Stacked sheet surface deformation measuring device and method based on multi-contact micro-mirror

Abstract

The present application belongs to the technical field of surface three-dimensional topography measurement, and discloses a kind of based on the stacked sheet surface deformation measurement device and method of multi-contact microreflector.The measurement device includes light source, array mask, beam splitter, mirror, multi-contact microreflector and camera, beam splitter is set behind light source, array mask is set between light source and beam splitter, mirror and multi-contact microreflector are all set behind beam splitter, and the stacked sheet to be measured is set behind multi-contact microreflector;Array mask is used to distribute the light emitted by light source according to the distribution of mask array into multiple parallel incident light, and a light beam is used to detect the surface deformation of a single stacked sheet;The front end of multi-contact microreflector is provided with multiple microreflectors, and in the measurement process, a single microreflector is inserted between adjacent measured stacked sheets for detection.By the present application, the problem of simultaneous measurement of surface deformation of multiple stacked sheets in stacked sheet is solved.

Description

Technical Field

[0001] This invention belongs to the technical field of surface three-dimensional topography measurement, and more specifically, relates to a device and method for measuring the deformation of stacked sheet curved surfaces based on multi-touch micro-mirrors. Background Technology

[0002] Stacked wafers often have many layers, and under environmental stresses such as high temperature and pressure, they inevitably warp and bend. Over time, this significantly impacts device performance. Therefore, accurate measurement of the surface morphology changes of each wafer in the stack is crucial for real-time monitoring of device deformation and, consequently, predicting device lifespan. However, the spacing between stacked wafers is typically from a few micrometers to a few millimeters, making it difficult to measure such minute gaps using conventional techniques. Besides stacked wafers, this measurement challenge also exists for stacked metal sheets, laser-processed metal gaps, and multilayer materials—any object stacked with minute gaps presents this problem. Therefore, a high-precision, high-efficiency measurement device and surface morphology fitting method are needed to solve the measurement challenge of wafer gaps.

[0003] Currently, gap measurements in metallic materials generally employ the probe discharge method. This method relies on a click to move a probe with an applied DC voltage radially. The difference between the probe's travel distance and the initial installation gap is the gap distance. This method has significant measurement errors, a small measurement range, and is only suitable for conductive materials such as metals. However, for the widely used nanoscale measurements of gaps between stacked wafers ranging from a few micrometers to a few millimeters or even larger, existing conventional detection methods lack adequate measurement capabilities.

[0004] Therefore, a measurement system capable of accurately detecting the deformation of stacked wafers was developed. This system can efficiently and accurately measure and evaluate the deformation of stacked wafers. By using the measured data and algorithms, the surface morphology of each thin sheet in the stacked wafer can be fitted, which is beneficial for timely detection of morphological changes in the thin sheets in the stacked wafer, prediction of device performance and lifespan, and improvement of device utilization efficiency. Summary of the Invention

[0005] To address the above-mentioned deficiencies or improvement needs of existing technologies, this invention provides a device and method for measuring the surface deformation of stacked sheets based on multi-touch micro-mirrors, solving the problem of simultaneously measuring the surface deformation of multiple stacked sheets.

[0006] To achieve the above objectives, according to one aspect of the present invention, a device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors is provided. This device includes a light source, an array mask, a beam splitter, a mirror, multi-touch micromirrors, and a camera.

[0007] The beam splitter is located behind the light source, the array mask is located between the beam splitter and the light source, the reflector and the multi-touch micro-reflector are both located behind the beam splitter, and the stacked sheet under test is located behind the multi-touch micro-reflector.

[0008] The array mask is used to divide the light emitted by the light source into multiple parallel incident beams according to the distribution of the mask array. One beam of light is used to detect the surface deformation of a stack of sheets under test. The front end of the multi-touch micro-mirror is provided with multiple micro-mirrors. During the measurement process, a single micro-mirror extends into the space between adjacent stacks of sheets under test for detection. The distance between the micro-mirrors is set according to the gap between adjacent stacks of sheets under test.

[0009] The light emitted by the light source is split into several parallel beams by the pinhole array mask. For one of these parallel beams, the beam splitter separates it into two beams with different directions. One beam enters the reflector as a reference beam, and the other enters one of the micro-reflectors in the multi-touch micro-reflector array as a measurement beam. The measurement beam is reflected by the multi-touch micro-reflector array and illuminates the surface of the stack under test. The reflected beam returns to the beam splitter along the same path. At the same time, the reference beam is reflected by the reflector and enters the beam splitter. Both the reference beam and the measurement beam are reflected by the beam splitter and enter the camera to converge, thereby forming an interference pattern.

[0010] More preferably, the surface of the array mask has a linear array of pinholes, the distance between the pinhole arrays corresponding to the contact spacing of the multi-contact micromirrors.

[0011] More preferably, the multi-touch micromirror includes a substrate and a plurality of contacts disposed on the substrate, the substrate being made of a light-transmitting material, and the bottom surface of the contacts being attached to the surface of the substrate.

[0012] More preferably, the contact is a miniature right-angle prism, the hypotenuse of which is a micro-reflector. Light enters from the side of the substrate, enters the micro-reflector from the right-angle side of the miniature right-angle prism, is reflected by the micro-reflector and irradiates the surface of the stacked wafer under test, the reflected light after being reflected by the surface of the stacked wafer under test irradiates the micro-reflector, and then returns along the same path.

[0013] More preferably, the contact is a microchannel prism, which includes two microchannels. The connection between the two microchannels is a right-angled bevel, which is a micromirror. Light enters one of the microchannels from the bottom surface of the substrate, is reflected by the micromirror, enters the other channel, propagates in the other channel, and reaches the surface of the stack to be tested. The reflected light is then reflected by the surface of the stack to be tested and shines on the micromirror before returning along the same path.

[0014] More preferably, the substrate includes a clamping portion and a transition portion, the clamping portion being used to clamp the contact, the transition portion being used to connect the contact and the clamping portion, and a micro planar reflector being provided at the front end of the contact, the micro planar reflector being a micro reflector.

[0015] More preferably, the miniature planar reflector uses a brittle sheet material as the substrate, with a silver or aluminum film plated on the surface, and a silicon dioxide protective film attached to the surface of the silver or aluminum film, and the contact size is 1µm to 10mm.

[0016] More preferably, the stacked sheet to be tested is a stacked sheet-like object, including stacked semiconductor wafers, stacked metal sheets, or stacked chips.

[0017] More preferably, the measuring device further includes a first displacement stage, a second displacement stage, and a third displacement stage. The first displacement stage is disposed below the reflector and is used to adjust the position of the reflector. The second displacement stage is disposed below the multi-contact micro-reflector and is used to adjust the position of the multi-contact micro-reflector. The third displacement stage is used to place the stacked sheet to be tested, and the stacked sheet to be tested is rotated or moved by the rotation or movement of the third displacement stage.

[0018] According to another aspect of the present invention, a method for performing measurement using the above-described measuring device is provided, the method comprising the following steps:

[0019] S1 Adjust the positions of the reflector and the multi-touch micro-reflector to form multiple interference patterns in the camera; wherein each contact of the multi-touch micro-reflector is located between adjacent stacked sheets to be tested;

[0020] S2 Calculate the distance between the reflection point of the light in the multi-touch micro-mirror and the reflection point of the light on the surface of the stacked sheet to be tested, that is, the elevation value at the reflection point on the surface of the stacked sheet to be tested;

[0021] S3 Rotate the stacked sheet under test and record the rotation angle. Repeat steps S1 to S2 until the elevation values ​​of multiple reflection points on each surface of the stacked sheet under test are obtained.

[0022] S4 Using the elevation value of each reflection point and the rotation angle, fit all multiple reflection points to obtain the surface curve of the stacked sheet under test, and determine whether the surface of the stacked sheet under test has deformed based on the fitted surface.

[0023] In step S3, the tilt angle of the reflection point also needs to be calculated using the elevation value; the tilt angle of the reflection point is calculated according to the following formula:

[0024]

[0025] in, It is the distance in the camera used to calculate the deflection of the reflected light from the optical path relative to the reflected light from the reference optical path in the Y direction. , It is the distance from the point where the light beam is incident on the multi-touch micromirror to the reflection point of the stacked sheet under test. It is the sum of the distances between the multi-touch micromirrors and the beam splitter and the camera;

[0026] During the fitting process, the method used for fitting must be determined based on the tilt angle of the reflection point. If the tilt angle is less than the preset threshold, the two-dimensional Griddata interpolation algorithm is used for fitting; otherwise, the cubic polynomial fitting algorithm is used.

[0027] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0028] 1. In this invention, a pinhole array mask and a multi-touch micro-mirror are used together. The array mask is used to split the light into multiple beams. Each beam forms an individual interference pattern after passing through the beam splitter mirror and a single micro-mirror in the multi-touch micro-mirror. Multiple parallel beams can simultaneously measure the surfaces of multiple stacked sheets under test, realizing simultaneous measurement of multiple surfaces under test and improving measurement efficiency.

[0029] 2. The stacked sheets to be measured in this invention have narrow gaps, generally between a few micrometers and a few millimeters. Existing gap measurements mainly rely on mechanical probe conductivity measurements, which are very limited in measurement scenarios. This invention is based on the principle of optical measurement and collects the reflected light data of the stacked sheets through multi-touch micro-mirrors to obtain the deformation of the stacked sheets. It has high measurement accuracy and strong applicability.

[0030] 3. The size of the micro-reflector contacts in the multi-contact micro-reflector of the present invention is generally 1µm to 10mm. This size is designed according to the gap between the stacked sheets to be tested, adapting to the measurement requirements of different gap distances between the stacked sheets. It corresponds to the design of the pinhole array mask, so that the parallel light emitted can be accurately incident on the contacts in each multi-contact micro-reflector, thereby measuring the surface deformation of each stacked sheet to be tested in the stacked sheets. When facing the measurement requirements of stacked sheets with different gaps, the measuring device only needs to replace the pinhole array mask and multi-contact micro-reflector with the corresponding stacked sheet gap size, which increases the application range of the measuring device and improves the efficiency of the measuring device.

[0031] 4. The measurement method of the present invention is based on the principle of interference. The elevation and angle data of multiple measurement points on each sheet in the stack can be obtained by simply operating the measuring device. The deformation of the stack can be obtained by using the two-dimensional Griddata interpolation algorithm and the cubic polynomial fitting algorithm. The measurement method is simple and reliable, the accuracy is guaranteed, and the repeatability is high. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a device for measuring the deformation of stacked sheet surfaces constructed according to a preferred embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram illustrating the tilt angle measurement principle of the stacked sheet reflection point constructed according to a preferred embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of a multi-touch micromirror constructed according to a preferred embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure of a multi-touch micromirror constructed according to another preferred embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the structure of a multi-touch micromirror constructed according to another preferred embodiment of the present invention;

[0037] Figure 6 This is a fitting result diagram of the sheet torsional bending deformation surface constructed according to a preferred embodiment of the present invention;

[0038] Figure 7 This is a fitting result diagram of the concave-convex bending deformation surface of a thin sheet constructed according to a preferred embodiment of the present invention.

[0039] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0040] 1-Light source, 2-Array mask, 3-Brightness splitter, 4-First displacement stage, 5-Reflector, 6-Reference optical path, 7-Camera, 8-Second displacement stage, 9-Multi-touch micro-reflector, 10-Measurement optical path, 11-Stacked sheet under test, 12-Third displacement stage, 13-Clamping part, 14-Contact, 15-Transition part, 16-Substrate, 17-Micro-reflector, 18-Single stacked sheet, 19-Reflection point, 20-Tangent of reflection point on stacked sheet, 21-Camera display screen, 22-Beam reflected from reference optical path into camera, 23-Beam reflected from measurement optical path into camera. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0042] like Figure 1 As shown, a measuring device for the gap between stacked wafers includes: a light source 1, a pinhole array mask 2, a beam splitter 3, a first displacement stage 4, a reflector 5, a second displacement stage 8, and a multi-touch micro-reflector 9.

[0043] Beam splitter 3 connects reference optical path 6 and measurement optical path 10. Reference optical path 6 is located in the direction of the reflected light path of beam splitter 3, and measurement optical path 10 is located in the direction of the transmitted light path of beam splitter 3. A first displacement stage 4 is mounted on reference optical path 6, and a reflector 5 is mounted on the first displacement stage 4. The reflector 5 reflects the light source 1 from reference optical path 6 into beam splitter 3. A second displacement stage 8 is mounted on measurement optical path 10, and a multi-touch micro-reflector 9 is mounted on the second displacement stage 8. The multi-touch micro-reflector 9 reflects the light source 1 from measurement optical path 10 onto the stacked wafer and reflects the reflected light from the stacked wafer into beam splitter 3. The stacked wafer 11 to be tested is placed on a third displacement stage 12, and the rotation of the third displacement stage causes the stacked wafer to rotate.

[0044] The multi-touch micromirror 9 can measure the interference signal from the micromirror to the wafer. Especially when the spacing between stacked wafers is typically a few micrometers to a few millimeters, the structure of the multi-touch micromirror 9 of this invention can efficiently and accurately measure the deformation of each wafer in the stack.

[0045] The surface of the array mask 2 has a linear array of pinholes, and the distance between the pinhole arrays corresponds to the contact spacing of the multi-contact micromirrors.

[0046] The multi-contact micromirror 9 includes a substrate 16 and multiple contacts, with the bottom surface of each contact attached to the substrate 16.

[0047] like Figure 3 As shown, in one embodiment of the present invention, the substrate 16 includes a clamping portion 13 and a transition portion 15. The clamping portion 13 is used to clamp the contact, and the transition portion 15 is used to connect the contact and the clamping portion. The transition portion 15 prevents the metal substrate 16 from bending excessively. A miniature planar reflector is provided at the front end of the contact 14. The clamping portion 13 of the sheet-like silver-plated planar multi-contact micro-reflector 9 is fixed in the measurement optical path 10 by a fixture. The contact 14 extends into the gap between the stacked sheets, and the transition portion 15 prevents the metal substrate 16 from bending excessively.

[0048] The front end of the contact is provided with a micro-reflector 17, which is a miniature plane mirror. The sheet-like silver-plated plane mirror of the miniature plane mirror is based on a brittle sheet material such as metal or glass, and the surface is coated with a silver film or an aluminum film. A layer of silicon dioxide protective film is attached to the surface of the silver film or aluminum film.

[0049] like Figure 4 As shown, in another embodiment of the present invention, the substrate 16 is made of a light-transmitting material, such as a glass substrate. The substrate 16 of the multi-contact micro-reflector 9 with a micro-right-angle prism array is fixed in the measurement optical path 10 by a clamp, and the micro-right-angle prism array extends into the gap between the stacked sheets. The contact is a micro-right-angle prism, and the hypotenuse of the micro-right-angle prism is a micro-reflector 17. Light enters from the side of the substrate 16, enters the micro-reflector from the right-angle side of the micro-right-angle prism, is reflected by the micro-reflector and illuminates the surface of the stacked sheet under test. The reflected light after being reflected by the surface of the stacked sheet under test illuminates the micro-reflector and then returns along the same path.

[0050] The micro right-angle prism array is made of photoresist silicon oxide material, etc. The micro right-angle prism is a right-angled triangular prism with a right-angle side size of 1um to 10mm, which is fabricated on a glass substrate 16 using photolithography or two-photon polymerization printing technology.

[0051] like Figure 5 As shown, in another embodiment of the present invention, the substrate 16 is made of a light-transmitting material, such as a glass substrate, and the contact is a microchannel prism. The microchannel prism includes two microchannels, and the connection between the two channels is a right-angled bevel, which is a micro-reflector 17. The microchannel prism 18 extends vertically into the gap between the stacked sheets. The light beam is incident from the back of the substrate 16, and undergoes total internal reflection in the right-angled bevel of the microchannel prism 18, reaching the stacked sheet under test. The light beam is then reflected again from the stacked sheet under test onto the right-angled bevel of the microchannel prism 18 and reflected back, thereby obtaining the surface information of the stacked sheet under test.

[0052] Micro-channel prism arrays with individual sizes ranging from 1µm to 10mm, along with photoresist silicon oxide and other materials, are fabricated on a substrate using two-photon polymerization printing technology.

[0053] The measurement object of this invention is a stacked sheet-like object, including but not limited to stacked semiconductor wafers, stacked metal sheets, stacked chips, etc.

[0054] As a preferred embodiment of the present invention, light source 1 is a parallel light source, or it may include multiple light sources and multiple lenses adjusted to be parallel light.

[0055] As a preferred embodiment of the present invention, the measuring device further includes an observation camera, which is positioned in the opposite direction to the reference optical path 6. In actual testing, the device also includes a controller and a processing terminal, with one end of the controller connected to the third displacement stage 12 and the other end connected to the processing terminal.

[0056] As a preferred embodiment of the present invention, Figure 1 The measuring device also features a light-shielding enclosure that surrounds all components outside the wafer box, preventing external light from affecting the measurement results.

[0057] exist Figure 1 The device also includes a stacking wafer box, in which the wafer to be tested is placed when testing stacked wafers. The stacking wafer box is only used as a measuring device to test its measurement performance. In actual application of the measuring device, the object being tested is an indivisible finished stacked wafer such as a stacked chip.

[0058] like Figure 2 As shown, the measurement principle of this invention is as follows:

[0059] A schematic diagram of the tilt angle measurement between the single stacked plate 18 below the multi-touch micromirror and the single stacked plate 18 above the multi-touch micromirror. The angle between the reflection point 19 on the stacked sheet 18 below the multi-touch micromirror, the tangent 20 on the stacked sheet, and the horizontal plane is shown in the figure. Required parameters: shown on camera display screen 21, The distance in the Y direction offset of the light beam 23 reflected from the reference light path to the camera 7 relative to the light beam 22 reflected from the reference light path to the camera. The distance between the reflection point in the multi-contact micromirror 9 and the reflection point on the single stacked plate 18 below the multi-contact micromirror (elevation data of the reflection point). The sum of the distances between the multi-touch micromirror 9, the beam splitter 3, and the camera 7. .

[0060] Figure 6 It is to utilize Figure 1 The fitting result of the torsional bending deformation surface of the thin sheet obtained from the data measured by the device is used. Figure 1 The device for measuring the gap between stacked sheets measures the elevation data of 6 points on the edges of two adjacent thin sheets in the stacked sheets, and uses the two-dimensional Griddata interpolation algorithm to fit the torsional bending deformation surface of the thin sheets.

[0061] Figure 7 It is to utilize Figure 1 The fitting result of the thin sheet's concave-convex bending deformation surface obtained from the data measured by the device is used. Figure 1The device for measuring the gap between stacked sheets measures the elevation data and tilt angle of eight points on the edges of two adjacent thin sheets in the stacked sheets, and uses a cubic polynomial fitting algorithm to fit the concave-convex bending deformation surface of the thin sheet.

[0062] A second aspect of the invention provides a method for measuring the gap between stacked wafers, the method comprising:

[0063] S1 Adjust the first displacement stage and the second displacement stage respectively so that the distance between the reflector and the multi-touch micro-reflector and the beam splitter is equal. At this time, the position of the first displacement stage is taken as the initial position.

[0064] S2 Adjust the position of the third displacement stage so that the multi-touch micro-reflector is placed above the stacked sheet to be tested, and the camera generates multiple interference patterns for measuring the stacked sheet;

[0065] S3. Adjust the position of the first displacement stage. Multiple interference pattern signals are obtained from the camera. The distance between the multi-touch micromirror and the reflection point on the surface of the stacked wafer under test is calculated, i.e., the elevation value at the reflection point on the surface of the stacked wafer under test. Repeat the above steps to find the elevation value of each reflection point on the surface of the stacked wafer. The elevation value is calculated using existing interference principles, which will not be elaborated here.

[0066] S4 Rotate the third displacement stage and record the rotation angle. Repeat steps S1 to S3 until the elevation values ​​of multiple reflection points on the surface of each stacked sheet to be tested are obtained.

[0067] S5 uses the elevation value of each reflection point and the rotation angle of the third displacement stage to fit all reflection points to obtain the surface curve of the stacked sheet under test, and determines whether the surface of the stacked sheet under test has been deformed based on the fitted surface.

[0068] In step S3, the tilt angle of the reflection point also needs to be calculated using the elevation value. The tilt angle of the reflection point is calculated according to the following formula:

[0069]

[0070] Furthermore, during the fitting process, the method used for fitting needs to be determined based on the tilt angle of the reflection point. If the tilt angle is less than a preset threshold, the two-dimensional Griddata interpolation algorithm is used for fitting; otherwise, the cubic polynomial fitting algorithm is used.

[0071] The device provided by this invention utilizes a multi-touch micro-mirror 9, which is mounted on a second displacement stage. This allows the device to reflect the light source 1 on the measurement optical path 10 onto the stacked wafer under test via the multi-touch micro-mirror 9, and to reflect the reflected light from the stacked wafer under test into the beam splitter 3. By adjusting the first displacement stage 4 in the reference optical path 6 to change the optical path, multiple interference patterns containing wafer gap distance information are acquired in the observation camera. By adjusting the orientation of the stacked wafer under test, edge point data of multiple wafer gaps can be measured, and a fitting algorithm can be used to fit the bending deformation of the stacked wafer.

[0072] The measuring device of the present invention includes a second displacement stage, which is located in the X direction of the measuring optical path 10 and does not interfere with the positional relationship of other components on the measuring optical path 10. This second displacement stage is used to adjust the position and orientation of the measuring optical path 10. Therefore, especially during the device debugging phase, the second displacement stage allows for more convenient fine-tuning of the position of the measuring optical path 10, enabling the light source 1 exiting the beam splitter 3 to be aligned with the multi-touch micromirror 9.

[0073] Based on the measuring device of this invention, the measuring principle is as follows: Incoherent light emitted from light source 1 is converted into several parallel beams by a pinhole array mask. The parallel beams are then split into two beams by beam splitter 3. One beam is incident on reference optical path 6, where a first displacement stage 4 equipped with a reflector 5 reflects the beam. The other beam is incident on measurement optical path 10, where a multi-touch micro-reflector 9 and a stacked sheet reflect the beam back. The reflected light from reference optical path 6 and measurement optical path 10 is again split by beam splitter 3, ultimately forming observable interference fringes in the camera. When light source 1 is turned on, the displacement stage of measurement optical path 10 is adjusted so that light source 1 in measurement optical path 10 is incident on the multi-touch micro-reflector 9. Simultaneously, the displacement of the first displacement stage 4 of reference optical path 6 is adjusted, and the light reflected from measurement optical path 10 forms multiple interference patterns on the camera. A computer program controls the reference optical path 6, the first displacement stage 4, and the observation camera. As the first displacement stage 4 moves slowly and uniformly, the interference light intensity of the observation camera is measured at regular intervals. The wafer gap is monitored and observed by measuring the changes in interference light intensity. All component control can be performed by the computer. The light intensity data is converted into corresponding displacement data, and the wafer gap measurement results are obtained based on the analysis and evaluation of the displacement data.

[0074] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors, characterized in that, The measuring device includes a light source (1), an array mask (2), a beam splitter (3), a reflector (5), a multi-touch micromirror (9), and a camera (7), wherein, The beam splitter (3) is located behind the light source (1), the array mask (2) is located between the beam splitter (3) and the light source (1), the reflector (5) and the multi-touch micro-reflector (9) are both located behind the beam splitter (3), and the stacked sheet to be tested (11) is located behind the multi-touch micro-reflector (9); The array mask (2) is used to divide the light emitted by the light source into multiple parallel incident light beams according to the distribution of the mask array. One beam of light is used to detect the surface deformation of a single stacked sheet. The front end of the multi-touch micro-reflector (9) is provided with multiple micro-reflectors. During the measurement process, a single micro-reflector extends into the space between adjacent stacked sheets to be tested for detection. The distance between the micro-reflectors is set according to the gap between adjacent stacked sheets in the stacked sheet to be tested. The light emitted by the light source (1) is split into several parallel beams by the array mask (2). For one of the parallel beams, the beam is split into two beams with different directions by the beam splitter (3). One beam enters the reflector (5) as a reference beam, and the other beam enters one of the micro-reflectors in the multi-touch micro-reflector (9) as a measurement beam. The measurement beam is reflected by the multi-touch micro-reflector (9) and shines on the surface of the stack to be tested. The reflected beam returns to the beam splitter (3) along the original path. At the same time, the reference beam is reflected by the reflector (5) and enters the beam splitter (3). The reference beam and the measurement beam are both reflected by the beam splitter (3) and enter the camera (7) to merge, thereby forming an interference pattern.

2. The device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors as described in claim 1, characterized in that, The surface of the array mask (2) has a linear array of pinholes, and the distance between the pinhole arrays corresponds to the contact spacing of the multi-touch micromirror (9).

3. The device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors as described in claim 1 or 2, characterized in that, The multi-touch micromirror (9) includes a substrate (16) and a plurality of contacts (14) disposed on the substrate (16). The substrate (16) is made of a light-transmitting material, and the bottom surface of the contacts (14) is attached to the surface of the substrate (16).

4. The device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors as described in claim 3, characterized in that, The contact (14) is a miniature right-angle prism, and the hypotenuse of the miniature right-angle prism is a micro-reflector (17). Light enters from the side of the substrate (16), enters the micro-reflector (17) from the right-angle side of the miniature right-angle prism, and is reflected by the micro-reflector (17) onto the surface of the stack to be tested. The reflected light after being reflected by the surface of the stack to be tested illuminates the micro-reflector (17) and then returns along the same path.

5. The device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors as described in claim 3, characterized in that, The contact (14) is a microchannel prism, which includes two microchannels. The connection between the two channels is a right-angled bevel, which is a micro-reflector (17). Light enters one of the microchannels from the bottom surface of the substrate (16), is reflected by the micro-reflector (17), enters the other channel, propagates in the other channel, and reaches the surface of the stack to be tested. The reflected light after being reflected by the surface of the stack to be tested shines on the micro-reflector (17) and then returns along the same path.

6. The device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors as described in claim 3, characterized in that, The substrate (16) includes a clamping portion and a transition portion. The clamping portion is used to clamp the contact (14), and the transition portion is used to connect the contact (14) and the clamping portion. A micro planar reflector is provided at the front end of the contact (14), which is a micro reflector (17).

7. The device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors as described in claim 6, characterized in that, The micro planar reflector is based on a brittle sheet material, with a silver or aluminum film plated on the surface. A layer of silicon dioxide protective film is attached to the surface of the silver or aluminum film, and the contact (14) has a size of 1um to 10mm.

8. A device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors as described in claim 1 or 2, characterized in that, The stacked sheet to be tested (11) is a stacked sheet-like object, including stacked semiconductor wafers, stacked metal sheets or stacked chips.

9. A device for measuring the deformation of stacked sheet surfaces based on multi-touch micromirrors as described in claim 1 or 2, characterized in that, The measuring device also includes a first displacement stage (4), a second displacement stage (8), and a third displacement stage (12). The first displacement stage (4) is located below the reflector (5) and is used to adjust the position of the reflector (5). The second displacement stage (8) is located below the multi-touch micro-reflector (9) and is used to adjust the position of the multi-touch micro-reflector (9). The third displacement stage (12) is used to place the stacked sheet to be tested. The stacked sheet to be tested is rotated or moved by the rotation or movement of the third displacement stage.

10. A method for measuring using the measuring device according to any one of claims 1-9, characterized in that, The method includes the following steps: S1 Adjust the positions of the reflector and the multi-touch micro-reflector to form multiple interference patterns in the camera; wherein each contact of the multi-touch micro-reflector is located between adjacent stacked sheets to be tested; S2 Calculate the distance between the reflection point of the light in the multi-touch micro-mirror and the reflection point of the light on the surface of the stacked sheet to be tested, that is, the elevation value at the reflection point on the surface of the stacked sheet to be tested; S3 Rotate the stacked sheet under test and record the rotation angle. Repeat steps S1 to S2 until the elevation values ​​of multiple reflection points on each surface of the stacked sheet under test are obtained. S4 Using the elevation value of each reflection point and the rotation angle, fit all multiple reflection points to obtain the surface curve of the stacked sheet under test, and determine whether the surface of the stacked sheet under test has deformed based on the fitted surface. In step S3, the tilt angle of the reflection point also needs to be calculated using the elevation value; the tilt angle of the reflection point is calculated according to the following formula: in, It is the distance in the camera used to calculate the deflection of the reflected light from the optical path relative to the reflected light from the reference optical path in the Y direction. , It is the distance from the point where the light beam is incident on the multi-touch micromirror to the reflection point of the stacked sheet under test. It is the sum of the distances between the multi-touch micromirrors and the beam splitter and the camera; During the fitting process, the method used for fitting must be determined based on the tilt angle of the reflection point. If the tilt angle is less than the preset threshold, the two-dimensional Griddata interpolation algorithm is used for fitting; otherwise, the cubic polynomial fitting algorithm is used.

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