TWI864504B - Method and system for calibrating wafer alignment - Google Patents

Abstract

The present application relates to a method for calibrating wafer alignment. In one embodiment of the present application, the method for calibrating wafer alignment includes: providing a first identification plate having a first surface and a second surface opposite to the first surface, and having a first identification, the first identification being located on the first surface of the first identification plate; providing a second identification plate having a first surface and a second surface opposite to the first surface, and having a second identification, the second identification being located on the first surface of the second identification plate; placing the first identification plate on the second surface; The first surface of the identification plate is placed face to face with the first surface of the second identification plate; a microscope is provided to focus the first identification above the second surface of the first identification plate and obtain a first focal length Z1; the first identification plate is taken out, the microscope is focused on the second identification above the first surface of the second identification plate and obtain a second focal length Z2; and a compensation parameter ΔZ is determined, which is the second focal length Z2 minus the first focal length Z1.

Description

Method and system for calibrating wafer alignment

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

Wafer bonding technology is to use external force to generate molecular force between two homogeneous or heterogeneous wafers to bond the two wafers into a whole. In wafer bonding technology, alignment accuracy is an important parameter.

With the development of chip technology, the integration of chips is getting higher and higher, and the requirements for wafer bonding alignment accuracy are gradually increasing. The wafer alignment process is to collect images of the alignment marks prepared on the surfaces of two wafers by upper and lower microscopes respectively, and align the wafers by analyzing the images collected by the two sets of microscopes. The system error brought by the upper and lower microscopes is inherent and will reduce the wafer alignment accuracy. The current method mainly uses thin films for confocal calibration, but this method does not compensate for the thickness of the film, which will reduce the confocal calibration effect.

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

In one embodiment, the present application provides a method for calibrating wafer alignment, comprising: providing a first identification plate having a first surface and a second surface opposite to the first surface, and having a first identification, wherein the first identification is located on the first surface of the first identification plate; providing a second identification plate having a first surface and a second surface opposite to the first surface, and having a second identification, wherein the second identification is located on the first surface of the second identification plate; placing the first identification plate on the second surface of the second identification plate; The first surface of a marking plate is placed face to face with the first surface of the second marking plate; a microscope is provided, so that the microscope focuses on the first marking above the second surface of the first marking plate and obtains a first focal length Z1; the first marking plate is taken out, so that the microscope focuses on the second marking above the first surface of the second marking plate and obtains a second focal length Z2; and a compensation parameter △Z is determined, which is the second focal length Z2 minus the first focal length Z1.

According to the embodiment of the present application, in the above method, placing the first surface of the above first identification plate and the first surface of the above second identification plate face to face includes: providing a platform; and placing the above second identification plate on the above platform so that the above second identification is exposed to the focusing path of the above microscope.

According to an embodiment of the present application, the method further comprises: moving the platform on the focusing path of the microscope so that the microscope focuses on the first mark or the second mark.

According to the embodiment of this application, the first identification plate comprises transparent glass or quartz.

According to an embodiment of the present application, the method further includes performing the following operations after determining the compensation parameter △Z: 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 △Z.

According to an embodiment of the present application, the method further comprises: providing a second microscope so that the second microscope focuses on the first mark below the first surface of the first mark plate.

In another aspect, the present application also provides a system for calibrating wafer alignment, comprising: a processor; and a compensation measurement device, comprising: a first identification plate having a first identification; a second identification plate having a second identification, wherein the first identification and the second identification are placed face to face; and a microscope, which, under the control of the processor, focuses on the first identification on the first identification plate on a focusing path to obtain a first focal length Z1, and then focuses on the second identification on the second identification 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.

According to the embodiment of the present application, the first identification plate has a first surface and a second surface opposite to the first surface, wherein the first identification plate is located on the first surface of the first identification plate, and the second identification plate has a first surface and a second surface opposite to the first surface, wherein the second identification plate is located on the first surface of the second identification plate.

According to an embodiment of the present application, the system further includes a platform, which moves on the focusing path under the control of the processor.

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

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

The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects and advantages will be apparent from the above description and drawings and the scope of the application.

1011:Microscope

30: First identification plate

30a: First surface

30b: Second surface

50: Second identification plate

50a: first surface

50b: Second surface

70: Movable platform

81:First microscope

82: Second microscope

100:System

101: Compensation measurement device

102: Wafer alignment and calibration device

103: Processor

412: Operation

414: Operation

416: Operation

418: Operation

420: Operation

422: Operation

424: Operation

426: Operation

428: Operation

430: Operation

812: First objective lens

822: Second objective lens

1012:Objective lens

P: Focus path

P1: Focus path

M1: First identification

M2: Second identity

Z1: First focal length

Z2: Second focal length

Z3: Focal length

ZC: Compensating focal length

ZL: focal length

△Z: Compensation parameter

The disclosure in this specification refers to and includes the following figures: FIG. 1 is a schematic diagram of a system for calibrating wafer alignment according to some embodiments of the present application; FIG. 2A and FIG. 2B are schematic diagrams of operations performed by the compensation measurement device in FIG. 1 according to some embodiments of the present application; FIG. 3A, FIG. 3B and FIG. 3C are schematic diagrams of operations performed by the wafer alignment calibration device in FIG. 1 according to some embodiments of the present application; FIG. 4 is a flow chart of a method for calibrating wafer alignment according to some embodiments of the present application.

As a rule, the various features illustrated in the drawings may not be drawn to scale. Therefore, the sizes of the various features may be arbitrarily enlarged or reduced for clarity. The shapes of the components illustrated in the drawings are exemplary shapes only and do not limit the actual shapes of the components. In addition, the implementation schemes illustrated in the drawings may be simplified for clarity. Therefore, the drawings may not illustrate all components of a given device or apparatus. Finally, the same reference numerals may be used throughout the specification and drawings to represent the same features.

In order to better understand the spirit of the present invention, the following is a further explanation of some embodiments of the present invention.

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/certain) embodiments" or "according to other (some/certain) embodiments" used in this specification do not necessarily refer to different specific embodiments. The purpose is, for example, that the subject matter advocated includes a combination of all or part of the exemplary specific embodiments. The meaning of "upper" and "lower" referred to herein is not limited to the relationship directly presented in the drawings, and should include descriptions with clear corresponding relationships, such as "left" and "right", or the opposite of "upper" and "lower". The term "connected" referred to herein should be understood to cover "directly connected" and "connected via one or more intermediate components". The names of various components used in this manual are for illustrative purposes only and are not limiting. Different manufacturers may use different names to refer to components with the same function.

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

FIG. 1 is a schematic diagram of a system 100 for calibrating wafer alignment according to some embodiments of the present application.

Referring to FIG. 1 , the system 100 includes a compensation measurement device 101, a wafer alignment calibration device 102, and a processor 103. Under the control of the processor 103, the compensation measurement device 101 performs operations related to compensation and generates data Z1 and Z2 related to compensation. The processor 103 determines the compensation parameter ΔZ based on the compensation data Z1 and Z2. Under the control of the processor 103, the wafer alignment calibration device 102 performs operations related to calibration based on the compensation parameter ΔZ and generates data ZC and ZL of the height of the upper and lower microscopes after calibration. The processor 103 has related hardware and computer programs to support the operation of the compensation measurement device 101 and the wafer alignment calibration device 102. The components and operation of the compensation measurement device 101 will be discussed in detail below with reference to Figures 2A and 2B, and the components and operation of the wafer alignment calibration device 102 will be discussed in detail below with reference to Figures 3A, 3B and 3C.

FIG. 2A and FIG. 2B are schematic diagrams of operations performed by the compensation measurement device 101 in FIG. 1 according to some embodiments of the present application.

Referring to FIG. 2A , the compensation measuring device 101 includes a microscope 1011, a first identification plate 30, and a second identification plate 50. The microscope 1011 has an objective lens 1012. The first identification plate 30 has a first surface 30a and a second surface 30b opposite to the first surface 30a, and has a first identification M1 located on the first surface 30a. According to an embodiment of the present application, the first identification plate 30 comprises transparent glass or quartz. According to one embodiment of the present application, the first identification 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 the present application, the first identification plate 30 is circular, with a diameter of approximately 10 to 20 mm and a thickness of approximately 1 mm. The second identification plate 50 has a first surface 50a and a second surface 50b opposite to the first surface 50a, and has a second identification mark M2 located on the first surface 50a. The first identification plate 30 and the second identification plate 50 are placed on the movable platform 70 in a manner that the first identification mark M1 and the second identification mark M2 face each other, wherein the first identification mark M1 and the second identification mark M2 do not need to be aligned with each other. The movable platform 70 and the microscope 1011 can move relative to each other on the focusing path P of the microscope 1011 so that the first identification mark M1 and the second identification mark M2 enter the field of view of the microscope 1011, so as to facilitate the focusing of the microscope 1011.

According to the embodiment of the present 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 1011 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 the first focal length Z1, which is the distance between the objective lens 1012 of the microscope 1011 and the first mark M1. Afterwards, the first mark plate 30 is taken out from the movable platform 70.

Please refer to FIG. 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 1011 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 1012 of the microscope 1011 and the second mark M2 after the first mark plate 30 is taken out.

The processor 103 determines the compensation parameter △Z 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, that is, △Z=Z2-Z1. △Z is the compensation amount for the thickness of the first marking plate 30 when the first marking plate 30 is used for confocal calibration. This compensation amount will be used to calibrate wafer alignment.

FIG. 3A, FIG. 3B, and FIG. 3C are schematic diagrams of operations performed by the wafer alignment calibration device 102 in FIG. 1 according to some embodiments of the present application.

Referring to FIG. 3A , the wafer alignment calibration device 102 includes a first microscope 81, a second microscope 82, and a first identification 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 is focused on the first identification M1 above the second surface 30b of the first identification 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 identification M1, wherein the focusing path P1 of the first microscope 81 is determined by the center of the first identification M1 and the first objective lens 812 of the first microscope 81. Afterwards, the processor 103 determines the compensated focal length ZC of the first microscope 81 based on the focal length Z3 and the compensation parameter △Z, which is the focal length Z3 plus the compensation parameter △Z, that is, ZC=Z3+△Z.

Please refer to FIG. 3B . Under the control of the processor 103 , the first marking 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 marking M1 of the first marking plate 30 and the first objective lens 812 of the first microscope 81 is the compensation focal length ZC.

Afterwards, please refer to FIG. 3C . Under the control of the processor 103 , the second microscope 82 is focused 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. Afterwards, the focal length ZC and the focal length ZL can be used to align the upper and lower wafers when wafer bonding.

According to the embodiment of the present application, the microscope 1011 in FIG. 2A and FIG. 2B and the first microscope 81 and the second microscope 82 in FIG. 3A, FIG. 3B and FIG. 3C have the same magnification.

FIG. 4 is a flow chart of a method for calibrating wafer alignment according to some embodiments of the present application.

Referring to FIG. 4 , in operation 412 , a first identification plate is provided, which has a first identification.

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

In operation 416, the first identifier is placed face to face with the second identifier.

In operation 418, a microscope is provided so that the microscope focuses on the first mark on a focusing path and obtains a first focal length Z1.

In operation 420, the first identification plate is removed.

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

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

In operation 426, a first microscope is provided so that the first microscope focuses on the first mark above the first mark plate and obtains a focal length Z3.

In operation 428, the first microscope is compensated so that its compensated focal length ZC is the focal length Z3 plus the compensation parameter △Z.

In operation 430, a second microscope is provided so that the second microscope focuses on the first mark below the first mark plate to obtain a focal length ZL.

The focal length ZC and focal length ZL can be used to align the upper and lower wafers when wafer bonding.

Compared with the current method, the thickness of the film used for confocal calibration is not compensated, resulting in a decrease in the confocal calibration effect. The method and system for calibrating wafer alignment in this application uses a transparent marker plate for confocal calibration, and compensates for the thickness of the transparent marker plate, which can reduce the system error caused by the upper and lower microscopes and improve the confocal calibration effect of the upper and lower microscopes.

The description herein is provided to enable one skilled in the art to make or use the invention. Various modifications to the invention will be readily apparent to one skilled in the art, and the general principles defined herein may 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 to be accorded the widest scope consistent with the principles and novel features disclosed herein.

412: Operation

414: Operation

416: Operation

418: Operation

420: Operation

422: Operation

424: Operation

426: Operation

428: Operation

430: Operation

Claims (13)

A method for calibrating wafer alignment, comprising: Providing a first identification plate, which has a first surface and a second surface opposite to the first surface, and has a first identification, and the first identification is located on the first surface of the first identification plate; Providing a second identification plate, which has a first surface and a second surface opposite to the first surface, and has a second identification, and the second identification is located on the first surface of the second identification plate; Placing the first surface of the first identification plate and the first surface of the second identification plate face to face; Providing a microscope, focusing the microscope on the first identification above the second surface of the first identification plate, and obtaining a first focal length Z1; Taking out the first identification plate, focusing the microscope on the second identification above the first surface of the second identification plate, and obtaining a second focal length Z2; and Determine the compensation parameter ΔZ, which is the second focal length Z2 minus the first focal length Z1. The method of claim 1, wherein placing the first surface of the first identification plate face to face with the first surface of the second identification plate comprises: providing a platform; and placing the second identification plate on the platform so that the second identification is exposed to the focusing path of the microscope. The method of claim 2 further comprises: Moving the platform on the focusing path of the microscope so that the microscope focuses on the first mark or the second mark. The method of claim 1, wherein the first marking plate comprises transparent glass or quartz. The method of claim 1 further includes performing the following operations after determining the compensation parameter ΔZ: Providing a first microscope so that the first microscope focuses on the first mark above the second surface of the first mark plate and obtains 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. The method of claim 5 further comprises: Providing a second microscope so that the second microscope focuses on the first mark below the first surface of the first mark plate. A system for calibrating wafer alignment, comprising: a processor; and a compensation measurement device, comprising: a first identification plate having a first identification; a second identification plate having a second identification, wherein the first identification and the second identification are placed face to face; and a microscope, which, under the control of the processor, focuses the first identification on the first identification plate on a focusing path to obtain a first focal length Z1, and then focuses the second identification on the second identification 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. A system as claimed in claim 7, wherein the first identification plate has a first surface and a second surface opposite to the first surface, wherein the first identification plate is located on the first surface of the first identification plate, and the second identification plate has a first surface and a second surface opposite to the first surface, wherein the second identification plate is located on the first surface of the second identification plate. A system as claimed in claim 7, wherein the first identification plate comprises transparent glass or quartz. The system of claim 7 further comprises a platform, which moves along the focusing path under the control of the processor. The system of claim 7 further includes a wafer alignment calibration device, wherein the wafer alignment calibration device includes: A first microscope, which focuses on the first mark above the first mark plate under the control of the processor 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. The system of claim 11, wherein the wafer alignment calibration device further comprises: A second microscope, which focuses on the first mark below the first mark plate under the control of the processor. A system as in claim 12, wherein the microscope, the first microscope and the second microscope have the same magnification.