Wafer correction method based on straight edge as standard and application
By using a wafer correction method based on straight edges as the standard, the problem of wafer positioning deviation in existing technologies has been solved, achieving efficient and precise wafer processing, improving yield and reducing production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-21
- Publication Date
- 2026-03-10
AI Technical Summary
In existing wafer fabrication processes, correction algorithms based on the assumption of a standard circle are unable to accurately capture the true shape of non-standard circles, leading to wafer positioning deviations that affect processing accuracy and yield, especially for large-size wafers.
A wafer alignment method based on straight edges is adopted. By initially locating the center, large edge, and small edge of the wafer, the wafer position is adjusted so that the large edge is parallel to the Y-axis. The cutting path is planned based on the large edge to avoid center positioning deviation and improve yield and processing efficiency.
It improves wafer yield and processing efficiency, reduces production costs, and avoids over-cutting or under-cutting problems caused by center positioning deviation.
Smart Images
Figure CN121646339A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of chip processing, and relates to a chip processing method, in particular to a wafer correction method based on a straight edge as a standard and application. BACKGROUND
[0002] At present, with the rapid development of the semiconductor industry, the quality and processing precision of wafers, as the core substrate material for manufacturing integrated circuits, directly determine the performance and yield of downstream chips. As the integration level of chips continues to improve and the process technology continues to break through to the micro-nano level, the market has increasingly stringent requirements for the size specifications, shape precision and edge quality of wafers. Wafer edge processing is a key link in the wafer manufacturing process, and its main purpose is to remove burrs, micro-cracks and defect layers on the edge of the wafer through grinding, polishing and other processes to improve the mechanical strength of the wafer and the adaptability of subsequent processes such as photolithography and etching. Wafer size measurement is a crucial inspection link before edge processing - only by accurately obtaining the actual size parameters and shape characteristics of the wafer can reliable positioning reference and process parameters be provided for edge processing equipment to ensure the accuracy and stability of the processing process.
[0003] However, the current mainstream wafer processing process in the industry is as follows: the wafer rough is placed on a wafer calibration device, the center of the wafer rough is calculated by means of laser scanning, and then the wafer rough is fixed. Based on the center of the wafer rough, a circle is cut along the circumference of the wafer rough to obtain a finished wafer.
[0004] However, abnormal shapes of the wafer rough may occur during wafer manufacturing (such as excessive ovality and local deformation due to uneven crystal growth and cutting process deviation), and the drawbacks of existing correction methods become more prominent. When facing a larger wafer, due to its larger mass, it is easily affected by gravity and clamping force to produce slight deformation, and the existing correction algorithm based on the standard circle assumption is difficult to capture its true shape, resulting in deviation of the center positioning. At this time, cutting a circle along the wafer rough based on the center as a reference is easy to cause excessive cutting or insufficient cutting in some areas of the wafer rough, affecting the processing precision and yield, significantly increasing the production cost and reducing the production efficiency. SUMMARY
[0005] In view of the defects and deficiencies of the prior art, in a first aspect, the present application provides a wafer correction method based on a straight edge as a standard, and in a second aspect, the present application provides a wafer processing method.
[0006] A wafer correction method based on a straight edge as a standard, comprising the following steps: Step 1, place the wafer rough on the wafer correction device and input the parameters of the wafer rough; Step 2, rotate the wafer rough to preliminarily position the center, the large edge and the small edge of the wafer; Step 3, adjust the position of the wafer rough, so that the large edge is parallel to the Y axis, the distance between the large edge and the Y axis is equal to the distance between the large edge of the preset finished wafer and the center, and the straight line connecting the midpoint of the large edge and the center overlaps the X axis, i.e. the correction is completed.
[0007] Preferably, in step 3, the specific process of making the large edge parallel to the Y axis is as follows: move the large edge to the laser detection position, move the wafer rough along the Y direction, measure the values of the front, middle and rear three points of the large edge, and record them as y1, y0 and y2 respectively, and judge whether the three points are on the same straight line and the straight line is parallel to the Y axis; if the condition is met, proceed to the next adjustment process; if the condition is not met, rotate the wafer rough clockwise or counterclockwise to meet the condition.
[0008] Preferably, in step 3, the specific process of making the distance between the large edge and the Y axis equal to the distance between the large edge of the preset finished wafer and the center is as follows: detect the distance between the large edge and the Y axis by laser, and record it as X1, and record the distance between the large edge of the preset finished wafer and the center as X0; if X1=X0, the condition is met, and proceed to the next adjustment process; if the condition is not met, move the wafer along the X axis to meet the condition.
[0009] Preferably, in step 3, the specific process of making the straight line connecting the midpoint of the large edge and the center overlap the X axis is as follows: take y0 as the reference, rotate the wafer rough 90° clockwise, record the value Z1 of the center to y1, rotate the wafer rough 90° counterclockwise, record the value Z2 of the center to C, calculate Y1 from y1 and Z1 and calculate Y2 from y1 and Z2 according to the Pythagorean theorem, and if Y1=Y2, it means that the upper and lower parts of the large edge are equal with the X axis as the dividing point; if not, move the wafer rough along the Y direction and repeat the adjustment process to meet the condition.
[0010] Preferably, in step 3, the specific process of making the straight line connecting the midpoint of the large edge and the center overlap the X axis is as follows: take y0 as the reference, rotate the wafer rough 90° clockwise, record the value Z1 of the center to y1, rotate the wafer rough 90° counterclockwise, record the value Z2 of the center to C, calculate Y1 from y1 and Z1 and calculate Y2 from y2 and Z2 according to the Pythagorean theorem, and measure the depth h of the small edge to the large edge; if the small edge is located in the direction of Y1, when Y1+h=Y2, it means that the upper and lower parts of the large edge are equal with the X axis as the dividing point; if the small edge is located in the direction of Y2, when Y1=Y2+h, it means that the upper and lower parts of the large edge are equal with the X axis as the dividing point; if not, move the wafer rough along the Y direction and repeat the adjustment process to meet the condition.
[0011] Preferably, in step 3, the position of the wafer roughcast is adjusted, with an error of 0-0.02mm.
[0012] In a second aspect, the present application provides a wafer processing method, comprising: correcting a wafer roughcast by the above-mentioned correction method, taking the large edge position of the wafer roughcast as a reference, planning a cutting path along the two ends of the large edge position as starting points, cutting the wafer along the cutting path, and obtaining a wafer finished product.
[0013] Preferably, the wafer roughcast is positioned based on the large edge position, the radial straight line length of the wafer roughcast passing through the center and being perpendicular to the large edge position is set as R1, the diameter of the wafer is preset as R0, d=R1-R0, and the processing times and the processing initial position are calculated based on the size of d.
[0014] Compared with the prior art, the present application has the following obvious beneficial effects: (1) The present application provides a new wafer correction method, i.e. a wafer correction method based on a straight edge, which does not need to process the straight edge of the wafer again, thereby improving the processing efficiency and the yield.
[0015] (2) If the wafer roughcast is not a standard circle, the existing wafer positioning processing cannot accurately position the center, thereby affecting the qualified rate of wafer processing, while the wafer positioning processing method provided by the present application does not need to take the center as a correction reference, allows a certain error in the positioning process, has little influence on the subsequent wafer processing, and can improve the yield. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 Fig. 1 is a schematic diagram of a wafer correction method in the prior art and a wafer correction method provided by the present application; Figure 2 Fig. 2 is a rectangular coordinate system diagram of a wafer roughcast provided by the present application; Figure 3 Fig. 3 is a schematic diagram of a wafer roughcast and a finished product after cutting in the correction method provided by Example 1; Figure 4 Fig. 4 is a schematic diagram of a wafer roughcast and a finished product after cutting in the correction method provided by Example 2. DETAILED DESCRIPTION
[0017] The present application provides the following specific technical solutions.
[0018] A wafer correction method based on a straight edge as a standard, comprising the following steps: Step 1, placing a wafer roughcast on a wafer correction device and inputting the parameters of the wafer roughcast; Step 2, rotating the wafer roughcast for one circle, and preliminarily positioning the center position, the large edge position and the small edge position of the wafer; Step 3, adjust the position of the wafer rough to make the long side parallel to the Y axis, the distance between the long side and the Y axis equal to the distance between the long side of the preset finished wafer and the center of the circle, and the straight line connecting the midpoint of the long side and the center of the circle overlap with the X axis, that is, the correction is completed.
[0019] Figure 1 The left side of the figure is the profile of the wafer rough and the finished wafer in the prior art with the center of the circle as the positioning reference; Figure 1 The right side of the figure is the profile of the wafer rough and the finished wafer in the wafer correction method provided by the present application with the long side as the positioning reference.
[0020] For the case that the wafer rough in the prior art is not a standard circle, the correction algorithm based on the assumption of a standard circle is difficult to capture the true shape of the wafer rough, which is prone to cause deviation in the positioning of the center of the circle. When cutting, the center of the circle is taken as the reference, and a round of cutting is performed along the circumferential direction of the wafer rough, which is prone to cause overcutting or insufficient cutting in some areas, affecting the machining precision and the yield.
[0021] The inventors have proposed a new wafer processing method, which uses the long side of the wafer rough as the positioning reference. The center of the wafer rough after positioning does not need to overlap with the center of the target wafer. In the subsequent cutting process, the long side of the wafer rough is taken as the starting point to plan the finished wafer, which can avoid the problems caused by the deviation in the positioning of the center of the circle in the prior art, and improve the yield. Moreover, the long side does not need to be cut again, which can avoid damaging the cleavage plane and improve the processing efficiency.
[0022] Preferably, in step 3, the specific process of making the long side parallel to the Y axis is as follows: move the long side to the laser detection position, move the wafer rough along the Y direction, measure the values of the front, middle and rear three points of the long side, and record them as y1, y0 and y2 respectively, and judge whether the three points are on the same straight line and the straight line is parallel to the Y axis; if the condition is met, proceed to the next adjustment process; if the condition is not met, rotate the wafer rough in the clockwise or counterclockwise direction to meet the condition.
[0023] Preferably, in step 3, the specific process of making the distance between the long side and the Y axis equal to the distance between the long side of the preset finished wafer and the center of the circle is as follows: measure the distance between the long side and the Y axis by laser, and record it as X1, and the distance between the long side of the preset finished wafer and the center of the circle is recorded as X0; if X1 = X0, the condition is met, and the next adjustment process is entered; if the condition is not met, move the wafer along the X axis to meet the adjustment.
[0024] Preferably, if the wafer blank does not have a small edge, the specific process in step 3 to make the straight line connecting the midpoint of the large edge and the center of the circle overlap with the X-axis is as follows: using y0 as a reference, rotate the wafer blank 90° clockwise and record the value Z1 from the center of the circle to y1; rotate the wafer blank 90° counterclockwise and record the value Z2 from the center of the circle to C; calculate Y1 based on y1 and Z1 according to the Pythagorean theorem, and calculate Y2 based on y1 and Z2. If Y1=Y2, it means that the upper and lower parts of the large edge are equal with the X-axis as the dividing point; if not, move the wafer blank along the Y direction and repeat the adjustment process to make it meet the condition.
[0025] In practical applications, if Y1≠Y2, and if Y1>Y2, the distance L moved along the Y2 direction is L=(Y1-Y2) / 2, and then the above adjustment process is repeated; if Y1<Y2, the distance L moved along the Y1 direction is L=(Y2-Y1) / 2, and then the above adjustment process is repeated.
[0026] Preferably, if the wafer blank has a small edge, the specific process in step 3 to make the straight line connecting the midpoint of the large edge and the center of the circle overlap with the X-axis is as follows: Taking y0 as the reference, rotate the wafer blank 90° clockwise and record the value Z1 from the center of the circle to y1; rotate the wafer blank 90° counterclockwise and record the value Z2 from the center of the circle; calculate Y1 based on y1 and Z1, and calculate Y2 based on y1 and Z2, and measure the depth h from the small edge to the edge of the circle; if the small edge is located in the Y1 direction, when X3 + h = X4, it means that the upper and lower parts of the large edge are equal with the X-axis as the dividing point; if the small edge is located in the Y2 direction, when X3 = X4 + h, it means that the upper and lower parts of the large edge are equal with the X-axis as the dividing point; otherwise, move the wafer blank along the Y direction and repeat the adjustment process to make it meet the conditions.
[0027] Figure 2 This is a schematic diagram of the rectangular coordinate system of various key points after laser inspection of the wafer roughing provided by the present invention. Figure 2 The three key points of the large straight edge, as well as Y1 and Y2, can be clearly observed.
[0028] Preferably, in step 3, the position of the wafer blank is adjusted with an error of 0~0.02mm.
[0029] In a second aspect, the present invention provides a wafer processing method, comprising: correcting a wafer blank by the above-mentioned correction method, planning a cutting path with the large edge of the wafer blank as a reference and the two ends of the large edge as starting points, cutting the wafer along the cutting path to obtain a finished wafer.
[0030] Preferably, the wafer blank is positioned with the large edge as the reference. The radial straight length of the wafer blank that passes through the center and is perpendicular to the large edge is set as R1. The diameter of the wafer is preset to be R0, and d = R1 - R0. The number of processing steps and the initial processing position are calculated based on the size of d.
[0031] In practical applications, the number of machining passes and the initial machining position are determined by the value of d. If d is large, the number of machining passes can be increased appropriately; if d is small, the number of machining passes can be reduced appropriately. For example, if d is 1mm, the feed rate per pass can be set to 0.2mm, resulting in 5 machining passes; if d is 0.5mm, the feed rate per pass can be set to 0.025mm, resulting in 2 machining passes. The initial machining position is the position where the grinding wheel just begins to contact the wafer. The initial machining position is determined by d and should be at least equal to or slightly greater than d.
[0032] To make the technical problems, technical solutions and technical advantages of the present invention clearer, a detailed description will be given below with reference to specific examples. However, the scope of protection of the present invention is not limited to the following specific embodiments.
[0033] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.
[0034] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.
[0035] Example 1: A wafer straightening method based on straight edges, wherein the wafer blank to be straightened does not have small edges, includes the following steps: Step 1: Place the wafer blank on the rotary table. The rotary table moves the wafer blank to the test area. The rotary table rotates the wafer blank one revolution. The PLC control console receives data transmitted from the laser transmitter and laser receiver, initially locates the center position and the large edge position of the wafer, and records the y1, y0, and y2 of the large edge position.
[0036] Step 2: The rotary table moves and rotates the wafer blank so that the large edge of the wafer blank is located in the test area. It is determined whether y1, y0, and y2 are on the same straight line. If yes, proceed to step 3; if not, remove the wafer blank and process and polish the large edge again, and then repeat steps 1 to 2.
[0037] Step 3: Determine whether the straight line connecting y1, y0, and y2 is parallel to the Y-axis. If yes, proceed to step 4; otherwise, the rotary table rotates the wafer blank so that the straight line connecting y1, y0, and y2 is parallel to the Y-axis.
[0038] Step 4: The laser detects the distance from the large edge to the Y-axis, which is recorded as X1. The distance from the large edge to the center of the pre-set finished wafer is recorded as X0. If X1=X0, the condition is met, and proceed to step 5; if the condition is not met, move the wafer along the X-axis to make it meet the condition.
[0039] Step 5: Using y0 as the reference, rotate the wafer blank 90° clockwise and record the value Z1 from the center to y1; rotate the wafer blank 90° counterclockwise and record the value Z2 from the center to C, then proceed to step 6; if the condition is not met, the rotary table moves the wafer blank along the Y direction and repeats step 5 again until Z1=Z2, then proceed to step 6.
[0040] Step 6: Calculate the radial straight length R1 of the wafer blank that passes through the center and is perpendicular to the large edge. The preset diameter of the wafer is R0. Determine the cutting length d = R1 - R0 along the X direction. The outline of the finished wafer after cutting is determined by the three parameters Y1, Y2 and d. The number of cutting times is determined according to the size of d. The finished wafer is obtained after cutting.
[0041] Figure 3 This is a schematic diagram of the wafer blank and the finished product after cutting in the correction method provided in Example 1.
[0042] Example 2: A wafer straightening method based on straight edges is provided, wherein the wafer blank to be straightened has small edges, and steps 1 to 4 are the same as in Example 1.
[0043] Step 5: Using y0 as the reference, rotate the wafer blank 90° clockwise and record the value Z1 from the center to y1; rotate the wafer blank 90° counterclockwise and record the value Z2 from the center; calculate Y1 from y1 and Z1 using the Pythagorean theorem, and calculate Y2 from y1 and Z2, and measure the depth h from the small side to the edge of the circle; if the small side is located in the Y1 direction, then Y1 + h = Y2, and the condition is met; if the small side is located in the Y2 direction, then Y1 = Y2 + h, and the condition is met, proceed to step 6; if the condition is not met, the rotary table moves the wafer blank along the Y direction, and step 5 is repeated until the condition is met.
[0044] Step 5: Calculate the radial straight length R1 of the wafer blank that passes through the center and is perpendicular to the large edge. The preset diameter of the wafer is R0. Determine the cutting length d = R1 - R0 along the X direction. The outline of the finished wafer after cutting is determined by the three parameters Y1, Y2 and d. The number of cutting times is determined according to the size of d. The finished wafer is obtained after cutting.
[0045] Figure 4 This is a schematic diagram of the wafer blank and the finished product after cutting in the correction method provided in Example 2.
[0046] It can be seen that the wafer processing method provided by the present invention can significantly improve the yield of wafers and reduce losses and costs.
[0047] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope of the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A wafer straightening method based on straight edges as the standard, characterized in that, The method comprises the following steps: Step 1, placing the wafer rough into a wafer correction device, and inputting parameters of the wafer rough; Step 2, rotating the wafer rough for one circle, and preliminarily positioning the center of the wafer, the large edge position and the small edge position; Step 3, adjusting the position of the wafer rough, so that the large edge position is parallel to the Y axis, the distance from the large edge position to the Y axis is equal to the distance from the large edge position of the preset finished wafer to the center, and the straight line connecting the midpoint of the large edge position and the center overlaps the X axis, thereby completing the correction.
2. The wafer correction method based on straight edges as a standard as described in claim 1, characterized in that, In step 3, the specific process of making the large edge position parallel to the Y axis is as follows: moving the large edge position to a laser detection position, moving the wafer rough along the Y direction, measuring the values of the front, middle and rear three point positions of the large edge position, and recording the values as y1, y0 and y2 respectively, and judging whether the three point positions are on the same straight line and the straight line is parallel to the Y axis; if the condition is met, the next adjustment process is entered; if the condition is not met, rotating the wafer rough in the clockwise or counterclockwise direction to meet the condition.
3. The method of claim 1 or 2, wherein the straight edge is a standard wafer. In step 3, the specific process of making the distance from the large edge position to the Y axis equal to the distance from the large edge position of the preset finished wafer to the center is as follows: detecting the distance from the large edge position to the Y axis by laser, and recording the distance as X1, and recording the distance from the large edge position of the preset finished wafer to the center as X0; if X1=X0, the condition is met, and the next adjustment process is entered; if the condition is not met, moving the wafer along the X axis direction to meet the condition.
4. The method of claim 1, wherein the straight edge is a reference edge of a wafer. In step 3, if the wafer rough has no small edge position, the specific process of making the straight line connecting the midpoint of the large edge position and the center overlap the X axis is as follows: taking y0 as the reference, rotating the wafer rough by 90° in the clockwise direction, recording the value Z1 of the center to y1; rotating the wafer rough by 90° in the counterclockwise direction, recording the value Z2 of the center to C; calculating Y1 from y1 and Z1 and calculating Y2 from y1 and Z2 according to the Pythagorean theorem; if Y1=Y2, it indicates that the upper and lower parts of the large edge position are equal with the X axis as the dividing point; if not, moving the wafer rough along the Y direction, and repeating the adjustment process to meet the condition. 5. The method of claim 1, wherein the straight edge is a reference edge of a wafer. In step 3, if the wafer rough is processed with a small edge position, the specific process of making the straight line connecting the midpoint of the large edge position and the center overlap the X axis is as follows: taking y0 as the reference, rotating the wafer rough by 90° in the clockwise direction, recording the value Z1 of the center to y1; rotating the wafer rough by 90° in the counterclockwise direction, recording the value Z2 of the center; calculating Y1 from y1 and Z1 and calculating Y2 from y2 and Z2 according to the Pythagorean theorem; measuring the depth h of the small edge to the large edge; if the small edge is located in the Y1 direction, when Y1+h=Y2, it indicates that the upper and lower parts of the large edge position are equal with the X axis as the dividing point; if the small edge is located in the Y2 direction, when Y1=Y2+h, it indicates that the upper and lower parts of the large edge position are equal with the X axis as the dividing point; if not, moving the wafer rough along the Y direction, and repeating the adjustment process to meet the condition. 6. The method of claim 1, wherein the straight edge is a reference edge of a wafer. 5 In step 3, the error of adjusting the position of the wafer rough is 0-0.02 mm.
7. A wafer processing method characterized by, The wafer rough is corrected by the correction method in any one of claims 1-6, the large edge position of the wafer rough is taken as the reference, the cutting path is planned along the two ends of the large edge position as the starting points, the wafer is cut along the cutting path, and the finished wafer is obtained.