A method and system for intelligent control of wafer thinning surface type and flatness

Abstract

The application discloses a kind of thinning wafer surface type and flatness intelligent control method and system, belong to the field of semiconductor manufacturing.The system includes intelligent air floatation main shaft, wafer surface type identification system, flatness measurement system, intelligent adjustment algorithm system, main shaft angle adjustment device and main shaft operating state monitoring system.Through real-time monitoring main shaft state and combining machine learning optimization strategy, system automatically adjusts the inclination of main shaft, gas flow and cooling water flow, ensure that the surface type quality and flatness in wafer thinning process meet the requirements.Wafer surface type identification system and flatness measurement system measure wafer surface data in real time by laser range finder, generate surface type three-dimensional model.The control method and system of the application can automatically adjust the working state of main shaft according to real-time data, reduce manual intervention, improve the surface type control precision and processing yield of wafer, with the characteristics of intelligentization, accurate control and high reliability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor wafer packaging thinning, and in particular to a method and system for controlling wafer surface shape and flatness through intelligent spindle adjustment. Background Technology

[0002] With the rapid development of global electronic information technology, the integrated circuit industry has become a commanding height for my country's high-tech development. my country's high-end chip manufacturing faces numerous restrictions, particularly regarding high-precision semiconductor equipment. In silicon wafer processing, after slicing, the wafer needs to be ground to thin it, removing the unevenness caused by multi-wire cutting. In the front-end processes, wafer bonding technology, which employs advanced packaging processes, also requires wafers to be thinner. During chip packaging, the back of the wafer needs to be ground to achieve the goal of thinner chip packaging. It is evident that wafer thinning processes are used in all stages of wafer manufacturing, and the requirements for the thinned wafer surface shape and flatness are becoming increasingly stringent.

[0003] Spin-on wafer grinding is a widely used wafer thinning technology. During wafer thinning, the wafer to be thinned is vacuum-adsorbed onto a stage and rotates together. The grinding wheel's cutting edge passes through the center of the wafer to achieve semi-contact grinding, reducing grinding heat and ensuring stable grinding force. The wafer thinning spindle drives a diamond thinning wheel to rotate at high speed and continuously feed along the axial direction to grind the wafer. The spindle is fixed inside a bushing via a support adjustment end, and the bushing moves along the Z-axis lead screw guide of the thinning equipment. In the thinning process, the operator needs to adjust the two adjustment ends of the spindle to control the surface profile according to the desired profile. The adjustment end is a differential thread; rotating the differential thread tilts the spindle and controls the wafer profile. In spin-on wafer grinding, wafer profile and flatness are two crucial aspects for judging wafer quality. If these two aspects fail to meet requirements, various negative impacts will occur on the chip fabrication process, such as fragmentation, depth of focus, alignment issues, uneven polishing, and uneven deposition. The flatness of the wafer surface also affects the number of stacked layers in 3D stacked packaging, thus impacting the integration density, performance, and lifespan of integrated circuit chips. Currently, the thinning spindle of wafer thinning equipment requires experienced operators to manually adjust the spindle angle. The workspace is limited, necessitating repeated grinding, wafer surface measurement, and manual spindle angle adjustments. Furthermore, this method cannot regulate the spindle's operating state to ensure adequate wafer flatness. The spindle's operating state changes after prolonged operation, making it impossible to guarantee optimal spindle performance. To avoid repetitive spindle adjustments, achieve automatic angle adjustment and compensation, and better control the flatness of the wafer after thinning, developing an intelligent control method for wafer surface shape and flatness is crucial.

[0004] In the field of existing wafer thinning spindle angle adjustment methods and devices, Beijing CETC Electronic Equipment Co., Ltd. disclosed an automatic spindle angle adjustment device (CN105563317A) for semiconductor-specific equipment. One end of the adjustment mechanism of this device is connected to the transmission mechanism, and the other end of the adjustment mechanism is fixedly connected to the spindle. The spindle angle is adjusted by controlling the backplate feed through a motor. However, the adjustable angle direction of the spindle is singular, and the adjustment data comes only from the wafer thickness detected by the measuring instrument. Moreover, the measuring instrument cannot accurately measure the wafer's surface shape and flatness. There is no intelligent algorithm to precisely control the adjustment device, and it cannot control the flatness of the wafer after thinning. Guangdong Zhaoheng Intelligent Technology Co., Ltd. applied for a fine-tuning mechanism and method for semiconductor processing precision equipment to adjust the position of the wafer stage. The adjustment device realizes the rotation angle and fine-tuning height of the wafer stage through two adjustment mechanisms respectively; drive mechanism. Simultaneously, the fine-tuning mechanism utilizes the lead screw transmission to convert linear motion into rotational motion. The yaw angle of the threaded sleeve and drive motor achieves the process of converting linear motion into rotational motion. By adjusting the transmission clearance between the lead screw and the threaded seat, zero-backlash transmission is achieved, which can largely meet the precision adjustment requirements of the semiconductor industry. However, this adjustment method controls the wafer surface shape by adjusting the height and tilt angle of the turntable, which is not as simple as controlling the tilt angle of the spindle. Furthermore, this patent does not achieve intelligent control and cannot simultaneously control flatness. Among them, Ningbo Xinfeng Precision Technology Co., Ltd. proposed a grinding spindle adjustment device (CN115194191A), which uses the rotation of two threaded sections with different pitches to achieve precision adjustment. However, the angles between the first and second adjustment mechanisms and the fixed end of this device can only be evenly distributed at 120°. This distribution method cannot eliminate the problem of mutual interference between the spindle adjustment devices. In summary, existing patents for controlling wafer thinning profiles are still limited to manual, non-intelligent, and complex processes. They cannot achieve one-click selection of process formulas for wafer profiles or real-time online detection and feedback of the thinning process. Furthermore, existing invention patents only achieve fixed micro-displacements at certain points of the spindle through mechanical structures, resulting in a single profile optimization effect. They do not simultaneously optimize both profile and flatness. They rely on manual detection methods to continuously cycle through the thinning-measurement-adjustment process, failing to achieve an automated intelligent control process that completes the wafer loading-thinning-profile optimization-wafer unloading. Summary of the Invention

[0005] The purpose of this invention is to provide an intelligent control method and system for the surface shape and flatness of thinned wafers, which solves the problems of inconvenient operation due to limited operating space when adjusting the spindle tilt angle, inability to accurately control the surface shape and flatness, inability to automatically adjust the spindle tilt angle according to the required surface shape, and the need for operators to adjust the spindle tilt angle based on experience.

[0006] To achieve the above objectives, this invention provides an intelligent control system for thinning wafer profiles and flatness, comprising an intelligent air-bearing spindle, a wafer profile recognition system, a flatness measurement system, an intelligent adjustment algorithm system, a spindle angle adjustment device, a spindle operation status monitoring system, and a spindle air pressure and cooling water flow rate adjustment device. After wafer grinding, the turntable transfers the wafer to the wafer profile recognition system, where an intelligent camera captures and identifies the wafer profile, classifying it accordingly. Then, the wafer enters the flatness measurement system to measure the flatness of the wafer after grinding, obtaining the wafer's flatness value. The profile type and flatness data are transmitted to the intelligent adjustment algorithm system, which, through AI recognition algorithms and spindle operation status recognition algorithms, provides spindle angle adjustment, spindle air pressure, and cooling water flow rate data. Based on the data provided by the algorithm system, the spindle angle adjustment device begins adjusting the spindle angle to the target value, and the spindle air pressure and cooling water flow rate adjustment device begins adjusting the spindle air pressure and cooling water flow rate valves to the target values. The wafer re-enters the grinding chamber, and grinding begins based on the new spindle angle, air pressure, and cooling water flow rates. After grinding, surface shape recognition and flatness measurement are performed again until the process requirements are met.

[0007] The intelligent spindle includes a motor, differential thread, water flow control valve, air flow control valve, temperature sensor, vibration sensor, displacement sensor, and laser rangefinder. For example... Figure 6 As shown.

[0008] The lower end of the spindle is equipped with two adjusting ends and one fixed end, all evenly distributed around the circumference of the spindle. Alternatively, the fixed end can be located above the perpendicular bisector of the two adjusting ends. The upper threaded sleeve of the differential threaded adjusting end is fastened to the spindle, and the lower threaded sleeve is fastened to the spindle mounting plate. The upper and lower threaded sleeves of the adjusting end are connected by a differential screw, which has two sections of threads with different pitches but the same nominal diameter. The lower end of the differential screw is connected to a motor, driving the motor to rotate the differential screw, thereby tilting the spindle. Figure 3 As shown. The main function of the fixed end is to achieve small-angle rotation without deformation. It is preferably a ball joint, but it can also be achieved by a spherical bearing, etc.

[0009] The water flow valve and the air flow valve are installed on the water inlet pipe and the air inlet pipe, respectively. After receiving a signal, they change the water flow rate and the air supply.

[0010] Temperature and vibration sensors are installed on the outside of the spindle near the thrust bearing and on the end face of the spindle, respectively, to transmit signals to the computer.

[0011] The displacement sensor is located above the rotor and measures the rotor's levitation height after the rotor floats up.

[0012] The laser rangefinder is located above the wafer and can transmit distance signals from various points on the wafer to the computer during grinding.

[0013] The spindle monitoring system can detect vibration, temperature, rotor lift height, and air supply pressure during spindle operation. Based on the detected data, a database is built. If the detected values ​​differ from those during normal spindle operation, an alarm will be triggered promptly, and the system will intelligently analyze the cause to assist technicians in troubleshooting, preventing more serious spindle damage, and enabling targeted spindle repairs.

[0014] The wafer surface shape recognition system records and analyzes the position of each point on the wafer after the computer receives the signal from the laser rangefinder, automatically generates a 3D model of the wafer, and then obtains the wafer surface shape, thickness and flatness.

[0015] The intelligent adjustment algorithm system described herein can be used to directly adjust the stable semi-contact grinding position of the wafer thinning spindle, thereby controlling the wafer profile. This method utilizes a laser rangefinder to measure the wafer profile in real time during the grinding process, using the height coordinates of the adjustment point to replace the actual rotation coordinates of the grinding wheel's cutting edge. This simplifies the cumbersome calculation method of traditionally calculating the spindle's cutting edge height and provides real-time feedback on the spindle angle during grinding. Furthermore, this method is adaptable to different distributions of the adjustment device, exhibiting universality in wafer angle adjustment. A novel adjustment device is also proposed, employing an inner and outer ring differential thread. The improved algorithm directly obtains the grinding wheel's coordinates, and the coordinate values ​​are used to control the motor's direct drive of the differential thread rotation, thereby controlling the grinding wheel height adjustment and significantly improving the equipment's angle adjustment accuracy. This invention enables precise adjustment of the spindle angle, controls the wafer profile, and improves the wafer thinning effect. It can achieve non-contact measurement and real-time monitoring and feedback of the wafer profile by taking points on the thinned wafer in real time. It has high reliability, avoids errors caused by manual adjustment, and improves the vulnerability caused by small pitch fine threads.

[0016] The intelligent control method includes the following steps, such as: Figure 7 As shown.

[0017] S1. Monitor the spindle's operating status in real time using multiple sensors to determine whether the spindle is in normal working condition;

[0018] S2. Adjust the motor rotation angle and change the spindle tilt angle according to the preset surface shape target;

[0019] S3. Automatically adjust the airflow and cooling waterflow based on the surface shape and flatness data of the thinned wafer;

[0020] S4. Analyze the wafer surface shape and determine whether the surface shape is qualified through the wafer surface shape recognition system;

[0021] S5. When the surface shape is not up to standard, the system readjusts the spindle tilt angle and running status according to the surface shape error, and performs grinding again until the surface shape meets the requirements.

[0022] S6. Repeat steps S4 to S5 until the wafer meets the expected surface shape and flatness requirements;

[0023] S7. The machine learning system records the error between the simulated results based on the requirements of surface shape and flatness and the actual grinding results, in order to improve the adjustment strategy in the next step, such as... Figure 8 As shown;

[0024] Taking an 8-inch silicon wafer and a thinning grinding wheel as an example, the diameter of the thinning grinding wheel is D1, the diameter of the silicon wafer is D2, and the wafer diameter is approximately the diameter of the outer cutting edge of the grinding wheel, denoted as R. Figure 9 As shown: A Cartesian coordinate system is established with the grinding wheel axis and the silicon wafer axis being thinned as Z1 and Z2 axes, respectively, and the grinding plane as the XOY plane. X1Y1Z1 and X2Y2Z2 are shown in the figure, with Y1 and Y2 being collinear. During the grinding process, the grinding wheel, originally located in the X1OY1 plane, controls the height of points A, B, and C through the spindle adjustment device to achieve semi-contact grinding of the silicon wafer, thereby controlling the surface shape after grinding and reducing heat generation during the grinding process. A`C` is the grinding outer edge of the grinding wheel after the angle is adjusted, and A`B` is the part where the grinding wheel is in semi-contact with the wafer. a, b, and c are the adjustment displacements at points A, B, and C, respectively. To simplify the coordinate transformation calculation, point A can be set as a fixed point, and the height changes at points B and C can be calculated.

[0025] Since wafer radius R1 = grinding wheel diameter R2 = R, after establishing the geometric model, we know that: O1C = O1B = O1A = AB = BC;

[0026] At this moment, in X1OY1, the coordinates of point A are ( Point B has coordinates (0, R, 0), and point C has coordinates ( ). );

[0027] Assuming an ideal state, during the spindle angle adjustment process, the rotation axis always passes through the origin of the coordinate system X1Y1Z1. A perpendicular line is drawn from point O1 to O1C, intersecting the grinding edge in the X1OY1 plane at point M and intersecting AB at point N. When adjusting the height of point C, points A, B, and C rotate around the line MN to points A', B', and C' respectively. The unit vector with MN as the axis is... According to the formula for rotation about any axis in a spatial rectangular coordinate system.

[0028]

[0029] in Rotation matrix for 3D coordinate transformation in the first 3 rows and 3 columns for:

[0030]

[0031] Where K = 1 - cosθ;

[0032]

[0033] Therefore, the coordinates of points A', B', and C' in the X1Y1Z1 coordinate system after rotation by θ° are:

[0034] ( (), , , (), )

[0035] Geometrically, the curve with radius R containing the grinding edge must pass through points A', B', and C'. The unit vector of the straight line containing the X1 axis is also present at this point. for:

[0036] ,

[0037] If point B is adjusted at this point, that is, the entire arc is rotated... The line in question rotates, that is, points A', B', and C' rotate around it. Rotation, assuming the rotation angle is α, can be derived from the same reasoning into the rotation matrix.

[0038]

[0039] Where K′=1-cosα.

[0040] We can then derive the relationship between the coordinates and angles of the three points A``, B``, and C`` in the X1Y1Z1 coordinate system after rotation.

[0041] Since the assumption holds, the center coordinates of the circle determined by points A'', B'', and C'' remain (0, 0, 0), and the curve is a surface determined by these three points.

[0042] The cross-sectional shape of a sphere with the origin of coordinate axes X1Y1Z1 and radius R.

[0043] Represent the plane containing points A'', B'', and C'' using vector notation, and find the coordinates of A'' as the base point. , The normal vector of the plane equation can be calculated from two vectors using geometric relationships. for:

[0044]

[0045] The equation of curve A1 with radius R passing through points A'', B'', and C'' is: Where M, N, and P are normal vectors. The coordinate components.

[0046] The current curve equation is in the X1Y1Z1 coordinate system. Through a translation transformation, the curve can be transformed into the X2Y2Z2 coordinate system to obtain equation A2. The actual wafer surface shape is obtained by rotating equation A1 around the Z2 axis in the X2Y2Z2 coordinate system. As shown in the figure, A2 is obtained by translating A1. A2 needs to be further transformed into the X2Y2Z2 coordinate system to obtain the equation of A2, as follows.

[0047]

[0048] At this point, the curve rotates around the Z2 axis, and the equation of the surface swept by the arc is the surface shape equation of the wafer grinding under ideal conditions.

[0049] Assuming point A is fixed at this moment, the Z-coordinate values ​​of points B and C are the actual adjusted height. By controlling the range of coordinate values, the surface equation of the grinding arc sweep can be obtained under different adjustment height conditions.

[0050] This rotational transformation process yields the relationship between the adjustment angle and the corresponding surface height curve. Furthermore, by understanding the relationship between the angle and the height of the corresponding adjustment end, the wafer surface profile can be controlled in real time.

[0051] Therefore, the present invention provides a method and system for intelligent control of wafer thinning surface shape and flatness using the above-described structure, which has the following beneficial effects:

[0052] (1) Improve wafer thinning accuracy. An intelligent air-bearing spindle and a high-precision adjustment device are adopted. The spindle tilt angle is adjusted by differential thread to achieve precise control of wafer surface shape and flatness, reduce the error of traditional manual adjustment, and improve processing accuracy.

[0053] (2) Automated adjustment reduces manual intervention. Traditional wafer thinning requires repeated manual measurement and adjustment, while the present invention, through intelligent adjustment algorithm and machine learning system, can analyze wafer surface data in real time and automatically adjust spindle tilt angle, air pressure and cooling water flow, which greatly reduces the complexity of manual operation and improves production efficiency.

[0054] (3) Real-time monitoring to improve stability. A multi-sensor system (temperature, vibration, displacement, air pressure, etc.) is used to monitor the spindle's operating status in real time, and the data is compared and analyzed in conjunction with a database to ensure that the equipment is always in the best working condition, reduce quality problems caused by changes in the spindle's status, and improve the stability and lifespan of the equipment.

[0055] (4) Intelligent learning and adaptive optimization. Through machine learning algorithms, the system can record the surface error of each grinding operation, establish a data model and continuously optimize the adjustment strategy, thereby continuously improving the accuracy and consistency of the grinding process and realizing intelligent and adaptive process optimization.

[0056] (5) Improve semiconductor production efficiency. Since the system can automatically optimize the spindle angle and working status, it reduces the time loss caused by manual adjustment, while ensuring high-precision processing, thereby improving the processing efficiency of semiconductor wafers and making it suitable for large-scale production needs.

[0057] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the left-side structure according to an embodiment of the present invention. Figure 2 This is a top view of the structural diagram according to an embodiment of the present invention. Figure 3 This is a cross-sectional view of the fixed end and the adjusting end according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the fixed end structure of the spindle adjustment device according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the adjusting end structure of the spindle adjusting device according to an embodiment of the present invention. Figure 6 A schematic diagram of the differential screw at the adjusting end of the main spindle adjusting device. Figure 7 This is one driving method for the automatic input device of the adjustment end in an embodiment of the present invention. Figure 8 This is a flowchart of machine learning based on intelligent algorithms. Figure 9 This is a schematic diagram of the geometric model for adjusting the wafer spindle angle according to the present invention, showing the coordinate positions and rotational relationship of points A, B, and C.

[0059] Figure Labels

[0060] 1. Spindle fixing plate; 2. Thinning spindle; 3. Thinning grinding wheel; 4. Spindle angle adjustment end; 5. Spindle fixing end; 6. Wafer; 7. Wafer stage; 8. Non-contact measuring instrument; 201. Flow sensor; 202. Pressure sensor; 203. Vibration sensor; 204. Temperature sensor; 205. Flow controller; 206. Pressure controller; 207. Displacement sensor; 401. Adjustment end; 402. Adjustment end two; 501. 502. Fixed end threaded sleeve; 503. Fixed end ball head; 504. Fixed end washer sleeve; 505. Washer; 701. Fixing screw; 702. Ceramic suction cup; 703. Porous ceramic; 40101. Adjusting end upper threaded sleeve; 40102. Adjusting end lower threaded sleeve; 40103. Adjusting end locking nut; 40104. Adjusting end differential screw; 40105. Differential thread zone one; 40106. Differential thread zone two; 40107. Drive motor; Detailed Implementation

[0061] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0062] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0063] Example

[0064] See Figure 1 , Figure 2 , Figure 3 and Figure 5 The spindle angle adjustment end 4 and the spindle angle fixing end 5 are mounted on the spindle fixing plate 1 to support the thinning spindle 2. The thinning grinding wheel 3 is mounted below the thinning spindle and rotates at high speed with the spindle. The wafer support stage 7 is positioned entirely below the thinning spindle, with its center directly below the grinding wheel. Before wafer thinning, the wafer 6 is held in the center by the porous ceramic 702 in the ceramic chuck 701 on the wafer support stage 7 and rotates with the wafer support stage 7. The 201 water flow sensor and the 205 water flow control valve are located on the water inlet pipe; the 206 air flow control valve and the 202 barometer are located on the air line; the 203 vibration sensor is mounted on the spindle end face and placed perpendicular to each other; the 204 temperature sensor is located on the outside of the upper and lower main thrust bearings; and the 207 displacement sensor is located above the rotor.

[0065] Wafer surface shape recognition system: A laser rangefinder is used to measure in real time, obtain distance signals of various points on the wafer surface, and then generate a three-dimensional model of the wafer surface and calculate the wafer surface shape.

[0066] Flatness measurement system: Acquires wafer flatness data through a focused rangefinder, measures wafer thickness variation and generates data.

[0067] Intelligent adjustment algorithm system: including machine learning algorithm, it processes surface shape and flatness data in real time and gives adjustment instructions for spindle angle, air flow rate and cooling water flow rate.

[0068] Spindle angle adjustment device: Adjusts the spindle tilt angle according to the instructions output by the intelligent adjustment algorithm system to ensure the conformity of the wafer surface.

[0069] Spindle operation status monitoring system: Real-time monitoring of spindle temperature, vibration, displacement and air pressure, and ensures that the spindle is operating in the best condition by comparing with normal values ​​in the database.

[0070] Wafer Fixing and Preparation: First, place the wafer to be thinned onto the wafer stage and fix it in place using ceramic chucks. The wafer stage rotates with the spindle to ensure the wafer remains stable during the thinning process.

[0071] Spindle Angle Adjustment: Based on the preset wafer surface profile target, the motor of the intelligent air-bearing spindle is driven by a differential screw to adjust the spindle's tilt angle, making the wafer's grinding surface profile close to the required profile. The intelligent air-bearing spindle regulates air pressure through an air flow control valve to ensure that the spindle operates under optimal working conditions.

[0072] Wafer Surface Recognition and Flatness Measurement: During the grinding process, the wafer surface recognition system measures wafer surface data in real time using a laser rangefinder and generates a 3D surface model. Subsequently, the flatness measurement system calculates the wafer's flatness value. Based on the measurement results, the intelligent adjustment algorithm system calculates the parameters that need to be adjusted and controls the water flow control valve and air flow control valve to adjust the cooling water flow and air flow.

[0073] Intelligent control and feedback adjustment: When the wafer's surface shape or flatness value does not meet the requirements, the system uses real-time measurement data and algorithms to optimize the adjustment strategy, adjusting the spindle angle, airflow, and cooling water flow to ensure the wafer meets the expected surface shape and flatness requirements. The machine learning system continuously optimizes the adjustment strategy by recording the error of each grinding operation, improving grinding accuracy.

[0074] Repeat grinding until the target is met: Once the wafer's surface shape and flatness meet the requirements, the grinding process ends. If the wafer is still unqualified, the system will automatically return the wafer to the grinding position and repeat the adjustment and grinding until the surface shape and flatness fully meet the process standards.

[0075] Using the methods described above, this embodiment can precisely control the surface profile and flatness during the wafer thinning process, reducing errors associated with traditional manual adjustments and improving production efficiency and wafer quality stability. The intelligent adjustment system can provide real-time feedback on parameter changes during the grinding process, and through continuous learning and optimization, further improves the accuracy of surface profile control, reducing the need for manual intervention. Furthermore, the machine learning system can optimize adjustment strategies based on historical data, reducing production problems caused by equipment failures or environmental changes.

Claims

1. A smart control system for thinning wafer surface shape and flatness, characterized in that, include: The intelligent air-bearing spindle includes an air-bearing spindle and a motor, differential thread, air flow control valve, water flow control valve, temperature sensor, vibration sensor, and displacement sensor on the spindle. A wafer surface shape recognition system is used to acquire wafer surface data using a laser rangefinder and generate a 3D model of the surface shape. The flatness measurement system calculates the flatness of the wafer based on the generated three-dimensional surface model and generates relevant data; The intelligent adjustment algorithm system automatically adjusts the spindle's working status based on wafer surface data and flatness data, including motor rotation angle, spindle tilt angle, air pressure, and cooling water flow rate. Spindle angle adjustment device, used to adjust the tilt angle of the spindle to optimize the wafer surface shape; The spindle operation status monitoring system is used to monitor the spindle's temperature, vibration, displacement, and air pressure in real time to ensure that the spindle operates in a normal condition. The intelligent air-bearing spindle precisely controls the tilt angle through the spindle angle adjustment device, ensuring that the wafer surface shape can be adjusted during the thinning process. The wafer surface shape recognition system and flatness measurement system collect data in real time, and the intelligent adjustment algorithm system analyzes and calculates to optimize the adjustment strategy. The spindle operation status monitoring system detects the spindle operation through multiple sensors and combines flow control to ensure its stability, thereby achieving high-precision thinning and improving wafer surface quality and flatness. The intelligent adjustment algorithm system is as follows, taking an 8-inch silicon wafer and a thinning grinding wheel as an example. The diameter of the thinning grinding wheel is D1, the diameter of the silicon wafer is D2, and the wafer diameter is the diameter of the outer cutting edge of the grinding wheel, denoted as R. The axis of the grinding wheel and the axis of the silicon wafer being thinned are defined as the Z1 axis and Z2 axis, respectively. The grinding plane is the XOY plane. A Cartesian coordinate system X1Y1Z1 and X2Y2Z2 is established, with Y1 and Y2 collinear. During the grinding process, the height of three points A, B, and C is controlled by the spindle adjustment device to achieve semi-contact grinding. The coordinates of point A are ( Point B has coordinates (0, R, 0), and point C has coordinates ( ). A perpendicular line from point O1 to O1C is drawn, intersecting the grinding edge in the X1OY1 plane at point M and AB at point N. When adjusting the height of point C, points A, B, and C rotate around the line containing MN, where MN is the unit vector of the axis. The formula for rotating a spatial rectangular coordinate system about an arbitrary axis is: Where K = 1 - cosθ, is the three-dimensional coordinate transformation rotation matrix. The coordinate transformation satisfies [X';Y';Z']=R 3×3 [X;Y;Z], after rotating θ°, the coordinates of points A', B', and C' are respectively (X;Y;Z). (), , , (), X1 axis unit vector The rotation matrix of the entire circular arc about the x-angle by an angle α. Where K'=1-cosα, after rotation, the three points A'', B'', and C'' determine the center of the circle as (0, 0, 0), the curve is the cross section of the plane AX+BY+CZ+D=0 and the sphere with the origin as the center and radius R, the plane normal vector b=A''B''×A''C'', the curve equation A1 with radius R is x²+y²+z²=R² and MX+NY+PZ+D=0, M, N, and P are the components of the normal vector b, after coordinate transformation to the X2Y2Z2 coordinate system, we get equation A2, the surface equation of equation A2 rotated around the Z2 axis is the ideal wafer grinding surface equation, after fixing point A'', the Z-axis coordinates of B'' and C'' are the actual adjustment height, the relationship between the adjustment angle and the surface height is obtained by rotation transformation, and combined with the relationship between the angle and the height of the adjustment end, the wafer surface is controlled in real time.

2. The intelligent control system for thinning wafer surface shape and flatness according to claim 1, characterized in that, The lower end of the intelligent air-bearing spindle is equipped with two adjusting ends and one fixed end. The adjusting ends achieve the adjustment of the spindle tilt angle through differential threads.

3. The intelligent control system for thinning wafer surface shape and flatness according to claim 1, characterized in that, The motor drives the differential screw to rotate, thereby adjusting the spindle tilt angle. The air flow control valve and water flow control valve respectively adjust the air pressure and cooling water flow of the spindle to meet the grinding process requirements.

4. The intelligent control system for thinning wafer surface shape and flatness according to claim 1, characterized in that, The wafer surface shape recognition system acquires wafer surface data in real time using a laser rangefinder and generates a three-dimensional surface shape model to calculate the wafer surface shape.

5. The intelligent control system for thinning wafer surface shape and flatness according to claim 1, characterized in that, The flatness measurement system includes a focused rangefinder, used to measure the flatness of the wafer and output relevant data.

6. A method for intelligent control of wafer thinning profile and flatness, applied to the system described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Monitor the spindle's operating status in real time using multiple sensors to determine whether the spindle is in normal working condition; S2. Adjust the motor rotation angle and change the spindle tilt angle according to the preset surface shape target; S3. Automatically adjust the airflow and cooling waterflow based on the surface shape and flatness data of the thinned wafer; S4. Analyze the wafer surface shape and determine whether the surface shape is qualified through the wafer surface shape recognition system; S5. When the surface shape is not up to standard, the system readjusts the spindle tilt angle and running status according to the surface shape error, and performs grinding again until the surface shape meets the requirements. S6. Repeat steps S4 to S5 until the wafer meets the expected surface shape and flatness requirements; S7. The machine learning system records the error between the simulated results based on the requirements of surface shape and flatness and the actual grinding results, so as to improve the adjustment strategy next time.

7. The intelligent control method for thinned wafer surface shape and flatness according to claim 6, characterized in that, The intelligent adjustment algorithm system records the surface shape and flatness errors of each grinding operation through machine learning and optimizes the adjustment strategy to improve grinding accuracy.

8. The intelligent control method for thinned wafer surface shape and flatness according to claim 6, characterized in that, Step S1 further includes: determining whether the spindle is in normal working condition by detecting the spindle temperature, vibration, displacement and air pressure.

9. The intelligent control method for thinned wafer surface shape and flatness according to claim 6, characterized in that, Step S4 further includes: acquiring distance data of various points on the wafer surface using a laser rangefinder, generating a three-dimensional surface model, and calculating the flatness of the wafer.

10. The intelligent control method for thinned wafer surface shape and flatness according to claim 6, characterized in that, Step S5 further includes: when the wafer surface shape is unqualified, the intelligent system calculates and adjusts the spindle angle and operating status, and adjusts the air flow control valve and water flow control valve to make the wafer meet the expected surface shape and flatness requirements.

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