Retaining ring and chemical polishing device
By setting a specific arrangement of grooves on the retaining ring to control the flow direction of the polishing liquid, the problem of excessive removal of silicon wafer edges in chemical mechanical polishing is solved, and a more uniform polishing effect is achieved.
Patent Information
- Application Number
- CN202421459878.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-24
- Publication Date
- 2025-04-04
- Estimated Expiration
- 2034-06-24
AI Technical Summary
During chemical mechanical polishing, the problem of excessive removal of silicon wafer edges.
A holding ring is designed, and a plurality of sets of trenches are provided on the holding ring, each set of trenches including a first trenches and a second trenches, and the flow direction of the second trenches flows from the first position to the second position to reduce the accumulation and removal of the polishing liquid at the edge of the silicon wafer.
By slowing down the inlet speed of polishing liquid and accelerating its discharge speed, the amount of edge removal of silicon wafers is reduced, solving the problem of excessive edge removal.
Smart Images
Figure CN222711819U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of semiconductor processing, in particular to a retaining ring and a chemical polishing device. Background Art
[0002] In the semiconductor process flow, chemical mechanical polishing (CMP) is a very important process, sometimes also called chemical mechanical planarization (CMP). The so-called chemical mechanical polishing is a process that uses a combination of chemical and mechanical effects to remove excess materials from semiconductor silicon wafers and obtain a flat surface. Specifically, this polishing method usually clamps the silicon wafer to be polished by a polishing head and presses it on a high-speed rotating polishing pad with a certain pressure, and achieves the purpose of flattening through the mutual friction between the polishing pad and the wafer under the action of a polishing slurry containing chemical polishing agents and abrasive particles.
[0003] The existing polishing head for chemical mechanical polishing includes a retaining ring, which fixes the silicon wafer so that each area of the polishing pad is at the same height, which can effectively solve the problem of over-grinding of the silicon wafer. During the chemical mechanical polishing process, part of the polishing liquid is brought to the silicon wafer by the polishing pad, and part of it is brought to the silicon wafer by the grooves set on the retaining ring. In addition, the grooves on the retaining ring also have the function of discharging debris and polishing liquid without polishing ability. However, the existing chemical mechanical polishing results show that there is still a problem of excessive removal of silicon wafer edges. Utility Model Content
[0004] The utility model aims to provide a retaining ring and a chemical polishing device to solve the problem in the prior art that the amount of silicon wafer edge removal is too high when chemical mechanical polishing is performed on the silicon wafer.
[0005] In order to solve the above technical problems, the utility model provides a retaining ring for a polishing head, wherein the retaining ring is provided with a plurality of groups of grooves, the plurality of groups of grooves are sequentially arranged along the circumference of the retaining ring, and each group of grooves includes a first groove and a second groove;
[0006] In each group of the grooves, the first grooves are connected with the outer ring and the inner ring of the retaining ring along the first direction, and the second grooves include a first part and a second part connected to each other at an angle, the first part is connected with the first groove at a first position, the second part is connected with the first groove at a second position, and the first part and the second part are connected at a third position, wherein the first position is closer to the outer ring of the retaining ring relative to the second position, and in the first direction, the third position is closer to the inner ring of the retaining ring relative to the second position, so that the flow direction of the polishing liquid in the second groove is maintained from the first position to the second position.
[0007] Optionally, in the retaining ring, in the first direction, a distance between the third position and the second position is 1 to 3 mm.
[0008] Optionally, in the retaining ring, in each group of the grooves, both sides of the first grooves are provided with the second grooves connected thereto.
[0009] Optionally, in the retaining ring, the number of the second grooves located on each side of the first groove is greater than or equal to 3.
[0010] Optionally, in the retaining ring, the second grooves located on both sides of the first groove are symmetrically distributed with respect to the first groove or staggeredly distributed in the first direction.
[0011] Optionally, in the retaining ring, there is a first distance between the third position and the first position, and there is a second distance between the third position and the second position, and the first distance is 1.5 times to 2 times the second distance.
[0012] Optionally, in the retaining ring, the first direction is a radial direction of the retaining ring, or the first direction is a direction on a plane where the retaining ring is located that forms an angle with the radial direction.
[0013] Optionally, in the retaining ring, the groove width of the first groove is equal to or greater than the groove width of the second groove.
[0014] Optionally, in the retaining ring, the width of the first groove is 1 to 3 times the width of the second groove.
[0015] The utility model also provides a chemical polishing device, comprising: a retaining ring as described in any of the preceding items.
[0016] In summary, the utility model provides a retaining ring and a chemical polishing device, wherein a plurality of groups of grooves are arranged on the retaining ring, and the plurality of groups of grooves are arranged in sequence along the circumference of the retaining ring, and each group of grooves includes a first groove and a second groove; in each group of grooves, the first groove is connected with the outer ring and the inner ring of the retaining ring along a first direction, and the second groove includes a first part and a second part connected to each other at an angle, the first part is connected with the first groove at a first position, the second part is connected with the first groove at a second position, and the first part and the second part are connected at a third position, wherein the first position is closer to the outer ring of the retaining ring than the second position, and in the first direction, the third position is closer to the inner ring of the retaining ring than the second position, so that the flow direction of the polishing liquid in the second groove is maintained from the first position to the second position. By using the retaining ring provided by the utility model, when the polishing liquid flows from the outer ring to the inner ring of the retaining ring, a part of it enters the first groove, and the other part enters the second groove and then flows back to the first groove. The polishing liquid flowing back into the first groove will slow down the entry speed of the polishing liquid on the one hand, and accelerate the discharge speed of the polishing liquid on the other hand, thereby reducing the amount of polishing liquid brought to the edge of the silicon wafer by the groove on the retaining ring, thereby achieving the purpose of reducing the amount of polishing liquid removed from the edge of the silicon wafer. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 A schematic diagram of the structure of a retaining ring provided in an embodiment of the utility model;
[0018] Figure 2 A schematic diagram of a partial structure of another retaining ring provided in an embodiment of the utility model;
[0019] Figure 3 A schematic diagram of an arrangement of the second grooves in the retaining ring provided by the utility model;
[0020] Figure 4 A schematic diagram of another arrangement of the second grooves in the retaining ring provided by the present invention;
[0021] The descriptions of the reference numerals are as follows:
[0022] 10-groove; 101-first groove; 102-second groove; 1021-first part; 1022-second part. DETAILED DESCRIPTION
[0023] The technicians of the present application have found that the grooves on the retaining ring bring more polishing liquid to the edge of the silicon wafer, which is a key factor causing excessive removal of the silicon wafer edge. In view of this, the utility model provides a retaining ring that reduces the amount of polishing liquid brought to the edge of the silicon wafer by the grooves on the retaining ring to reduce the removal of the silicon wafer edge.
[0024] In order to make the purpose, advantages and features of the utility model clearer, the utility model is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different proportions are used. It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish between the various components, elements, steps, etc. in the specification, and are not used to represent the logical relationship or sequential relationship between the various components, elements, steps, etc.
[0025] The utility model provides a retaining ring, which is used for a polishing head. Figure 1 As shown, the retaining ring is provided with a plurality of groups of grooves 10, and the plurality of groups of grooves 10 are arranged in sequence along the circumference of the retaining ring.
[0026] Please combine Figure 2 and Figure 3 Each group of the grooves 10 includes a first groove 101 and a second groove 102; in each group of the grooves 10, the first groove 101 is connected with the outer ring and the inner ring of the retaining ring along a first direction, and the second groove 102 includes a first part 1021 and a second part 1022 that are connected to each other at an angle, the first part 1021 is connected with the first groove 101 at a first position, and the second part 1022 is connected with the first groove 101 at a second position, wherein the first position is closer to the outer ring of the retaining ring than the second position. Figure 3 The position A shown in is the first position, Figure 1 The position B shown in is the second position. In addition, Figure 3 As shown in , position C is the outer ring position of the retaining ring, and position D is the inner ring position of the retaining ring.
[0027] It should be understood that, in the retaining ring provided by the present invention, the opening directions of the first groove 101 and the second groove 102 are both perpendicular to the plane where the retaining ring is located in general scenarios, and the channel directions of the first groove 101 and the second groove 102 (i.e., the directions for the polishing liquid to flow in and out) are both on the plane where the retaining ring is located. For example, the first direction is the flow direction of the first groove 101, and the first direction can be as follows: Figure 1 As shown in , it is a direction that is at an angle to the radius direction of the retaining ring, or as shown in Figure 2 As shown in , it is the radial direction of the retaining ring.
[0028] Furthermore, in the retaining ring provided by the utility model, the first part 1021 and the second part 1022 are connected at a third position, and in the first direction, the third position is closer to the inner ring of the retaining ring than the second position, so that the second part 1022 can be tilted toward the outer ring of the retaining ring, that is, the angle formed by the second part 1022 and the line L2 between position A and position B is an obtuse angle, so that the flow direction of the polishing liquid in the second groove can always be maintained from the first position to the second position, that is, the flow of the polishing liquid in the second groove is always unidirectional: flowing in from the first position and flowing out from the second position.
[0029] Figure 3 The E position shown in is the third position. Figure 3 As shown in , in the first direction, position E is closer to the inner ring of the retaining ring than position B, that is, closer to position D, so that the second part 1022 can be tilted toward the outer ring of the retaining ring, and the line L2 between position E and position B forms an obtuse angle with the line L0 between position A and position B. In this way, the polishing liquid can only flow out from position B but cannot flow in from position B. Therefore, after the polishing liquid flows into the second groove 102 at position A, it flows back to the first groove 101 toward the outer ring of the retaining ring at position B. The polishing liquid flowing back from position B to the first groove 101 will slow down the speed of the polishing liquid entering from position C on the one hand, and accelerate the speed of discharging the polishing liquid to position C on the other hand, thereby reducing the amount of polishing liquid brought to the edge of the silicon wafer by the groove 10 on the retaining ring, thereby achieving the purpose of reducing the amount of silicon wafer edge removal.
[0030] Preferably, in the first direction, the distance between the third position and the second position is 1 to 3 mm, that is, the third position is 1 to 3 mm closer to the inner ring of the retaining ring than the second position. Specifically, Figure 1 As shown in , the distance d1 between the E position and the B position in the first direction is 1-3 mm, specifically 1 mm, 2 mm or 3 mm.
[0031] In this embodiment, there is a first distance L1 between the third position and the first position (i.e., between position E and position A), and a second distance L2 between the third position and the second position (i.e., between position E and position B). Preferably, L1 is 1.5 to 2 times of L2. For example, the length of L1 is 3 to 9 mm, and the length of L2 is 2 to 6 mm.
[0032] In addition, in this embodiment, the groove width d3 of the first groove 101 is greater than or equal to the groove width d2 of the second groove 102. Preferably, the groove width of the first groove is 1 to 3 times the groove width of the second groove, so as to ensure that debris and polishing liquid without polishing ability are discharged in time.
[0033] Please continue to see Figure 3 Preferably, in each group of the grooves 10, both sides of the first groove 101 are provided with the second grooves 102 connected thereto. Further preferably, the number of the second grooves 102 located on each side of the first groove 101 is greater than or equal to 3. By providing the second grooves 102 on both sides, and the number of the second grooves 102 is greater than or equal to 3, the effect of slowing down the entry speed of the polishing liquid and accelerating the discharge speed of the polishing liquid can be further ensured. The present application does not impose any special restrictions on the position arrangement relationship of the second grooves 102 on both sides of the first groove 101. In order to facilitate the structural design, preferably, as Figure 3 As shown in , the second grooves 102 located on both sides of the first groove 101 are designed to be symmetrically distributed with respect to the first groove 101, or as Figure 4 As shown in FIG. 1 , the second grooves 102 located on both sides of the first groove 101 are designed to be staggered in the first direction.
[0034] In addition, an embodiment of the utility model further provides a chemical polishing device, which includes a retaining ring as described in this embodiment.
[0035] Specifically, the chemical polishing device provided in this embodiment may include: a polishing pad and a polishing head, the polishing head includes a retaining ring as described in this embodiment, when chemical polishing is performed, the retaining ring is sleeved outside the silicon wafer, and the polishing head drives the retaining ring and the silicon wafer to rotate around their own axes at the eccentric position of the polishing pad, and during the polishing process, polishing liquid is continuously injected onto the retaining ring and the polishing pad.
[0036] In summary, the retaining ring and chemical polishing device provided by the embodiments of the utility model are provided with multiple groups of grooves on the retaining ring, and the multiple groups of grooves are arranged in sequence along the circumference of the retaining ring, and each group of the grooves includes a first groove and a second groove; in each group of the grooves, the first groove is connected with the outer ring and the inner ring of the retaining ring along a first direction, and the second groove includes a first part and a second part connected to each other at an angle, the first part is connected with the first groove at a first position, and the second part is connected with the first groove at a second position, and the first part and the second part are connected at a third position, wherein the first position is closer to the outer ring of the retaining ring than the second position, and in the first direction, the third position is closer to the inner ring of the retaining ring than the second position, so that the flow direction of the polishing liquid in the second groove is maintained from the first position to the second position. By using the retaining ring provided by the utility model, when the polishing liquid flows from the outer ring to the inner ring of the retaining ring, a part of it enters the first groove, and the other part enters the second groove and then flows back to the first groove. The polishing liquid flowing back into the first groove will slow down the entry speed of the polishing liquid on the one hand, and accelerate the discharge speed of the polishing liquid on the other hand, thereby reducing the amount of polishing liquid brought to the edge of the silicon wafer by the groove on the retaining ring, thereby achieving the purpose of reducing the amount of polishing liquid removed from the edge of the silicon wafer.
[0037] In addition, it should be recognized that although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the above disclosed technical content can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.
Claims
1. A retaining ring for a polishing head, characterized in that: The retaining ring is provided with a plurality of groups of grooves, the plurality of groups of grooves are sequentially arranged along the circumference of the retaining ring, and each group of grooves includes a first groove and a second groove; In each group of the grooves, the first grooves are connected with the outer ring and the inner ring of the retaining ring along the first direction, and the second grooves include a first part and a second part connected to each other at an angle, the first part is connected with the first groove at a first position, the second part is connected with the first groove at a second position, and the first part and the second part are connected at a third position, wherein the first position is closer to the outer ring of the retaining ring relative to the second position, and in the first direction, the third position is closer to the inner ring of the retaining ring relative to the second position, so that the flow direction of the polishing liquid in the second groove is maintained from the first position to the second position.
2. The retaining ring according to claim 1, characterized in that In the first direction, the distance between the third position and the second position is 1 to 3 mm.
3. The retaining ring according to claim 1, characterized in that In each group of the grooves, both sides of the first grooves are provided with the second grooves connected therewith.
4. The retaining ring according to claim 3, characterized in that The number of the second grooves located on each side of the first groove is greater than or equal to three.
5. The retaining ring according to claim 3, characterized in that: The second grooves located on both sides of the first groove are symmetrically distributed with respect to the first groove or staggeredly distributed in the first direction.
6. The retaining ring according to claim 1, wherein: There is a first distance between the third position and the first position, and there is a second distance between the third position and the second position, and the first distance is 1.5 times to 2 times the second distance.
7. The retaining ring according to claim 1, characterized in that The first direction is a radial direction of the retaining ring, or the first direction is a direction on a plane where the retaining ring is located that forms an angle with the radial direction.
8. The retaining ring according to claim 1, wherein: The groove width of the first groove is equal to or greater than the groove width of the second groove.
9. The retaining ring according to claim 8, characterized in that The width of the first groove is 1 to 3 times the width of the second groove.
10. A chemical polishing device, characterized in that: include: A retaining ring as claimed in any one of claims 1 to 9.