Measurement apparatus and method for measuring deformation and surface microstructure of stacked sheet

Abstract

The present invention belongs to the technical field of morphology measurement. Disclosed are a measurement apparatus and method for measuring the deformation and surface microstructure of a stacked sheet. The measurement apparatus comprises a light source, a collimating lens, a light splitter, an objective lens, an optical path difference compensation glass plate, a reflecting mirror, a displacement stage, a beam steering micro device, a tube lens and a camera. During a measurement process, the light splitter splits light in the light source into transmitted light and refracted light, the transmitted light passes through the beam steering micro device, extends between adjacent stacked sheets to be measured, and then becomes measurement light, the measurement light is reflected to the surfaces of the stacked sheets, the optical path difference compensation glass plate is used for compensating for an optical path difference generated by the measurement light passing through the beam steering micro device, the reflecting mirror is used for reflecting the refracted light from the light splitter as reference light into the tube lens, and the tube lens is used for converging the reference light and the measurement light to form an interference information pattern in the camera. By means of the measurement method in the present invention, the problem of it being difficult to accurately measure the curved surface deformation of the surface of each layer of thin sheet in a stacked sheet and the morphology of the surface microstructure of the stacked sheet can be solved.

Description

A measuring device and method for measuring deformation and surface microstructure of stacked sheets

Technical field

[0001] The present invention belongs to the technical field of topography measurement, and more specifically, relates to a device and method for measuring the deformation and surface microstructure of a stacked sheet. [Background Technology]

[0002] With the rapid advancement of materials science and engineering, stacked-sheet structures are increasingly being used in fields such as microelectronics and optical components. However, existing measurement techniques are often limited to surface measurements, making it difficult to meet the demand for high-precision measurement of interlayer deformation in stacked sheets. In particular, there is currently no comprehensive method for accurately measuring the overall deformation of each sheet in a stack, the surface microstructure of the sheet, and the three-dimensional topography of the sidewalls of gaps in structures with gaps.

[0003] Traditional measurement methods such as laser interferometry, white light interferometry, laser confocal microscopy, spectral confocal microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM) have limitations in surface measurement because they are often unable to penetrate deep into the internal layers of stacked sheets for accurate measurement. Traditional methods are even more difficult to measure the three-dimensional topography of thin surface microstructures and the three-dimensional topography of the sidewalls of gaps in structures with gaps.

[0004] Therefore, a new technology is urgently needed to achieve comprehensive and accurate measurement of the overall deformation of each layer of thin sheets in the stacked sheets, the surface microstructure of the thin sheets, and the three-dimensional morphology of the side walls of the gaps in the gap structure.

[0005] [Summary of the invention]

[0006] In response to the deficiencies of the prior art, the present invention provides a device and method for measuring the deformation of stacked sheets and the three-dimensional morphology of the microstructure on the sheet, which solves the problems of measuring the surface deformation of thin sheets in the stacked sheets and the three-dimensional morphology of the microstructure on the thin sheets.

[0007] To achieve the above objectives, according to a first aspect of the present invention, a measuring device for measuring deformation and surface microstructure of a stacked sheet is provided, characterized in that it includes a beam splitter, wherein the refracted light path of the beam splitter passes through a first surface of the beam splitter and a surface opposite the first surface, and the transmitted light path of the beam splitter passes through a second surface of the beam splitter and a surface opposite the second surface, wherein the first surface and the second surface are not opposite to each other;

[0008] and, a first objective lens, a first translation stage, a reflector, and a tube lens and a camera arranged in sequence at a rear end of a first surface opposite to the first surface of the beam splitter, wherein the first translation stage is used to load and drive the reflector to move;

[0009] and a light source and a collimating lens sequentially arranged at the front end of the second surface of the beam splitter, and a second objective lens, a beam steering micro-device, and a second displacement platform sequentially arranged at the rear end of the opposite surface of the second surface of the beam splitter, wherein the second displacement platform is used to load and drive the displacement and rotation of the stacked sheets to be measured, and the beam steering micro-device is used to extend between adjacent stacked sheets to be measured during the measurement process;

[0010] The refraction optical path and the transmission optical path are used as the reference optical path and the measurement optical path of the measuring device respectively, and the tube lens is used to merge the reference light and the measurement light in the reference optical path and the measurement optical path to form an interference information pattern in the camera.

[0011] According to one embodiment of the present invention, the measuring optical path is perpendicular to the reference optical path.

[0012] According to one embodiment of the present invention, a glass sheet for compensating for optical path difference is further provided between the first objective lens and the first translation stage, and the glass sheet for compensating for optical path difference is used to compensate for the optical path difference generated when the measuring light passes through the beam steering micro-device.

[0013] According to one embodiment of the present invention, the light beam steering micro-device is a micro-mirror or a micro-prism, and the size of the micro-mirror or micro-prism is 1-10000 microns.

[0014] According to one embodiment of the present invention, the stacked sheets to be tested are stacked sheet-like objects or structures with gaps, including stacked semiconductor wafers, stacked metal sheets, stacked chips, and structures with grooves or gaps.

[0015] According to one embodiment of the present invention, the camera is a CMOS camera or a CCD camera.

[0016] According to one embodiment of the present invention, the measuring device further comprises a light shielding box, and the spectrometer is located in the middle of the light shielding box.

[0017] According to another aspect of the present invention, the present invention also provides a method for measuring the deformation and surface microstructure of a stacked sheet using the above-mentioned measuring device, the method comprising the following steps:

[0018] S1: adjusting the positions of the reflector and the stacked sheets to be tested so that they are respectively located within the effective working distances of the first objective lens and the second objective lens, and controlling the light beam steering micro-device to extend between adjacent stacked sheets to be tested;

[0019] S2: Controlling the first translation stage to drive the reflective mirror to move, observing the interference fringes of the microstructure on the surface of the stacked sheet through the camera, and collecting all the interference information patterns of the microstructure on the surface of the stacked sheet;

[0020] S3: Using the interference information pattern collected in S2, the three-dimensional morphology information of the surface microstructure of the stacked sheet is calculated;

[0021] Alternatively, the height variation of a plurality of edge points on a single sheet in the stack is measured, and a deformation pattern of the entire single sheet in the stack is fitted based on the height variation.

[0022] According to one embodiment of the present invention, step S3 includes:

[0023] S3.1: Recording the movement distance of the first translation stage corresponding to the maximum light intensity at each pixel in the interference information pattern, and summarizing and reconstructing the movement distances to obtain initial three-dimensional topography information of the stacked sheet surface microstructure;

[0024] S3.2: Optimize the initial three-dimensional morphology information using at least one algorithm selected from the group consisting of a direct solution method, a phase shift method, and an envelope curve fitting method to obtain final three-dimensional morphology information of the surface microstructure of the stacked sheet.

[0025] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0026] 1. The measuring device of the present invention is based on the principle of optical measurement. It collects reflected light data from the surface of the stacked sheet through a beam steering micro-device to obtain the deformation of the stacked sheet and the three-dimensional morphology of the microstructure on the sheet. Compared with the traditional mechanical probe measurement method, it has higher measurement accuracy and wider application measurement scenarios. It not only solves the limitations of traditional measurement methods in interlayer measurement, but also provides a new and efficient means for the in-depth research and application of stacked sheets and other micro-nano structures, which has important practicality and promotion value.

[0027] 2. The beam steering micro-device of the present invention has a small size. During the measurement process, the beam steering micro-device is extended between adjacent stacked sheets to be measured so that the measuring beam is accurately reflected to the measuring area, thereby completely and accurately mapping the three-dimensional morphology and height changes of the microstructure on the surface of the stacked sheets.

[0028] 3. Since an optical path difference is generated between the reference light and the measurement light when the light beam passes through the beam steering microdevice, the present invention provides an optical path difference compensation glass sheet between the first objective lens and the first translation stage to compensate for the optical path difference generated by the light beam passing through the beam steering microdevice. This can cause the reference light path and the measurement light path to produce a clear interference pattern in the camera, thereby obtaining precise measurement data and ensuring accurate measurement results.

Brief Description of the Drawings

[0029] 1 is a schematic diagram of a measuring device for measuring deformation and surface microstructure of a stacked sheet constructed according to an embodiment of the present invention;

[0030] FIG2 is an observation diagram of the surface microstructure of the stacked sheet obtained by a measuring device provided in an embodiment of the present invention under an optical microscope;

[0031] FIG3 is a diagram showing the measurement results of the surface microstructure and cross-sectional height of a stacked sheet constructed according to an embodiment of the present invention;

[0032] FIG4 is a diagram showing measurement results of a thin sheet deformation surface in a stacked sheet constructed according to an embodiment of the present invention.

[0033] Figure numerals: 1. light source, 2. collimating lens, 3. spectrometer, 4. first objective lens, 5. glass plate for compensating optical path difference, 6. first translation stage, 7. reflecting mirror, 8. reference optical path, 9. second objective lens, 10. beam steering microdevice, 11. stacked plate, 12. measuring optical path, 13. tube lens, 14. camera, 15. second translation stage. [Specific implementation method]

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is 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 for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0035] The measurement object in the present invention is a stacked sheet object or a structure with a gap, including but not limited to stacked semiconductor wafers, stacked metal sheets, stacked chips, structures with grooves or gaps, etc.

[0036] As shown in Figure 1, a device for measuring the deformation of a stacked wafer and the three-dimensional topography of on-chip microstructures includes: a light source 1, a collimating lens 2, a beam splitter 3, an objective lens 4, a glass sheet 5 for compensating for optical path difference, a translation stage 6, a reflector 7, a beam steering microdevice 10, a tube lens 13, a camera 14, and a second translation stage 15.

[0037] The spectrometer 3 is used to connect the reference optical path 8 and the measurement optical path 12. The reference optical path 8 is located in the direction of the refractive optical path of the spectrometer 3, and the measurement optical path 12 is located in the direction of the transmitted optical path of the spectrometer 3. The reference optical path 8 is provided with a first objective lens 4, a glass plate 5 for compensating optical path difference, a first translation stage 6, and a reflector 7. The first translation stage 6 is equipped with a reflector 7, which is used to reflect the light on the reference optical path 8 into the spectrometer 3. The measurement optical path 12 is provided with a second objective lens 9, a beam steering micro-device 10, and a stacked plate 11. The beam steering micro-device 10 is used to reflect the light on the measurement optical path 12 onto the stacked plate, and to reflect the reflected light from the stacked plate into the spectrometer 3. The stacked plate 11 to be measured is placed on a second translation stage 15, and the rotation of the second translation stage 15 drives the stacked plate to be measured to move or rotate.

[0038] The beam steering microdevice 10 can transmit interference signals to the thin slices. Especially when the spacing between stacked slices is typically a few microns to a few centimeters, the measurement device of this embodiment can efficiently and accurately measure the deformation of the slices in the stack and the three-dimensional morphology of the microstructures on the slices.

[0039] The thickness and refractive index of the optical path difference compensating glass sheet 5 should correspond to the optical path difference generated by the light beam passing through the beam steering microdevice, ΔL=n×d, where ΔL is the optical path difference generated by the beam steering microdevice, and n and d are the refractive index and thickness of the optical path difference compensating glass sheet 5, respectively.

[0040] In this embodiment, the micro-mirror is formed by 3D printing with two-photon polymer glue and has a size of 10 microns.

[0041] In this embodiment, the measuring device further includes another observation camera, which is arranged in the opposite direction of the reference light path 8. In actual testing, the measuring device further includes a controller and a processing terminal.

[0042] In this embodiment, the measuring device further comprises a peripheral light-shielding box, which surrounds all components of the measuring device to prevent external light from affecting the measurement results.

[0043] The measurement method of this embodiment is as follows:

[0044] S1: adjusting the positions of the reflector and the stacked sheets to be tested so that they are respectively located within the effective working distances of the first objective lens and the second objective lens, and controlling the light beam steering micro-device to extend between adjacent stacked sheets to be tested;

[0045] S2: Controlling the first translation stage to drive the reflective mirror to move, observing the interference fringes of the microstructure on the surface of the stacked sheet through the camera, and collecting all the interference information patterns of the microstructure on the surface of the stacked sheet;

[0046] S3.1: Record the movement distance of the first translation stage corresponding to the maximum light intensity at each pixel in the interference information pattern in S2, and aggregate the movement distances to obtain initial three-dimensional topography information of the stacked sheet surface microstructure;

[0047] S3.2: Correcting the initial three-dimensional topography information using a direct solution method, a phase shift method, and an envelope curve fitting method to obtain final three-dimensional topography information of the stacked sheet surface microstructure;

[0048] S3.3: Measure the height changes of multiple edge points of a single sheet in the stack, and use a fitting algorithm to fit the overall deformation pattern of the single sheet in the stack according to the height changes.

[0049] In this embodiment, the effective working distance of the first objective lens and the second objective lens is not less than half the length of the light shielding box.

[0050] The results of optical microscope observation of the microstructure on the thin slices in the stacked sheet of this embodiment are shown in Figure 2. Using the measurement device shown in Figure 1, the three-dimensional morphology and cross-sectional height of the microstructure on the stacked sheet are obtained through step S3, as shown in Figure 3. The deformation surface measurement results of the thin slices in the stacked sheet, obtained through step S4, are shown in Figure 4, demonstrating the feasibility of this measurement device.

[0051] It will be easily understood by those skilled in the art 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 in the scope of protection of the present invention.

Claims

1. A measuring device for measuring the deformation and surface microstructure of stacked sheets, characterized in that, Comprising a beam splitter, wherein the refraction optical path of the beam splitter penetrates through the first surface of the beam splitter and the opposite surface of the first surface, and the transmission optical path of the beam splitter penetrates through the second surface of the beam splitter and the opposite surface of the second surface, and the first surface and the second surface are not opposite surfaces of each other; And a first objective lens, a first displacement stage, a reflector arranged successively at the front end of the first surface of the beam splitter, and a tube lens and a camera arranged successively at the rear end of the opposite surface of the first surface of the beam splitter, wherein the first displacement stage is used for loading and driving the reflector to displace; And a light source, a collimating lens arranged successively at the front end of the second surface of the beam splitter, and a second objective lens, a beam steering micro-device and a second displacement platform arranged successively at the rear end of the opposite surface of the second surface of the beam splitter, wherein the second displacement stage is used for loading and driving the stack of wafers to be measured to displace and rotate, and the beam steering micro-device is used for extending between adjacent wafers to be measured during measurement; Wherein, the refraction optical path and the transmission optical path are respectively used as the reference optical path and the measurement optical path of the measuring device, and the tube lens is used for converging the reference light and the measurement light in the reference optical path and the measurement optical path to form an interference information pattern in the camera.

2. The measuring device for measuring the deformation and surface microstructure of stacked wafers according to claim 1, wherein, The measurement optical path is perpendicular to the reference optical path.

3. The measuring device for measuring the deformation and surface microstructure of stacked sheets according to claim 1, wherein There is also a compensating optical path difference glass sheet between the first objective lens and the first displacement stage, and the compensating optical path difference glass sheet is used for compensating the optical path difference generated by the measurement light passing through the beam steering micro-device.

4. A measuring device for measuring the deformation and surface microstructure of stacked sheets according to claim 1, characterized in that, The beam steering micro-device is a micro-mirror or a micro-prism, and the size of the micro-mirror or the micro-prism is 1-10,000 microns.

5. The measuring device for measuring the deformation and surface microstructure of stacked wafers according to claim 1, wherein The camera is a CMOS camera or a CCD camera.

6. The measuring device for measuring the deformation and surface microstructure of stacked sheets according to claim 1, characterized in that, The measuring device further includes a light-shielding box body, and the beam splitter is located in the middle of the light-shielding box body.

7. A method for measuring the deformation and surface microstructure of stacked sheets using the measuring device according to any one of claims 1-6, characterized in that, Including: S1: Adjust the positions of the reflector and the stack of wafers to be measured so that they are respectively within the effective working distances of the first objective lens and the second objective lens, and control the beam steering micro-device to extend between adjacent wafers to be measured; S2: Control the first displacement stage to drive the reflector to move, observe the interference fringes of the micro-structure on the surface of the wafer stack in the camera, and collect all the interference information patterns of the micro-structure on the surface of the wafer stack; S3: Use the interference information patterns collected in S2 to calculate the three-dimensional topography information of the micro-structure on the surface of the wafer stack; And / or, measure the height changes of multiple edge points on a single thin wafer in the wafer stack, and fit the overall deformation pattern of the single thin wafer in the wafer stack according to the height changes.

8. The method according to claim 7, wherein Step S3 includes: S3.1: Record the moving distance of the first displacement stage corresponding to when the light intensity of each pixel point in the interference information pattern reaches the maximum value, and after summarizing and reconstructing the moving distance data to obtain the initial three-dimensional topography information of the micro-structure on the surface of the wafer stack; S3.2: Optimize the initial three-dimensional topography information by using at least one algorithm among the direct solution method, the phase-shifting method, and the envelope curve fitting method to obtain the final three-dimensional topography information of the micro-structure on the surface of the wafer stack.

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