Positioning method for wafer in edge etching chamber

Abstract

The present application discloses a positioning method for positioning a wafer in an edge etching chamber, and relates to the field of semiconductor processes. The positioning method includes: inputting the position parameters of the initial mechanical center point in the edge etching chamber into a transmission device, controlling the transmission device to transmit the wafer to the edge etching chamber according to the position parameters; performing an edge etching process on the wafer; selecting multiple sampling circles with different radius values ​​on the edge area of ​​the wafer; selecting multiple sampling points from each sampling circle, and detecting the etching rate of each sampling point; calculating the average etching rate of multiple sampling points on each sampling circle; determining the offset and offset direction between the initial mechanical center point and the ideal center point in the edge etching chamber according to a preset function; inputting the compensation parameters of the above offset into the transmission device to obtain the compensated mechanical center point. The present application can solve the problem of position deviation of the wafer in the edge etching chamber, which reduces the process accuracy and affects the product quality.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor process technology, and specifically relates to a method for positioning a wafer in an edge etching chamber. Background Art

[0002] Semiconductor equipment processes wafers through physical and chemical means, some of which require a vacuum environment. The modules that implement these processes are called process modules. The transfer of wafers from atmospheric air to a vacuum environment requires a transport system, which includes a robot, transition chamber, and vacuum chamber.

[0003] During the wafer transfer process, a robot in the atmosphere places the wafer in a transition chamber. A robot in the vacuum chamber then transfers the wafer from the transition chamber to the process module chamber, where the wafer is then processed. However, before the wafer undergoes edge etching in the process module chamber, the center of the edge etching chamber stored in the robot deviates from the ideal center, and there are certain design tolerances. This causes the wafer to have positional deviations in the process module chamber after transfer, resulting in changes in the etching rate, reduced process accuracy, and impacted product quality. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a positioning method for a wafer in an edge etching chamber, which can solve the problem of position deviation of the wafer in the edge etching chamber, thereby reducing process accuracy and affecting product quality.

[0005] In order to solve the above technical problems, this application is implemented as follows:

[0006] An embodiment of the present application provides a method for positioning a wafer in an edge etching chamber, the method comprising:

[0007] Inputting the position parameters of the initial mechanical center point in the edge etching chamber into a transmission device, and controlling the transmission device to transmit the wafer to the edge etching chamber according to the initial position parameters of the mechanical center point;

[0008] performing an edge etching process on the wafer;

[0009] Selecting a plurality of sampling circles with different radius values ​​on the edge area of ​​the wafer, selecting a plurality of sampling points from each of the sampling circles, and detecting the etching rate of each of the sampling points;

[0010] Calculating an average etching rate of the plurality of sampling points on each of the sampling circles;

[0011] Determining, according to the etching rates of the plurality of sampling points and the average etching rate of the plurality of sampling points on each sampling circle, an offset amount and an offset direction between the initial mechanical center point and an ideal center point in the edge etching chamber according to a preset function;

[0012] The compensation parameter of the offset between the initial mechanical center point and the ideal center point in the edge etching chamber is input into the transmission device to obtain the compensated mechanical center point.

[0013] In an embodiment of the present application, based on the etching rates of multiple sampling points on the wafer and the average etching rate of multiple sampling points on each sampling circle, and according to a preset function, the offset and offset direction between the initial mechanical center point and the ideal center point in the edge etching chamber can be determined, and then a compensation parameter is obtained for the offset, and the compensation parameter is input into the transmission device to obtain the compensated mechanical center point, that is, to determine the precise center point in the edge etching chamber, so that when the transmission device transmits the wafer to the edge etching chamber, the wafer can be placed at the ideal center point in the edge etching chamber, thereby ensuring the transmission accuracy of the wafer, and then ensuring the etching accuracy, and improving product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a flowchart of a positioning method in one of the embodiments disclosed in the present application;

[0015] Figure 2 This is a flowchart of a positioning method in another embodiment disclosed in the embodiments of the present application;

[0016] Figure 3 This is a schematic diagram of taking eight sampling points on a sampling circle on a wafer in an embodiment of the present application. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0018] The terms "first," "second," and the like in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "first," "second," and the like generally distinguish objects of a class and do not limit the number of objects. For example, the first object may be one or more.

[0019] The embodiments of the present application are described in detail below through specific embodiments and their application scenarios in conjunction with the accompanying drawings.

[0020] refer to Figure 1 , the embodiment of the present application discloses a positioning method for positioning a wafer in an edge etching chamber, the positioning method comprising:

[0021] S10: inputting the position parameters of the initial mechanical center point in the edge etching chamber into the transmission device, and controlling the transmission device to transmit the wafer to the edge etching chamber according to the position parameters of the initial mechanical center point.

[0022] Optionally, the transmission device can be a robot arm having an input module, through which a control program, motion parameters, coordinate system, etc. can be input. Based on this, after inputting the position parameters of the initial mechanical center point, the robot arm uses the input position parameters of the initial mechanical center point as the position parameters of the center point of the transmission position in the edge etching chamber, so that when the robot arm transfers the wafer to the transmission position in the edge etching chamber, the center of the wafer coincides with the center point of the transmission position (i.e., the initial mechanical center point), thereby determining that the wafer is in place. After the wafer is transferred, the process program can be started so that the wafer undergoes an edge etching process in the edge etching chamber.

[0023] Alternatively, the initial mechanical center position in the edge etch chamber can be obtained through mechanical measurement, such as by measuring and positioning, or using the robot's training function to position the edge. The obtained initial mechanical center position parameters are then input into the robot and saved so that the robot can subsequently transfer the wafer according to these position parameters.

[0024] S20: performing an edge etching process on the wafer.

[0025] Alternatively, an etching gas may be introduced into the edge etching chamber to excite the etching gas into a chemically reactive plasma, and the plasma may be used to etch the area to be etched on the wafer, thereby obtaining a wafer that has undergone the etching process. Of course, in addition to the above-mentioned methods, other related technologies may also be referred to, and the specific etching process is not limited in the embodiments of the present application.

[0026] S30: selecting a plurality of sampling circles with different radii on the edge region of the wafer, selecting a plurality of sampling points from each sampling circle, and detecting an etching rate at each sampling point.

[0027] In the embodiment of the present application, the radius of the wafer is set to R, and the radius values ​​of the multiple sampling circles selected on the wafer are r1, r2, r3...r n , and R≥r1>r2>r3>…r n , and set the difference between the radius of two adjacent sampling circles to Δr, where:

[0028] The multiple sampling points selected on the sampling circle with radius r1 are: ER 11 , ER 12 , ER 13 …ER 1m ;

[0029] The multiple sampling points selected on the sampling circle with a radius of r2 are: ER 21 , ER 22 , ER 23 …ER 2m ;

[0030] The multiple sampling points selected on the sampling circle with a radius of r3 are: ER 31 , ER 32 , ER 33 …ER 3m ;

[0031] The multiple sampling points selected on the sampling circle with a radius of r4 are: ER 41 , ER 42 , ER 43 …ER 4m ;

[0032] …

[0033] The radius is r n The multiple sampling points selected on the sampling circle are: ER n1 , ER n2 , ER n3 …ER nm .

[0034] Optionally, relevant instruments may be used to detect the etching rates of multiple sampling points on the wafer, for example, a thickness measuring instrument may be used.

[0035] For each of the above sampling points, the etching rate of each sampling point is detected by a detection instrument. The detected etching rates are: VER 11 VER 12 VER 13 …VER 1mVER 21 VER 22 VER 23 …VER 2m VER 31 VER 32 VER 33 …VER 3m VER 41 VER 42 VER 43 …VER 4m …VER nm , and record the etching rates at multiple sampling points.

[0036] S40: Calculate the average etching rate of multiple sampling points on each sampling circle.

[0037] Based on the etching rates of the above sampling points, the average etching rates of multiple sampling points on each sampling circle are calculated as follows:

[0038] Meanr1=(VER 11 +VER 12 +VER 13+ …VER 1m ) / m;

[0039] Meanr2=(VER 21 +VER 22 +VER 23+ …VER 2m ) / m;

[0040] Meanr3=(VER 31 +VER 32 +VER 33+ …VER 3m ) / m;

[0041] Meanr4=(VER 41 +VER 42 +VER 43+ …VER 4m ) / m;

[0042] …

[0043] Meaner n =(VER n1 +VER n2 +VER n3+ …VER nm ) / m.

[0044] S50: determining an offset and an offset direction between an initial mechanical center point and an ideal center point in the edge etching chamber according to the etching rates of the plurality of sampling points and the average etching rate of the plurality of sampling points on each sampling circle and according to a preset function.

[0045] It should be noted that the ideal center point can be understood as the point in the edge etching chamber where there is no positional deviation between the wafer and the transfer position in the edge etching chamber. In addition, the determination of the offset amount and offset direction will be explained in detail below.

[0046] S60: Inputting a compensation parameter of the offset between the initial mechanical center point and the ideal center point in the edge etching chamber into the transmission device to obtain a compensated mechanical center point.

[0047] It is understood that after the compensation parameters are input into the transfer device, the transfer device can make corrections based on the initial mechanical center point position parameters, thereby adjusting the position of the mechanical center point and ultimately obtaining a compensated mechanical center point. In this case, the compensated mechanical center point coincides with the ideal center point. In this way, the transfer device transfers the wafer to the edge etching chamber based on the compensated mechanical center point, ensuring that the center of the wafer coincides with the ideal center point of the edge etching chamber, thereby ensuring the position accuracy of the wafer.

[0048] Based on the above settings, the embodiment of the present application can determine the offset and offset direction between the initial mechanical center point and the ideal center point in the edge etching chamber according to the etching rates of multiple sampling points on the wafer and the average etching rate of multiple sampling points on each sampling circle, and according to a preset function, and then obtain a compensation parameter for the offset, and input the compensation parameter into the transmission device to obtain the compensated mechanical center point, that is, to determine the precise center point in the edge etching chamber, so that when the transmission device transmits the wafer to the edge etching chamber, the wafer can be placed at the ideal center point in the edge etching chamber, thereby ensuring the transmission accuracy of the wafer, and then ensuring the etching accuracy and improving product quality.

[0049] Optionally, determining the offset between the initial mechanical center point and the ideal center point in the edge etching chamber according to the etching rates of the plurality of sampling points and the average etching rate of the plurality of sampling points on each sampling circle and according to a preset function includes:

[0050] S51: determining a difference between the average etching rates of the plurality of sampling points on two adjacent sampling circles according to the etching rates of the plurality of sampling points and the average etching rate of the plurality of sampling points on each sampling circle.

[0051] In the embodiment of the present application, the differences in the average etching rates of multiple sampling points on two adjacent sampling circles are:

[0052] Δ1ER=(Meanr1-Meanr2);

[0053] Δ2ER=(Meanr2-Meanr3);

[0054] Δ3ER = (Meanr3 - Meanr4);

[0055] …

[0056] Δ n ER=(Meanr n -Meanr (n+1) ).

[0057] S52: The above preset function is: ΔL nm =(VER nm –Meanr n ) / (Meanr n –Meanr (n+1) )*Δr.

[0058] Among them, Meanr n is the average etching rate of multiple sampling points on the nth sampling circle, Meanr (n+1) is the average etching rate of multiple sampling points on the n+1th sampling circle, VER nm is the etching rate of the mth sampling point on the nth sampling circle, ΔL nm is the offset of the mth sampling point on the nth sampling circle relative to the ideal center point, and Δr is the difference in radius between two adjacent sampling circles.

[0059] In this way, the offset of each sampling point relative to the ideal center point can be calculated according to the above preset function.

[0060] Based on the above, we can see that points on the wafer with increased etching rates are offset away from the wafer center, while points with decreased etching rates are offset toward the wafer center. Therefore, the offset can be determined based on the change in etching rate at each point. A positive offset indicates that the point is offset away from the center, while a negative offset indicates that the point is offset toward the center.

[0061] S53: performing data statistics on the offset of each sampling point relative to the ideal center point, and confirming the offset between the initial mechanical center point and the ideal center point in the edge etching chamber according to the statistical results.

[0062] Optionally, performing statistical analysis on the offset of each sampling point relative to the ideal center, and confirming the offset between the initial mechanical center and the ideal center in the edge etching chamber based on the statistical results, including:

[0063] According to the offset of each sampling point relative to the ideal center point, the offset with the largest absolute value is selected;

[0064] The offset with the largest absolute value is taken as the offset between the initial mechanical center point and the ideal center point.

[0065] Optionally, the compensation parameter includes a compensation value and a compensation direction, wherein the compensation value is equal to the absolute value of the maximum offset, and the offset direction is the opposite direction of the offset direction of the sampling point corresponding to the offset with the largest absolute value relative to the ideal center point.

[0066] Based on this, the transmission parameters in the transmission device can be corrected according to the compensation value and compensation direction. According to the corrected transmission parameters, the wafer can be transmitted to the preset position, so that the compensated mechanical center point coincides with the ideal center point, ensuring the transmission accuracy of the wafer.

[0067] Optionally, the radius of the wafer is 150 mm, the radius of the sampling circles selected on the wafer ranges from 148 mm to 149.6 mm, and the difference between the radius values ​​of two adjacent sampling circles is no more than 0.3 mm.

[0068] Furthermore, the radius of the sampling circles selected on the wafer ranges from 149.0 mm to 149.6 mm, and the radius difference between two adjacent sampling circles is 0.2 mm.

[0069] Considering the specific circumstances of the wafer edge etching process in the embodiments of the present application, generally, there is essentially no plasma in areas away from the wafer edge, while there is more plasma in areas near the wafer edge. In other words, the plasma density gradually decreases from the outside to the inside, reaching zero at the center of the wafer. Based on this, changes in different locations on the wafer may lead to changes in plasma density, which in turn leads to changes in the etching rate.

[0070] In order to ensure that the etching rate can be detected smoothly, in the embodiment of the present application, a sampling circle is selected in the area near the edge of the wafer. The radius range of the selected wafer can be 148mm to 150mm. In addition, considering that when the radius of the sampling circle where the sampling point is located is less than 149mm, its etching rate will be significantly reduced, so the radius range of the sampling circle on the wafer can be selected to be 149mm to 150mm.

[0071] Considering that during actual chip production, a certain amount of space is reserved on the outer edge of the wafer for operations such as clamping, the radius of the sampling circle where the sampling point on the wafer is located will be slightly less than 150mm. Alternatively, a circle with a radius not exceeding 149.6mm can be selected on the wafer as the sampling circle.

[0072] Based on the above analysis, in the present embodiment, the sampling circle is set within the radius range of 149.0 to 149.6 mm. Of course, to obtain the difference in average etching rate between the sampling circle with a radius of 149.0 mm and the adjacent sampling circle, the data of each sampling point on the sampling circle with a radius of 148.8 mm can be added.

[0073] Optionally, the radius difference between two adjacent sampling circles is no greater than 0.3 mm, and specifically can be 0.1 mm, 0.2 mm, 0.3 mm, etc. However, considering that a smaller radius difference means fewer sampling points, which can easily lead to less sampled data and lack of representativeness, a larger radius difference means more sampling points, which can easily lead to too much sampled data and affect calculation speed. Optionally, the radius difference between two adjacent sampling circles is set to 0.2 mm.

[0074] It should be noted that, to improve accuracy, multiple sampling points can be selected on each sampling circle to reduce errors. Optionally, the number of sampling points selected on each sampling circle is greater than or equal to 8. Of course, even more sampling points can be selected to make the calculated offset of each sampling point relative to the ideal center point more accurate.

[0075] Optionally, when the mechanical center point coincides with the ideal center point, the etching rates of the sampling points on the sampling circle with the same radius value are the same; the etching rates of the sampling points on the sampling circles with different radius values ​​vary linearly with the radius value.

[0076] It should be noted here that, assuming that the center of the wafer coincides with the ideal center point, the etching rates of all points on the circle with the same radius value on the wafer are the same, and the etching rates of all sampling points on the sampling circles with different radius values ​​change linearly with the radius value. Specifically, as the radius value of the sampling circle decreases, the etching rate gradually decreases, showing a linear relationship. Based on this, when the center of the wafer does not coincide with the ideal center point, that is, when the wafer shifts, the etching rates of some points on the circle with the same radius value increase, and the etching rates of other points decrease. However, before and after the wafer shifts, the average etching rate of each point on the circle with the same radius value does not change.

[0077] Optionally, inputting the position parameters of the initial mechanical center point in the etching chamber into the transmission device includes:

[0078] placing the mechanical tooling in the edge etching chamber;

[0079] Taking the center of the mechanical tooling as the initial mechanical center point, and moving the finger of the transmission device to the initial mechanical center point, so that the transmission device generates the initial position parameter value of the mechanical center point;

[0080] Saves the position parameter value to the transmission device.

[0081] Based on the above settings, the transmission device can obtain the position of the initial mechanical center point by moving the finger of the transmission device to the initial mechanical center point, and generate a specific position parameter value to achieve initial position positioning.

[0082] Optionally, the etching rates of multiple sampling points on the wafer are detected, including:

[0083] Using a detection instrument to measure the film thickness of the wafer before the etching process to obtain a first film thickness;

[0084] Measuring the film thickness of the wafer after the etching process using a detection instrument to obtain a second film thickness;

[0085] The ratio of the difference between the first film thickness and the second film thickness to the etching time is the etching rate.

[0086] The specific detection method is as follows: Before the etching process, the film thickness on the wafer surface is measured to obtain a first film thickness H1. After the etching process is completed, the film thickness on the wafer surface is measured again to obtain a second film thickness H2. The difference between the two film thicknesses is divided by the etching time t to obtain the etching rate V. Specifically, V = (H1-H2) / t. Based on this method, the etching rate at each sampling point on the wafer can be calculated.

[0087] The following will be explained in detail using a wafer with a radius of 150 mm as an example.

[0088] Taking into account factors such as the distribution of etch rates on the wafer and actual chip production conditions, in this embodiment of the application, the radius of the sampling circle on the wafer is selected to range from 149.0 to 149.6 mm. To obtain the difference in average etch rate between the sampling circle with a radius of 149.0 mm and the adjacent sampling circle, data from each sampling point on the sampling circle with a radius of 148.8 mm can be added.

[0089] Optionally, in the embodiment of the present application, the radius difference between two adjacent sampling circles is set to 0.2mm. In this way, the radius values ​​of the sampling circles selected on the wafer are: 149.6mm, 149.4mm, 149.2mm, 149.0mm and 148.8mm, and 8 sampling points are selected from each sampling circle to collect data, such as Figure 3 As shown, the average etching rate of multiple sampling points on each sampling circle and the difference between the average etching rates of multiple sampling points on two adjacent sampling circles are calculated based on the etching rates of each sampling point on the five sampling circles. For details, please refer to Table 1.

[0090]

[0091] Table 1 Etching rate of each sampling point and average etching rate of multiple sampling points on the sampling circle of each radius value

[0092] The difference between the average etching rates of multiple sampling points on the sampling circle of two adjacent radius values

[0093] Based on the data in Table 1 above, and according to the preset function ΔL nm =(VER nm –Meanr n ) / (Meanr n –Meanr (n+1) )*Δr, the offset of each sampling point with n=1~4 and m=1~8 relative to the ideal center point can be calculated. In order to facilitate reading the data, the unit can be microns. At this time, the preset function is ΔL nm =(VER nm –Meanr n ) / (Meanr n –Meanr (n+1) )*Δr*1000. The specific data of the offset of each sampling point relative to the ideal center point can be seen in Table 2.

[0094]

[0095] Table 2 The offset of each sampling point relative to the ideal center point

[0096] Based on the data in Table 2 above, select the data with the largest absolute value. The absolute value of this data represents the offset between the sampling point and the ideal center point. The sign represents the direction, where a positive sign represents the direction away from the center of the circle, and a negative sign represents the direction close to the center of the circle. Therefore, the compensation value is the absolute value of the maximum value, and the compensation direction is the opposite direction of the offset direction. 1m =-132.6 μm has the largest absolute value. Thus, the compensation value of this sampling point is 132.6 μm, and the compensation direction is away from the center of the circle.

[0097] It should be noted here that the above method of taking the maximum value may have a certain error, and this error can be reduced by selecting more sampling points on each sampling circle.

[0098] By inputting the parameters corresponding to the above compensation values ​​and compensation directions into the transmission device, the original transmission parameters stored in the transmission device can be corrected to obtain the compensated mechanical center point, and the compensated mechanical center point coincides with the ideal center point to complete the confirmation of the precise center position in the edge etching chamber.

[0099] To summarize, the embodiment of the present application can obtain the offset between the mechanical center point and the ideal center point in the edge etching chamber through the etching rate of multiple sampling points on the wafer and the average etching rate of multiple sampling points on each sampling circle, and compensate for the offset to obtain the compensation parameter, and input the compensation parameter into the transmission device to correct the original transmission parameter in the transmission device, thereby achieving the purpose of calibrating the transmission station, thereby ensuring the transmission accuracy of the wafer, ensuring the etching uniformity, and thus improving product quality.

[0100] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

Claims

1. A method for positioning a wafer in an edge etching chamber, characterized in that: The positioning method includes: Inputting the position parameters of the initial mechanical center point in the edge etching chamber into a transmission device, and controlling the transmission device to transmit the wafer to the edge etching chamber according to the initial position parameters of the mechanical center point; performing an edge etching process on the wafer; Selecting a plurality of sampling circles with different radius values ​​on the edge area of ​​the wafer, selecting a plurality of sampling points from each of the sampling circles, and detecting the etching rate of each of the sampling points; Calculating an average etching rate of the plurality of sampling points on each of the sampling circles; According to the etching rates of the plurality of sampling points and the average etching rate of the plurality of sampling points on each sampling circle, the offset and offset direction between the initial mechanical center point and the ideal center point in the edge etching chamber are determined according to a preset function; wherein, according to the etching rates of the plurality of sampling points and the average etching rate of the plurality of sampling points on each sampling circle, the difference between the average etching rates of the plurality of sampling points on two adjacent sampling circles is determined, and the preset function is: ΔL nm =(VER nm –Meanr n ) / (Meanr n – Meaner （n+1） )*Δr, where: Meanr n is the average etching rate of multiple sampling points on the nth sampling circle, Meanr （n+1） is the average etching rate of multiple sampling points on the n+1th sampling circle, VER nm is the etching rate of the mth sampling point on the nth sampling circle, ΔL nm is the offset of the mth sampling point on the nth sampling circle relative to the ideal center point, Δr is the radius difference between two adjacent sampling circles, the offset of each sampling point relative to the ideal center point is calculated according to the preset function, the offset of each sampling point relative to the ideal center point is statistically analyzed, and the offset between the initial mechanical center point and the ideal center point in the edge etching chamber is determined based on the statistical results; The compensation parameter of the offset between the initial mechanical center point and the ideal center point in the edge etching chamber is input into the transmission device to obtain the compensated mechanical center point.

2. The positioning method according to claim 1, wherein: The performing of data statistics on the offset of each sampling point relative to the ideal center point, and confirming the offset between the initial mechanical center point and the ideal center point in the edge etching chamber according to the statistical results, includes: According to the offset of each sampling point relative to the ideal center point, the offset with the largest absolute value is selected; The offset with the largest absolute value is used as the offset between the initial mechanical center point and the ideal center point.

3. The positioning method according to claim 2, characterized in that: The compensation parameters include compensation value and compensation direction; The compensation value is equal to the absolute value of the maximum offset; The compensation direction is the opposite direction of the offset direction of the sampling point corresponding to the offset with the largest absolute value relative to the ideal center point.

4. The positioning method according to claim 1, wherein: The radius of the wafer is 150 mm, the radius of the sampling circles selected on the wafer ranges from 148 mm to 149.6 mm, and the difference in radius between two adjacent sampling circles is no more than 0.3 mm.

5. The positioning method according to claim 4, characterized in that: The radius of the sampling circles selected on the wafer ranges from 149.0 mm to 149.6 mm, and the radius difference between two adjacent sampling circles is 0.2 mm.

6. The positioning method according to claim 4 or 5, characterized in that: The number of the sampling points selected on each sampling circle is greater than or equal to 8.

7. The positioning method according to claim 1, characterized in that: When the mechanical center point coincides with the ideal center point, the etching rates of the sampling points on the sampling circle with the same radius value are the same; the etching rates of the sampling points on the sampling circles with different radius values ​​vary linearly with the radius value.

8. The positioning method according to claim 1, wherein: The step of inputting the position parameters of the initial mechanical center point in the edge etching chamber into a transmission device comprises: placing a mechanical tool in the edge etching chamber; Taking the center of the mechanical tool as the initial mechanical center point, and moving the finger of the transmission device to the initial mechanical center point, so that the transmission device generates the initial position parameter value of the mechanical center point; The position parameter value is saved to the transmission device.

9. The positioning method according to claim 1, characterized in that: The detecting the etching rate of each of the sampling points includes: Using a detection instrument to measure the film thickness of the wafer before the etching process to obtain a first film thickness; Measuring the film thickness of the wafer after the etching process using a detection instrument to obtain a second film thickness; The ratio of the difference between the first film thickness and the second film thickness to the etching time is the etching rate.

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