Device and method for grinding silicon wafer
By real-time monitoring and calculating the grinding thickness and rate of each area of the silicon wafer surface and adjusting the nozzle motion parameters, the problem of uneven distribution of the abrasive liquid in the prior art is solved, and uniform grinding of the film on the silicon wafer surface is achieved and uniform morphology of the film on the silicon wafer surface is achieved. improves the quality of chip products.
Patent Information
- Application Number
- CN202310975918.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-03
- Publication Date
- 2025-02-14
AI Technical Summary
The supply method of the existing chemical mechanical grinding equipment leads to the distribution of the grinding liquid that is too concentrated, affecting the removal rate and morphological uniformity of the film on the surface of the silicon wafer, and thus affecting the quality of chip products.
By obtaining the grinding thickness values and initial thickness values of each area of the silicon wafer surface in real time, calculate the grinding amount and grinding rate, and control the nozzle movement time proportion and speed according to the grinding rate feedback to achieve uniform distribution of grinding liquid on the grinding disc.
The uniform grinding of the film on the surface of the silicon wafer is achieved, which improves the grinding rate, while maintaining the uniformity of the silicon wafer morphology and improving the quality of the chip product.
Smart Images
Figure CN119427063A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of chemical mechanical polishing for integrated circuit manufacturing, and in particular to a device and method for polishing a silicon wafer. Background Art
[0002] Chemical mechanical polishing in chip manufacturing requires stable polishing rate, thickness and morphology. At present, the polishing liquid supply method of chemical mechanical polishing equipment is to supply it to the grinding disc at a fixed position, and use the centrifugal force of the grinding disc and the spreading effect of the grinding disc dresser to achieve uniform distribution of the polishing liquid. When the grinding disc rotates, the movement trajectory of the nozzle relative to the grinding disc is circular, such as Figure 1 However, this fixed position liquid supply method causes the grinding liquid to be distributed more concentratedly, and the grinding disc dresser needs a long time to achieve the ideal effect, which affects the removal rate of the thin film on the silicon wafer surface and the uniformity of the morphology, thereby affecting the quality of the chip product. Therefore, a new device and method for grinding silicon wafers is urgently needed to improve the above problems. Summary of the invention
[0003] The object of the present invention is to provide a device and method for grinding silicon wafers, which method is used to adjust the distribution state of grinding liquid on the grinding disk in real time to improve the grinding rate of the thin film on the surface of the silicon wafer.
[0004] In a first aspect, the present invention provides a method for grinding a silicon wafer, comprising: obtaining an initial thickness value of each area on the surface of the silicon wafer before grinding the silicon wafer; when grinding the surface of the silicon wafer, obtaining the grinding thickness value of each area in real time; calculating the grinding amount of each area according to the grinding thickness value and the initial thickness value; obtaining the grinding time, and calculating the grinding rate of each area according to the grinding amount and the grinding time; based on the feedback of the demand for the amount of grinding liquid in each area corresponding to the grinding rate of each area, controlling the movement time proportion and movement speed of the nozzle relative to each grinding interval of the grinding disk, so that the thickness of each area on the surface of the silicon wafer after grinding meets the requirements.
[0005] The method of the present invention has the following beneficial effects: when grinding the surface of the silicon wafer, the present invention obtains the grinding thickness value of each area in real time; calculates the amount of grinding in each area according to the grinding thickness value and the initial thickness value; obtains the grinding time, and can calculate the grinding rate of each area in real time according to the amount of grinding and the grinding time. According to the feedback of the grinding rate of each area corresponding to the demand for the amount of grinding liquid in the area, the movement time proportion and movement speed of the nozzle relative to each grinding interval of the grinding disk are controlled so that the thickness of each area on the surface of the silicon wafer after grinding meets the requirements, and the distribution state of the grinding liquid on the grinding disk is adjusted in real time so that the grinding liquid is evenly distributed on the grinding disk, which can improve the grinding rate of the thin film on the surface of the silicon wafer, while maintaining the uniformity of the silicon wafer morphology, which is conducive to improving the quality of the entire chip.
[0006] Optionally, the method of obtaining the initial thickness values of various areas on the surface of the silicon wafer before grinding the silicon wafer includes: before grinding the silicon wafer, setting M concentric circles on the upper surface of the silicon wafer with the center of the silicon wafer as the center of the circle, where M is an integer greater than 1; forming annular areas between adjacent concentric circles, and measuring the average thickness value of the silicon wafer in each of the annular areas as the initial thickness value of the annular areas.
[0007] Optionally, an average thickness value of the silicon wafer in a circular surface area surrounded by a circle adjacent to the center of the silicon wafer is measured as an initial thickness value of the circular surface area.
[0008] Optionally, the grinding time is obtained, and the grinding rate of each area is calculated according to the grinding amount and the grinding time, including: when grinding the silicon wafer surface, starting timing and recording the initial thickness value of each area; when grinding stops, stopping timing and recording the grinding thickness value of each area; calculating the grinding rate of each area according to the grinding amount of the area and the grinding time corresponding to the area.
[0009] Optionally, the grinding rate of each area is fed back according to the demand for the amount of grinding liquid in that area, so as to control the movement time proportion and movement speed of the nozzle relative to each grinding interval of the grinding disk, including: taking the axis of the grinding disk as the center, dividing the top surface of the grinding disk into a plurality of annular grinding intervals; for grinding intervals with higher grinding rates, the main unit controls the movement speed of the nozzle to be slower, so that the nozzle moves for a larger proportion of the time in the grinding interval.
[0010] In a second aspect, the present invention provides a device for grinding silicon wafers, comprising: a measuring unit, for obtaining the initial thickness value of each area on the surface of the silicon wafer before grinding the silicon wafer; when grinding the surface of the silicon wafer, the measuring unit obtains the grinding thickness value of each area in real time; a main machine, for calculating the grinding amount of each area according to the grinding thickness value and the initial thickness value; obtaining the grinding time, and calculating the grinding rate of each area according to the grinding amount and the grinding time; according to the demand feedback of the grinding rate of each area corresponding to the amount of grinding liquid in the area, controlling the movement time proportion and movement speed of the nozzle relative to each grinding interval of the grinding disk, so that the thickness of each area on the surface of the silicon wafer after grinding meets the requirements.
[0011] Optionally, one end of the nozzle is connected to a grinding liquid arm; the grinding liquid arm is used to drive the nozzle to reciprocate on the upper surface of the grinding disk so that the nozzle sprays grinding liquid to various areas of the silicon wafer surface; the main machine is electrically connected to the grinding liquid arm to control the movement time ratio and movement speed of the nozzle relative to each grinding interval of the grinding disk.
[0012] Optionally, M concentric circles are arranged on the upper surface of the silicon wafer with its center as the center, and M is an integer greater than 1; a circular ring area is formed between adjacent concentric circles, and the measuring unit is also used to measure the average thickness value of the silicon wafer in each of the circular ring areas before grinding the silicon wafer, as the initial thickness value of the circular ring area.
[0013] Optionally, the main station is also used to start timing and record the initial thickness value of each area when grinding the silicon wafer surface; stop timing and record the grinding thickness value of each area when grinding stops; calculate the grinding rate of each area based on the grinding amount of each area and the corresponding grinding time of the area.
[0014] Optionally, the top surface of the grinding disc is divided into a number of annular grinding intervals with the axis of the grinding disc as the center. For grinding intervals with higher grinding rates, the main unit is used to control the nozzle movement speed more slowly so that the nozzle spends a larger proportion of time moving in the grinding interval.
[0015] Optionally, it also includes a grinding disc and a grinding head; the grinding head and the grinding liquid arm are both arranged on the top side of the grinding disc; the grinding head is used to load the silicon wafer and press the lower surface of the silicon wafer toward the grinding disc, and the upper surface of the grinding disc is used to grind the lower surface of the silicon wafer.
[0016] Optionally, a dresser is further provided on the top side of the grinding disc, and when the dresser contacts the grinding disc, it is used to abrade the grinding disc to maintain a consistent degree of abrasion in various regions of the grinding disc.
[0017] Optionally, the grinding head is used to drive the silicon wafer to rotate and rub relative to the grinding disk, and the grinding disk is used to rotate around a central axis perpendicular to the grinding disk; the diameter of the grinding disk is N times the silicon wafer, and N is greater than 2. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a structural schematic diagram of a device for grinding silicon wafers in the prior art;
[0019] Figure 2 A schematic flow chart of a method for grinding a silicon wafer provided by the present invention;
[0020] Figure 3 A schematic diagram of the top view of a device for grinding silicon wafers provided by the present invention;
[0021] Figure 4 A schematic diagram of a curve showing the thickness of a silicon wafer in each region when the distance from the nozzle to the center of the grinding disk provided by the present invention is different;
[0022] Figure 5 A schematic diagram of the trajectory and time proportion of the nozzle movement in each grinding interval provided by the present invention.
[0023] Figure 6 A schematic side view of the structure of a device for grinding silicon wafers provided by the present invention.
[0024] Numbers in the figure:
[0025] 1. Grinding disc; 11. First motor; 2. Grinding head; 21. Second motor; 22. Measuring unit; 3. Grinding liquid arm; 31. Nozzle; 32. Third motor; 4. Dresser; 5. Mainframe; 6. Silicon wafer; 61. First area; 62. Second area. DETAILED DESCRIPTION
[0026] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.
[0027] In view of the problems existing in the existing technology, such as Figure 2 As shown, the present invention provides a method for grinding silicon wafers, comprising: S1, obtaining the initial thickness value of each area on the surface of the silicon wafer before grinding the silicon wafer; S2, when grinding the surface of the silicon wafer, obtaining the grinding thickness value of each area in real time; S3, calculating the grinding amount of each area according to the grinding thickness value and the initial thickness value; S4, obtaining the grinding time, and calculating the grinding rate of each area according to the grinding amount and the grinding time; S5, according to the demand feedback of the grinding rate of each area corresponding to the amount of grinding liquid in the area, controlling the movement time proportion and movement speed of the nozzle relative to each grinding interval of the grinding disk, so that the thickness of each area on the surface of the silicon wafer after grinding meets the requirements.
[0028] It is worth noting that, in this embodiment, when grinding the surface of the silicon wafer, the grinding thickness value of each area is obtained in real time; the grinding amount of each area is calculated according to the grinding thickness value and the initial thickness value; the grinding time is obtained, and the grinding rate of each area can be calculated in real time according to the grinding amount and the grinding time. According to the feedback of the demand for the amount of grinding liquid in each area corresponding to the grinding rate of each area, the movement time proportion and movement speed of the nozzle relative to each grinding interval of the grinding disk are controlled so that the thickness of each area on the surface of the silicon wafer after grinding meets the requirements, and the distribution state of the grinding liquid on the grinding disk is adjusted in real time so that the grinding liquid is evenly distributed on the grinding disk, which can improve the grinding rate of the thin film on the surface of the silicon wafer, while maintaining the uniformity of the silicon wafer morphology, which is conducive to improving the quality of the entire chip.
[0029] like Figure 3 As shown, in some embodiments, obtaining the initial thickness values of various areas on the surface of the silicon wafer 6 before grinding the silicon wafer 6 includes: before grinding the silicon wafer 6, arranging 4 concentric circles on the upper surface of the silicon wafer 6 with the center of the silicon wafer 6 as the center of the circle.
[0030] Specifically, a circular area is formed between adjacent concentric circles, and the average thickness value of the silicon wafer 6 in each of the circular areas is measured as the initial thickness value of the circular area. It is worth noting that M concentric circles can be set on the upper surface of the silicon wafer 6, and M is an integer greater than 1. In other specific embodiments, a circular surface area is formed by a circle adjacent to the center of the silicon wafer 6, and the average thickness value of the silicon wafer 6 in the circular surface area is measured as the initial thickness value of the circular surface area. For example, the number of the concentric circles is set to 7, and the top surface of the silicon wafer 6 is provided with 1 circular surface area and 6 annular areas.
[0031] Exemplarily, the initial thickness value of the first region 61 is TH1, the grinding thickness value of the first region 61 is THK1, and the grinding amount RA1 of the first region 61 can be calculated; the initial thickness value of the second region 62 is TH2, the grinding thickness value of the second region 62 is THK2, and the grinding amount RA2 of the second region 62 can be calculated; the initial thickness value of the seventh region is TH7, the grinding thickness value of the seventh region is THK7, and the grinding amount RA7 of the seventh region can be calculated.
[0032] More specifically, the initial thickness of the first region 61 and the second region 62 are both 240 nm. The grinding thickness of the first region 61 is 160 nm, and the grinding thickness of the second region 62 is 170 nm. The grinding amount of the first region 61 is 80 nm, and the grinding amount of the second region 62 is 70 nm.
[0033] In other embodiments, the grinding time is obtained, and the grinding rate of each area is calculated according to the grinding amount and the grinding time, including: when grinding the surface of the silicon wafer 6, starting the timing and recording the initial thickness value of each area; when the grinding stops, stopping the timing and recording the grinding thickness value of each area; calculating the grinding rate of each area according to the grinding amount of each area and the grinding time corresponding to the area.
[0034] For example, it is known that the grinding amount RA1 of the first area 61 is 80nm and the grinding amount RA2 of the second area 62 is 70nm; when the grinding time of the first area 61 and the second area 62 is 10s, the grinding rate RR1 of the first area 61 is 8nm / s, and the grinding rate RR2 of the second area 62 is 7nm / s; it is worth noting that the grinding time can be set to a non-zero default value to avoid calculation errors when the denominator is zero.
[0035] In some other embodiments, the feedback of the grinding rate of each area corresponding to the demand for the amount of grinding liquid in the area controls the movement time proportion and movement speed of the nozzle 31 relative to each grinding interval of the grinding disc 1, including: taking the axis of the grinding disc 1 as the center, dividing the top surface of the grinding disc 1 into a plurality of annular grinding intervals; for a grinding interval with a higher grinding rate, the main stage 5 controls the movement speed of the nozzle 31 to be slower, so that the nozzle 31 has a larger movement time proportion in the grinding interval. For a grinding interval with a lower grinding rate, the main stage 5 controls the movement speed of the nozzle 31 to be faster, so that the nozzle 31 has a smaller movement time proportion in the grinding interval.
[0036] It is worth noting that the boundary of the grinding interval is tangent to the boundary of the area. This embodiment facilitates the movement of the nozzle 31 in different grinding intervals. The grinding interval of the grinding disc 1 drives the grinding liquid to move to the area corresponding to the silicon wafer 6 to achieve the addition of grinding liquid to different areas.
[0037] Specifically, Figure 4 As shown, with the axis of the grinding disc 1 as the center, the top surface of the grinding disc 1 is divided into a circular grinding zone and six annular grinding zones. The circular grinding zone is the first grinding zone, which is located at the center of the grinding disc 1. The second grinding zone, the third grinding zone, the fourth grinding zone, the fifth grinding zone, the sixth grinding zone and the seventh grinding zone are sequentially arranged outward from the first grinding zone.
[0038] like Figure 5As shown, specifically, when the grinding rate in the first grinding interval is higher than the expected grinding rate, the proportion of the time that the nozzle 31 moves in the first grinding interval is controlled to be reduced from 12% to 10%, so as to reduce the amount of grinding liquid in the first grinding interval and achieve the expected grinding rate of 7.5nm / s; when the grinding rate in the second grinding interval is lower than the expected grinding rate, the proportion of the time that the nozzle 31 moves in the second grinding interval is controlled to be increased from 10% to 12%, so as to increase the amount of grinding liquid in the second grinding interval and achieve the expected grinding rate of 7.5nm / s.
[0039] like Figure 6 As shown, the present invention provides a device for grinding silicon wafers, including: a measuring unit 22, used to obtain the initial thickness value of each area on the surface of the silicon wafer 6 before grinding the silicon wafer 6; when grinding the surface of the silicon wafer 6, the measuring unit 22 obtains the grinding thickness value of each area in real time; a main stage 5, used to calculate the grinding amount of each area according to the grinding thickness value and the initial thickness value; obtain the grinding time, and calculate the grinding rate of each area according to the grinding amount and the grinding time; according to the demand feedback of the grinding rate of each area corresponding to the amount of grinding liquid in the area, control the movement time proportion and movement speed of the nozzle 31 relative to each grinding interval of the grinding disk 1, so that the thickness of each area on the surface of the silicon wafer 6 after grinding meets the requirements.
[0040] Specifically, the measuring unit 22 is a wafer thickness measuring instrument, and the host platform 5 is a host computer. The wafer thickness measuring instrument is electrically connected to the host computer, and the host computer is used to control the wafer thickness measuring instrument to measure the thickness of the silicon wafer 6 and record the thickness for calculation.
[0041] Specifically, one end of the nozzle 31 is connected to a grinding liquid arm 3; the grinding liquid arm 3 is used to drive the nozzle 31 to reciprocate on the upper surface of the grinding disk 1, so that the nozzle 31 sprays grinding liquid to various areas on the surface of the silicon wafer 6; the main machine 5 is electrically connected to the grinding liquid arm 3 to control the movement time ratio and movement speed of the nozzle 31 relative to each grinding interval of the grinding disk 1.
[0042] More specifically, the polishing liquid arm 3 is provided with a liquid pump for pumping the polishing liquid to the nozzle 31. The mainframe 5 is electrically connected to the liquid pump. Figure 3 , the grinding liquid arm 3 swings back and forth, and the nozzle 31 reciprocates along an arc trajectory.
[0043] In some embodiments, it also includes a grinding disc 1 and a grinding head 2; the grinding head 2 and the grinding liquid arm 3 are both arranged on the top side of the grinding disc 1; the grinding head 2 is used to load the silicon wafer 6 and press the lower surface of the silicon wafer 6 toward the grinding disc 1, and the upper surface of the grinding disc 1 is used to grind the lower surface of the silicon wafer 6. Specifically, the grinding disc 1 and the grinding head 2 are both set in a disc shape; the collar end surface of the grinding disc 1 is set to be rough, and is used to grind the bottom end surface of the silicon wafer 6.
[0044] In some embodiments, a dresser 4 is further provided on the top side of the grinding disc 1. When the dresser 4 contacts the grinding disc 1, it is used to abrade the grinding disc 1 to maintain a uniform degree of abrasion in each area of the grinding disc 1. Specifically, the dresser 4 is provided in a strip shape; in some other specific embodiments, the dresser 4 is provided in a disc shape. It is worth noting that the dresser 4 can be provided in any shape.
[0045] In some embodiments, the grinding head 2 is used to drive the silicon wafer 6 to rotate and rub relative to the grinding disk 1, and the grinding disk 1 is used to rotate around a central axis perpendicular to the grinding disk 1; the diameter of the grinding disk 1 is 3 times that of the silicon wafer 6. Specifically, the grinding head 2 is detachably connected to the silicon wafer 6. When the silicon wafer 6 is installed on the grinding head 2, the grinding head 2 is relatively fixed to the silicon wafer 6. The bottom end surface of the silicon wafer 6 is in contact with the top end surface of the grinding disk 1 and does not contact the center position of the grinding disk 1. It is worth noting that the diameter of the grinding disk 1 is N times that of the silicon wafer 6, and N can be greater than 2. This setting can prevent the center position of the grinding disk 1 from contacting the silicon wafer 6. Since the rotation speed of the center position of the grinding disk 1 is 0, it can avoid the situation where the grinding rate of some areas of the silicon wafer 6 is too slow.
[0046] Please refer to Figure 6 The bottom center of the grinding disc 1 is connected to a first motor 11, which is used to drive the grinding disc 1 to rotate when the first motor 11 is working; the top center of the grinding head 2 is connected to a second motor 21, which is used to drive the grinding head 2 and the silicon wafer 6 to rotate together when the second motor 21 is working; the end of the grinding liquid arm 3 away from the grinding disc 1 is connected to a third motor 32, which is used to drive the grinding liquid arm 3 and the nozzle 31 to reciprocate together when the third motor 32 is working. It is worth noting that please refer to Figure 3 The reciprocating trajectory of the nozzle 31 does not exceed the grinding disc 1. This arrangement can ensure that the grinding liquid falls on the grinding disc 1, avoiding the waste of grinding liquid.
[0047] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.
Claims
1. A method for grinding a silicon wafer, characterized in that: include: Obtaining the initial thickness values of various areas on the surface of the silicon wafer before grinding the silicon wafer; When grinding the surface of the silicon wafer, obtaining the grinding thickness value of each area in real time; Calculate the grinding amount of each area according to the grinding thickness value and the initial thickness value; Acquiring grinding time, and calculating the grinding rate of each area according to the grinding amount and the grinding time; Based on the feedback of the grinding rate of each area and the amount of grinding liquid required in that area, the movement time proportion and movement speed of the nozzle relative to each grinding interval of the grinding disk are controlled so that the thickness of each area on the surface of the silicon wafer after grinding meets the requirements.
2. The method according to claim 1, characterized in that The step of obtaining the initial thickness values of various regions on the surface of the silicon wafer before grinding the silicon wafer comprises: Before grinding the silicon wafer, M concentric circles are set on the upper surface of the silicon wafer with the center of the silicon wafer as the center, where M is an integer greater than 1; an annular area is formed between adjacent concentric circles, and the average thickness value of the silicon wafer in each of the annular areas is measured as the initial thickness value of the annular area.
3. The method according to claim 2, characterized in that A circular surface area surrounded by a circle adjacent to the center of the silicon wafer is used to measure the average thickness value of the silicon wafer in the circular surface area as the initial thickness value of the circular surface area.
4. The method according to claim 1, characterized in that: Acquiring the grinding time, and calculating the grinding rate of each area according to the grinding amount and the grinding time, including: When grinding the silicon wafer surface, start timing and record the initial thickness value of each area; when grinding stops, stop timing and record the grinding thickness value of each area; calculate the grinding rate of each area based on the grinding amount of each area and the corresponding grinding time of the area.
5. The method according to claim 1, characterized in that The method of controlling the movement time proportion and movement speed of the nozzle relative to each grinding zone of the grinding disc according to the feedback of the grinding rate of each zone corresponding to the demand of the grinding liquid amount of the zone includes: With the axis of the grinding disc as the center, the top surface of the grinding disc is divided into several annular grinding zones; for grinding zones with higher grinding rates, the main machine controls the nozzle movement speed to be slower, so that the nozzle moves in the grinding zone for a larger proportion of time.
6. A device for grinding silicon wafers, characterized in that: include: A measurement unit, used to obtain the initial thickness value of each area on the surface of the silicon wafer before grinding the silicon wafer; When grinding the surface of the silicon wafer, the measuring unit obtains the grinding thickness value of each area in real time; A main machine, used for calculating the grinding amount of each area according to the grinding thickness value and the initial thickness value; The grinding time is obtained, and the grinding rate of each area is calculated according to the grinding amount and the grinding time; based on the demand feedback of the grinding rate of each area corresponding to the amount of grinding liquid in the area, the movement time proportion and movement speed of the nozzle relative to each grinding interval of the grinding disk are controlled so that the thickness of each area on the surface of the silicon wafer after grinding meets the requirements.
7. The device according to claim 6, characterized in that One end of the nozzle is connected to a grinding liquid arm; The polishing liquid arm is used to drive the nozzle to reciprocate on the upper surface of the polishing disk so that the nozzle sprays the polishing liquid to various areas on the surface of the silicon wafer; The main machine is electrically connected to the grinding liquid arm to control the movement time ratio and movement speed of the nozzle relative to each grinding interval of the grinding disc.
8. The device according to claim 6, characterized in that M concentric circles are arranged on the upper surface of the silicon wafer with its center as the center, where M is an integer greater than 1; a circular ring area is formed between adjacent concentric circles, and the measuring unit is also used to measure the average thickness value of the silicon wafer in each of the circular ring areas before grinding the silicon wafer, as the initial thickness value of the circular ring area.
9. The device according to claim 6, characterized in that The main machine is also used to start timing and record the initial thickness value of each area when grinding the silicon wafer surface; stop timing and record the grinding thickness value of each area when grinding stops; calculate the grinding rate of each area according to the grinding amount of each area and the corresponding grinding time of the area.
10. The device according to claim 6, characterized in that The top surface of the grinding disc is divided into a number of annular grinding zones with the axis of the grinding disc as the center. For grinding zones with higher grinding rates, the main station is used to control the nozzle movement speed to be slower so that the nozzle moves in the grinding zone for a larger proportion of time.