Baffle ring structure for improving uniformity of wafer coating

Abstract

The utility model discloses a baffle ring structure for improving the uniformity of a wafer plating layer, a to-be-plated surface of a wafer is divided into a plurality of electroplating areas and a plurality of non-electroplating areas, and the non-electroplating areas are annularly distributed on the edge of the to-be-plated surface at intervals; the baffle ring structure comprises a ring body and a plurality of baffle blocks which are arranged on the inner side of the ring body and correspond to the non-electroplating areas in a one-to-one mode, the porous baffle is fixedly installed on the ring body, and the baffle blocks correspondingly shield through holes, close to the edge, in the baffle in the current flowing direction. According to the utility model, on one hand, the porous baffle plate is arranged on the ring body, and the plurality of baffle blocks matched with the non-electroplating area at the edge of the wafer shield the through holes at the edge of the baffle plate so as to reduce the current density at the edge and optimize the uniformity of current distribution, so that the uniformity of plating layer distribution is effectively improved, and the electroplating quality is obviously improved; the structure is simple, implementation is convenient, and the machining cost is low.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor equipment, and specifically relates to a retaining ring structure for improving the uniformity of wafer plating. Background Technology

[0002] In the field of gold plating in vertical electroplating equipment, different wafer aperture types often require specific components to be configured on the machine to improve the uniformity of electroplating. For example, there are two common wafer aperture types: 1. No edge aperture, that is, the invalid area at the edge of the wafer is not electroplated, and only the central area of ​​the wafer is electroplated; 2. Edge aperture, that is, the invalid area at the edge of the wafer and the central area of ​​the wafer are electroplated at the same time.

[0003] Currently, in the gold wafer electroplating process where the edges are not open, the patterns on the surface of the gold wafer are generally designed as long strips to provide more I / O interfaces for back-end packaging applications. Compared with the square patterns on the surface of copper wafers, the conventional perforated baffles do not significantly improve the edge effect of current. As a result, when gold wafers are electroplated, the edge effect of current causes the edge plating layer to be thicker, resulting in poor uniformity of plating thickness distribution and making it difficult to meet process requirements. Summary of the Invention

[0004] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a novel retaining ring structure for improving the uniformity of wafer coating.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0006] A retaining ring structure for improving the uniformity of wafer plating is disclosed. The wafer surface to be plated is divided into electroplating areas and non-electroplated areas. Multiple non-electroplated areas are distributed in a ring at intervals along the edge of the surface to be plated. The retaining ring structure includes a ring body, multiple blocks disposed on the inner side of the ring body and corresponding to the multiple non-electroplated areas, and a perforated baffle fixedly mounted on the ring body. The multiple blocks block the through holes near the edge of the baffle in the direction of current flow. In the orthographic projection on the surface to be plated, each block partially or completely overlaps with the corresponding non-electroplated area.

[0007] According to a specific embodiment and preferred aspect of this utility model, the center line of the ring body is arranged parallel to the center line of the wafer, and the baffle is fixedly installed on the ring body on the side near the surface to be plated. This facilitates installation and implementation.

[0008] Preferably, the centerline of the ring body coincides with the centerline of the wafer, or the centerlines of the ring body, the wafer, and the baffle coincide.

[0009] Preferably, a first annular protrusion and a second annular protrusion are formed on the side of the ring body away from the surface to be plated, with the first annular protrusion and the second annular protrusion forming a connecting groove that is connected to the baffle by bolts.

[0010] Specifically, the thickness of the first annular protrusion is less than the thickness of the second annular protrusion. The baffle abuts against the first annular protrusion and fits against the inner wall of the second annular protrusion from its edge. This improves the compactness and stability of the connection structure between the baffle and the retaining ring, saving electroplating space and preventing the baffle from wobbling relative to the retaining ring during electroplating solution flow. Furthermore, it allows for quick and precise installation of the baffle using the inner wall of the second annular protrusion as a reference.

[0011] Preferably, the inner wall of the first annular protrusion is flush with the inner wall of the ring body, and the outer wall of the second annular protrusion is flush with the outer wall of the ring body; a plurality of blocks are arranged in a circumferential array around the center line of the ring body, and each block is flush with the ring body from the side away from the surface to be plated and flush with the first annular protrusion from the side closer to the surface to be plated.

[0012] Preferably, the baffle is spaced apart from the surface to be plated. Here, the space created by the baffle and the surface to be plated reduces the edge current density while allowing the ion current to reach the entire wafer surface for electroplating after passing through the through-holes on the baffle that are not blocked by the baffle, thus ensuring the formation of a coating in the edge areas of the wafer.

[0013] Preferably, each stop is an arc extending around the center line of the ring body. This design is applicable to unplated areas of wafers with arbitrary contours, offering high practicality.

[0014] Preferably, in the orthographic projection of the surface to be plated, each stop has the same contour as the corresponding non-plating area. Here, customizing the stops according to the contour of the non-plating area results in the best reduction of the current edge effect.

[0015] Furthermore, the ring body and multiple stops are integrally molded, facilitating manufacturing.

[0016] Due to the implementation of the above technical solution, this utility model has the following advantages compared with the prior art:

[0017] Existing porous baffles are not very effective in improving the edge effect of current in gold wafer electroplating processes. This results in thicker edge plating layers due to the closed edges of the wafer, leading to poor uniformity of plating thickness and failing to meet process requirements. This application addresses this issue by designing a baffle ring structure to improve wafer plating uniformity, cleverly resolving the shortcomings of existing technologies. In this structure, a porous baffle is mounted on a ring body, with multiple baffle blocks located inside the ring body in front of and tightly fitted to the baffle. Both blocks are positioned in front of the plating surface on the wafer, leaving space between them. During electroplating, the multiple baffle blocks block the through-holes near the edge of the baffle in the direction of current flow, reducing the edge current density and thus decreasing the current reaching non-plating areas on the wafer, thereby mitigating the edge effect. Therefore, compared with the prior art, this utility model has the advantages of both: firstly, by installing a porous baffle on the ring body and using multiple baffles that cooperate with the non-electroplated area of ​​the wafer edge to shield the through holes at the upper edge of the baffle to reduce the edge current density and optimize the uniformity of current distribution, thereby effectively improving the uniformity of the plating distribution and significantly improving the electroplating quality; secondly, it has a simple structure, is easy to implement and has low cost. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural schematic diagram (first view) of the retaining ring structure used to improve the uniformity of wafer coating in Example 1;

[0019] Figure 2 This is a three-dimensional structural schematic diagram (second view) of the retaining ring structure used to improve the uniformity of wafer coating in Example 1;

[0020] Figure 3 This is a schematic diagram of the main structure of the retaining ring structure used to improve the uniformity of wafer plating in Example 1;

[0021] Figure 4 for Figure 3 Schematic diagram of the sectional view along the central AA direction;

[0022] Figure 5 This is a schematic diagram of the front view of the wafer;

[0023] Figure 6 This is a schematic diagram of the main structure of the retaining ring structure used to improve the uniformity of wafer coating in Example 2;

[0024] Wherein: 1. Ring body; 11. First annular protrusion; 12. Second annular protrusion; 13. Connecting groove;

[0025] 2. Stop;

[0026] Y, wafer; m, surface to be plated; m1, plated area; m2, non-plated area;

[0027] B, baffle; k, through hole. Detailed Implementation

[0028] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0029] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0031] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0032] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0033] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0034] Example 1

[0035] like Figures 1 to 5 As shown, this embodiment illustrates a retaining ring structure for improving the uniformity of wafer plating, which includes a ring body 1 and a retaining block 2.

[0036] Specifically, in this embodiment, one side of the wafer Y is the surface to be plated m, and the surface to be plated m is divided into an electroplating area m1 and a non-electroplating area m2. There are multiple non-electroplating areas m2, which are distributed in a ring at intervals on the edge of the surface to be plated m. Each non-electroplating area m2 is distributed around the center of the wafer and has a stepped shape with an area that gradually increases.

[0037] In this example, the center line of the ring body 1 is set parallel to the center line of the wafer Y, and the porous baffle B is fixedly installed on the ring body 1 on the side close to the surface to be plated m.

[0038] In some specific embodiments, the center lines of the ring body 1, the wafer Y, and the baffle B are aligned. The ring body 1 has a first annular protrusion 11 and a second annular protrusion 12 spaced apart on the side near the surface to be plated m. A connecting groove 13 is formed between the first annular protrusion 11 and the second annular protrusion 12, which is connected to the baffle B by bolts. The thickness of the first annular protrusion 11 is less than the thickness of the second annular protrusion 12. The baffle B abuts against the first annular protrusion 11 and fits against the inner wall of the second annular protrusion 12 from its edge. At the same time, the end face of the baffle B is flush with the end face of the second annular protrusion 12 to achieve a flat side surface of the entire retaining ring structure.

[0039] In this example, the baffle 2 is positioned inside the ring body 1 and corresponds one-to-one with multiple non-electroplated areas m2. The multiple baffles 2 are located between the baffle B and the surface to be plated m, and in the direction of current flow, they block the through-holes k near the edge of the baffle B. In the orthographic projection onto the surface to be plated m, each baffle 2 partially or completely overlaps with its corresponding non-electroplated area m2. It should be noted that the area of ​​the corresponding non-electroplated area m2 that each baffle 2 can block is determined by experiments and numerical simulations based on actual production conditions. This is a conventional technique and therefore, it is clear that it is feasible and will not be elaborated upon here.

[0040] In some specific embodiments, the inner wall of the first annular protrusion 11 is flush with the inner wall of the ring body 1, and the outer wall of the second annular protrusion 12 is flush with the outer wall of the ring body 1; a plurality of blocks 2 are arranged in a circular array around the center line of the ring body 1, and each block 2 is flush with the ring body 1 from the side away from the surface to be plated m and flush with the first annular protrusion 11 from the side closer to the surface to be plated m; the baffle B is spaced apart from the surface to be plated m; each block 2 is an arc extending around the center line of the ring body 1 to match the non-plating area of ​​arbitrary contour; at the same time, in the orthographic projection on the surface to be plated m in this embodiment, each block 2 may only cover the corresponding non-plating area m2, or it may cover part of the non-plating area m2 and part of the adjacent plating area m1.

[0041] Furthermore, in this embodiment, the ring body 1 and multiple stops 2 are integrally formed.

[0042] In summary, by adopting this baffle ring structure, a porous baffle is installed on the ring body, and multiple baffles located inside the ring body are positioned in front of and tightly fitted to the porous baffle. Both are positioned in front of the surface to be plated on the wafer, leaving space between them. During electroplating, the multiple baffles block the through-holes near the edge of the baffle in the direction of current flow, thereby reducing the edge current density and thus reducing the current reaching the non-plating areas on the wafer, thereby mitigating the edge effect. Therefore, compared with the prior art, this utility model has several advantages. First, by installing a porous baffle on the ring body and using multiple blocks that cooperate with the non-electroplated areas of the wafer edge to shield the through holes at the upper edge of the baffle to reduce the edge current density and optimize the uniformity of current distribution, it effectively improves the uniformity of the plating layer distribution and significantly improves the electroplating quality. Second, the structure is simple, easy to implement, and low in cost. Third, the connection layout of the ring body and the baffle in this application improves the compactness and stability of the connection structure between the baffle and the retaining ring, which not only saves electroplating space but also prevents the baffle from shaking relative to the retaining ring during the flow of the electroplating solution. In addition, it can achieve rapid and accurate installation of the baffle by using the inner wall of the second annular protrusion as a reference. Fourth, by creating a space between the baffle and the surface to be plated, the edge current density is reduced while the ion current can still reach the entire surface of the wafer for electroplating after passing through the through holes on the baffle that are not shielded by the blocks, ensuring the formation of the plating layer in the edge area of ​​the wafer. Fifth, the use of arc-shaped blocks makes it applicable to non-electroplated areas of the wafer with any contour, making it highly practical.

[0043] Example 2

[0044] Combination Figure 6 As shown, the retaining ring structure used to improve the uniformity of wafer plating in this embodiment is basically the same as that in Embodiment 1, except that:

[0045] In this embodiment, in the orthographic projection on the surface to be plated m, each baffle 2 has the same outline as the corresponding non-plating area m2. That is, in this embodiment, the baffles 2 are distributed around the center of the wafer (or the center of the ring body 1) in a stepped shape with gradually increasing area. Here, by customizing the baffles according to the outline of the non-plating area, the current edge effect is reduced most effectively.

[0046] The present utility model has been described in detail above, with the aim of enabling those skilled in the art to understand its contents and implement it. However, this description should not be construed as limiting the scope of protection of the present utility model. All equivalent changes or modifications made in accordance with the spirit and essence of the present utility model should be included within the scope of protection of the present utility model.

Claims

1. A retaining ring structure for improving the uniformity of wafer plating, wherein the surface to be plated on the wafer is divided into plating areas and non-plating areas, wherein the non-plating areas are multiple and distributed in a ring-shaped interval at the edge of the surface to be plated, characterized in that, The retaining ring structure includes a ring body, multiple retaining blocks disposed on the inner side of the ring body and corresponding one-to-one with the multiple non-electroplated areas, a perforated baffle fixedly installed on the ring body, and the multiple retaining blocks forming a shielding effect on the through holes near the edge of the baffle in the direction of current flow. In the orthographic projection of the surface to be plated, each retaining block partially or completely overlaps with the corresponding non-electroplated area.

2. The retaining ring structure for improving wafer coating uniformity according to claim 1, characterized in that, The centerline of the ring body is parallel to the centerline of the wafer, and the baffle is fixedly installed on the ring body on the side close to the surface to be plated.

3. The retaining ring structure for improving wafer coating uniformity according to claim 2, characterized in that, The centerline of the ring body coincides with the centerline of the wafer, or the centerlines of the ring body, the wafer, and the baffle coincide.

4. The retaining ring structure for improving wafer coating uniformity according to claim 3, characterized in that, The ring body has a first annular protrusion and a second annular protrusion spaced apart on the side near the surface to be plated, wherein a connecting groove is formed between the first annular protrusion and the second annular protrusion to be connected to the baffle by bolts.

5. The retaining ring structure for improving wafer coating uniformity according to claim 4, characterized in that, The thickness of the first annular protrusion is less than the thickness of the second annular protrusion, and the baffle abuts against the first annular protrusion and fits against the inner wall of the second annular protrusion from the edge.

6. The retaining ring structure for improving wafer coating uniformity according to claim 4 or 5, characterized in that, The inner wall of the first annular protrusion is flush with the inner wall of the ring body, and the outer wall of the second annular protrusion is flush with the outer wall of the ring body; a plurality of the blocks are arranged in a circular array around the center line of the ring body, and each block is flush with the ring body from the side away from the surface to be plated and flush with the first annular protrusion from the side closer to the surface to be plated.

7. The retaining ring structure for improving wafer coating uniformity according to claim 1, characterized in that, The baffle is spaced apart from the surface to be plated.

8. The retaining ring structure for improving wafer coating uniformity according to claim 1, characterized in that, Each of the stops is an arc extending around the center line of the ring body.

9. The retaining ring structure for improving wafer coating uniformity according to claim 1, characterized in that, In the orthographic projection of the surface to be plated, the outline of each block is the same as that of the corresponding non-plating area.

10. The retaining ring structure for improving wafer coating uniformity according to claim 1, characterized in that, The ring body and the plurality of stops are integrally formed.

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