CN117532493A

CN117532493A - Wafer grinding device

Info

Publication number: CN117532493A
Application number: CN202311482241.XA
Authority: CN
Inventors: 张佳浩; 洪嘉悦; 曾柏翔; 李瑞评; 杨胜裕; 孟乐; 刘聪毅
Original assignee: Fujian Jingan Optoelectronics Co Ltd
Current assignee: Fujian Jingan Optoelectronics Co Ltd
Priority date: 2023-11-09
Filing date: 2023-11-09
Publication date: 2024-02-09

Abstract

The application provides a wafer grinding device, which comprises a first grinding disc, a second grinding disc, an annular gear, a sun wheel and at least one planet wheel; the planet wheel is provided with at least one limiting hole for limiting the wafer. The radial distance L of the limiting hole exposed out of the first grinding disc is larger than the radius R of the limiting hole, so that a part of the wafer is ground between the first grinding disc and the second grinding disc in the grinding process, and the other part of the wafer is not ground outside the first grinding disc and the second grinding disc, so that the moment capable of enabling the wafer to rotate is generated when the stress on two sides of the wafer is different, the rotation speed of the wafer in the grinding process is increased, the wafer revolves under the action of a planet wheel in the grinding process, rotates under the action of a single-side moment, the edge warpage of the wafer can be further modified, the surface form of the wafer is improved, and the planarization processing of the wafer is realized.

Description

Wafer grinding device

Technical Field

The application relates to the technical field of wafer processing and manufacturing, in particular to a wafer grinding device.

Background

In the hard disk grinding process, the clamp revolves and is in high-speed opposite grinding with the upper disc and the lower disc, the abrasive particles can grind and remove the unevenness and impurities on the surface of the wafer consistently, and the flatness is restored. However, consistent grinding makes it difficult to repair the edge warpage and the face shape of the polysilicon. Because of the warpage of the wafer, the heights of the edges of the wafer are inconsistent, and the wafer cannot be effectively repaired in a consistent revolution grinding mode in the grinding process.

Disclosure of Invention

The purpose of the present application is to provide a wafer polishing device, so as to improve the surface type improvement and warp restoration capability for a wafer, and realize the planarization processing of the wafer.

In order to achieve the above purpose, the present application adopts the following technical scheme:

the wafer grinding device comprises a first grinding disc, a second grinding disc, an inner gear ring, a sun wheel and at least one planet wheel; the planetary gears are respectively meshed with the inner teeth of the inner gear ring and the outer teeth of the sun gear, and the first grinding disc and the second grinding disc are respectively positioned on two opposite sides of the planetary gears; the planet wheel is provided with at least one limiting hole for limiting the wafer; and setting the radius of the limiting hole as R, and setting the radial distance of the limiting hole exposing the first grinding disc as L, wherein L is more than R.

In some embodiments, R < L < 1.25R.

In some embodiments, the radial distance from the edge of the first grinding disc and/or the second grinding disc to the inner gear ring is set to be a disc tooth space D, and the outer tooth length of the planet is set to be C; r < D-2C < 1.25R when the wafer being polished is 2 inches or 4 inches in diameter.

In some embodiments, the radial distance from the edge of the first grinding disc and/or the second grinding disc to the inner gear ring is set to be a disc tooth space D, and the outer tooth length of the planet is set to be C; when the wafer being polished has a diameter of 6 inches, 0.75R < D-2C < R.

In some embodiments, the radial distance from the edge of the first grinding disc and/or the second grinding disc to the inner gear ring is set to be a disc tooth space D, and the outer tooth length of the planet is set to be C; when the wafer being polished has a diameter of 8 inches, 0.5R < D-2C < 0.75R.

In some embodiments, the radial distance from the edge of the first grinding disc and/or the second grinding disc to the inner gear ring is set to be a disc tooth space D, and the outer tooth length of the planet is set to be C; when the wafer being polished has a diameter of 12 inches, 0.25R < D-2C < 0.5R.

In some embodiments, the wafer spin rate is > 100/Erpm, wherein the wafer has a diameter of E inches.

In some embodiments, the wafer has a planar convergence of concentric circles, the proportion of concentric circles being > 90%.

In some embodiments, the bow of the wafer is within-3*E/4 μm, wherein the wafer has a diameter of E inches.

In some embodiments, the wafer has a warp less than 7*E/4 μm, wherein the wafer has a diameter of E inches.

Compared with the prior art, the beneficial effect of this application:

the application provides a wafer grinding device, which comprises a first grinding disc, a second grinding disc, an annular gear, a sun wheel and at least one planet wheel; the planetary gear is respectively meshed with the inner teeth of the inner gear ring and the outer teeth of the sun gear, and the first grinding disc and the second grinding disc are respectively positioned on two opposite sides of the planetary gear; the planet wheel is provided with at least one limiting hole for limiting the wafer. The radial distance L of the limiting hole exposed out of the first grinding disc is larger than the radius R of the limiting hole, so that a part of the wafer is ground between the first grinding disc and the second grinding disc in the grinding process, and the other part of the wafer is not ground outside the first grinding disc and the second grinding disc, so that the moment capable of enabling the wafer to rotate is generated when the stress on two sides of the wafer is different, the rotation speed of the wafer in the grinding process is increased, the wafer revolves under the action of a planet wheel in the grinding process, rotates under the action of a single-side moment, the edge warpage of the wafer can be further modified, the surface form of the wafer is improved, and the planarization processing of the wafer is realized.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1a shows a conceptual diagram of a saddle-like shaped wafer; FIG. 1b shows a conceptual diagram of a pass-through wafer; FIG. 1c shows a conceptual diagram of a concentric oval wafer; FIG. 1d shows a conceptual diagram of a concentric circular wafer;

fig. 2 is a schematic structural diagram of a wafer polishing apparatus according to an embodiment of the present application.

Reference numerals illustrate:

1. an inner gear ring; 2. a first abrasive disk; 3. a second abrasive disk; 4. a planet wheel; 5. and a limiting hole.

Detailed Description

The following detailed description of specific embodiments of the present application is provided merely to illustrate the application and not to limit the application in any way.

In the description of the present application, it should be noted that, directions or positional relationships indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., are directions or positional relationships based on those shown in the drawings, or are directions or positional relationships that are conventionally put in use of the product of the application, are merely for convenience of description of the present application and simplification of description, and are not indicative or implying that the apparatus or element to be referred to must have a specific direction, be configured and operated in a specific direction, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the term "connected" should be construed broadly, and for example, it may be a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

Wafers, also known as substrates or wafer substrates, typically exhibit different profiles due to bending, warping or twisting caused by uneven wafer stress distribution in the prior art. In the prior art, the wafer has a saddle-like shape as shown in fig. 1a, if the wafer is bent in opposite directions in two perpendicular directions, as shown in fig. 1a to 1 d. Therefore, such a wafer surface shape is generally called a saddle shape. As shown in fig. 1b, if the wafer is flat in one direction and curved to a greater extent in the other direction, the wafer surface pattern exhibiting this type of curvature is generally referred to as a through-type. As shown in fig. 1c, if the wafer has the same bending direction in different directions but different bending degrees in different directions, the wafer surface form has a concentric oval shape. Fig. 1d shows a concentric circular wafer, and the wafer bending has better convergence due to the relatively uniform stress distribution throughout the concentric circular wafer and the same degree of bending in each direction.

In order to solve the problems in the prior art, the present application provides a wafer polishing apparatus, and the following detailed description of the present application refers to the accompanying drawings.

Fig. 2 shows a wafer polishing apparatus in an embodiment of the present application. As shown in fig. 2, the wafer grinding device includes an inner gear ring 1, a sun gear (not shown in the figure), a first grinding disc 2, a second grinding disc 3 and a plurality of planet gears 4, wherein a plurality of limiting holes 5 for placing wafers are formed in the body of the planet gears 4, the limiting holes 5 are circular through holes, the size of each limiting hole 5 is equal to that of each wafer, so that the wafers can be placed in the limiting holes 5 or taken out of the limiting holes 5, limiting effect is achieved on the wafers, and the wafers are prevented from traversing in the grinding process. In some embodiments, the wafer may be a gallium nitride wafer. The external teeth of each planet wheel 4 are respectively meshed with the internal teeth of the annular gear 1 and the external teeth of the sun gear, the first grinding disc 2 and the second grinding disc 3 are respectively positioned on two opposite sides of each planet wheel 4, and each planet wheel 4 is positioned in the same plane.

Wherein, the rotation direction of the first grinding disc 2 is opposite to the rotation direction of the second grinding disc 3, and the rotation direction of the inner gear ring 1 is opposite to the rotation direction of the sun gear. The rotation axis of the grinding device is generally perpendicular to the horizontal plane, i.e. the first grinding disc 2 may be an upper grinding disc, located above the planet wheels 4; the second grinding disc 3 may be a lower grinding disc, located below the planet wheels 4. The first grinding disc 2 applies pressure to the wafer placed in the limiting hole 5 by using a pressing device connected with the grinding disc and its own weight. In one embodiment, the pressure applicator may be, for example, an air cylinder, a hydraulic cylinder, or the like.

In the manufacture of semiconductor wafers, a lapping and polishing process is indispensable. In free abrasive grinding, the planet wheel bears the wafer in the double-sided grinding process and is driven by the inner and outer gear rings to do planetary motion, namely, rotation and revolution motion occurs. When the free abrasive is used for grinding, the wafer is difficult to spin in the clamp, and the warping of the edge is difficult to repair. Therefore, existing free abrasive grinding cannot efficiently process the wafer flat. The applicant found that, when the planetary wheel 4 in the existing grinding device completes the grinding operation of the wafer, the wafer is difficult to spin during the grinding process due to the consistent grinding of the disk surfaces of the first grinding disk 2 and the second grinding disk 3, the space of the disk surface is compact, and the characteristic of the grinding device makes it impossible to set a combined clamp to enhance the rotation of the wafer. Therefore, the polishing apparatus of the related art can easily obtain a wafer surface shape having insufficient flatness as shown in fig. 1a to 1 c.

Based on this, the embodiment of the application provides a wafer polishing device, which can improve the planarization processing capability of a wafer by improving the rotation speed of the wafer in the polishing process, so as to improve the surface shape of the wafer.

As shown in fig. 2, the radius of the limiting hole is set to be R, the radial distance from the edge of the first grinding disc 2 to the ring gear 1 is called the disc tooth distance D, the maximum exposure length L of the limiting hole is set, and the external tooth length of the planet wheel 4 is set to be C. The maximum exposure length L of the limiting hole can be understood as the radial distance of the limiting hole 5 exposing the first grinding disc 2, and the maximum exposure length L of the limiting hole can be approximately the radial length of the wafer exposing the first grinding disc 2 because the size of the wafer is matched with the size of the limiting hole 5; the external tooth length of the planet wheel 4 is understood to be the vertical length of the external tooth. It can be understood that, since the first grinding disc 2 and the second grinding disc 3 are disposed symmetrically up and down, the radial distance from the edge of the first grinding disc 2 to the ring gear 1 and the radial distance from the edge of the second grinding disc 3 to the ring gear 1 mean the same meaning; the radial maximum distance that the limiting holes 5 are exposed to the first abrasive disk 2 and the radial distance that the limiting holes 5 are exposed to the second abrasive disk 3 are meant to be the same. It should be noted that, in actual polishing of the wafer, the radius of the limiting hole is generally about 0.1mm larger than the radius of the corresponding wafer to be polished, so that in this application, the radius of the wafer is approximately equal to the radius of the limiting hole.

In some embodiments, in order to increase the spin rate of the wafer, and also to avoid excessive total thickness deviation (Total Thickness Variation, TTV) of the polished wafer, the exposed length of the wafer at the edge of the first polishing platen 2 may be greater than the radius of the wafer, i.e., L > R. In the polishing process, if the wafer is exposed excessively, the stability of the wafer is affected, and the polishing flatness of the wafer is reduced. Therefore, the relationship between the wafer and the wafer polishing apparatus is R < L < 1.25R. The exposed part of the wafer is stressed differently from the part polished in the polishing disc, so that a moment is generated, and the wafer rotates during the polishing process.

Further, in some embodiments, the relationship between the dimensions of the wafer and other components of the wafer polishing apparatus may be determined according to a specific use scenario. Wafers of different sizes need to correspond to different disk tooth spacing relationships based on the stability of the wafer during polishing. If the diameter of the wafer is 2 inches or 4 inches, the relation between the limiting hole 5 or the wafer and other parts of the wafer grinding device is R < D-2C < 1.25R; when the diameter of the wafer is 6 inches, the relation between the limiting hole 5 or the wafer and other parts of the wafer grinding device is 0.75R < D-2C < R; when the diameter of the wafer is 8 inches, the relation between the limiting hole 5 or the wafer and other parts of the wafer grinding device is 0.5R < D-2C < 0.75R; when the diameter of the wafer is 12 inches, the relation between the limiting hole 5 or the wafer and other parts of the wafer grinding device is 0.25R < D-2C < 0.5R.

By utilizing the wafer grinding device, the rotation speed of the wafer (the diameter is E inch) in the grinding process can reach 100/Erpm, the warping repair capability is improved, the surface shape of the wafer is converged into a concentric circle, and the proportion of the concentric circle is more than 90%. The curvature of the wafer is within-3*E/4 mu m, the warp value warp is smaller than 7*E/4 mu m by 100%, and the planarization processing of the wafer is realized.

The foregoing is merely a preferred embodiment of the present application, and it should be noted that modifications and substitutions can be made by those skilled in the art without departing from the technical principles of the present application, and these modifications and substitutions should also be considered as being within the scope of the present application.

Claims

1. The wafer grinding device is characterized by comprising a first grinding disc, a second grinding disc, an inner gear ring, a sun wheel and at least one planet wheel;

the planetary gears are respectively meshed with the inner teeth of the inner gear ring and the outer teeth of the sun gear, and the first grinding disc and the second grinding disc are respectively positioned on two opposite sides of the planetary gears;

the planet wheel is provided with at least one limiting hole for limiting the wafer;

and setting the radius of the limiting hole as R, and setting the radial distance of the limiting hole exposing the first grinding disc as L, wherein L is more than R.

2. The wafer polishing apparatus as set forth in claim 1 wherein R < L < 1.25R.

3. The wafer grinding device according to claim 1, wherein a radial distance from the edge of the first grinding disc and/or the second grinding disc to the ring gear is set to be a disc tooth space D, and an outer tooth length of the planetary gear is set to be C;

r < D-2C < 1.25R when the wafer being polished is 2 inches or 4 inches in diameter.

4. The wafer grinding device according to claim 1, wherein a radial distance from the edge of the first grinding disc and/or the second grinding disc to the ring gear is set to be a disc tooth space D, and an outer tooth length of the planetary gear is set to be C;

when the wafer being polished has a diameter of 6 inches, 0.75R < D-2C < R.

5. The wafer grinding device according to claim 1, wherein a radial distance from the edge of the first grinding disc and/or the second grinding disc to the ring gear is set to be a disc tooth space D, and an outer tooth length of the planetary gear is set to be C;

when the wafer being polished has a diameter of 8 inches, 0.5R < D-2C < 0.75R.

6. The wafer grinding device according to claim 1, wherein a radial distance from the edge of the first grinding disc and/or the second grinding disc to the ring gear is set to be a disc tooth space D, and an outer tooth length of the planetary gear is set to be C;

when the wafer being polished has a diameter of 12 inches, 0.25R < D-2C < 0.5R.

7. The wafer polishing apparatus according to any one of claims 1 to 6, wherein the wafer spin rate is > 100/Erpm, and wherein the wafer has a diameter of E inches.

8. The wafer polishing apparatus according to any one of claims 1 to 6, wherein the planar shape of the wafer converges to concentric circles, and the ratio of the concentric circles is > 90%.

9. The wafer polishing apparatus according to any one of claims 1 to 6, wherein the wafer has a bow of within-3*E/4 μm and a diameter of E inches.

10. The wafer polishing apparatus according to any one of claims 1 to 6, wherein the wafer has a warp of less than 7*E/4 μm, and wherein the wafer has a diameter of E ".