Wafer processing method and system
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-12-08
- Publication Date
- 2026-08-11
AI Technical Summary
[0003]但是，在多片晶圆连续修边时，会出现刀具脱皮(peeling)和晶圆崩边(chipping)的问题
[0014]与现有技术相比，本申请的晶圆处理方法及其系统具有如下有益效果：先采用硬度较大的第一刀具去除晶圆边缘的棱角，将对刀具磨损较严重的位置打磨成圆角，再采用硬度较小的第二刀具对晶圆进行宽度和深度的处理。采用第一刀具和第二刀具共同完成第二次修边，能够防止在第二次修边时损伤刀具，不仅可以延长刀具的使用寿命，还可以解决因采用破损刀具修边时形成的残留结构在后续的减薄工艺中整块脱落导致的晶圆破片问题。
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Figure CN116246940B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor device manufacturing technology, and in particular to a wafer processing method and system thereof. Background Technology
[0002] During wafer packaging, to avoid chipping defects at the wafer edges caused by the grinding process, the wafer edges are usually trimmed before grinding. Current trimming processes use high-speed rotation of cutting tools to mechanically grind the wafer edges.
[0003] However, when multiple wafers are continuously trimmed, problems such as tool peeling and wafer chipping can occur. Summary of the Invention
[0004] The technical problem to be solved by this application is the problem of tool peeling and wafer edge chipping that occurs during continuous trimming of multiple wafers.
[0005] To address the aforementioned technical problems, this application provides a wafer processing method, comprising: providing a first wafer and a second wafer bonded to the first wafer, wherein the edge of the second wafer includes a sharp corner formed after a first trimming; performing a second trimming on the edges of the first wafer and the second wafer, wherein the second trimming includes: removing the sharp corner using a first tool, wherein the working surface of the first tool is a concave arc shape; and then removing a portion of the edges of the first wafer and the second wafer using a second tool, wherein the working surface of the second tool is a plane, and the hardness of the first tool is greater than the hardness of the second tool.
[0006] In this embodiment of the application, the arc shape has an angle of 30° to 180°, and when the first tool processes the edge, the angle between the tool body and the surface of the second wafer is 20° to 60°.
[0007] In the embodiments of this application, the first cutting tool has a mesh size of 500 to 1000 mesh, and the second cutting tool has a mesh size of 1200 to 2000 mesh.
[0008] In this embodiment of the application, the material of the first cutting tool includes abrasive with a first particle size, and the material of the second cutting tool includes abrasive with a second particle size, wherein the first particle size is larger than the second particle size.
[0009] In this embodiment of the application, the method for bonding the first wafer and the second wafer includes: providing a second wafer; performing a first trimming to remove a portion of the edge of the second wafer and form a sharp edge on the edge of the second wafer; bonding the second wafer to the first wafer and thinning the second wafer to a target thickness.
[0010] In this embodiment of the application, when the area processed by the first tool reaches the position of the second tool, the second tool begins to work.
[0011] This application also provides a wafer processing system for trimming the edges of a first wafer and a second wafer bonded to the first wafer, wherein the edge of the second wafer includes an edge formed after a first trimming. The wafer processing system includes: a wafer stage for supporting the first wafer and the second wafer; a first cutting tool for removing the edge, wherein the working surface of the first cutting tool is a concave arc shape; and a second cutting tool for removing a portion of the edges of the first wafer and the second wafer, wherein the working surface of the second cutting tool is a plane, and the hardness of the first cutting tool is greater than the hardness of the second cutting tool.
[0012] In this embodiment of the application, the arc shape has an angle of 30° to 180°, and when the first tool processes the edge, the angle between the tool body and the surface of the second wafer is 20° to 60°.
[0013] In the embodiments of this application, the first cutting tool has a mesh size of 500 to 1000 mesh, and the second cutting tool has a mesh size of 1200 to 2000 mesh.
[0014] Compared with existing technologies, the wafer processing method and system of this application have the following beneficial effects: First, a first tool with higher hardness is used to remove the sharp edges of the wafer, and the areas where the tool wear is severe are ground into rounded corners. Then, a second tool with lower hardness is used to process the width and depth of the wafer. Using the first and second tools together to complete the second trimming can prevent damage to the tools during the second trimming, which can not only extend the tool's service life, but also solve the problem of wafer breakage caused by residual structures formed when trimming with damaged tools, which may detach completely in subsequent thinning processes. Attached Figure Description
[0015] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale. Wherein:
[0016] Figure 1 Photographs showing tool damage after continuous edge trimming of multiple wafers in existing processes;
[0017] Figure 2 Photographs of damaged wafers after continuous edge trimming of multiple wafers in existing processes;
[0018] Figures 3 to 6 This is a schematic diagram of the structural steps in the existing wafer processing method;
[0019] Figure 7 These are local optical microscope and SEM images of the bonding structure after the second trimming in the prior art.
[0020] Figure 8 This is a magnified view of the edge of the tool after the second trimming in the prior art;
[0021] Figure 9 This is a schematic flowchart of a wafer processing method according to an embodiment of this application;
[0022] Figures 10 to 12 This is a schematic diagram of the structure of each step of the wafer processing method according to an embodiment of this application. Detailed Implementation
[0023] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.
[0024] Current wafer packaging processes can lead to tool damage and wafer chipping issues when performing continuous edge trimming on multiple wafers. Figure 1 The image shows a photograph of the tool after it has been continuously trimmed across multiple wafers; the damage is located at the edge of the tool. Figure 2 This image shows a damaged photograph of the fifth wafer after continuous edge trimming; the damaged area is visible. Figure 2 The location indicated by the middle arrow. In light of current tool wear and wafer chipping issues, an in-depth study of existing wafer packaging processes was conducted. The study revealed that the tool is already worn during the trimming of the first wafer. As multiple wafers are continuously trimmed, the wear on the tool gradually increases, eventually leading to peeling. Continuing to use worn tools for wafer trimming will cause wafer chipping and even wafer breakage.
[0025] Furthermore, the factors causing tool damage in the current process will be investigated. (Reference) Figure 3First, the functional wafer 10 undergoes a first trimming process, removing some of the structure from the edges of the functional wafer 10. (Reference) Figure 4 The functional wafer 10 is then bonded to the carrier wafer 20. (Reference) Figure 5 The functional wafer is thinned by 10 to the target thickness. (Reference) Figure 6 A second edge trimming process is performed on the functional wafer 10 and the carrier wafer 20 to remove some of the edge structure of the functional wafer 10 and the carrier wafer 20. Combined with... Figure 7 The left image is a local optical microscope image after the second trimming, and the right image is a local SEM image at different magnifications after the second trimming. The optical microscope image shows black lines at the location of the second trimming, and the SEM image confirms that these black lines are protruding ridge structures 30.
[0026] refer to Figure 8 A magnified view of the tool after the second trimming revealed significant groove-shaped defects on its edge. Furthermore, the distance between the defect location and the tool edge was 0.3mm to 0.4mm, perfectly matching the location of the ridge structure formed after the second trimming. This indicates that the ridge structure formed during the second trimming is a residual structure caused by tool wear. Further investigation into the process between the first and second trimming stages is needed to determine the primary cause of tool wear.
[0027] Investigations revealed that tool wear is related to the shape of the functional wafer's edge after the first trimming. Because the functional wafer's edge has sharp corners after the first trimming, these sharp corners damage the tool during the second trimming, creating groove-shaped defects on the tool edge. When the same tool is used again to trim both the functional wafer and the carrier wafer a second time, these groove-shaped defects on the tool leave trimming residue at the corresponding location on the wafer. Figure 6 and Figure 7 The image shows an edge structure. In subsequent thinning processes, the remaining edge structure will detach in the form of large particles, thus damaging the wafer. During continuous edge trimming of multiple wafers, the tool cannot be changed frequently, so the same tool must be used continuously for trimming. As a result, the groove defects on the tool edge will gradually worsen, eventually leading to tool breakage, which in turn causes wafer edge chipping. At the same time, the detached particles can also cause wafer breakage, affecting yield.
[0028] Through the above in-depth analysis, the root cause of tool wear and wafer edge chipping was finally found. Based on the analysis results, this application improves the existing process and provides a wafer processing method. In the second trimming process, the method first uses a tool with higher hardness to smooth the edges of the wafer, and then uses a tool with lower hardness to complete the trimming task. This can ensure the trimming effect while preventing tool damage, extending tool life, and avoiding wafer breakage caused by large particles falling off during the thinning process.
[0029] refer to Figure 9 The wafer processing method of this application embodiment includes:
[0030] Step S1: Provide a first wafer and a second wafer bonded to the first wafer, wherein the edge of the second wafer includes a sharp corner formed after a first trimming;
[0031] Step S2: Perform a second edge trimming on the edges of the first wafer and the second wafer, wherein the second edge trimming includes:
[0032] Step S21: Remove the edge using a first tool, wherein the working surface of the first tool is a concave arc shape;
[0033] Step S22: Then, a second tool is used to remove part of the edge of the first wafer and the second wafer, wherein the working surface of the second tool is a plane, and the hardness of the first tool is greater than the hardness of the second tool.
[0034] refer to Figure 10The method provides a first wafer 100 and a second wafer 200 bonded to the first wafer 100. The method of bonding the first wafer 100 and the second wafer 200 includes: providing the second wafer 200, which may be a functional wafer, and forming a first dielectric layer (not shown) on the second wafer 200 for bonding, the material of the first dielectric layer including a nitride layer; performing a first edge trimming on the second wafer 200 to remove a portion of the edge of the second wafer 200, forming a sharp angle at the edge of the second wafer 200, typically a right angle of 90° or close to 90°, to prevent damage to the wafer during subsequent thinning processes; bonding the second wafer 200 to the first wafer 100, wherein the first wafer 100 may be a carrier wafer, and forming a second dielectric layer (not shown) on the first wafer 100 for bonding, the material of the second dielectric layer including silicon oxide; and thinning the second wafer 200 to a target thickness after the bonding operation is completed. Since the thinning process only reduces the thickness of the wafer, the edge 300 is still retained after the second wafer 100 is thinned.
[0035] Next, the edges of the first wafer 100 and the second wafer 200 are trimmed a second time.
[0036] refer to Figure 11 The first tool 400, which can be a grinding wheel, is used to remove the edge 300. The first tool 400 is made of abrasive and binder, wherein the abrasive has a large initial particle size, resulting in a high surface roughness. Due to the large particle size of the abrasive, the first tool 400 has high hardness and is less prone to damage when grinding the edge 300. The working surface of the first tool 400 is designed as a concave arc shape, which can grind the edge 300 into a rounded corner that is less likely to damage the tool. Ideally, the degree of the concave arc shape and the inclination of the tool body during operation should be matched to achieve the best grinding effect. In this embodiment of the application, the arc angle is 30° to 180°, and when processing the edge 300, the angle between the blade of the first tool 400 and the surface of the second wafer 200 is 20° to 60°, and the mesh size of the first tool 400 is 500 mesh to 1000 mesh.
[0037] refer to Figure 12After the first tool 400 processes the edge 300, a second tool 500 removes part of the edges of the first wafer 100 and the second wafer 200, completing the second trimming. Since the edge of the second wafer 200 no longer has sharp edges, the hardness of the second tool 500 can be slightly lower than that of the first tool 400. The material used to make the second tool 500 may include an abrasive with a second particle size and a binder, and the second particle size is smaller than the first particle size, so the second tool 500 has a smaller roughness, and the mesh size can be 1200-2000 mesh. The working surface of the second tool 500 is flat, and the tool body can be perpendicular to the surfaces of the first wafer 100 and the second wafer 200 during trimming. The second tool 500 can be a grinding wheel.
[0038] The second trimming region extends inward from the edges of the first wafer 100 and the second wafer 200 by a specific width, and extends inward from the surface of the second wafer 200 into the first wafer 100 by a specific thickness. In some embodiments, the specific width of the second trimming region extending inward from the edge of the first wafer 100 can be 0.5 mm to 5 mm, and the specific depth in the first wafer 100 can be 20 μm to 300 μm.
[0039] Although the first tool 400 has a relatively high surface roughness, resulting in a rough rounded corner surface after grinding, this rough surface can be removed by subsequent edge trimming with the second tool 500, which has a lower surface roughness. Therefore, adding an edge trimming step with the first tool 400 will not adversely affect the wafer quality. Furthermore, the second tool 500 can be activated as soon as the area processed by the first tool 400 reaches its position, without waiting for the first tool 400 to finish its work. Therefore, adding an edge trimming step with the first tool 400 will not affect the machine's throughput.
[0040] This application also provides a wafer processing system for trimming the edges of a first wafer and a second wafer bonded to the first wafer. The first wafer can be a carrier wafer, and the second wafer can be a functional wafer. The edges of the second wafer include sharp corners formed after a first trimming. The wafer processing system may include a wafer stage, a first cutting tool, and a second cutting tool. The wafer stage is used to support the first and second wafers. The first cutting tool is used to remove the sharp corners of the second wafer's edges. The working surface of the first cutting tool is a concave arc shape, which can transform the sharp corners into rounded corners that are less likely to damage the tool. The first cutting tool also has a high hardness. The second cutting tool is used to remove a portion of the edges of the first and second wafers, and the working surface of the second cutting tool is a plane. The hardness of the second cutting tool is less than that of the first cutting tool. The first and second cutting tools can be grinding wheels.
[0041] In some embodiments, the arc angle is 30° to 180°, and when the first tool processes the edge, the angle between the tool body and the horizontal plane is 20° to 60°. In some embodiments, the mesh size of the first tool is 500 to 1000 mesh, and the mesh size of the second tool is 1200 to 2000 mesh.
[0042] In summary, this application conducts an in-depth investigation into the root causes of tool wear and wafer edge chipping. Based on the findings, it improves the trimming process by using a first tool with higher hardness to grind heavily worn edges, transforming them into rounded corners. A second tool with lower hardness then completes the width and depth trimming. This two-tool approach, using two different tools together in the second trimming process, ensures effective trimming while extending tool life. It also prevents wafer breakage caused by trimming residue from damaged tools detaching during the thinning process. Furthermore, the second tool can be activated as soon as the area treated by the first tool reaches its position, eliminating the need to wait for the first tool to finish. Therefore, the wafer processing system of this application can solve the problems of tool peeling and wafer edge chipping without affecting machine throughput, thereby significantly improving wafer yield.
[0043] After reading this application, those skilled in the art will understand that the foregoing content is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. Such changes, improvements, and modifications are all within the spirit and scope of the exemplary embodiments of this application.
[0044] It should be understood that the term "and / or" as used in this embodiment includes any or all combinations of one or more of the associated listed items. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element.
[0045] Similarly, it should be understood that when an element such as a layer, region, or substrate is referred to as being "on" another element, it may be directly on that other element, or there may be intermediate elements present. Conversely, the term "directly" means without intermediate elements. It should also be understood that the terms "comprising," "including," "including," or "comprises," as used in this application, indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.
[0046] It should also be understood that although the terms first, second, third, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, without departing from the teachings of this application, a first element in some embodiments may be referred to as a second element in other embodiments. The same reference numerals or the same reference signs denote the same elements throughout the specification.
[0047] Furthermore, this application specification describes exemplary embodiments by referring to idealized exemplary cross-sectional views and / or plan views and / or perspective views. Therefore, differences from the illustrated shapes are foreseeable due to factors such as manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but should include deviations in shape caused, for example, by manufacturing processes. For instance, etched areas shown as rectangular typically have circular or curved features. Therefore, the regions shown in the figures are substantially schematic, and their shapes are not intended to illustrate the actual shape of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.
Claims
1. A wafer processing method, characterized in that, include: A first wafer and a second wafer bonded to the first wafer are provided, wherein the edge of the second wafer includes a sharp corner formed after a first trimming, the sharp corner being away from the bonding surface between the first wafer and the second wafer; The edges of the first wafer and the second wafer are trimmed a second time, wherein the second trimming includes: The first tool is used to remove the edges, wherein the working surface of the first tool is a concave arc shape; Then, a second tool is used to remove part of the edges of the first wafer and the second wafer, wherein the working surface of the second tool is a plane, and the hardness of the first tool is greater than that of the second tool.
2. The wafer processing method according to claim 1, characterized in that, The arc shape has an angle of 30° to 180°, and when the first tool processes the edge, the angle between the tool body and the surface of the second wafer is 20° to 60°.
3. The wafer processing method according to claim 1, characterized in that, The first cutting tool has a mesh size of 500 to 1000, and the second cutting tool has a mesh size of 1200 to 2000.
4. The wafer processing method according to claim 1, characterized in that, The material of the first cutting tool includes abrasive with a first particle size, and the material of the second cutting tool includes abrasive with a second particle size, wherein the first particle size is larger than the second particle size.
5. The wafer processing method according to claim 1, characterized in that, The method for bonding the first wafer and the second wafer includes: Provide a second wafer; The first trimming is performed to remove part of the edge of the second wafer, forming sharp edges on the edge of the second wafer; The second wafer is bonded to the first wafer, and the second wafer is thinned to the target thickness.
6. The wafer processing method according to claim 1, characterized in that, When the area processed by the first cutter reaches the position of the second cutter, the second cutter begins to work.
7. A wafer processing system for trimming the edges of a first wafer and a second wafer bonded to the first wafer, wherein the edges of the second wafer include sharp corners formed after a first trimming, characterized in that... include: A wafer stage for supporting the first wafer and the second wafer; A first cutting tool is used to remove the edge, which is far away from the bonding surface between the first wafer and the second wafer, and the working surface of the first cutting tool is a concave arc shape. A second cutting tool is used to remove a portion of the edges of the first and second wafers, wherein the working surface of the second cutting tool is a plane, and the hardness of the first cutting tool is greater than that of the second cutting tool.
8. The wafer processing system according to claim 7, characterized in that, The arc shape has an angle of 30° to 180°, and when the first tool processes the edge, the angle between the tool body and the surface of the second wafer is 20° to 60°.
9. The wafer processing system according to claim 7, characterized in that, The first cutting tool has a mesh size of 500 to 1000, and the second cutting tool has a mesh size of 1200 to 2000.
10. The wafer processing system according to claim 7, characterized in that, The first and second cutting tools are grinding wheel cutters.
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