TWI664389B - Apparatus and method for measuring thickness or height variation of object - Google Patents

Abstract

The present invention discloses an object which is installed on an upper part of an object to measure the object. Device and method for changing thickness or height of an object. The disclosed measuring device includes a light source that emits detection light, a light focusing unit that focuses the detection light and irradiates the target object, and a light sensing unit that detects a change in reflected light emitted from a reflection surface of the target object, It further includes a Shack-Hartman sensor; and a computing unit that calculates a change in height of the reflecting surface by using a change in the reflected light detected by the light sensing unit.

Description

Device and method for measuring thickness or height change of object

The present invention relates to a measuring device and a measuring method, and more particularly, to a device and a method capable of measuring a change in the thickness or height of an object or a shape of an object.

A shack-hartmann sensor is a device that measures the strain or aberration of a light wavefront reflected from a specific area in the field of astronomical telescopes or optometry, and is usually used to use The strain or aberration of the light wave surface measured in this way is smaller than the shape of the measurement surface in a specific area.

However, the Shack-Hartman sensor has a limit that cannot measure the change in the overall thickness or height of an object. For example, when measuring the thickness difference between wafers with different thicknesses stacked on a reference surface such as a surface of a platform, a Shack-Hartman sensor cannot measure the thickness difference or may There are major constraints. The reason is that the size of the probe light irradiated to the object needs to be large enough to cover all wafers and reference planes, and the reference plane becomes the reflection plane of the probe light, and the height difference between the reference plane and the measurement plane should not exceed The limit of measurement for a Shack-Hartman sensor (for example, About 30 times the metering wavelength).

According to an embodiment of the present invention, an apparatus and method for measuring the height, thickness, or height change of an object, or measuring the shape of an object are provided.

In one aspect of the present invention, there is provided a measuring device that is provided on an upper portion of a target object and measures a change in thickness or height of the target object. The measuring device includes a light source that emits probe light; light focusing A light detecting unit that focuses the detection light and irradiates the target object; a light sensing unit that detects a change in the reflected light emitted from the reflective surface of the target object, and includes a shack-hartmann sensor; and The computing unit calculates a change in the height of the reflecting surface using a change in the reflected light detected by the light sensing unit.

Here, the Shack-Hartman sensor can detect a change in the light wavefront of the reflected light.

The measuring device may further include a beam splitter. The beam splitter is provided between the light source and the light focusing portion, and transmits either one of the detection light and the reflected light and reflects the other of the detection light and the reflected light. . The measurement device can be installed so that it can move up and down with respect to a target object.

The arithmetic unit may calculate a change in the height of the reflecting surface by using a Zernike polynomials that expresses a change in the reflected light detected by the light sensing unit in a mathematical expression. Here, the height variation of the reflecting surface can be related to the defocus of the Zernike polynomial. The (defocus) term coefficient value changes.

Objects can be stacked on the platform. In this case, the platform may include a reflective surface that reflects the measurement beam.

In another aspect, a measurement method is provided, which is a method of measuring a change in the thickness or height of an object to be measured by a measurement device including a light source, a light focusing portion, a light sensing portion, and a calculation portion. The light source emits detection light. The focusing unit focuses the detection light. The light sensing unit includes a Shaker-Hartman sensor that detects changes in the reflected light. The computing unit calculates the height change. The measuring method includes at least the following steps: after setting the reference point of the measuring device , The step of inputting calibration data corresponding to the up and down movement of the reference point to the arithmetic unit; the step of loading the target object on the platform; the step of irradiating the target object with the detection light emitted from the light source by the light focusing unit A step of detecting a change in the reflected light emitted from the reflective surface of the target object by the light sensing portion; and a step of calculating a change in the height of the reflective surface by using the change in the reflected light detected by the light sensing portion by the computing portion.

A beam splitter may be provided between the light source and the light focusing portion to transmit either one of the detection light and the reflected light and reflect the other of the detection light and the reflected light.

The computing unit may calculate a change in the height of the reflecting surface using a Zernike polynomial that expresses a change in the reflected light detected by the light sensing unit in a mathematical expression. Here, the change in the height of the reflecting surface may correspond to the change in the defocus term coefficient value of the Zernike polynomial.

The correction data may include a change in the defocus term coefficient value of the Zernike polynomial caused by the reference point moving up and down.

The steps for inputting the calibration data to the calculation part may include at least the following steps Step: a step of loading a reference object on the platform; a step of setting a reference point of the measuring device on the reference object; a step of measuring a change in a defocus term coefficient value caused by the vertical movement of the reference point; and a step of storing correction data in the calculation section step.

Here, the step of measuring a change in the defocus term coefficient value caused by the vertical movement of the reference point may include at least the following steps: a step of the light sensing unit detecting a change in a light wave surface of the reflected light caused by the vertical movement of the reference point; and a calculation unit A step of measuring a change in a defocus term coefficient value using a change in a light wave surface of the reflected light detected by the light sensing section.

The step of inputting the correction data to the arithmetic unit may include the following steps: a step of setting a reference point of the measuring device on the platform; a step of measuring a change in a defocus term coefficient value caused by the vertical movement of the reference point; and storing the correction data to Steps of the arithmetic unit.

Here, the step of measuring a change in the defocus term coefficient value caused by the vertical movement of the reference point may include at least the following steps: a step of the light sensing unit detecting a change in a light wave surface of the reflected light caused by the vertical movement of the reference point; and a calculation unit A step of measuring a change in a defocus term coefficient value using a change in a light wave surface of the reflected light detected by the light sensing section.

According to the embodiment of the present invention, the height change of the reflective surface of the target object can be measured by: the light focusing portion focuses the detection light and irradiates the target object, including light sensing by a Shack-Hartmann sensor The detection unit detects a light wave surface change of the reflected light reflected from the target object, and the calculation unit uses the reflected light detected by the light sensing unit. Calculate the coefficient value of the defocus term of the light wave surface change. This makes it possible to effectively and accurately measure changes in the thickness or height of a target object such as a wafer or a plate-like object. In addition, when the probe light emitted from the light source is scanned toward the target object, the shape of the target object corresponding to the scan line or scan area can be measured. In addition, the change in thickness or height measured by the light sensor section including the Shack-Hartmann sensor has nothing to do with the degree of inclination of the light sensor section. Therefore, when the measurement device is installed, it can be optically easier. Arrange the light sensing section.

50‧‧‧platform

51‧‧‧ reference object

55‧‧‧Object

100‧‧‧ measuring device

110‧‧‧light source

120‧‧‧ Beamsplitter

130‧‧‧light focusing section

140‧‧‧Light Sensor

150‧‧‧ Computing Department

401 ~ 407‧‧‧step

L1‧‧‧Probe Light

L2‧‧‧Reflected light

P‧‧‧ benchmark

S‧‧‧Reflective surface

S1‧‧‧Reflective surface

S2‧‧‧Reflective surface

t1‧‧‧thickness

t, t2‧‧‧thickness

W‧‧‧ light wave surface

△ h‧‧‧height change

FIG. 1 is a diagram schematically showing a measurement device according to an exemplary embodiment of the present invention.

2a to 2c are diagrams for explaining a principle of measuring a change in thickness or height of an object using the measurement device shown in FIG. 1.

FIG. 3 is a diagram exemplarily showing a defocus term coefficient value calculated from a change in the reflected light detected in accordance with the height of the reflecting surface in FIGS. 2a to 2c.

FIG. 4 is a flow chart for explaining a measurement method according to another exemplary embodiment of the present invention.

5a and 5b are diagrams showing specific examples of the measurement method shown in FIG. 4.

6a and 6b are diagrams showing another example of the measurement method shown in FIG. 4.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments illustrated below do not limit the scope of the present invention, but are provided to explain the present invention to those skilled in the art. In the figure, the same reference numerals denote the same constituent elements, and the size or thickness of each constituent element may be exaggerated for clarity of explanation. In addition, when it is described that a specific material layer exists on a substrate or other layer, the material layer may exist in direct contact with the substrate or other layer, or may exist between the material layer and the substrate or other layer. The other third layer. In addition, in the following examples, the substances constituting each layer are merely examples, and other substances may be used in addition to the examples.

FIG. 1 is a diagram schematically showing a measurement device according to an exemplary embodiment of the present invention. The measuring device 100 shown in FIG. 1 can measure the thickness or height change of an object, or measure the shape of an object.

Referring to FIG. 1, the measurement device 100 may be provided on an upper portion of a target object 55 stacked on the platform 50. The measurement device 100 in this embodiment may include a light source 110, a light focusing unit 130, a light sensing unit 140, and a computing unit 150. Here, a beam splitter 120 may be further provided between the light source 110 and the light focusing portion 130.

The light source 110 emits probe light L1 that is radiated to the target object 55 in order to measure the height of the target object 55. The probe light L1 emitted from the light source 110 can be transmitted through the beam splitter 120 as described above. Here, the beam splitter 120 may transmit any one of the detection light L1 and the reflected light L2 to be described later and reflect the other of the detection light L1 and the reflected light L2. FIG. 1 exemplarily shows a case where the beam splitter 120 transmits the probe light L1 and reflects the reflected light L2. However, this embodiment is not limited Here, the beam splitter 120 may be configured to reflect the probe light L1 and transmit the reflected light L2. The detection light L1 passing through the beam splitter 120 is focused by the light focusing unit 130 and then irradiated to the target object 55 stacked on the stage 50.

The probe light L1 focused by the light focusing unit 130 and irradiated to the target object 55 is reflected from the reflection surface of the target object 55. The reflected light L2 reflected from the target object 55 in this manner can be detected by the light sensing unit 140 after being reflected by the beam splitter 120 through the light focusing portion 130. In this embodiment, the light sensor 140 may include a shack-hartmann sensor capable of detecting a change in the light wavefront of the reflected light L2. The Shack-Hartmann sensor measures the strain or aberration of the light wave surface of the reflected light L2, thereby detecting the change of the light wave surface of the reflected light L2 with respect to the detection light L1.

The computing unit 150 can measure the change in the height of the reflecting surface of the object 55 using the change in the reflected light L2 detected by the light sensing unit 140. Specifically, if the light sensing unit 140 detects a change in the light wave surface of the reflected light L2, it sends an electrical signal corresponding to the change in the light wave surface to the computing unit 150. In addition, the calculation unit 150 can measure the height of the reflection surface of the target object 55 by constructing a Zernike polynomials as a mathematical model by changing the light wave surface of the reflected light L2 detected by the light sensing unit 140. Variety. The Zernike polynomials can be composed of multiple terms. The terms constituting the Zernike polynomials here refer to optical aberrations and are independent of each other. The coefficient value constituting the defocus term among the terms of such Zernike polynomials can determine the thickness or height change of the target object 55. The detailed description of this content will be described later.

The measurement device 100 can be installed so that it can move up and down with respect to the target object 55. For example, in FIG. 1, the measurement device 100 can move up and down in the z direction, or the platform 50 on which the object 55 is stacked can move up and down in the z direction. Both the measurement device 100 and the stage 50 can move in the z direction.

2a to 2c are diagrams for explaining a principle of measuring a change in thickness or height of an object using the measurement device shown in FIG. 1.

FIG. 2 a shows a state where the detection light L1 emitted from the light source 110 is focused by the light focusing unit 130 and is incident on the reflection surface S, and then is reflected from the reflection surface S. Referring to FIG. 2 a, the detection light L1 emitted from the light source 110 and transmitted through the beam splitter 120 is focused by the light focusing portion 130 and then incident on the reflection surface S. Here, the detection light L1 can be focused on the reflection surface S to form a light-condensing point. Then, the detection light L1 can be reflected on the reflecting surface S, and the reflected light L2 is reflected by the beam splitter 120 and then incident on the light sensing part 140.

The light sensing part 140 including a Shack-Hartman sensor can detect a change in the light wave surface of the reflected light L2 reflected from the reflection surface S. In FIG. 2a, the light wave surface W of the reflected light L2 reflected from the reflection surface S is the same as the detection light L1, and both are plane wavefronts, so there is no change in the light wave surface of the reflected light L2. As described above, it is possible to set the reflecting surface S that changes the light wave surface of the non-reflected light L2 as a reference surface that serves as a reference for height measurement. Here, the height of the reference plane can be set to "0", for example.

As described above, if there is no change in the light wave surface of the reflected light L2 reflected from the self-reflecting surface S, the coefficient value of the defocus term in the Zernike polynomial stored in the arithmetic unit 150 can be "0". In this case, the height of the reflecting surface S can be set to be equal to the reference surface. The height is the same as "0".

FIG. 2b shows a state where the detection light L1 emitted from the light source 110 is focused by the light focusing unit 130 and is incident on the reflection surface S and then reflected. In FIG. 2b, the reflective surface S is disposed at a position higher than the reference surface. In this case, the height of the reflective surface S may have a “positive (+)” value. Referring to FIG. 2 b, the detection light L1 emitted from the light source 110 and transmitted through the beam splitter 120 is focused by the light focusing portion 130 and then incident on the reflection surface S. Here, since the reflection surface S is disposed at a position higher than the reference surface, the detection light L1 passing through the light focusing section 130 is defocused on the reflection surface S. In addition, such detection light L1 may be reflected on the reflection surface S, and the reflected light L2 is reflected by the beam splitter 120 and then incident on the light sensing unit 140. In this case, the reflected light L2 reflected by the beam splitter 120 may be incident on the light sensing portion 140 while being diffused.

The light sensing unit 140 including a Shack-Hartman sensor can detect a change in a light wave surface of the reflected light L2 emitted from the reflection surface S. As shown in FIG. 2b, the light wave surface W of the reflected light L2 reflected from the reflection surface S located at a position higher than the reference surface becomes a convex shape and is incident on the light sensing unit 140. As described above, if the light wave surface of the reflected light L2 detected by the light sensing section 140 becomes convex, the coefficient of the defocus term in the Zernike polynomial stored in the computing section 150 may have a "positive ( +) "Value.

FIG. 2C shows a case where the probe light L1 emitted from the light source 110 is focused by the light focusing section 130 and is incident on the reflection surface S and then reflected. In FIG. 2 c, the reflective surface S may be disposed at a position lower than the reference surface. In this case, the height of the reflective surface S may have a “negative (-)” value. Referring to FIG. 2c, the detection light L1 emitted from the light source 110 and transmitted through the beam splitter 120 is focused by the light focusing portion 130 and then incident on a reflecting surface S. Here, since the reflection surface S is disposed at a position lower than the reference surface, the detection light L1 passing through the light focusing portion 130 can be defocused on the reflection surface S. In addition, such detection light L1 may be reflected on the reflection surface S, and the reflected light L2 is reflected by the beam splitter 120 and then incident on the light sensing unit 140. In this case, the reflected light L2 reflected by the beam splitter 120 may be incident on the light sensor 140 while converging.

The light sensing part 140 including a Shack-Hartman sensor can detect a change in the light wave surface of the reflected light L2 reflected from the reflection surface S. As shown in FIG. 2c, the light wave surface W of the reflected light L2 reflected from the reflection surface S located at a position lower than the reference surface becomes a concave shape and is incident on the light sensing unit 140. As described above, if the light wave surface of the reflected light L2 detected by the light sensing section 140 becomes a concave shape, the coefficient of the defocus term in the Zernike polynomial stored in the arithmetic section 150 may have a "negative (- )"value.

FIG. 3 is a diagram exemplarily showing a defocus term coefficient value calculated from a change in the reflected light detected in accordance with the height of the reflecting surface in FIGS. 2a to 2c.

Referring to FIG. 3, when the height of the reflecting surface S and the height of the reference surface are the same as “0”, the coefficient of the defocus term of the Zernike polynomial becomes “0”. In addition, it can be seen that when the height of the reflecting surface S has a “positive (+)” value higher than the reference surface, the coefficient of the defocus term of the Zernike polynomial has a “positive (+)” value. In this case, the higher the height of the reflecting surface S, the larger the coefficient value of the defocus term. On the other hand, it can be seen that when the height of the reflecting surface S has a "negative (-)" value lower than the reference surface, the coefficient of the defocus term of the Zernike polynomial has a "negative (-)" value. In this case, the lower the height of the reflecting surface S, the smaller the coefficient value of the defocus term. As described below, the value of the defocus term coefficient value corresponding to the change in height of the reflecting surface S as described above The change can be stored as calibration data in the calculation unit 150 of the measurement device 100.

On the other hand, the above has exemplarily explained the case where the reflection surface S when the light wave surface of the unreflected light L2 is changed, that is, when the coefficient value of the defocus term is "0" is set to be a height measurement Datum of datum. However, this embodiment is not limited to this, and the reflection surface S whose coefficient value of the defocus term becomes a "positive (+)" value or a "negative (-)" value may be set as a reference surface. In this case, the coefficient of the defocus term can also be changed corresponding to the change in the height of the reflecting surface S relative to the reference plane. The change in the height of the reflecting surface can be determined by using the change in the defocus term coefficient value calculated in this way. And make calibration data.

FIG. 4 is a flow chart illustrating a measurement method according to another exemplary embodiment of the present invention. FIG. 4 shows a method of measuring a change in thickness or height of an object using the measurement device 100 shown in FIG. 1.

Referring to Fig. 4, first, a reference point of the measurement device is set (step 401). Here, the reference point can be set to a reference plane having a height of “0” as described above. As described below, such a reference point can be set on the reflective surface of a reference object or on the reflective surface of a platform.

Next, the coefficient value of the defocus term corresponding to the vertical movement of the reference point is measured (step 402). Here, the reference point can be moved up and down by moving the reflecting surface up and down from the reference plane as shown in FIG. 2a to FIG. 2c. With this type of reference point moving up and down, the light wave surface of the reflected light L2 changes. After detecting the change in the light wave surface of the reflected light L2 by the light sensing unit 140, the coefficient value of the defocus term of the Zernike polynomial stored in the calculation unit 150 can be measured using the light wave surface change. Next, it will be shown that The correction data of the change in the defocus term coefficient value caused by the vertical movement of the measured reference point is stored in the calculation unit 150 (step 403).

Next, the target object 55 to be measured is loaded on the platform 50 (step 404). After the measurement device 100 moves to the above-mentioned reference point position, the detection light L1 is emitted from the light source 110 to irradiate the target object 55 (step 405). Here, the detection light L1 emitted from the light source 110 may be focused by the light focusing portion 130 after being transmitted through the beam splitter 120 and irradiated to the target object 55.

Next, the light sensor 140 detects a light wave surface change of the reflected light L2 emitted from the reflection surface of the target object 55 (step 406). Specifically, the detection light L1 passing through the light focusing unit 130 is reflected on the reflection surface of the target object 55, and the reflected light L2 reflected in this manner is incident on the light sensing unit 140. Here, the reflected light L2 emitted from the reflection surface of the target object 55 may be reflected by the beam splitter 120 through the light focusing portion 130 and then incident on the light sensing portion 140. In addition, the light sensing part 140 including a Shack-Hartman sensor may detect a change in a light wave surface of the reflected light L2.

Next, the change in the height of the reflecting surface of the target object 55 is measured using the change in the reflected light L2 detected by the light sensor 140 (step 407). Specifically, the light wave surface change of the reflected light L2 detected by the light sensing unit 140 is input to the calculation unit 150, and the calculation unit 150 calculates the defocus term of the Zernike polynomial using the light wave surface change of the reflected light L2. Coefficient value. Then, the calculated coefficient value of the defocus term is compared with the correction data stored in the calculation unit 150, whereby the height change of the reflection surface of the target object 55 with respect to the reference point can be measured. The thickness of the measurement target object 55 may also be measured using the change in the height of the reflecting surface measured in this manner.

5a and 5b are diagrams showing specific examples of the measurement method shown in FIG. 4.

Referring to FIG. 5 a, a reference object 51 is loaded on the platform 50. Here, the reference object 51 may have a known thickness t1. Next, the reference point P of the measurement device 100 is set. The reference point P of the measurement device 100 can be set on the reflection surface S1 of the reference object 51. Next, the detection light L1 emitted from the light source 110 of the measurement device 100 and transmitted through the beam splitter 120 is focused by the light focusing unit 130 and then incident on the reflection surface S1 of the reference object 51. Then, the detection light L1 can be reflected on the reflecting surface S1, and the reflected light L2 is reflected by the beam splitter 120 and then incident on the light sensing part 140.

The light sensing part 140 including a Shack-Hartman sensor can detect a change in the light wave surface of the reflected light L2 reflected from the reflection surface S1 of the reference object 51. In FIG. 5a, there is shown a case where the light wave surface W of the reflected light L2 reflected from the reflection surface S1 of the reference object 51 and incident on the light sensing unit 140 becomes a plane wave surface as shown in FIG. 2a, so there is no reflected light L2 Light wave surface changes. As described above, the reflection surface S1 of the reference object 51 without a change in the light wave surface of the reflected light L2 may correspond to the reference surface serving as a reference for height measurement. Here, the height of the reference plane can be set to "0".

As described above, if there is no change in the light wave surface of the reflected light L2 reflected from the reflection surface S1 of the reference object 51, the coefficient value of the defocus term in the Zernike polynomial stored in the arithmetic unit 150 can be "0".

Next, the coefficient value of the defocus term corresponding to the vertical movement of the reference point P is measured. Here, the reference point P can be moved up and down by moving the reflection surface S1 of the reference object 51 up and down from the reference plane as shown in FIGS. 2b and 2c. Available with platform 50 This type of vertical movement of the reference point P is achieved by moving up and down with at least one of the measurement devices 100.

The light wave surface change of the reflected light L2 of the reference object 51 occurs as the reference point P moves up and down. After detecting the light wave surface change of the reflection surface S1 by the light sensing unit 140, the light wave surface change measurement and storage can be used. The coefficient value of the defocus term of the Zernike polynomial used in the arithmetic unit 150.

Specifically, if the reflection surface S1 of the reference object 51 moves upward from the reference plane as shown in FIG. 2b, the height of the reference point P has a “positive (+)” value. In this case, the reflection from the reference object 51 is The light wave surface W of the reflected light L2 reflected from the surface S1 becomes a convex shape and is detected by the light sensing unit 140. As described above, if the light wave surface of the reflected light L2 detected by the light sensing unit 140 becomes a convex shape, the Zernike polynomial of the light wave surface change of the reflected light L2 stored in the calculation unit 150 is represented by a formula. The coefficient of the defocus term may have a "positive (+)" value.

Next, if the reflection surface S1 of the reference object 51 moves downward from the reference plane as shown in FIG. 2c, the height of the reference point P has a "negative (-)" value. In this case, the reflection surface S1 of the reference object 51 The light wave surface of the reflected reflected light L2 becomes a concave shape and is detected by the light sensor 140. As described above, if the light wave surface W of the reflected light L2 detected by the light sensing section 140 becomes a concave shape, the coefficient of the defocus term in the Zernike polynomial stored in the arithmetic section 150 may have a "negative ( -)"value. On the other hand, the above description has been made of the case where the reflection surface S1 is set as the reference for the height measurement when the wave surface of the unreflected light L2 changes, that is, when the coefficient value of the defocus term is "0". surface. However, it is not limited to this, and may be The reflection surface S1 when the wavefront of the reflected light L2 changes, that is, when the coefficient value of the defocus term has a "positive (+)" value or a "negative (-)" value is set as a reference for height measurement. surface.

As described above, the change in the defocus term coefficient value caused by the vertical movement of the reference point P is calculated, and the correction data calculated in this way is stored in the arithmetic unit 150. In addition, the reference object 51 may be unloaded from the platform 50.

Referring to FIG. 5 b, a target object 55 to be measured is loaded on the platform 50. After the measurement device 100 moves to the position of the reference point P, the detection light L1 is emitted from the light source 110 and irradiates the target object 55. Here, the detection light L1 emitted from the light source 110 may be focused by the light focusing portion 130 after being transmitted through the beam splitter 120 and irradiated to the target object 55.

The light sensor 140 detects a light wave surface change of the reflected light L2 emitted from the reflection surface S2 of the target object 55. Specifically, the detection light L1 via the light focusing unit 130 is reflected on the reflection surface S2 of the target object 55, and the reflected light L2 is incident on the light sensing unit 140. Here, the reflected light L2 emitted from the reflection surface S2 of the target object 55 may be reflected by the beam splitter 120 through the light focusing portion 130 and then incident on the light sensing portion 140. The light sensing part 140 including a Shack-Hartman sensor can detect a change in the wavefront of the reflected light L2.

The change in height of the reflection surface S2 of the target object 55 is measured using a change in the reflected light L2 detected by the light sensing unit 140. Specifically, the light wave surface change of the reflected light L2 detected by the light sensing unit 140 is input to the calculation unit 150, and the calculation unit 150 calculates the dispersion of the Zernike polynomial using the light wave surface change of the reflected light L2. The coefficient value of the focal term. In addition, the height change Δh of the reflection surface S2 of the target object 55 can be measured by comparing the coefficient value of the defocus term calculated in this way with the correction data stored in the arithmetic unit 150. When the thickness t1 of the reference object 51 is added to the height change Δh of the reflection surface S2 of the target object 55 measured in this manner, the thickness t2 of the target object 55 can be measured.

6a and 6b are diagrams showing other examples of the measurement method shown in FIG. 4.

6a, the reference point P of the measurement device 100 is set. Here, the reference point P of the measurement device 100 can be set to the reflection surface S1 of the stage 50. Next, the detection light L1 emitted from the light source 110 and transmitted through the beam splitter 120 is focused by the light focusing portion 130 and then incident on the reflection surface S1 of the stage 50. In addition, the detection light L1 may be reflected on the reflecting surface S1, and the reflected light L2 is reflected by the beam splitter 120 and then incident on the light sensing unit 140.

The light sensing part 140 including a Shack-Hartman sensor may detect a change in the light wave surface of the reflected light L2 reflected from the reflection surface S1 of the platform 50. In FIG. 6a, it is shown that the light wave surface W of the reflected light L2 reflected from the reflection surface S1 of the platform 50 and incident on the light sensing unit 140 becomes a plane wave surface as shown in FIG. 2a. Light wave surface changes. As described above, the reflection surface S1 of the stage 50 where the light wave surface of the reflected light L2 does not change may correspond to a reference surface serving as a reference for height measurement. Here, the height of the reference plane can be set to "0". As described above, if there is no change in the light wave surface of the reflected light L2 reflected from the reflection surface S1 of the stage 50, the coefficient value of the defocus term in the Zernike polynomial stored in the arithmetic unit 150 can be "0".

Next, the coefficient of the defocus term corresponding to the up and down movement of the reference point P is measured. value. Here, the reference point P can be moved up and down by moving the reflection surface S1 of the platform 50 up and down from the reference plane as shown in FIG. 2b and FIG. 2c. The reference point P can be moved up and down by moving at least one of the stage 50 and the measurement device 100 up and down.

The light wave surface change of the reflected light L2 reflected on the reflection surface S1 of the stage 50 as the reference point P moves up and down. After the light wave surface change of the reflected light L2 is detected by the light sensing unit 140, the light wave can be used. The surface change measures the coefficient value of the defocus term of the Zernike polynomial stored in the calculation unit 150. Here, since the content of measuring the coefficient value of the defocus term corresponding to the up and down movement of the reference point P has been described in detail in the above embodiment, the description of the above content is omitted. As described above, the change in the defocus term coefficient value caused by the vertical movement of the reference point P is calculated, and the correction data obtained in this way is stored in the arithmetic unit.

On the other hand, the above description has been made of the case where the reflection surface S1 is set as the reference for the height measurement when the wave surface of the unreflected light L2 changes, that is, when the coefficient value of the defocus term is "0". surface. However, it is not limited to this, and the reflection in the case where the wave surface of the reflected light L2 is changed, that is, the reflection when the coefficient value of the defocus term has a "positive (+)" value or a "negative (-)" value The plane S1 is set as a reference plane that serves as a reference for height measurement.

6b, a target object 55 to be measured is mounted on the platform 50. After the measurement device 100 moves to the position of the reference point P, the detection light L1 is emitted from the light source 110 and irradiates the target object 55. Here, the detection light L1 emitted from the light source 110 may be focused by the light focusing portion 130 after being transmitted through the beam splitter 120 and irradiated to Target object 55.

The light sensor 140 detects a light wave surface change of the reflected light L2 emitted from the reflection surface S2 of the target object 55. Specifically, the detection light L1 via the light focusing unit 130 is reflected on the reflection surface S2 of the target object 55, and the reflected light L2 is incident on the light sensing unit 140. Here, the reflected light L2 emitted from the reflection surface S2 of the target object 55 may be reflected by the beam splitter 120 through the light focusing portion 130 and then incident on the light sensing portion 140. In addition, the light sensing part 140 including a Shack-Hartman sensor may detect a change in a light wave surface of the reflected light L2.

The change in height of the reflection surface S2 of the target object 55 is measured using a change in the reflected light L2 detected by the light sensing unit 140. Specifically, the light wave surface change of the reflected light L2 detected by the light sensing unit 140 is input to the calculation unit 150, and the calculation unit 150 calculates the coefficient of the defocus term of the Zernike polynomial using the light wave surface change of the reflected light. value. In addition, the height change Δh of the reflection surface S2 of the target object 55 can be measured by comparing the calculated coefficient value of the defocus term with the correction data stored in the calculation unit 150. Here, the height change Δh of the reflection surface S2 of the target object 55 may correspond to the thickness t of the target object.

As described above, the height change of the reflecting surface of the target object 55 can be measured by the light focusing unit 130 focusing the detection light L1 and irradiating the target object 55, including the light sense of the Shack-Hartmann sensor. The detection unit 140 detects a change in the light wave surface of the reflected light L2 reflected from the target object 55, and the calculation unit 150 calculates a coefficient value of the defocus term using the change in the light wave surface of the reflected light detected by the light detection unit 140. This makes it possible, for example, to efficiently and accurately measure a target object 55 such as a wafer or a plate-like object. Thickness or height. In addition, if the detection light L1 emitted from the light source 110 is scanned toward the target object 55, the shape of the target object 55 corresponding to the scan line or scan area can also be measured. In addition, the change in thickness or height measured by the light-sensing section 140 including a Shack-Hartman sensor is independent of the degree of inclination of the light-sensing section 140. Therefore, when the measuring device 100 is installed, the optical The light sensor 140 is arranged in a relatively easy manner.

The embodiments of the present invention have been described above, but the above embodiments are merely examples. Those skilled in the art should understand that various modifications and other equivalent embodiments can be implemented according to the above embodiments.

Claims (5)

A measuring method for measuring a change in thickness or height of a target object by using a measuring device including a light source, a light focusing section, a light sensing section, and a computing section. The light source emits detection light, and the light focusing section applies detection light to the detection light. Performing focusing, the light sensing unit includes a Shack-Hartman sensor that detects a change in reflected light, the computing unit calculates a change in height, and the measuring method includes: after setting a reference point of the measuring device And inputting the correction data corresponding to the upward and downward movement of the reference point to the computing unit includes: loading a reference object on the platform; setting the reference point of the measuring device on the reference object; A change in the defocus term coefficient value caused by the reference point moving up and down; and storing the correction data in the arithmetic unit, wherein the platform includes a reflection measurement beam and a reference surface that becomes a height measurement reference; loading on the platform The target object; irradiating the target object with the detection light emitted from the light source by the light focusing part; the light sensing part detecting from the object A change in the reflected light emitted from a reflection surface of the object; and the calculation unit calculates a change in height of the reflection surface using a change in the reflected light detected by the light sensing unit, wherein the correction The data includes changes in the defocus term coefficient value of the Zernike polynomial caused by the reference point moving up and down. The measuring method according to item 1 of the scope of application for a patent, wherein between the light source and the light focusing section is provided to transmit any one of the detection light and the reflected light and reflect the detection light and A beam splitter of the other of the reflected light. The measurement method according to item 1 of the scope of patent application, wherein the calculation section calculates the reflection surface using a Zernike polynomial that expresses a change in the reflected light detected by the light sensing section with a numerical expression. The height changes. The measuring method according to item 3 of the scope of patent application, wherein a change in the height of the reflecting surface corresponds to a change in a defocus term coefficient value of the Zernike polynomial. The measuring method according to item 3 of the scope of patent application, wherein measuring a change in a defocus term coefficient value caused by the reference point moving up and down includes: the light sensing unit detecting all the factors caused by the reference point moving up and down The light wave surface change of the reflected light; and the arithmetic unit determining a change in the defocus term coefficient value using the light wave surface change of the reflected light detected by the light sensing portion.