Method and system for calibrating wafer alignment

Abstract

This application relates to a method for calibrating wafer alignment. In one embodiment of this application, the method for calibrating wafer alignment includes: providing a first marking plate having a first surface and a second surface opposite to the first surface, and having a first mark located on the first surface of the first marking plate; providing a second marking plate having a first surface and a second surface opposite to the first surface, and having a second mark located on the first surface of the second marking plate; placing the first surface of the first marking plate and the first surface of the second marking plate face to face; providing a microscope, focusing the microscope on the first mark above the second surface of the first marking plate, and obtaining a first focal length Z1; removing the first marking plate, focusing the microscope on the second mark above the first surface of the second marking plate, and obtaining a second focal length Z2; and determining a compensation parameter ΔZ, which is the second focal length Z2 minus the first focal length Z1.

Description

Technical Field

[0001] This application generally relates to the field of semiconductor processing equipment, and more specifically, to a method and system for calibrating wafer alignment. Background Technology

[0002] Wafer bonding technology combines two homogeneous or heterogeneous wafers into a single unit by applying external force to induce molecular forces between them. Alignment accuracy is a crucial parameter in wafer bonding technology.

[0003] With the development of chip technology, chip integration is becoming increasingly sophisticated, leading to higher requirements for wafer bonding alignment accuracy. The wafer alignment process involves using two microscopes (upper and lower) to capture images of alignment marks on the surfaces of two wafers. Analysis of these images from both microscopes is then used to align the wafers. However, the systematic errors introduced by the upper and lower microscopes are inherent and reduce wafer alignment accuracy. Current methods primarily use thin films for confocal calibration, but these methods do not compensate for film thickness, which diminishes the effectiveness of confocal calibration. Summary of the Invention

[0004] This application provides a method and system for calibrating wafer alignment, which uses a transparent label plate for confocal calibration and compensates for the thickness of the transparent label plate, thereby reducing systematic errors caused by the upper and lower microscopes and improving the confocal calibration effect of the upper and lower microscopes.

[0005] In one aspect, this application provides a method for calibrating wafer alignment, comprising: providing a first marking plate having a first surface and a second surface opposite to the first surface, and having a first mark, the first mark being located on the first surface of the first marking plate; providing a second marking plate having a first surface and a second surface opposite to the first surface, and having a second mark, the second mark being located on the first surface of the second marking plate; placing the first surface of the first marking plate and the first surface of the second marking plate face to face; providing a microscope, focusing the microscope on the first mark above the second surface of the first marking plate, and obtaining a first focal length Z1; removing the first marking plate, focusing the microscope on the second mark above the first surface of the second marking plate, and obtaining a second focal length Z2; and determining a compensation parameter ΔZ, which is the second focal length Z2 minus the first focal length Z1.

[0006] According to an embodiment of this application, in the method, placing the first surface of the first label plate and the first surface of the second label plate face to face includes: providing a platform; and placing the second label plate on the platform so that the second label is exposed on the focusing path of the microscope.

[0007] According to an embodiment of this application, the method further includes: moving the platform along the focusing path of the microscope to focus the microscope on the first mark or the second mark.

[0008] According to an embodiment of this application, the first label plate comprises transparent glass or quartz.

[0009] According to an embodiment of this application, the method further includes performing the following operations after determining the compensation parameter ΔZ: providing a first microscope, focusing the first microscope on the first mark above the second surface of the first mark plate, and obtaining a focal length Z3; and compensating the first microscope so that its compensated focal length ZC is the focal length Z3 plus the compensation parameter ΔZ.

[0010] According to an embodiment of this application, the method further includes: providing a second microscope, such that the second microscope focuses on the first mark below a first surface of the first mark plate.

[0011] On the other hand, this application also provides a system for calibrating wafer alignment, comprising: a processor; and a compensation measuring device including: a first marker plate having a first marker; a second marker plate having a second marker, wherein the first marker and the second marker are placed face to face; and a microscope, under the control of the processor, focusing on the first marker above the first marker plate on a focusing path to obtain a first focal length Z1, and then focusing on the second marker above the second marker plate on the focusing path to obtain a second focal length Z2, wherein the processor determines a compensation parameter ΔZ based on the first focal length Z1 and the second focal length Z2, which is the second focal length Z2 minus the first focal length Z1.

[0012] According to an embodiment of this application, the first signboard has a first surface and a second surface opposite to the first surface, wherein the first sign is located on the first surface of the first signboard, and the second signboard has a first surface and a second surface opposite to the first surface, wherein the second sign is located on the first surface of the second signboard.

[0013] According to an embodiment of this application, the system further includes a platform that moves along the focusing path under the control of the processor.

[0014] According to an embodiment of this application, the system further includes a wafer alignment calibration device, the wafer alignment calibration device including: a first microscope, which, under the control of the processor, focuses on the first mark above the first mark plate to obtain a focal length Z3, wherein the processor determines a compensated focal length ZC of the first microscope based on the focal length Z3 and the compensation parameter ΔZ, which is the focal length Z3 plus the compensation parameter ΔZ.

[0015] According to an embodiment of this application, the wafer alignment and calibration device further includes: a second microscope, which, under the control of the processor, focuses on the first mark below the first mark plate.

[0016] Details of one or more embodiments of this application are set forth in the following figures and description. Other features, objectives, and advantages will become apparent from the description, figures, and claims. Attached Figure Description

[0017] The following figures are mentioned and included in the disclosure in this specification:

[0018] Figure 1 This is a schematic diagram of a system for calibrating wafer alignment according to some embodiments of this application;

[0019] Figure 2A and Figure 2B According to some embodiments of this application, by Figure 1 A schematic diagram illustrating the operation performed by the compensation measuring device in the diagram;

[0020] Figure 3A , Figure 3B and Figure 3C According to some embodiments of this application, by Figure 1 A schematic diagram of the operations performed by the wafer alignment and calibration device in the diagram;

[0021] Figure 4 This is a flowchart of a method for calibrating wafer alignment according to some embodiments of this application.

[0022] By convention, the various features illustrated in the figures may not be drawn to scale. Therefore, for clarity, the dimensions of various features may be arbitrarily enlarged or reduced. The shapes of the components illustrated are merely exemplary and do not limit the actual shapes of the components. Furthermore, for clarity, the embodiments illustrated may be simplified. Therefore, the figures may not depict all components of a given device or apparatus. Finally, the same reference numerals may be used throughout the specification and figures to denote the same features. Detailed Implementation

[0023] To better understand the spirit of the present invention, the following description, in conjunction with some embodiments of the present invention, will provide further details.

[0024] The terms "in one embodiment" or "according to one embodiment" used in this specification do not necessarily refer to the same specific embodiment, and the terms "in other (some / some) embodiments" or "according to other (some / some) embodiments" used in this specification do not necessarily refer to different specific embodiments. The purpose is to, for example, include combinations of all or some of the exemplary embodiments. The meaning of "upper" and "lower" as used herein is not limited to the relationship directly presented in the drawings, but should include descriptions with explicit corresponding relationships, such as "left" and "right," or the opposite of "upper" and "lower." The term "connection" as used herein should be understood to encompass both "direct connection" and "connection via one or more intermediate components." The names of various components used in this specification are for illustrative purposes only and are not intended to be limiting; different manufacturers may use different names to refer to components with the same function.

[0025] Various embodiments of the invention are discussed in detail below. Although specific embodiments are discussed, it should be understood that these embodiments are for illustrative purposes only. Those skilled in the art will recognize that other components and configurations can be used without departing from the spirit and scope of the invention.

[0026] Figure 1 This is a schematic diagram of a system 100 for calibrating wafer alignment according to some embodiments of this application.

[0027] Please see Figure 1 System 100 includes a compensation measurement device 101, a wafer alignment and calibration device 102, and a processor 103. Under the control of the processor 103, the compensation measurement device 101 performs compensation-related operations and generates compensation-related data Z1 and Z2. Based on the compensation-related data Z1 and Z2, the processor 103 determines the compensation parameter ΔZ. Under the control of the processor 103, the wafer alignment and calibration device 102 performs calibration-related operations based on the compensation parameter ΔZ and generates calibration-related data ZC and ZL for the upper and lower microscopes in height. The processor 103 has the necessary hardware and computer programs to support the operation of the compensation measurement device 101 and the wafer alignment and calibration device 102. The components and operation of the compensation measurement device 101 will be described below. Figure 2A and Figure 2B A detailed discussion will follow, while the components and operation of the wafer alignment and calibration device 102 will be described below. Figure 3A , Figure 3B and Figure 3C Let's discuss this in detail.

[0028] Figure 2A and Figure 2BAccording to some embodiments of this application, by Figure 1 A schematic diagram of the operation performed by the compensation measuring device 101.

[0029] Please see Figure 2A The compensation measuring device 101 includes a microscope 10, a first label plate 30, and a second label plate 50. The microscope 10 has an objective lens 112. The first label plate 30 has a first surface 30a and a second surface 30b opposite to the first surface 30a, and has a first label M1 located on the first surface 30a. According to an embodiment of this application, the first label plate 30 comprises transparent glass or quartz. According to one embodiment of this application, the first label plate 30 is rectangular, with a length and width of approximately 10 to 20 mm and a thickness of approximately 1 mm. According to another embodiment of this application, the first label plate 30 is circular, with a diameter of approximately 10 to 20 mm and a thickness of approximately 1 mm. The second label plate 50 has a first surface 50a and a second surface 50b opposite to the first surface 50a, and has a second label M2 located on the first surface 50a. The first label plate 30 and the second label plate 50 are placed on a movable platform 70 with the first label M1 and the second label M2 facing each other, wherein the first label M1 and the second label M2 do not necessarily need to be aligned with each other. The movable platform 70 and the microscope 10 can move relative to each other on the focusing path P of the microscope 10 so that the first marker M1 and the second marker M2 enter the field of view of the microscope 10, so as to facilitate the focusing of the microscope 10.

[0030] According to an embodiment of this application, under the control of the processor 103, the movable platform 70 is moved in the direction of the focusing path P so that the microscope 10 focuses on the first mark M1 of the first mark plate 30 above the second surface 30b of the first mark plate 30, and obtains a first focal length Z1, which is the distance between the objective lens 112 of the microscope 10 and the first mark M1. Then, the first mark plate 30 is removed from the movable platform 70.

[0031] Please see Figure 2B Under the control of the processor 103, the movable platform 70 is moved in the direction of the focusing path P so that the microscope 10 focuses on the second mark M2 above the first surface 50a of the second mark plate 50 and obtains the second focal length Z2, which is the distance between the objective lens 112 of the microscope 10 and the second mark M2 after the first mark plate 30 is removed.

[0032] The processor 103 determines a compensation parameter ΔZ based on the first focal length Z1 and the second focal length Z2, which is the second focal length Z2 minus the first focal length Z1, i.e., ΔZ = Z2 - Z1. ΔZ is the compensation amount for the thickness of the first marker plate 30 when performing confocal calibration using the first marker plate 30. This compensation amount will be used to calibrate wafer alignment.

[0033] Figure 3A , Figure 3B and Figure 3C According to some embodiments of this application, by Figure 1 A schematic diagram of the operation performed by the wafer alignment and calibration device 102.

[0034] Please see Figure 3A The wafer alignment and calibration device 102 includes a first microscope 81, a second microscope 82, and a first marker plate 30. The first microscope 81 has a first objective lens 812, and the second microscope 82 has a second objective lens 822. Under the control of the processor 103, the first microscope 81 focuses on the first marker M1 above the second surface 30b of the first marker plate 30 to obtain a focal length Z3, which is the distance between the first objective lens 812 of the first microscope 81 and the first marker M1. The focusing path P1 of the first microscope 81 is determined by the center of the first marker M1 and the first objective lens 812 of the first microscope 81. Then, the processor 103 determines the compensated focal length ZC of the first microscope 81 based on the focal length Z3 and the compensation parameter ΔZ, which is the focal length Z3 plus the compensation parameter ΔZ, that is, ZC = Z3 + ΔZ.

[0035] Please see Figure 3B Under the control of the processor 103, the first marker plate 30 is moved relative to the first microscope 81 in the direction of the focusing path P1, so that the distance between the first marker M1 of the first marker plate 30 and the first objective lens 812 of the first microscope 81 is the compensation focal length ZC.

[0036] Please refer to the following: Figure 3C Under the control of the processor 103, the second microscope 82 focuses on the first mark M1 below the first surface 30a of the first mark plate 30 to obtain a focal length ZL, which is the distance between the second objective lens 822 of the second microscope 82 and the first mark M1. The focal lengths ZC and ZL can then be used for alignment of the upper and lower wafers during wafer bonding.

[0037] According to the embodiments of this application, Figure 2A and Figure 2B Microscope 10 and Figure 3A , Figure 3B and Figure 3C The first microscope 81 and the second microscope 82 have the same magnification.

[0038] Figure 4 This is a flowchart of a method for calibrating wafer alignment according to some embodiments of this application.

[0039] Please see Figure 4 In operation 412, a first identification plate is provided, which has a first identification.

[0040] In operation 414, a second identification plate is provided, which has a second identification.

[0041] In operation 416, the first and second identifiers are placed face to face.

[0042] In operation 418, a microscope is provided, which is then focused on the first mark on the focusing path, and a first focal length Z1 is obtained.

[0043] In operation 420, the first label plate is removed.

[0044] In operation 422, the microscope is focused on the second mark on the focusing path, and the second focal length Z2 is obtained.

[0045] In operation 424, the compensation parameter ΔZ is determined, which is the second focal length Z2 minus the first focal length Z1.

[0046] In operation 426, a first microscope is provided, which is then focused on the first mark above the first mark plate, and a focal length Z3 is obtained.

[0047] In operation 428, the first microscope is compensated so that its compensated focal length ZC is the focal length Z3 plus the compensation parameter ΔZ.

[0048] In operation 430, a second microscope is provided and focused on the first mark below the first mark plate to obtain a focal length ZL.

[0049] Focal lengths ZC and ZL can be used for alignment of the upper and lower wafers during wafer bonding.

[0050] Compared to current methods, which do not compensate for the thickness of the film used for confocal calibration, resulting in reduced confocal calibration effectiveness, the method and system for wafer alignment proposed in this application use a transparent marker plate for confocal calibration and compensate for the thickness of the transparent marker plate. This reduces systematic errors caused by the upper and lower microscopes and improves the confocal calibration effect of the upper and lower microscopes.

[0051] The description herein is provided to enable those skilled in the art to make or use the invention. Various modifications to the invention will readily be apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the spirit or scope of the invention. Therefore, the invention is not limited to the examples and designs described herein, but is given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calibrating wafer alignment, comprising: A first signboard is provided, having a first surface and a second surface opposite to the first surface, and having a first sign located on the first surface of the first signboard; A second signboard is provided, having a first surface and a second surface opposite to the first surface, and having a second sign located on the first surface of the second signboard; Place the first surface of the first signboard and the first surface of the second signboard face to face; A microscope is provided, which is used to focus the first mark above the second surface of the first mark plate and obtain a first focal length Z1; Remove the first label plate, make the microscope focus on the second label above the first surface of the second label plate, and obtain the second focal length Z2; and Determine the compensation parameter ΔZ, which is the second focal length Z2 minus the first focal length Z1.

2. The method of claim 1, wherein placing the first surface of the first signboard face-to-face with the first surface of the second signboard comprises: Provide a platform; and The second label is placed on the platform so that the second label is exposed on the focusing path of the microscope.

3. The method according to claim 2, further comprising: The platform is moved along the focusing path of the microscope to make the microscope focus on the first or second mark.

4. The method of claim 1, wherein the first label plate comprises transparent glass or quartz.

5. The method of claim 1, further comprising performing the following operations after determining the compensation parameter ΔZ: A first microscope is provided, which is used to focus the first mark above the second surface of the first marking plate, and a focal length Z3 is obtained; and The first microscope is compensated so that its compensated focal length ZC is the focal length Z3 plus the compensation parameter ΔZ.

6. The method of claim 5, further comprising: A second microscope is provided, which is used to focus on the first mark below the first surface of the first mark plate.

7. A system for calibrating wafer alignment, comprising: processor; and Compensation measuring device, comprising: The first signboard has the first sign; A second signboard having a second sign, wherein the first sign and the second sign are placed facing each other; and The microscope, under the control of the processor, focuses on the first marker above the first marker plate along the focusing path to obtain a first focal length Z1, and then focuses on the second marker above the second marker plate along the focusing path to obtain a second focal length Z2. The processor determines a compensation parameter ΔZ based on the first focal length Z1 and the second focal length Z2, which is the second focal length Z2 minus the first focal length Z1.

8. The system of claim 7, wherein the first signboard has a first surface and a second surface opposite to the first surface, wherein the first sign is located on the first surface of the first signboard, and the second signboard has a first surface and a second surface opposite to the first surface, wherein the second sign is located on the first surface of the second signboard.

9. The system of claim 7, wherein the first signboard comprises transparent glass or quartz.

10. The system of claim 7, further comprising a platform that moves along the focusing path under the control of the processor.

11. The system of claim 7, further comprising a wafer alignment calibration device, the wafer alignment calibration device comprising: A first microscope, under the control of the processor, focuses on the first mark above the first mark plate to obtain a focal length Z3. The processor determines the compensated focal length ZC of the first microscope based on the focal length Z3 and the compensation parameter ΔZ, which is the focal length Z3 plus the compensation parameter ΔZ.

12. The system of claim 11, wherein the wafer alignment and calibration apparatus further comprises: A second microscope, under the control of the processor, focuses on the first mark below the first mark plate.

13. The system of claim 12, wherein the microscope, the first microscope, and the second microscope have the same magnification.

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