objective lens 42 and the stacked body W. The optical path length changing element 46a is the thinnest, the thicknesses are decreasing in the order of 46b, 46c, 46d, and 46e, and the optical path length changing element 46f is the thickest. In other words, by placing the objective lens 42 and the optical path length changing element 46a facing each other, the focal length f of the objective lens 42 becomes the shortest (also referred to as shortening), and the objective lens 42 and the optical path length changing element 46f are placed facing each other. Thus, the focal length f of the objective lens 42 is the longest (also referred to as longer). Therefore, by switching which of the optical path length changing elements 46a to 46f is used, the position (also referred to as height) formed by the objective lens 42 can be shifted back and forth (up and down in the drawing).

  The turret 47 rotates a plurality of optical path length changing elements 46a to 46f while fixing them. Specifically, the turret 47 has openings arranged at equal angles (60 degrees in the drawing) with respect to the rotation axis of the rotary motor 48, and the optical path length changing elements 46a to 46f are provided in the openings, respectively. The optical path length changing elements 46a to 46f used for observation can be switched by rotating the turret 47.

  The rotation mechanism 48 rotates the turret 47. Specifically, the rotation mechanism 48 is configured to rotate the turret 47 in one direction at high speed.

  In FIG. 2, the average position or the center position (hereinafter referred to as the reference focal position) of the focal length f of the imaging regions F (1) to F (6) is offset from the surface position of the stacked body W by the average thickness. RM) is set. Then, the focal length swing mechanism 45 rotates the turret 47 to thereby move the near position RN nearer (upper in the figure) than the reference focal position RM and farther than the reference focal position RM (in the figure). The focal length f of the objective lens 42 is switched in a stepwise manner (below 6) in FIGS.

  In the focal length swing mechanism 45, based on the moving speed in the XY direction of the stage mechanism, the field size in the XY direction of the imaging regions F (1) to F (6), the number of stages of the optical path length changing elements 46a to 46f, and the like. Thus, the imaging rate (also referred to as an interval) is determined, and the rotation speed of the turret 47 is set based on the imaging rate and the sizes of the optical path length changing elements 46a to 46f.

  Since the confocal microscope unit 4 has such a configuration, the observation light from the region at a position deviated from the focal point of the objective lens 42 is shielded by the pinhole array 43 and is not imaged. The imaging regions F (1) to F (6) having different focal lengths f set inside can be switched while taking an image while focusing on these regions.

The length measuring device 5 measures the distance between the laminated body W and the confocal microscope unit 4.
Specifically, the surface of the laminate W is irradiated with the measurement beam LB at a predetermined inclination angle (also referred to as an incident angle), and the deviation of the incident position of the measurement beam LB reflected by the surface of the laminate W is measured. , Measure the distance. More specifically, the length measuring device 5 can be exemplified by a so-called laser displacement meter, and an electrical signal (analog signal), displacement data (digital signal), or the like corresponding to the distance to the measurement object is output.

  The relative movement unit 6 integrally moves the illumination unit 3, the confocal microscope unit 4, and the length measuring device 5 relative to the holding unit 2. Specifically, the relative moving unit 6 includes an elevating mechanism, a slider mechanism, and a rotating mechanism 63.

  The lifting mechanism integrally moves the illumination unit 3, the confocal microscope unit 4, and the length measuring device 5 in the thickness direction (that is, the Z direction) of the stacked body W. Specifically, the lifting mechanism includes a Z-axis stage 60.

The Z-axis stage 60 includes a pair of rails extending in the Z direction, a slider part that moves on the rails, and a slider drive part that moves and stops the slider part. The slider drive unit can be configured by a combination of a servo motor or pulse motor that rotates and stops by signal control from the control unit CN and a ball screw mechanism. In addition, the Z-axis slider 60 is provided with an encoder for detecting the current position and movement amount of the slider portion as necessary. Examples of this encoder include a linear member called a linear scale in which fine irregularities are carved at a predetermined pitch, and a rotary encoder that detects a rotation angle of a motor that rotates a ball screw.
Specifically, the Z-axis stage 60 is attached to the apparatus frame 10f via a support column 11f. Furthermore, the illumination unit 3, the confocal microscope unit 4, and the length measuring device 5 are respectively attached to the slider portion of the Z-axis stage 60 via a coupling fitting (not shown).

  The slider mechanism is relatively moved in a direction (that is, X direction and / or Y direction) orthogonal to the thickness direction (that is, Z direction) of the stacked body W. Specifically, the slider mechanism includes an X-axis slider 61 and a Y-axis slider 62.

  The X-axis slider 61 is mounted on the device frame 10f, and moves the Y-axis slider 62 in the X direction at an arbitrary speed and stops it at an arbitrary position. Specifically, the X-axis slider includes a pair of rails extending in the X direction, a slider portion that moves on the rails, and a slider drive unit that moves and stops the slider portion. The slider drive unit can be configured by a combination of a servo motor or a pulse motor that rotates and stops by signal control from the control unit CN and a ball screw mechanism, a linear motor mechanism, or the like. In addition, the X-axis slider 61 is provided with an encoder for detecting the current position and movement amount of the slider portion. Examples of this encoder include a linear member called a linear scale in which fine irregularities are carved at a predetermined pitch, and a rotary encoder that detects a rotation angle of a motor that rotates a ball screw.

  The Y-axis slider 62 moves the rotating mechanism 63 at an arbitrary speed in the Y direction based on a control signal output from the control unit CN, and stops at an arbitrary position. Specifically, the Y-axis slider includes a pair of rails extending in the Y direction, a slider portion that moves on the rails, and a slider drive unit that moves and stops the slider portion. The slider drive unit can be configured by a combination of a servo motor or a pulse motor that rotates and stops by signal control from the control unit CN and a ball screw mechanism, a linear motor mechanism, or the like. Further, the Y-axis slider 62 is provided with an encoder for detecting the current position and movement amount of the slider portion. Examples of this encoder include a linear member called a linear scale in which fine irregularities are carved at a predetermined pitch, and a rotary encoder that detects a rotation angle of a motor that rotates a ball screw.

  The rotating mechanism 63 rotates the holding base 20 at an arbitrary speed in the θ direction and stops at an arbitrary angle. Specifically, the rotation mechanism 63 can be exemplified by a mechanism that rotates / stops at an arbitrary angle by signal control from an external device, such as a direct drive motor. On the rotating side member of the rotation mechanism 63, the holding table 20 of the substrate holding unit 2 is attached.

  Since the relative movement unit 6 has such a configuration, the ZXYθ is integrally formed with the imaging unit 3, the confocal microscope unit 4, and the length measuring device 5 while holding the stacked body W to be inspected. Independently or in combination with each other, they can be moved relative to each other at a predetermined speed or angle, or can be stopped at any position / angle.

The control unit CN controls the relative movement unit 6 and the devices of each unit.
Specifically, the control unit CN has a role as described below.
-Controlling the opening / closing mechanism of the holding unit 2 to switch the grip / release of the laminated body W-ON / OFF control of the illumination unit 3 and light quantity adjustment-Output an imaging trigger to the imaging camera 40 of the confocal microscope unit 4 The image output from the imaging camera 40 is acquired. The rotation mechanism 48 of the focal length swing mechanism 45 is controlled to change the angle of the turret 47 (that is, switching of the optical path length changing elements 46a to 46f).
Control the Z-axis stage 60, the X-axis slider 61, the Y-axis slider 62, and the rotation mechanism 63 of the relative movement unit 6 to move the holding unit 2 relatively at a predetermined speed or angle, or at any position / angle The signal corresponding to the distance from the surface of the laminated body W output from the length measuring device 5 is input, and the distance between the laminated body W and the confocal microscope unit 4 (that is, the confocal microscope unit 4) The lifting mechanism (specifically, the Z-axis stage 60) of the relative movement unit 6 is controlled (so-called copying control) so that the working distance WD) is constant.

  When a signal or data is input from a connected external device, the control unit CN performs processing according to a pre-registered program and outputs a processing result to the external device. Specifically, the control unit CN includes a computer, a programmable logic controller or the like (that is, hardware), and an execution program or the like (that is, software).

  Because of such a configuration, the void inspection apparatus 1 holds the stacked body W with the holding unit 2 and stacks the stacked body W with the length measuring device 5 while relatively moving the stacked body W in the X direction and / or the Y direction. The distance between the body W and the confocal microscope unit 4 can be measured and controlled so that the confocal microscope unit 4 follows the surface of the stacked body W (that is, the working distance WD becomes constant). At this time, the copying is controlled so that the reference focal position RM of the imaging regions F (1) to F (6) is arranged at a position offset by the average thickness from the surface position of the stacked body W. Even if the distance between the surface of the laminated body W and the interface K is deviated due to the variation in thickness, the focal length of the objective lens 42 is oscillated by the focal length oscillating mechanism 45 so that the distance K near or far from the interface K of the laminated body W is changed. It can be observed with the confocal microscope unit 4.

And if the inside of the laminated body W is observed with the confocal microscope section 4 according to the present invention, the majority of the illumination light L1 passes (also referred to as transmission) at the interface K where there is no void inside the laminated body W, Since much reflected light or scattered light does not occur, the observation light L2 becomes dark light. That is, the imaging camera 40 can only capture black or gray images. On the other hand, if there are voids B1 and B2 at the interface K, the illumination light L1 is reflected at the interface between the material constituting the laminate W and the voids B1 and B2, and part or all of the observation light L2 is imaged as bright light.
Therefore, by determining whether part or all of the observation light L2 observed with the confocal microscope unit 4 includes bright light, it is possible to inspect the voids hidden in the interface K of the stacked body W with high speed and high accuracy. .

[Another form]
In the above description, the distance between the stacked body W and the confocal microscope unit 4 is measured by the length measuring device 5 while the stacked body W is held by the holding unit 2 and the stacked body W is relatively moved in the X direction and / or the Y direction. The configuration for measuring and copying is illustrated. However, in implementing the present invention, the void inspection apparatus 1 is not limited to such a configuration, and may further include a mapping information registration unit described below, and the control unit CN may include the following functions. good.

  The mapping information registration unit registers mapping information in which the distance between the stacked body W and the confocal microscope unit 4 is associated with the XY position of the stacked body W while the stacked body W is held in the holding unit 2. is there. Specifically, the mapping information registration unit is configured by a part of functional blocks of hardware and software of the control unit CN.

  The mapping information is obtained by measuring the distance between the stacked body W and the confocal microscope unit 4 with the length measuring device 5 while relatively moving the stacked body W by the slider mechanism while the stacked body W is held in the holding unit 2. And registered in the mapping information registration unit.

  Based on the current position information and mapping information of the slider mechanism (specifically, the X-axis slider 61 and / or the Y-axis slider 61), the control unit CN lifts and lowers the mechanism (specifically, the Z-axis stage 60). It has a function to control.

  With such a configuration, when it is desired to inspect the void while performing the relative movement in the X direction and the Y direction at high speed, the follow-up delay of the lifting mechanism (specifically, the Z-axis stage 60), etc. This is preferable because defocusing (that is, the interface K deviates from the rocking range of the focal length rocking mechanism 45) due to the above can be prevented.

[Another form]
If the interface K to be imaged is not horizontal but tilted due to the warp or deformation of the stacked body W, the depth of field of the imaging regions F (1) to F (6) of the confocal microscope unit 4 In some cases, the interface K does not fit. In such a case, there is a possibility that minute voids hidden in the interface K cannot be detected correctly.

  Therefore, when there is warpage or deformation of the laminated body W, the void inspection apparatus 1 according to the present invention includes a holding unit 2B having the following configuration instead of the above-described holding unit 2, and the control unit CN has the following configuration. Such a configuration is preferable.

  The holding unit 2B includes a holding posture tilt mechanism that tilts the posture in which the stacked body W is held. Further, in addition to the above-described configuration, the control unit CN controls the holding posture tilting mechanism based on the current position information and mapping information of the slider mechanism, and inspects while maintaining the interface K of the stacked body W in a horizontal state. I am doing.

  FIG. 3 is a schematic view showing a holding unit in an example of another embodiment embodying the present invention. FIG. 3 shows a holding unit 2B having a configuration different from that of the holding unit 2 described above.

  The holding unit 2B holds the stacked body W. Specifically, the holding portion 2B is configured to support the outer peripheral portion of the stacked body W from the lower surface side and hold it in a predetermined posture. More specifically, the holding unit 2 includes a plurality of sliders 23 and lifting cylinders 25 (that is, the holding posture inclination according to the present invention) arranged so as to surround the outer edge of the stacked body W (in FIG. 3, three locations are illustrated). Mechanism).

  The slider 23 includes a mechanism (actuator, solenoid, etc.) that moves toward the center side / outside of the stacked body W, and is attached to the lifting cylinder 25 via a universal joint 24. Note that the movable portion of the slider 23 is provided with a suction portion for holding the outer peripheral lower surface of the stacked body W.

  The elevating cylinder 25 adjusts the vertical position (also referred to as height) of the slider 23 and is attached to the holding table 20. And as for the raising / lowering cylinder 25, the height of the movable part to which the slider 23 is attached is independently controlled based on the control signal from the control part CN.

  Note that how much the stack W is inclined to determine whether the interface K to be imaged is in a horizontal state (that is, the state where the interface K is within the depth of field) is based on mapping information registered in advance. And calculated by the control unit CN or the like. Then, the control unit CN acquires the current position information in the X direction and the Y direction while moving the stacked body W in the X direction and the Y direction by the slider mechanism (the X axis slider 61 and the Y axis slider 62). Based on the position information and pre-registered mapping information, the holding posture tilt mechanism (elevating cylinder 25 and the like) is controlled to adjust the tilt angle of the stacked body W. At this time, the control unit CN also controls the elevating mechanism (Z-axis stage 60) so that the working distance WD becomes constant.

FIG. 4 is a schematic diagram showing an overall configuration in another example embodying the present invention.
4A and 4B show a state in which the laminated body W whose center part is curved upward is inspected. FIG. 4A shows a state where the central portion of the stacked body W is imaged.
FIG. 4B shows a state where the peripheral part of the stacked body W is imaged.

  Since the void inspection apparatus 1 including the holding unit 2B has such a configuration, the interface K to be imaged in the depth of field of the imaging regions F (1) to F (6) of the focus microscope unit 4 is used. Even if the laminated body W is warped or deformed to a degree that does not fit, the laminated body is held by the holding unit 2B so that the interface K is within the depth of field (that is, in a horizontal state). The working distance WD can be kept constant while changing the inclination angle of W, and the fine voids hidden in the interface K can be correctly detected by swinging the focal length.

[Modification]
In addition, in the above, the laminated body W bonded silicon wafer, and illustrated the form whose wavelength of the illumination light L1 irradiated from the illumination part 3 is infrared light including 1000-1100 nm. A silicon wafer does not transmit visible light having a wavelength shorter than 900 nm, and the transmittance gradually increases from a wavelength of 900 nm or more. If the infrared light has a wavelength of approximately 1000 nm or more, a sufficient amount of light for observing the inside of the silicon wafer can be obtained. On the other hand, when the wavelength is longer than 1100 nm, the sensitivity characteristic is deteriorated when the imaging element 40P of the imaging camera 40 is a CCD or a CMOS. Moreover, if the imaging device 40P of the imaging camera 40 uses a compound such as InGaAs, the sensitivity at the wavelength is high, but the operation speed (imaging rate) becomes slow. Therefore, if the laminated body W is a laminate of silicon wafers, the wavelength of the illumination light L1 emitted from the illumination unit 3 is preferably infrared light including 1000 to 1100 nm.

  However, in realizing the present invention, the illumination light emitted from the illumination unit 3 toward the multilayer body W may be light having a wavelength other than this, and the wavelength characteristics (light) of the multilayer body W to be inspected may be used. And the like, and the light receiving sensitivity characteristics of the image sensor.

[Other variations]
In the above description, the focal length swing mechanism 45 switches the optical path length changing elements 46a to 46f by rotating the turret 47 by 60 degrees, and the focal length f of the objective lens 42 is changed step by step (as in raster scanning). When the turret is rotated once, the state returns to the original state and the same operation is repeated and illustrated. However, the optical path length changing elements 46a to 46f do not need to be arranged so that the focal length f is changed step by step by rotating the turret 47 by 60 degrees, but other orders (for example, 46a, 46c, 46e, 46b, 46d, and 47f, and 46a, 46d, 46b, 46e, 46c, and 47f).

  In the above description, the optical path length changing elements 46a to 46f are illustrated as parallel plates having different thicknesses, but may be configured by convex lenses or concave lenses having different curvatures.

  In the above description, the optical path length changing elements 46a to 46f are circular in shape, but may be fan-shaped or rectangular.

  In the above description, a configuration in which six parallel flat plates having different thicknesses are arranged as the optical path length changing elements 46a to 46f is illustrated. However, in realizing the present invention, the optical path length changing elements 46a to 46f are not limited to such a configuration, and may be configured by lenses having different curvatures. Further, the number of optical path length changing elements is not limited to six, and may be at least two.

  In the above description, the configuration in which the relative movement unit 6 includes the rotation mechanism 63 is illustrated. However, in realizing the present invention, the rotation mechanism 63 is not an essential configuration, and may be a configuration in which this is omitted.

In the above description, the configuration in which the confocal microscope unit 4 including the illumination unit 3 and the like are integrally moved up and down as the relative moving unit 6 is illustrated. However, the illumination unit 3 may be configured not to be moved up and down integrally with the confocal microscope unit 4 or the like as long as the irradiation range of the illumination light L1 can cover the imaging regions F (1) to F (6).

DESCRIPTION OF SYMBOLS 1 Void inspection apparatus 2 Holding | maintenance part 3 Illumination part 4 Confocal microscope 5 Length measuring device 6 Relative movement part CN Control part 20 Holding stand 21 Holding member 23 Slider 24 Universal joint 25 Lifting cylinder 40 Imaging camera (40P: Imaging element)
41 Lens barrel 42 Objective lens 43 Pinhole array 45 Focal length swing mechanism 46a to 46f Optical path length changing element 47 Turret 48 Rotating mechanism 60 Z-axis stage 61 X-axis slider 62 Y-axis slider 63 Rotating mechanism W Laminate (wafer, etc.)
K interface B1, B2 void F inspection area F (1) to F (6) imaging area WD working distance f focal distance L1 illumination light L2 observation light LB measurement beam RM reference focal position RN near position (top of rocking of focal distance) position)
RF far position (focal length lower end position)

Claims (4)

In the void inspection device that inspects voids hidden in the interface of the laminate,
A holding unit for holding the laminate;
An illumination unit that emits illumination light toward the laminate;
A confocal microscope unit for observing the inside of the laminate,
A length measuring device for measuring a distance between the laminate and the confocal microscope unit;
A relative movement unit that integrally moves the confocal microscope unit and the length measuring device relative to the holding unit;
A control unit for controlling the relative movement unit,
The relative movement unit is
An elevating mechanism that relatively moves in the thickness direction of the laminate, and a slider mechanism that relatively moves in a direction perpendicular to the thickness direction,
The controller is
While relatively moving the slider mechanism, based on the distance measured by the length measuring device, the elevation mechanism is relatively moved so that the working distance between the laminate and the confocal microscope unit is constant,
In the confocal microscope section,
A void inspection device comprising a focal length swing mechanism that swings a focal length within a predetermined range including an interface of the laminate. Mapping obtained by measuring the distance between the laminate and the confocal microscope unit with the length measuring device while relatively moving the laminate by the slider mechanism while holding the laminate in the holding unit. A mapping information registration unit for registering information;
The void inspection apparatus according to claim 1, wherein the control unit controls the lifting mechanism based on current position information of the slider mechanism and the mapping information. The holding unit includes a holding posture tilting mechanism that tilts a posture holding the stacked body,
The void inspection apparatus according to claim 2, wherein the control unit controls the holding posture tilt mechanism based on current position information of the slider mechanism and the mapping information. The laminate is a silicon wafer bonded together,
The void inspection apparatus according to claim 1, wherein a wavelength of illumination light emitted from the illumination unit includes 1000 to 1100 nm.