Germanium wafer chamfering method based on diameter optimization and double-grinding-wheel step-by-step grinding

Abstract

The invention discloses a germanium wafer chamfering method based on diameter optimization and double-grinding-wheel step-by-step grinding, and belongs to the technical field of semiconductor material machining. The method comprises the steps that in the slicing process, the diameter of a incoming germanium wafer is machined to be 1200-1300 microns larger than the diameter of a preset finished product, and sufficient chamfering machining allowance is provided; then, a step-by-step chamfering process is adopted, firstly, a metal bond grinding wheel with the abrasive particle size of 1000 meshes to 1500 meshes is used, and under the rotating speed of 2000 rpm to 4000 rpm and the feeding speed of 8 microns / s to 10 microns / s, rough chamfering machining is conducted for 3 times to 4 times at the single-time feeding amount of 300 microns to 400 microns, and then rough chamfering machining is conducted for 3 times to 4 times at the rotating speed of 2000 rpm to 4000 rpm and the feeding speed of 8 microns / s to 10 microns; and then switching to a resin binder grinding wheel with the abrasive particle size of 2000 meshes to 4000 meshes, and performing fine chamfering processing for 3 to 5 times at the rotating speed of 3000 rpm to 3500 rpm and the feeding speed of 5 mu m / s to 6 mu m / s at the single feeding amount of 10 mu m to 50 mu m. The problems that in a traditional method, the chamfering amount is insufficient, the machining efficiency and the surface quality cannot be considered at the same time, and the adaptability to large-diameter germanium wafers is poor are solved, and the comprehensive qualification rate of the wafers is increased.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material processing technology, specifically relating to a method for chamfering germanium wafers based on diameter optimization and step-by-step grinding with dual grinding wheels. Background Technology

[0002] Germanium wafers, as a crucial semiconductor material, develop mechanical damage layers, microcracks, and residual stress at their edges after initial forming processes such as cutting and grinding. These edge defects, reaching depths of tens of micrometers, are highly susceptible to propagation during subsequent high-temperature processes, leading to slip lines, dislocation multiplication, and even wafer breakage. Therefore, the quality of edge processing directly impacts the yield rate of subsequent epitaxial growth and device manufacturing.

[0003] Chamfering (or edge grinding) is a key process for eliminating the aforementioned edge defects. Currently, the industry commonly uses a single grinding wheel (usually a resin-bonded diamond wheel) for one-step chamfering of germanium wafers, which has the following problems: First, the chamfer removal amount is usually conservatively designed within the range of 1000μm to 1100μm, which cannot completely remove the edge damage layer caused by cutting and rolling; second, a single grinding wheel is difficult to balance processing efficiency and surface quality requirements; and third, it has poor adaptability to large-diameter wafers (such as 4-inch wafers), and the problem of edge stress concentration is prominent.

[0004] Therefore, developing a chamfering method that can achieve high removal volume, high efficiency, low damage, and is applicable to large-diameter germanium wafers is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a germanium wafer chamfering method based on diameter optimization and dual-wheel step-by-step grinding. By coordinating diameter design in the front-end slicing process and coarse and fine step-by-step grinding in the back-end chamfering process, it achieves thorough and efficient removal of edge damage layers and high-quality surface forming of large-diameter germanium wafers.

[0006] The present invention provides a method for chamfering germanium wafers based on diameter optimization and dual-wheel step-by-step grinding, comprising the following steps:

[0007] S1. Diameter Optimization Preparation: In the slicing process, the diameter of the incoming germanium wafer is processed to be 1200μm to 1300μm larger than the preset finished product diameter;

[0008] S2. Rough chamfering: The edge of the germanium wafer obtained in S1 is ground using a metal-bonded grinding wheel; the abrasive grit size of the metal-bonded grinding wheel is 1000-1500 mesh, the grinding wheel speed during processing is 2000-4000 rpm, the feed rate is 8-10 μm / s, the single feed depth is 300-400 μm, and the total number of feeds is 3-4.

[0009] S3. Fine chamfering: The edge of the germanium wafer processed in S2 is ground using a resin-bonded grinding wheel; the abrasive grit of the resin-bonded grinding wheel is 2000-4000 mesh, the grinding wheel speed is 2000-4000 rpm, the feed speed is 5-6 μm / s, the single feed depth is 10-50 μm, and the total number of feeds is 3-5.

[0010] The metal-bonded grinding wheel in S2 rotates at 2500 rpm.

[0011] The resin-bonded grinding wheel in S3 rotates at 3000 rpm.

[0012] The beneficial effects of this invention are:

[0013] Compared with existing technologies, this invention achieves efficient removal of edge damage layers and high-quality surface forming of germanium wafers by increasing the wafer diameter during the slicing process to allow sufficient machining allowance, and combining a step-by-step process of coarse chamfering and fine chamfering. This method utilizes the high material removal rate of a metal-bonded grinding wheel under a strategy of large cutting depth and few passes to quickly remove deep damage introduced by slicing and tumbling, forming a precise basic chamfer contour. Then, the dressing action of a resin-bonded grinding wheel under fine parameters effectively eliminates micro-cracks generated by coarse grinding and improves surface finish. Overall, this improves the edge integrity of the wafer and reduces the risk of slip line initiation and propagation in subsequent processes. Simultaneously, it can adapt to the requirements of large-size germanium wafers for chamfering amount and stress distribution, solving the problem of edge stress concentration and chipping caused by insufficient allowance in traditional processes, and improving the overall wafer yield. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments are briefly introduced below.

[0015] Figure 1 This is a process flow diagram of an embodiment of the present invention. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] Example 1

[0018] This embodiment uses a 4-inch germanium wafer with a finished diameter of 100.00 mm as an example. See also... Figure 1 As shown, the processing method of the present invention is carried out in the following steps:

[0019] 1. Diameter optimization preparation: In the slicing process, the diameter of the incoming germanium wafer is processed to be 1300μm larger than the preset finished product diameter, that is, the diameter of the blank germanium wafer is 101.30mm;

[0020] 2. Wafer loading: The blank germanium wafer is adsorbed onto the chuck of the processing machine tool;

[0021] 3. Rough chamfering: Start the metal-bonded grinding wheel, with an abrasive grit size of 1500 mesh, a grinding wheel speed of 2500 rpm, a feed rate of 10 μm / sec, a single feed depth of 390 μm, and 3 feeds for rough grinding;

[0022] 4. Fine chamfering: Switch to a resin-bonded grinding wheel with a grit size of 2000 mesh, a wheel speed of 3000 rpm, a feed rate of 5 μm / sec, a single feed depth of 50 μm, and 3 feeds for fine finishing.

[0023] 5. Wafer removal: After chamfering, the wafers are cleaned, dried, and then subjected to quality inspection.

[0024] Comparative Example 1

[0025] As a comparative example, 218 germanium wafers of the same specification were processed using a traditional single resin grinding wheel (2000 mesh) one-time chamfering process, with a margin of approximately 1100 μm.

[0026] The detection results of germanium wafers in Example 1 and Comparative Example 1 are shown in Table 1 below.

[0027] Table 1

[0028] Number of processed pieces Highlights Highlights percentage Edge breakage Percentage of edge collapse Overall pass rate Example 1 394 0 0% 1 0.25% 91.6% Comparative Example 1 218 30 13.76% 2 0.91% 86.7%

[0029] The results show that the method in Example 1 is effective in eliminating edge bright spots and reducing edge chipping, thereby significantly improving the chamfering pass rate of germanium wafers.

[0030] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not describe all details exhaustively, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification.

Claims

1. A method for chamfering germanium wafers based on diameter optimization and step-by-step grinding with dual grinding wheels, characterized in that, Includes the following steps: S1. Diameter Optimization Preparation: In the slicing process, the diameter of the incoming germanium wafer is processed to be 1200μm to 1300μm larger than the preset finished product diameter; S2. Rough chamfering: The edge of the germanium wafer obtained in S1 is ground using a metal-bonded grinding wheel; the abrasive grit size of the metal-bonded grinding wheel is 1000-1500 mesh, the grinding wheel speed during processing is 2000-4000 rpm, the feed rate is 8-10 μm / s, the single feed depth is 300-400 μm, and the total number of feeds is 3-4. S3. Fine chamfering: The edge of the germanium wafer processed in S2 is ground using a resin-bonded grinding wheel; the abrasive grit of the resin-bonded grinding wheel is 2000-4000 mesh, the grinding wheel speed is 2000-4000 rpm, the feed speed is 5-6 μm / s, the single feed depth is 10-50 μm, and the total number of feeds is 3-5.

2. The germanium wafer chamfering method based on diameter optimization and dual-wheel step-by-step grinding according to claim 1, characterized in that, The metal-bonded grinding wheel in S2 rotates at 2500 rpm.

3. The germanium wafer chamfering method based on diameter optimization and dual-wheel step-by-step grinding according to claim 1, characterized in that, The resin-bonded grinding wheel in S3 rotates at 3000 rpm.

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