Chamfer processing process for ameliorating roughness of chamfered surface of silicon wafer

Abstract

A chamfer processing process for ameliorating the roughness of a chamfered surface of a silicon wafer. The chamfer processing process comprises the following steps: a rough chamfer processing step involving fixing a silicon wafer on a chamfer grinding table, and the grinding table driving the silicon wafer toward a groove of a rough grinding wheel to undergo rough chamfer processing; and a fine chamfer processing step involving after the completion of the rough chamfer processing, moving the grinding platform to align same with a groove of a fine grinding wheel to perform fine chamfer processing, with the feed rate of the fine grinding wheel being 50-150 um / r and the rotation speed of the silicon wafer being 4-20 mm / s, wherein during the rough chamfer processing and the fine chamfer processing, the rotation speeds of grinding wheels are 3000-6000 r / min.

Description

Improved chamfering process for silicon wafers to reduce surface roughness Technical Field

[0001] This invention relates to the field of wafer fabrication technology, and more specifically, to a chamfering process for improving the roughness of the chamfered surface of silicon wafers. Background Technology

[0002] In the wafer fabrication industry, wafer chamfering is an indispensable step. The main purpose of wafer chamfering is to use a high-speed grinding wheel to grind and shape the edges of the silicon wafer into a specific shape, eliminating edge cutting stress caused by slicing, preventing edge breakage during subsequent processing, resulting in smooth wafer edges, and reducing other defects on the silicon wafer surface caused by the edges during silicon wafer epitaxy. With the improvement of domestic semiconductor processing technology and more efficient utilization of wafer dimensions, the impact of the chamfered area on the edges is becoming increasingly apparent. Therefore, solving the problem of rough chamfered surfaces is a crucial aspect of progress in the semiconductor industry.

[0003] Currently, domestic semiconductor wafer manufacturers generally use Tokyo Seimitsu equipment for wafer chamfering, employing grinding wheels to refine the chamfered edges. With the development of semiconductors, the requirements for chamfered surfaces are becoming increasingly stringent, and the roughness of the chamfered surface is receiving more and more attention from customers. Edge polishing can achieve a relatively perfect chamfered surface, but this significantly increases costs. Therefore, improving the roughness of the chamfered surface has become a challenge for many semiconductor wafer manufacturers.

[0004] Summary of the Invention

[0005] In view of the deficiencies in the prior art, the purpose of this invention is to provide a chamfering process that improves the roughness of the chamfered surface of silicon wafers.

[0006] The chamfering process for improving the roughness of the chamfered surface of a silicon wafer according to the present invention includes the following steps:

[0007] Rough chamfering process: Fix the silicon wafer on the chamfering grinding table. The grinding table moves the silicon wafer close to the groove of the rough grinding wheel to perform rough chamfering. The feed rate of the rough grinding wheel is 100-1000 mm / r.

[0008] Fine chamfering process: After the rough chamfering is completed, the grinding table is moved to align with the groove of the fine grinding wheel for fine chamfering. The feed rate of the fine grinding wheel is 50-150um / r, and the silicon wafer rotation speed is 4-20mm / s.

[0009] During both rough and fine chamfering processes, the grinding wheel speed is 3000-6000 r / min.

[0010] Preferably, the process further includes a preparatory step, which is performed before the rough chamfering step, and specifically includes the following steps:

[0011] Step 1: Load the silicon wafer to be beveled into the wafer cassette and place the wafer cassette in the loading area of ​​the beveling machine.

[0012] Step 2: The robotic arm takes the silicon wafer from the wafer cassette and places it on the machine's orientation calibration platform;

[0013] Step 3: The orientation calibration stage rotates and calibrates the silicon wafer to the corresponding position;

[0014] Step 4: The robotic arm picks up the calibrated silicon wafer from the orientation calibration table and places it on the grinding table.

[0015] Preferably, the process further includes a cleaning step, which is performed after the fine chamfering step, and specifically includes the following steps;

[0016] After the fine chamfering process is completed, the robotic arm picks up the silicon wafer and moves it to the cleaning table, where it is rinsed with pure water and dried with air.

[0017] Preferably, the process further includes a feeding step, which is performed after the cleaning step and specifically includes the following steps;

[0018] After cleaning, the robotic arm picks up the silicon wafers and moves them to the chamfering machine's unloading area, where the chamfered wafers are placed into the receiving wafer box.

[0019] Preferably, during the rough chamfering and fine chamfering processes, cooling water is sprayed onto the chamfered area and the grinding wheel groove at a flow rate of 2-4 L / min.

[0020] Preferably, in the rough chamfering step, the rough grinding wheel has a mesh size of 800.

[0021] Preferably, in the fine chamfering step, the fine grinding wheel has a mesh size of 3000.

[0022] Preferably, during the rough chamfering and fine chamfering processes, the vibration of each running axis of the chamfering grinding table is less than 5µm, the vibration of the grinding table surface is less than 10µm, the vibration of the grinding wheel axis is less than 5µm, and the vibration of the grinding wheel surface is less than 10µm.

[0023] Preferably, the silicon wafer rotation speed is designed based on the amount of silicon powder removed during the fine chamfering process.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention improves the chamfering process by optimizing the coordination between the chamfering feed rate and the grinding wheel rotation speed. By controlling the silicon wafer rotation speed, the amount of silicon powder ground by the grinding wheel per unit time is controlled, reducing damage to the wafer edge during the chamfering process and achieving a better wafer chamfer surface. Attached Figure Description

[0026] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1 is a schematic diagram of the process flow of the present invention;

[0028] Figure 2 is a physical image of the beveled plane of the silicon wafer obtained in Embodiment 1 of the present invention;

[0029] Figure 3 is a physical image of the beveled plane of the silicon wafer obtained as a comparative example of the present invention. Detailed Implementation

[0030] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0031] This invention discloses a chamfering process to improve the roughness of the chamfered surface of silicon wafers. The key point is to improve the chamfering process by optimizing the coordination between the chamfering feed rate and the grinding wheel rotation speed, and by controlling the amount of silicon powder ground by the grinding wheel per unit time, thereby reducing the damage to the wafer edge during the chamfering process, resulting in a better wafer chamfered surface.

[0032] The chamfering process for improving the roughness of silicon wafer chamfer surfaces according to the present invention specifically includes the following steps:

[0033] Step 1: Load the wafer to be beveled into a specific wafer box and place it in the beveling machine's loading area.

[0034] Step 2: The robotic arm takes the silicon wafer from the wafer box and places it on the machine's orientation calibration platform.

[0035] Step 3: The orientation calibration stage rotates and calibrates the silicon wafer to the corresponding position.

[0036] Step 4: The robotic arm picks up the calibrated silicon wafer from the calibration table and places it on the grinding table.

[0037] Step 5: The vacuum of the grinding table is turned on to fix the silicon wafer on the grinding table. The grinding table moves the silicon wafer slowly closer to the high-speed rotating grinding wheel to rough grind the groove (set the target diameter of the wafer according to the required feed rate).

[0038] Step 6: The machine starts rough chamfering according to the set parameters (the grinding table drives the silicon wafer to rotate, and the high-speed grinding wheel is used to round off the edges of the silicon wafer).

[0039] Step 7: After the rough chamfering is completed, the grinding table moves to align with the fine grinding groove of the grinding wheel, and the fine chamfering begins according to the set parameters of the machine.

[0040] Step 8: After the fine chamfering is completed, the vacuum of the grinding table is released, the robot arm picks up the silicon wafer and moves it to the cleaning table, where it is rinsed with pure water and dried with air.

[0041] Step 9: After cleaning, the robotic arm picks up the silicon wafer and moves it to the chamfering machine's unloading area, placing the chamfered silicon wafer into the receiving wafer box.

[0042] Preferably, during the fine chamfering process, the chamfering speed is controlled. If the chamfering process is too fast, it will increase the damage to the silicon wafer. If it is too slow, it will not only delay the efficiency, but also result in chamfering marks. The silicon wafer rotation speed is optimized to 4-20 mm / s during the chamfering process. The chamfering speed is designed according to the amount of silicon powder removed during the chamfering process.

[0043] During the chamfering process, the machining accuracy of the machine tool is controlled so that the vibration of each running axis of the chamfering grinding table is less than 5µm, the vibration of the grinding table surface is less than 10µm, the vibration of the grinding wheel axis is less than 5µm, and the vibration of the grinding wheel surface is less than 10µm.

[0044] The chamfering grinding wheel is designed with an 800-mesh roughing wheel and a 3000-mesh finishing wheel. The grinding wheel speed is 3000-6000 r / min. The feed rate of the roughing wheel is 100-1000 mm per pass, and the feed rate of the finishing wheel is 50-150 μm per pass.

[0045] Cooling water is sprayed during both rough and fine chamfering processes. The cooling water is divided into chamfering cooling water and grinding wheel groove rinsing cooling water, with a water flow rate of 2-4 L / min.

[0046] Example 1

[0047] This embodiment provides specific parameter selection for a chamfering process to improve the roughness of the silicon wafer chamfer surface. Specifically, experiments show that approximately 2.5 mm of silicon powder is removed during the finishing process. 3 At a speed of / s, a better wafer chamfer surface can be obtained. In this embodiment, the feed rate of the grinding wheel and the rotation speed of the silicon wafer are carefully managed to ensure that the amount of silicon powder removed is as close as possible to 2.5mm. 3 / s, thus obtaining a chamfered surface with lower roughness.

[0048] The specific parameter selections are shown in the table below:

[0049] Table 1: Parameter Selection Table

[0050] Table 1 discloses the processing technology for different chamfer types. In the chamfer type, R indicates that the chamfer is an R-type chamfer, H indicates that the chamfer has an included angle of 11°, G indicates that the chamfer has an included angle of 22°, K indicates that the grinding wheel grit is greater than 1500 mesh, and the number in parentheses indicates the radius of the chamfer's front end circle, in mm.

[0051] By selecting the above parameter range, a chamfer surface with a roughness Ra of 5-10um can be obtained. Using the silicon wafer rotation speed in the "preferred" column can achieve a faster processing speed while ensuring a better chamfer surface, resulting in the best overall performance. Furthermore, by setting a comparative example, the effect of the solution in this embodiment can be demonstrated. Specifically, when processing different chamfer types, if a silicon wafer rotation speed greater than 20mm / s is selected, the roughness range of the chamfer surface obtained is 15-25um. If a silicon wafer rotation speed less than 4mm / s is selected, the slow rotation speed will delay production capacity, resulting in low efficiency and other defects such as chamfer lines.

[0052] Therefore, it can be seen from the above comparison that a better chamfered surface can be obtained when the silicon wafer rotation speed is limited to 4-20 mm / s.

[0053] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They 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. Therefore, they should not be construed as limitations on this application.

[0054] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A chamfering process for improving the roughness of a chamfered surface of a silicon wafer, characterized by, The method comprises the following steps: A rough chamfering processing step: fixing the silicon wafer on a chamfering grinding table, the grinding table drives the silicon wafer to approach a rough grinding wheel groove, and rough chamfering processing is performed, the feeding amount of the rough grinding wheel is 100-1000mm / r; A fine chamfering processing step: after the rough chamfering processing is completed, the grinding table is moved to align with a fine grinding wheel groove, and fine chamfering processing is performed, the feeding amount of the fine grinding wheel is 50-150um / r, and the silicon wafer rotating speed is 4-20mm / s; During the rough chamfering processing and the fine chamfering processing, the rotating speed of the grinding wheel is 3000-6000r / min.

2. The beveling process for improving the roughness of a bevel surface of a silicon wafer according to claim 1, wherein The method further comprises a pre-preparation step, which is performed before the rough chamfering processing step, and specifically comprises the following steps: Step 1: loading the silicon wafer to be chamfered into a wafer box, and placing the wafer box on a loading area of a chamfering machine table; Step 2: taking the silicon wafer from the wafer box by a mechanical hand, and placing the silicon wafer on a position calibration table of the machine table; Step 3: rotating and calibrating the silicon wafer to a corresponding position by the position calibration table; Step 4: taking the calibrated silicon wafer from the position calibration table by the mechanical hand, and placing the silicon wafer on a grinding table.

3. The beveling process for improving the roughness of a bevel surface of a silicon wafer according to claim 1, wherein The method further comprises a cleaning step, which is performed after the fine chamfering processing step, and specifically comprises the following steps: After the fine chamfering processing is completed, the silicon wafer is taken by the mechanical hand and moved to a cleaning table, and the silicon wafer is cleaned by pure water and dried by air.

4. The beveling process for improving the roughness of a bevel surface of a silicon wafer according to claim 3, wherein The method further comprises a discharging step, which is performed after the cleaning step, and specifically comprises the following steps: After the cleaning is completed, the silicon wafer is taken by the mechanical hand and moved to a discharging area of the chamfering machine table, and the silicon wafer is placed into a receiving wafer box.

5. The beveling process for improving the roughness of a bevel surface of a silicon wafer according to claim 1, wherein During the rough chamfering processing and the fine chamfering processing, cooling water is sprayed to the chamfering processing position and the grinding wheel groove, and the water flow is 2-4L / min.

6. The beveling process for improving the roughness of a bevel surface of a silicon wafer according to claim 1, wherein During the rough chamfering processing step, the mesh number of the rough grinding wheel is 800.

7. The beveling process for improving the roughness of a bevel surface of a silicon wafer according to claim 1, wherein During the fine chamfering processing step, the mesh number of the fine grinding wheel is 3000.

8. The beveling process for improving the roughness of a bevel surface of a silicon wafer according to claim 1, wherein During the rough chamfering processing and the fine chamfering processing, the vibration of each running shaft of the chamfering grinding table is less than 5um, the vibration of the grinding table surface is less than 10um, the vibration of the grinding wheel shaft is less than 5um, and the vibration of the grinding wheel surface is less than 10um.

9. The beveling process for improving the roughness of a bevel surface of a silicon wafer according to claim 1, wherein The rotating speed of the silicon wafer is designed according to the amount of silicon powder removed during the fine chamfering processing.

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