CN113524027A

CN113524027A - Wafer holder and grinder

Info

Publication number: CN113524027A
Application number: CN202110911273.1A
Authority: CN
Inventors: 崔凯; 田国军
Original assignee: Beijing Semicore Microelectronics Equipment Co Ltd
Current assignee: Beijing Semicore Microelectronics Equipment Co Ltd
Priority date: 2021-08-09
Filing date: 2021-08-09
Publication date: 2021-10-22

Abstract

The invention discloses a wafer holder and a grinding machine, wherein the wafer holder comprises a support ring and a fixing ring, the support ring is provided with a first surface and a second surface which are opposite, and the first surface of the support ring is used for being connected with a grinding head when a wafer is ground; the fixed ring is arranged on the second surface of the support ring, the inner peripheral wall of the fixed ring is provided with a chamfer, the chamfer is arranged on one side of the fixed ring back to the support ring, the inner side of the fixed ring is provided with a fixed position for fixing a wafer, and the surface of the fixed ring is used for contacting with a grinding pad when the wafer is ground. The invention improves the structure of the wafer holder, shifts the contact point of the wafer holder and the grinding pad to the direction of the center of the wafer holder, and changes the deformation point of the grinding pad from the edge of the wafer to the position of the contact with the body of the wafer holder, thereby avoiding the problem of the increase of the grinding rate of the edge of the wafer caused by the increase of pressure.

Description

Wafer holder and grinder

Technical Field

The invention relates to the technical field of chip manufacturing, in particular to a wafer holder and a grinding machine.

Background

With the emerging gradual application of 5G, the super-high speed, super-low time delay, super-high density and other advantages of the super-high speed super-low time delay super-high density super-high speed super-high density super-high speed super-low time delay super-high speed super-high density super-high speed super-high density super-high speed super-low time delay super-high density super-high speed super-high density super-high speed super-low time super-high density super-high speed super-high density super-high speed super-high density super-high speed super-high density super-high speed super-high density super-high speed super-high density super-high speed super-high density super-high speed super-high technology enables the new technology to rapidly develop the new technology to develop the new technology. This requires that the chips produced by the 5G technology have high efficiency and low energy consumption. With the development of semiconductor chip manufacturing technology, the role and requirement of Chemical Mechanical Planarization (CMP) process for 200mm and above wafers (wafers) in chip production are increasing. Chip devices are smaller and narrower, and the requirements on the control accuracy of parameters such as the surface morphology and the unevenness of an in-chip (WITHIN WAFER, WIW for short) are higher and higher.

Currently, in the polishing process of a polishing machine, the polishing rate of the edge of a wafer is significantly higher than that of the middle area (as shown in fig. 1), so that the edge of the wafer and the center of the wafer have a significant height difference, and the overall uniformity is low, so that the quality of the polished wafer cannot meet the actual requirement.

Disclosure of Invention

The invention mainly aims to provide a wafer holder and a grinding machine, aiming at improving the grinding uniformity of a wafer and improving the yield of production and manufacturing.

In order to achieve the above object, the present invention provides a wafer holder for holding a wafer, the wafer holder comprising:

the supporting ring is provided with a first surface and a second surface which are opposite, and the first surface of the supporting ring is used for being connected with the grinding head when the wafer is ground; and

the fixed ring is arranged on the second surface of the support ring, the inner peripheral wall of the fixed ring is provided with a chamfer, the chamfer is arranged on one side of the support ring, the inner side of the fixed ring is provided with a fixed position for fixing a wafer, and the surface of the fixed ring is used for contacting with a grinding pad when the wafer is ground.

Optionally, the width of the chamfer is greater than 0.01 mm.

Optionally, the height of the chamfer is greater than 0.1 mm.

Optionally, the chamfer is a right angle chamfer, a rounded chamfer or an irregular chamfer.

Optionally, the chamfer is a single chamfer, two chamfers or multiple chamfers.

Optionally, the fixing ring is provided with a plurality of diversion trenches arranged at intervals for diverting the grinding fluid and water to the wafer during the grinding process and diverting the grinding waste out.

Optionally, the plurality of flow guide grooves are circumferentially and uniformly distributed on the fixing ring at intervals.

Optionally, the fixing ring is made of PPS or PP.

Optionally, the inner diameter of the fixing ring is 200mm or 300 mm.

Optionally, the material of the support ring is stainless steel.

Optionally, the retaining ring is provided with a pressure dividing groove for reducing an interaction force between the retaining ring and the polishing pad when the wafer is polished.

In order to achieve the above object, the present invention also proposes a grinder including the wafer holder as described above, the wafer holder including:

In the technical scheme of the invention, the wafer holder comprises a support ring and a fixing ring, wherein the support ring is provided with a first surface and a second surface which are opposite, and the first surface of the support ring is used for being connected with a grinding head when a wafer is ground; the fixed ring is arranged on the second surface of the support ring, the inner peripheral wall of the fixed ring is provided with a chamfer, the chamfer is arranged on one side of the fixed ring back to the support ring, the inner side of the fixed ring is provided with a fixed position for fixing a wafer, and the surface of the fixed ring is used for contacting with a grinding pad when the wafer is ground. It can be understood that when a wafer is ground, the contact point of the grinding pad and the fixing ring is the position of the bottom end of the chamfer, so that the contact point of the wafer holder and the grinding pad is deviated towards the center of the wafer holder, the deformation point of the grinding pad is changed from the edge of the wafer to the position in contact with the body of the wafer holder, the problem of increased grinding rate of the edge of the wafer caused by increased pressure is avoided, the grinding uniformity of the wafer is further improved, and the yield of production and manufacturing is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a graph of prior art wafer polishing rates;

FIG. 2 is a schematic diagram of a prior art wafer, wafer holder and polishing pad;

FIG. 3 is a schematic view of a backside structure of an embodiment of a wafer holder of the present invention;

FIG. 4 is a front view of the wafer holder according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view of a retaining ring according to a first embodiment of the wafer holder of the present invention;

FIG. 6 is a cross-sectional view of a retaining ring in a second embodiment of the wafer holder of the present invention;

FIG. 7 is a cross-sectional view of a retaining ring in a third embodiment of the wafer holder of the present invention;

FIG. 8 is a cross-sectional view of a retaining ring in a fourth embodiment of the wafer holder of the present invention.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				10	Support ring	21	Chamfering
20	Fixing ring	22	Diversion trench
				100	Wafer holder	200	Polishing pad
20a	Fixed position	300	Wafer

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" appearing throughout is to include three juxtapositions, exemplified by "A and/or B" including either scheme A, or scheme B, or a scheme in which both A and B are satisfied. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

In some exemplary techniques, during polishing, the polishing rate of the edge of the wafer is significantly higher than that of the middle region of the wafer (as shown in fig. 1 and 2, wherein 100 is the wafer holder, 200 is the polishing pad, and 300 is the wafer), resulting in a significant height difference between the edge of the wafer and the center of the wafer, and a low overall uniformity, such that the quality of the polished wafer cannot meet the actual requirement.

In order to improve the uniformity of wafer polishing and to improve the yield of production, the present invention provides a wafer holder, which is suitable for various polishing machines, especially 200mm or 300mm CMP polishing machines, but not limited thereto.

Referring to fig. 2 to 4, in an embodiment of the present invention, the wafer holder 100 includes a support ring 10 and a fixing ring 20, the support ring 10 has a first surface and a second surface opposite to each other, the first surface of the support ring 10 is used for connecting with a polishing head when polishing a wafer 300; the retaining ring 20 is disposed on the second surface of the support ring 10, the inner peripheral wall of the retaining ring 20 is provided with a chamfer 21, the chamfer 21 is disposed on a side of the retaining ring 20 facing away from the support ring 10, a retaining location 20a for retaining the wafer 300 is formed on an inner side of the retaining ring 20, and a surface of the retaining ring 20 is used for contacting with the polishing pad 200 when the wafer 300 is polished.

In this embodiment, the support ring 10 may be circular ring-shaped, and the support ring 10 may be made of metal material such as stainless steel, but not limited thereto. The fixing ring 20 may be fixed to the support ring 10 by bonding, the fixing ring 20 may be circular ring, and the fixing ring 20 may be made of PPS, PP, or other plastic materials. The PPS or PP material has the characteristics of acid and alkali resistance and higher hardness, and the problem that the grinding quality is influenced due to the fact that large blocks fall off in the consumption process is solved.

The inner diameter of the retaining ring 20 in this embodiment may preferably be 200mm or 300mm to fit a 200mm or 300mm CMP grinder. Here, the specific structure of the fixing ring 20 is not limited.

The chamfer 21 in the present embodiment may be a right-angle chamfer, a rounded chamfer, an irregular chamfer, or the like, and is not particularly limited herein.

In the solution of the present invention, the wafer holder 100 includes a support ring 10 and a fixing ring 20, the support ring 10 has a first surface and a second surface opposite to each other, the first surface of the support ring 10 is used for connecting with a polishing head when polishing the wafer 300; the retaining ring 20 is disposed on the second surface of the support ring 10, the inner peripheral wall of the retaining ring 20 is provided with a chamfer 21, the chamfer 21 is disposed on a side of the retaining ring 20 facing away from the support ring 10 (i.e., a side of the retaining ring 20 contacting the polishing pad 200), a retaining location 20a for retaining the wafer 300 is formed on an inner side of the retaining ring 20, and a surface of the retaining ring 20 is used for contacting the polishing pad 200 when the wafer 300 is polished. It can be understood that, when the wafer 300 is polished, the contact point between the polishing pad 200 and the fixing ring 20 is the bottom end position of the chamfer 21, so that the contact point between the wafer holder 100 and the polishing pad 200 is shifted toward the center of the wafer holder 100 (i.e. the direction away from the wafer 300 in the fixing position 20a in fig. 2), and the deformation point of the polishing pad 200 is changed from the edge of the wafer 300 to the position in contact with the body of the wafer holder 100, thereby avoiding the problem of increased polishing rate of the edge of the wafer 300 due to increased pressure, further improving the polishing uniformity of the wafer 300, and improving the yield of production.

In order to further improve the polishing uniformity of the wafer 300 and improve the yield of the production, in some embodiments, as shown in fig. 5 to 8, the width of the chamfer 21 on the inner peripheral wall of the retaining ring 20 may be set to be greater than 0.01mm, so as to ensure that the contact point between the wafer holder 100 and the polishing pad 200 is shifted toward the center of the wafer holder 100 without affecting the strength of the retaining ring 20 for fixing the wafer 300 and the strength of the retaining ring 20 connected with the supporting ring, the distance between the deformation point and the wafer 300 is safe, the edge of the wafer 300 is less affected, the polishing uniformity of the wafer 300 is further improved, and the yield of the production is improved.

In some embodiments, as shown in fig. 5 to 8, the height of the chamfer 21 on the retaining ring 20 may be greater than 0.1mm, so as to ensure that the contact point between the wafer holder 100 and the polishing pad 200 is shifted toward the center of the wafer holder 100, the distance between the deformation point and the wafer 300 is reasonable, the edge of the wafer 300 is less affected, and the thickness of the edge of the retaining ring 20 can meet the requirement of its own strength without affecting the connection strength between the retaining ring and other components, thereby avoiding the reduction of the service life due to the excessive deformation.

It should be further noted that the above-mentioned chamfers 21 may be right angle chamfers, fillet chamfers or irregular chamfers, and may be a single chamfers, or may be chamfers twice or chamfers for several times, so as to meet the stress requirements of different scenes or facilitate the processing and manufacturing, and the present disclosure is not limited herein. It should be explained that the primary chamfer means a chamfer formed by one processing; the secondary chamfer represents a chamfer formed by two processes, and the size of each section of chamfer is usually different in size or shape; the multiple chamfers refer to chamfers formed by multiple processes, and the size of each chamfer is usually different in size or shape, and can be a continuous chamfer structure or a discontinuous chamfer structure.

In some embodiments, as shown in fig. 5 to 8, the chamfer 21 of the fixing ring 20 in fig. 5 is a right-angle chamfer, the chamfer 21 of the fixing ring 20 in fig. 6 is a rounded chamfer, the chamfer 21 of the fixing ring 20 in fig. 7 is two consecutive right-angle chamfers, and the chamfer 21 of the fixing ring 20 in fig. 8 is two discontinuous right-angle chamfers. The specific structure of the chamfer 21 can be considered and designed according to the requirements of the actual application scene or the difficulty of processing and manufacturing, and is not limited herein.

To facilitate the addition of slurry and water to the wafer 300 and to facilitate the removal of polishing waste, in some embodiments, referring to fig. 4, the retaining ring 20 is provided with a plurality of flow channels 22 spaced apart from each other for guiding slurry and water to the wafer 300 during the polishing process and for guiding the removal of polishing waste.

In this embodiment, at least one pressure-dividing groove may be disposed between two adjacent guide grooves 22. Thus, the function of introducing polishing liquid and water and discharging polishing waste is realized, and the function of reducing the interaction force between the retainer ring 20 and the polishing pad 200 is also realized, thereby avoiding the problem of an increase in polishing rate of the edge of the wafer 300 due to an increase in polishing pressure, and improving the accuracy of the polishing machine in polishing the wafer 300.

It can be understood that the interaction force between the retaining ring 20 and the polishing pad 200 is divided into a plurality of dividing grooves, thereby further avoiding the problem of high polishing rate of the edge of the wafer 300 due to the increase of the polishing pressure, and further improving the precision of the polishing machine for polishing the wafer 300.

Further, referring to fig. 3, the plurality of guide grooves 22 are uniformly distributed on the fixing ring 20 at circumferential intervals, and the plurality of partial pressure grooves are uniformly distributed on the fixing ring 20 at circumferential intervals. It can be understood that, since the plurality of partial pressure grooves are uniformly distributed on the fixing ring 20 at circumferential intervals, the circumferential force applied to the fixing ring 20 is more uniform, and the stability and reliability of the wafer holder 100 are improved.

The present invention also proposes a grinder comprising a wafer holder, the specific structure of which is described with reference to the above-mentioned embodiments, and since the grinder proposed by the present invention comprises all the solutions of all the embodiments of the above-mentioned wafer holder, it has at least the same technical effects as the wafer holder, which are not described herein.

The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A wafer holder for housing a wafer, the wafer holder comprising:

2. The wafer holder of claim 1, wherein the chamfer has a width greater than 0.01 mm.

3. The wafer holder of claim 1, wherein the height of the chamfer is greater than 0.1 mm.

4. The wafer holder of claim 1, wherein the chamfer is a right angle chamfer, a rounded chamfer, or an irregular chamfer.

5. The wafer holder of claim 4, wherein the chamfer is a single chamfer, a double chamfer, or a multiple chamfer.

6. The wafer holder of claim 1, wherein the retaining ring has a plurality of spaced channels for directing slurry and water to the wafer and directing polishing waste away during polishing.

7. The wafer holder as claimed in claim 6, wherein the plurality of flow guide grooves are evenly distributed on the fixing ring at circumferential intervals.

8. The wafer holder of claim 1, wherein the retaining ring is made of PPS or PP.

9. The wafer holder of claim 1, wherein the retaining ring has an inner diameter of 200mm or 300 mm.

10. The wafer holder of claim 1, wherein the support ring is made of stainless steel.

11. The wafer holder of claim 1, wherein the retaining ring is provided with a pressure-dividing groove for reducing interaction between the retaining ring and a polishing pad when polishing a wafer.

12. A grinding machine comprising a wafer holder according to any one of claims 1 to 10.