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CN-120503084-B - Intelligent control method and system for surface shape and flatness of thinned wafer

CN120503084BCN 120503084 BCN120503084 BCN 120503084BCN-120503084-B

Abstract

The invention discloses an intelligent control method and system for the surface shape and flatness of a thinned wafer, and belongs to the field of semiconductor manufacturing. The system comprises an intelligent air floatation spindle, a wafer surface type identification system, a flatness measurement system, an intelligent adjustment algorithm system, a spindle angle adjustment device and a spindle running state monitoring system. By monitoring the state of the main shaft in real time and combining with a machine learning optimization strategy, the system automatically adjusts the inclination angle, the air flow and the cooling water flow of the main shaft, and ensures that the surface quality and the flatness in the wafer thinning process meet the requirements. The wafer surface type recognition system and the flatness measurement system measure the wafer surface data in real time through the laser range finder, and a surface type three-dimensional model is generated. The control method and the control system can automatically adjust the working state of the main shaft according to the real-time data, reduce manual intervention, improve the surface control precision and the processing yield of the wafer, and have the characteristics of intelligence, accurate control and high reliability.

Inventors

  • YE LEZHI
  • MENG WEN

Assignees

  • 北京工业大学

Dates

Publication Date
20260508
Application Date
20250312

Claims (10)

  1. 1. An intelligent control system for the surface shape and flatness of a thinned wafer, which is characterized by comprising: the intelligent air floatation main shaft comprises an air floatation main shaft, a motor on the main shaft, differential threads, an air flow control valve, a water flow control valve, a temperature sensor, a vibration sensor and a displacement sensor; The wafer surface type recognition system is used for acquiring wafer surface data through the laser range finder and generating a surface type three-dimensional model; the flatness measurement system calculates the flatness of the wafer according to the generated planar three-dimensional model and generates related data; the intelligent regulation algorithm system automatically regulates the working state of the main shaft according to the wafer surface data and the plane data, and comprises a motor rotation angle, a main shaft inclination angle, air pressure and cooling water flow; the main shaft angle adjusting device is used for adjusting the inclination angle of the main shaft so as to optimize the wafer surface shape; the main shaft running state monitoring system is used for monitoring the temperature, vibration, displacement and air pressure of the main shaft in real time and ensuring that the main shaft runs in a normal state; the intelligent air-float main shaft accurately controls the inclination angle through the main shaft angle adjusting device, ensures that the surface type of the wafer can be adjusted in the thinning process, the wafer surface type identification system and the flatness measuring system acquire data in real time, and the intelligent adjusting algorithm system analyzes, calculates and optimizes the adjustment strategy, the main shaft running state monitoring system detects the main shaft running condition through a plurality of sensors, and combines flow control to ensure the stability of the main shaft running state monitoring system, so that high-precision thinning is realized, and the quality and flatness of the wafer surface type are improved; The intelligent regulation algorithm system is that an 8-inch silicon wafer and a thinning grinding wheel are taken as an example, the diameter of the thinning grinding wheel is D1, the diameter of the silicon wafer is D2, the diameter of the outer edge of the wafer is R, the axis of the grinding wheel and the axis of the thinned silicon wafer are respectively defined as a Z1 axis and a Z2 axis, the grinding plane is an XOY plane, a Cartesian coordinate system X1Y1Z1 and X2Y2Z2 are established, and Y1 and Y2 are collinear, and half-contact grinding is realized by controlling A, B, C three-point heights through a main shaft regulating device in the grinding process, wherein the coordinate of A point is [ ) The coordinates of the point B are (0, R, 0), and the coordinates of the point C are% ) Perpendicular lines passing through O1 point and O1C are intersected with grinding edges in X1OY1 plane at M point and AB point at N point, and A, B, C points rotate around straight line where MN is located when the height of C point is adjusted, and unit vector with MN as axis is The rotation formula of the space rectangular coordinate system around any axis is Three-dimensional coordinate transformation rotation matrix, wherein k=1-cos θ The coordinate transformation satisfies [ X '; Y'; Z '] =R 3×3 [ X; Y; Z ], and the coordinates of the three points A', B 'and C' are sequentially [ (-Z) after rotating for θ degrees ),( , , ),( ) X1 axis unit vector Rotation matrix for rotating whole circular arc around x by alpha angle The center of a circle of the circle is (0, 0) determined BY three points of K ' =1-cos alpha, A ', B ', C ' after rotation, the curve is the cross section of a sphere with a plane AX+BY+CZ+D=0 and an origin as a center radius R, the normal vector b=A ' B ' X A ' C ' of the plane, the curve equation A1 of the radius R is X2 +y2+z2=R2 and MX+NY+PZ+D=0, M, N, P is a normal vector B component, the curve equation A2 is obtained BY coordinate transformation to an X2Y2Z2 coordinate system, the curve equation A2 rotating around the Z2 axis is an ideal wafer grinding surface equation, the Z-direction coordinate of B ' and C ' after the point A ' is fixed is an actual adjustment height, and the real-time control of the wafer surface type is realized BY rotating transformation to obtain the curve relation of the adjustment angle and the surface type height and the relation of the adjustment end.
  2. 2. The intelligent control system for the surface type and the flatness of the thinned wafer according to claim 1, wherein two adjusting ends and a fixed end are arranged at the lower end of the intelligent air floatation main shaft, and the adjusting ends realize the adjustment of the inclination angle of the main shaft through differential threads.
  3. 3. The intelligent control system for thinning wafer surface type and flatness according to claim 1, wherein the motor drives the differential screw to rotate so as to adjust the inclination angle of the spindle, and the air flow control valve and the water flow control valve respectively adjust the air pressure and the cooling water flow of the spindle so as to meet the grinding process requirement.
  4. 4. The intelligent control system for thinning wafer surface type and flatness of wafer according to claim 1, wherein the wafer surface type recognition system acquires wafer surface data in real time by a laser range finder and generates a surface type three-dimensional model to calculate the wafer surface shape.
  5. 5. The thinned wafer-level and planarity intelligent control system of claim 1 wherein said planarity measurement system comprises a focused distance meter for measuring the planarity of a wafer and outputting related data.
  6. 6. An intelligent control method for the surface shape and the flatness of a thinned wafer, which is applied to the system of any one of claims 1 to 5, and is characterized by comprising the following steps: S1, monitoring the running state of a main shaft in real time through a plurality of sensors, and judging whether the main shaft is in a normal working state or not; s2, according to a preset surface type target, adjusting the rotation angle of the motor and changing the inclination angle of the main shaft; S3, automatically adjusting air flow and cooling water flow according to the thinned surface type and flatness data of the wafer; s4, analyzing the surface shape of the wafer through a wafer surface shape recognition system and judging whether the surface shape is qualified or not; s5, when the surface shape is unqualified, the system readjusts the inclination angle and the running state of the main shaft according to the surface shape error, and grinding is performed again until the surface shape meets the requirements; S6, repeating the steps S4 to S5 until the wafer meets the expected surface type and flatness requirements; S7, the machine learning system records and learns errors between the simulated result and the actual ground result according to the requirements of the surface type and the flatness so as to improve the next adjustment strategy.
  7. 7. The intelligent control method for the surface profile and the flatness of a thinned wafer according to claim 6, wherein the intelligent adjustment algorithm system records the surface profile and the flatness error of each grinding through machine learning and optimizes an adjustment strategy to improve grinding accuracy.
  8. 8. The intelligent control method for wafer surface profile and flatness in accordance with claim 6, wherein step S1 further comprises determining whether the spindle is in a normal operation state by detecting the temperature, vibration, displacement, and air pressure of the spindle.
  9. 9. The intelligent control method for thinning wafer surface shape and flatness according to claim 6, wherein step S4 further comprises obtaining distance data of each point on the wafer surface by a laser range finder, generating a surface shape three-dimensional model, and calculating the flatness of the wafer.
  10. 10. The intelligent control method for thinning the wafer surface type and flatness according to claim 6, wherein step S5 further comprises the steps that when the wafer surface type is unqualified, the intelligent system calculates and adjusts the angle and the running state of the main shaft, and the wafer meets the expected surface type and flatness requirements through adjustment of the air flow control valve and the water flow control valve.

Description

Intelligent control method and system for surface shape and flatness of thinned wafer Technical Field The invention relates to the field of semiconductor wafer packaging thinning, in particular to a method and a system for controlling the surface shape and the flatness of a wafer through intelligent adjustment of a main shaft. Background With the rapid development of global electronic information technology, the integrated circuit industry has become a high point of high-tech development in China. The manufacture of high-end chips in China is limited, and particularly high-precision semiconductor equipment is limited. The wafer after slicing in the silicon wafer processing needs to be ground to be thin, and the unevenness caused by multi-line cutting is removed. Wafer bonding techniques employing advanced packaging processes in the previous process also require thinning of the wafer. In the chip packaging process, the goal of thinner chip packaging needs to be achieved by grinding the back of the wafer. It can be seen that the wafer thinning process is used in the full process of wafer manufacturing, and the requirements on the thinning surface type and the flatness of the wafer are higher and higher. Wafer self-rotation grinding is a wafer grinding thinning technique widely used at present. In the process of thinning the wafer, the wafer to be thinned is adsorbed on the wafer carrying table in vacuum and rotates together, the grinding edge of the grinding wheel passes through the center of the wafer to realize semi-contact grinding, so that the grinding heat is reduced, and meanwhile, the grinding force is ensured to be stable. The wafer thinning spindle drives the diamond thinning grinding wheel to rotate at a high speed and to continuously feed along the axial direction to grind the wafer, the whole spindle is fixed inside the spindle sleeve through the supporting and adjusting end, and the whole spindle sleeve completes feeding movement along with the Z-direction lead screw guide rail of the thinning equipment. In the thinning process, an operator needs to control the profile by adjusting both adjustment ends of the spindle according to the desired profile. The adjusting end is a differential thread, and the surface control of the wafer is realized at the same time by rotating the differential thread to realize the inclination of the main shaft. In the process of wafer self-rotation grinding, the wafer surface shape and flatness are two important aspects for judging whether the wafer quality is good or bad. If these two aspects are not satisfactory, various negative effects may be exerted on the chip manufacturing process, such as chipping problems, depth of focus problems, alignment problems, polishing non-uniformity, deposition non-uniformity, etc. The flatness of the wafer surface type also affects the number of stacked layers of the 3D stacked package, thereby affecting the integration level, performance and lifetime of the integrated circuit chip. The thinning spindle of the current wafer thinning equipment needs an experienced operator to manually adjust the spindle angle, the working space is narrow, grinding, measuring the wafer surface form and manually adjusting the spindle angle again are needed repeatedly, and the adjusting method cannot adjust the running state of the spindle to ensure that the wafer has qualified flatness. The running state of the main shaft of the thinning machine can change after long-time work, and the main shaft cannot be ensured to be in an optimal working state. In order to avoid repeated adjustment of the main shaft, realize automatic angle adjustment and compensation and better control of the planeness of the thinned wafer, it is important to develop an intelligent control method for the wafer surface shape and the planeness. The utility model discloses a device for automatically adjusting the angle of a main shaft (CN 105563317A) for semiconductor special equipment, which is characterized in that one end of an adjusting mechanism is connected with a transmission mechanism, the other end of the adjusting mechanism is fixedly connected with the main shaft, the angle of the main shaft is adjusted by controlling a back plate to feed through a motor, but the adjustable angle direction of the main shaft is single, an adjusted data source is only from the thickness of a wafer detected by a measuring instrument, the measuring instrument can not accurately measure the plane shape and the plane degree of the wafer, an intelligent algorithm is not used for accurately controlling the adjusting device, the plane degree after the wafer is thinned can not be controlled, the Guangdong megaintelligent technology limited company applies for a fine adjusting mechanism and a fine adjusting method for semiconductor processing precision equipment, the rotating angle and the fine adjusting height of a wafer bearing platform are respectively realized through two adjusting mechanisms, and