CN-122008021-A - Grinding wheel, preparation method, wafer thinning equipment and wafer thinning method

CN122008021ACN 122008021 ACN122008021 ACN 122008021ACN-122008021-A

Abstract

The application provides a grinding wheel, a preparation method, wafer thinning equipment and a thinning method. The grinding wheel comprises a grinding wheel matrix, an adhesive layer and an abrasive layer, wherein the adhesive layer is provided with two or more small layers with monotonically decreasing thermal expansion coefficients, monotonically increasing longitudinal thermal conductivity and monotonically decreasing rigidity on the surface of a ceramic filler in raw material composition from bottom to top, the bottom small layer is used for being in contact with the grinding wheel matrix, the top small layer is used for being in contact with the abrasive layer, each small layer is subjected to induced orientation treatment by using a magnetic field perpendicular to the plane direction of the small layer before solidification, and the adhesive layer adopts a gradient CTE composite modifier integrated design and is matched with a vertical thermal conductive filler gradient and orientation design to realize gradual transition of the thermal expansion coefficients and the vertical thermal conductivity from the side of the grinding wheel matrix to the side of the abrasive layer and form a penetrating vertical thermal conductive chain along the top-bottom direction to open up a direct path for longitudinal efficient heat dissipation.

Inventors

ZHANG LIFEI
LU XINCHUN
ZHAO YING
ZHAO DEWEN

Assignees

清华大学

Dates

Publication Date: 20260512
Application Date: 20251028

Claims (15)

1. The grinding wheel is characterized by comprising a grinding wheel matrix, an adhesive layer and an abrasive layer, wherein the abrasive layer is fixed on the grinding wheel matrix through the adhesive layer; the adhesive layer is provided with two or more small layers from bottom to top, and the raw material composition of each small layer independently comprises a resin system, ceramic filler and vertical heat conduction filler; The thermal expansion coefficient of each small layer from bottom to top is monotonically decreased, the longitudinal thermal conductivity is monotonically increased, and the surface energy and rigidity of the ceramic filler in the raw material composition are monotonically decreased; each of the small layers is subjected to induced orientation treatment using a magnetic field perpendicular to the plane direction in which the small layer is located, before curing.
2. The grinding wheel of claim 1, wherein the grinding wheel comprises a plurality of grinding wheels, The grinding wheel matrix is made of a metal matrix composite material; The abrasive layer adopts diamond abrasive particles; the resin system includes an epoxy resin and a reactive diluent.
3. A grinding wheel according to claim 2, wherein, The epoxy resin is one or a combination of more than two of epoxy resin E51, epoxy resin E44 and bio-based epoxy resin; the active diluent is selected from one or more than two of butyl glycidyl ether, C12-C14 alkyl glycidyl ether and neodecanoic acid glycidyl ether; the mass ratio of the epoxy resin to the reactive diluent is 3-5:1.
4. The grinding wheel of claim 1, wherein the bottom small layer has a coefficient of thermal expansion of 12-20 ppm/°c, the top small layer has a coefficient of thermal expansion of 5-10 ppm/°c, and the difference between the coefficients of thermal expansion of adjacent small layers is less than or equal to 10 ppm/°c.
5. The grinding wheel of claim 4, wherein the adhesive layer has three or more small layers with monotonically decreasing coefficients of thermal expansion from bottom to top, and wherein the intermediate small layer M disposed between the bottom small layer and the top small layer has a coefficient of thermal expansion of 10-15 ppm/°c.
6. Grinding wheel according to claim 1 or 5, characterized by comprising at least one of the following features 1) -4): 1) The surface energy of the ceramic filler in the raw material composition of the bottom small layer is more than or equal to 46 mN/m, and the surface energy of the ceramic filler in the raw material composition of the top small layer is less than or equal to 42 mN/m; When the middle small layer M exists, the surface energy of the ceramic filler in the raw material composition of the middle small layer M is 42-46 mN/M; 2) The elastic modulus of the ceramic filler in the raw material composition of the bottom small layer is more than or equal to 8 GPa, and the elastic modulus of the ceramic filler in the raw material composition of the top small layer is less than or equal to 4 GPa; when the middle small layer M exists, the elastic modulus of the ceramic filler in the raw material composition of the middle small layer M is 4-8 GPa; 3) The longitudinal thermal conductivity of the bottom small layer is less than or equal to 1.8W/m.K, and the longitudinal thermal conductivity of the top small layer is more than or equal to 3.2W/m.K; When the middle small layer M exists, the longitudinal heat conductivity of the middle small layer M is 2.0-2.4W/m.K; 4) The thickness of each small layer from bottom to top is monotonically decreasing, the thickness of the bottom small layer is 18-23 mu m, and the thickness of the top small layer is 8-12 mu m; When the intermediate small layer M is present, the thickness of the intermediate small layer M is 12-18 μm.
7. Grinding wheel according to claim 1 or 5, characterized by comprising at least one of the following features 1) -2): 1) Ceramic filler in the raw material composition of the bottom small layer uses a ceramic material with positive thermal expansion coefficient, and ceramic filler in the raw material composition of the top small layer uses a ceramic material with negative thermal expansion coefficient; when the middle small layer M exists, ceramic filler in the raw material composition of the middle small layer M uses a ceramic material with a negative thermal expansion coefficient; 2) Ceramic filler in the bottom small-layer raw material composition adopts KH550 modified ceramic material, and ceramic filler in the top small-layer raw material composition adopts KH570 modified ceramic material; when the middle small layer M exists, the ceramic filler in the raw material composition of the middle small layer M adopts a ceramic material modified by KH 560.
8. Grinding wheel according to claim 1 or 5, characterized by comprising at least one of the following features 1) -2): 1) The adding concentration of ceramic filler in the raw material composition of each small layer from bottom to top increases monotonically; the mass content of the ceramic filler in the bottom small layer raw material composition is 35-45% based on 100% of the mass of the resin system in the bottom small layer raw material composition, and 55-65% based on 100% of the mass of the resin system in the top small layer raw material composition; when the middle small layer M exists, the mass content of the ceramic filler in the raw material composition of the middle small layer M is 45-55% based on 100% of the mass of the resin system in the raw material composition of the middle small layer M; 2) The addition concentration of the vertical heat conduction filler in the raw material composition of each small layer from bottom to top is monotonically increased; The mass content of the vertical heat conduction filler in the bottom small layer raw material composition is 5-9% based on 100% of the mass of the resin system in the bottom small layer raw material composition; The mass content of the vertical heat conduction filler in the top small layer raw material composition is 11-20% based on 100% of the mass of the resin system in the top small layer raw material composition; When the middle small layer M exists, the mass content of the vertical heat conduction filler in the raw material composition of the middle small layer M is 9-11 percent based on 100 percent of the mass of the resin system in the raw material composition of the middle small layer M.
9. The grinding wheel of claim 1, wherein the vertical heat conductive filler comprises a first vertical heat conductive filler and a second vertical heat conductive filler, the first vertical heat conductive filler being a first heat conductive material capable of providing a heat conductive skeleton, the second heat conductive filler being a second heat conductive material capable of filling gaps in the first heat conductive filler; the first heat conducting material comprises one or more than two of a diamond heat conducting material and a cubic boron nitride heat conducting material; the second heat conducting material comprises one or a combination of more than two of aluminum nitride heat conducting materials, silicon nitride heat conducting materials and beryllium oxide heat conducting materials.
10. Grinding wheel according to claim 1 or 5, characterized by comprising at least one of the following features 1) -2): 1) The raw material composition of each small layer independently comprises a transverse heat conduction filler, wherein the transverse heat conduction filler comprises one or more than two of graphene nano sheets, plasma-treated aluminum oxide nano sheets and plasma-treated boron nitride nano sheets; 2) The raw material composition of each small layer independently comprises a conductive reinforcing filler, wherein the conductive reinforcing filler comprises one or more of carboxylated carbon nanotubes, silver-plated nano particles and graphene.
11. The grinding wheel of claim 10, wherein the grinding wheel comprises, When the transverse heat conduction filler exists, the transverse heat conduction filler in the raw material composition of each small layer is the same; when the conductive reinforcing filler is present, the conductive reinforcing filler in the raw material composition of each of the small layers is the same.
12. The grinding wheel of claim 10, wherein the grinding wheel comprises, When the transverse heat conduction filler exists, the addition concentration of the transverse heat conduction filler in the raw material composition of each small layer from bottom to top monotonically increases; The mass content of the transverse heat conduction filler in the bottom small layer raw material composition is 5-6% based on 100% of the mass of the resin system in the bottom small layer raw material composition; the mass content of the transverse heat conduction filler in the top small layer raw material composition is 6-8% based on 100% of the mass of the resin system in the top small layer raw material composition; When the middle small layer M exists, the mass content of the transverse heat conduction filler in the raw material composition of the middle small layer M is 8-10% based on 100% of the mass of the resin system in the raw material composition of the middle small layer M; when the conductive reinforcing filler exists, the addition concentration of the conductive reinforcing filler in the raw material composition of each small layer from bottom to top monotonically increases; the mass content of the conductive reinforcing filler in the bottom small layer raw material composition is 1-1.5% based on 100% of the mass of the resin system in the bottom small layer raw material composition; the mass content of the conductive reinforcing filler in the top small layer raw material composition is 1.5-3% based on 100% of the mass of the resin system in the top small layer raw material composition; When the middle small layer M exists, the mass content of the conductive reinforcing filler in the raw material composition of the middle small layer M is 1-1.5 percent based on 100 percent of the mass of the resin system in the raw material composition of the middle small layer M.
13. A method of manufacturing a grinding wheel according to any one of claims 1 to 12, comprising the steps of: 1) Coating each small layer on the grinding wheel substrate in sequence from the bottom small layer to the top small layer; 2) After finishing the coating treatment of each small layer, carrying out gradient heating solidification to obtain an adhesive layer of the grinding wheel for thinning the wafer, which is connected with the grinding wheel matrix; 3) And (3) performing lamination bonding on the top surface of the adhesive layer of the grinding wheel for wafer thinning, which is connected with the grinding wheel matrix, and the abrasive layer, and further performing integral curing to prepare the grinding wheel for wafer thinning.
14. The wafer thinning equipment is characterized by comprising the grinding wheel prepared by the grinding wheel according to any one of claims 1-12 or the grinding wheel prepared by the preparation method according to claim 13, wherein the abrasive layer comprises a plurality of grinding blocks, annular grooves are formed in the middle of the annular bottom surface of the grinding wheel matrix along the circumferential direction of the grinding wheel, the grinding blocks are inserted into the grooves of the grinding wheel matrix and are distributed at intervals along the circumferential direction of the grinding wheel, and the adhesive layer is arranged between the bottom of the annular grooves and the grinding blocks.
15. A wafer thinning method, characterized in that the wafer thinning method comprises thinning a wafer using the wafer thinning apparatus according to claim 14.

Description

Grinding wheel, preparation method, wafer thinning equipment and wafer thinning method The application is a divisional application of patent application of the application with the application number 2025115509830, which is filed on the day of 2025, 10 and 28. Technical Field The application belongs to the technical field of wafer grinding, and particularly relates to a grinding wheel, a preparation method, wafer thinning equipment and a thinning method. Background Three-dimensional integrated circuits (3D ICs) are an important technological path for the semiconductor industry to continue moore's law, improving chip performance and integration. The core idea is to stack a plurality of chips or functional layers in a vertical direction, and realize interlayer electrical connection Through-Silicon Via (TSV) and other interconnection technologies, so as to realize higher functional density in a limited space. Wafer thinning is a critical support process in 3D IC fabrication, the main purpose of which is to thin the wafer from the original thickness to an ultra-thin state suitable for vertical integration. Ultra-thin wafers are the physical basis for achieving 3D stacking and are critical to optimizing electrical performance and thermal management. As the number of stacked layers of 3D ICs increases, the demand for thickness reduction of individual wafers is becoming increasingly stringent. Meanwhile, 3D IC technology places extremely high demands on the surface quality of thinned wafers, including excellent total thickness bias (Total Thickness Variation, TTV) and extremely low surface roughness (Roughness Average, ra), to ensure accuracy, uniformity and stability of subsequent bonding processes. To achieve the above-mentioned thinning objective, the wafer thinning apparatus generally processes an ultrathin wafer by using a physical grinding action of a grinding wheel. The equipment has to precisely design and control the grinding structure and the grinding process, and can meet the processing requirements (such as thickness is less than or equal to 10 mu m, TTV is less than or equal to 1.5 mu m and Ra is less than or equal to 5 nm) of ultrathin wafers, and simultaneously, the manufacturing cost and the production efficiency are both considered. In a wafer grinding system, differences in Coefficient of Thermal Expansion (CTE) between the grinding wheel base, the abrasive layer, and the adhesive layer affect each other through stress transfer. In the currently mainstream wafer grinding system, the adhesive layer is usually made of traditional epoxy resin adhesive, and the grinding wheel matrix is usually made of metal/ceramic substrate. The traditional epoxy resin adhesive (with the thermal expansion coefficient of 60-80 ppm/°c) has obvious thermal expansion coefficient difference with a metal/ceramic substrate (such as aluminum alloy with the thermal expansion coefficient of about 23 ppm/°c) and an abrasive layer, and interfacial shear stress is induced when the temperature changes, so that encapsulation delamination, microcracking or precision reduction are caused, even if the adhesive layer is used as a buffer, the thermal expansion coefficient difference between a grinding wheel substrate and the abrasive layer can still cause the separation and deformation of the abrasive layer, and the abrasive layer is transmitted to a grinding interface to influence cutting stability, so that the surface of a wafer is damaged. In the semiconductor wafer thinning process, the balance between grinding efficiency and processing quality is always an industry pain point. When the traditional grinding wheel is used for increasing the feeding amount to increase the processing number (UPH) per hour, the interface deformation and grinding vibration are aggravated due to the fact that the thermal expansion Coefficients (CTE) of a grinding wheel matrix, an abrasive layer and an adhesive layer are not matched, so that the surface roughness Ra of a wafer is increased. Especially in the Z2 fine grinding stage, the contradiction between efficiency and quality is prominent, and the main manifestation is that blind lifting of the feed rate (namely, accelerating of the feed rate) can affect the surface integrity of the wafer, and the conservation of the feed rate parameters can restrict the capacity lifting. Therefore, the improvement of the machining quantity per hour on the premise of stable surface roughness is required to be realized, so that the high efficiency and the precise machining are both realized. At present, a plurality of new technologies are developed in the industry to improve the processing quantity per hour on the premise of realizing stable surface roughness, however, the new technologies have a plurality of problems, and the problem that the thermal expansion coefficients of the abrasive layer and the matrix are not matched in the wafer thinning process cannot be effectively solved. For example, CN117245570a disclose