Quartz jig for silicon ring processing and application thereof

Abstract

A quartz jig for machining silicon rings and its application, comprising: a disc-shaped body; the material of the disc-shaped body includes fused silica with a SiO2 mass content ≥99.9%; a central through hole is provided at the axis of the disc-shaped body; the radially inner region of the disc-shaped body includes an inner annular support surface; the radially outer region of the disc-shaped body includes an outer mounting flange surface; the outer mounting flange surface and the inner annular support surface are coaxially arranged, and the upper and lower openings of the mounting holes on the outer mounting flange surface are countersunk structures, and the edges of the mounting holes are provided with arc transition structures; the central through hole, the stepped edges of the inner annular support surface, and the chamfer positions of the outer mounting flange surface are all provided with arc chamfers. By using fused silica material and combining it with the low-stress structure of the disc-shaped body, the two work together to enable the quartz jig to achieve high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation during the machining of silicon rings in an integrated manner.

Description

Technical Field

[0001] This application belongs to the field of semiconductor precision machining technology, specifically relating to a quartz jig for silicon ring machining and its application. Background Technology

[0002] In the field of precision machining, for workpieces with thin-walled structures and high precision requirements (such as plasma confinement rings in semiconductor equipment), the machining accuracy will affect the product performance and yield. Traditional mechanical clamping methods are prone to workpiece deformation, affecting machining accuracy. The commonly used wax bonding process in industry involves coating a wax layer on the tooling reference surface to bond the workpiece to the tooling, machining the workpiece and tooling as a whole, and then heating to melt the wax layer after machining to remove the workpiece, thereby eliminating clamping deformation. Currently, most tooling is metal tooling, which has the following problems in practical applications: 1. Thermal deformation affects dewaxing accuracy: During the final heating and dewaxing, the metal tooling expands due to heat (high coefficient of thermal expansion), while the workpiece has already been machined to its final dimensions. Deformation of the tooling can cause compressive stress on the wax layer, or the workpiece placement surface may be uneven due to changes in tooling dimensions when removing the workpiece, and may even damage the inner wall of the workpiece. 2. Long-term use leads to precision degradation: Repeated hot and cold cycles (heating during waxing, cooling and curing, room temperature during processing, and reheating during dewaxing) gradually release residual stress within the metal tooling, causing a gradual loss of flatness in the tooling's reference surface. Once the reference surface is deformed, the parallelism and thickness dimensions of products bonded to it by the wax layer will inevitably be unstable after processing. 3. Thermal stress safety hazards: During rapid heating and dewaxing, if the metal tooling experiences uneven local thermal expansion, and the expansion coefficients do not match those of the cured wax layer or the workpiece material, internal stress will be generated. This may sometimes produce noise or even micro-cracks, posing a safety hazard to the product (especially products made of hard and brittle materials). 4. Surface damage risk: After long-term use, the surface of the metal tooling may wear or develop burrs, which may scratch the surface of the already processed high-precision product during bonding and dewaxing.

[0003] Therefore, it is necessary to develop a quartz fixture for silicon ring processing, so that the fixture can achieve high-precision processing, low workpiece deformation, no surface scratches, and no stress accumulation while processing the workpiece, thereby ensuring stable product quality, reducing processing costs, and improving the safety of the processing process. Summary of the Invention

[0004] This application provides a quartz fixture for machining silicon rings. By using fused quartz material and combining it with a low-stress structure of a disc-shaped body, the two work together to enable the quartz fixture to achieve high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation during the machining of silicon rings in an integrated manner. This ensures stable product quality, reduces processing costs, extends tooling life, and improves the safety of the machining process.

[0005] In a first aspect, this application provides a quartz jig for processing silicon rings, comprising: a disk-shaped body; The material of the disc-shaped body includes fused silica with a SiO2 mass content ≥ 99.9%; The disc-shaped main body has a central through hole at its axis; the central through hole is used for the positioning and avoidance of the axis system of the disc-shaped main body; The radially inner region of the disc-shaped body includes an inner annular support surface, which is used to bond and position the silicone ring with a wax layer; the flatness of the inner annular support surface is ≤0.005mm. The radially outer region of the disc-shaped main body includes an outer mounting flange surface; the outer mounting flange surface is used for mounting and fixing the disc-shaped main body; the outer mounting flange surface and the inner annular support surface are coaxially arranged; the inner annular support surface protrudes axially from the outer mounting flange surface, forming a stepped structure between them; the outer mounting flange surface includes a mounting hole, the upper and lower openings of the mounting hole are countersunk structures, and the edge of the mounting hole opening is provided with an arc transition structure; The central through hole, the stepped edge of the inner annular support surface, and the chamfered position of the outer mounting flange surface are all provided with rounded chamfers, and the radius of the rounded chamfers R≥2mm; The quartz fixture has a centrally symmetrical structure and is used for grinding and dewaxing silicon rings.

[0006] This application utilizes a quartz jig constructed by combining fused silica material with a disc-shaped main structure. The quartz material has a near-zero coefficient of thermal expansion, which reduces jig deformation during subsequent heating and dewaxing, thereby improving the thickness and parallelism consistency of the silicon ring product. Furthermore, the high hardness of the quartz material makes it resistant to high temperatures and wear, preventing scratches on the workpiece surface. Simultaneously, the rounded chamfers in the inner annular support surface and the mounting holes and rounded chamfers in the outer mounting flange surface reduce stress concentration, overcoming the inherent brittleness of quartz material and its tendency to break. The centrally symmetrical structure of the quartz jig also ensures uniform heating and prevents twisting deformation. Through the combination of fused silica material and the disc-shaped main structure, the quartz jig achieves high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation when processing silicon rings, thus ensuring stable product quality, reducing processing costs, extending tooling life, and improving process safety.

[0007] In this application, fused silica is an amorphous glass formed by rapidly cooling high-purity silicon dioxide after melting. Specifically, the mass content of SiO2 in the fused silica is ≥99.9%.

[0008] In this application, the flatness of the inner annular support surface can be tested using a dial indicator for comparative measurement.

[0009] In this application, the chamfer position of the outer mounting flange surface refers to the location at the radial maximum outer diameter of the quartz fixture.

[0010] In some embodiments, the inner annular support surface is provided with a plurality of threaded holes spaced at equal angles along the same circumference, the number of which is 4 to 8. In this application, a threaded hole refers to a hole with internal threads machined on a part, used for connection and fixation with externally threaded components such as bolts and studs. When the inner annular support surface meets this condition, stress concentration can be reduced, preventing quartz material from breaking. This allows for high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation during the machining of silicon rings using quartz fixtures, thereby ensuring stable product quality, reducing processing costs, extending tooling life, and improving the safety of the machining process.

[0011] In some embodiments, the radius R of the chamfer is ≥ 5 mm. When the radius of the chamfer meets this range, stress concentration can be further reduced, quartz material breakage can be avoided, and high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation can be achieved when machining silicon rings with quartz fixtures. This ensures stable product quality, reduces processing costs, extends tooling life, and improves the safety of the processing.

[0012] In some embodiments, the back of the outer mounting flange surface is provided with at least one annular reinforcing rib concentric with the outer mounting flange surface. When the outer mounting flange surface meets this condition, stress concentration can be reduced, preventing quartz material from breaking. This enables high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation when machining silicon rings with quartz fixtures, thereby ensuring stable product quality, reducing processing costs, extending tooling life, and improving the safety of the machining process.

[0013] In some embodiments, the annular reinforcing rib is located inside the outer mounting flange surface; the inner edge of the annular reinforcing rib and the outer edge of the silicon ring are projected onto the axial direction of the disc-shaped body. When the silicon ring workpiece meets the above conditions during machining, the load acting on the support surface can be transferred to the annular reinforcing rib on the back of the outer mounting flange surface. Relying on the circumferential force transmission characteristics of the closed annular rib, the local concentrated compressive stress is dispersed, preventing the support surface from denting or warping deformation, keeping the reference flatness of the support surface stable, and preventing the workpiece from undergoing extrusion deformation due to local deformation of the tooling. This effectively ensures the machining dimensions and accuracy, thereby guaranteeing stable product quality, reducing machining costs, extending tooling life, and improving the safety of the machining process.

[0014] In some embodiments, the depth of the countersunk structure is greater than or equal to the axial thickness of the bolt head, used to accommodate the bolt head so that it does not protrude from the inner annular support surface or the outer mounting flange surface after assembly. When the countersunk hole meets this condition, stress concentration during bolt tightening can be eliminated, preventing quartz material breakage. This, in turn, enables high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation when processing silicon rings with quartz fixtures. Consequently, it ensures stable product quality, reduces processing costs, extends tooling life, and improves the safety of the processing.

[0015] In some embodiments, the coefficient of thermal expansion of the quartz fixture is ≤5×10⁻⁶. -7 / ℃. When the quartz fixture meets this condition, it can remain undeformed, stress-free, and noiseless during heating, and avoid scratching the workpiece surface. As a result, when machining silicon rings with the quartz fixture, high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation can be achieved, thereby ensuring stable product quality, reducing processing costs, extending tooling life, and improving the safety of the processing.

[0016] In some embodiments, the surface roughness Ra of the quartz fixture is ≤0.2μm; preferably, the surface roughness Ra of the quartz fixture is ≤0.1μm. When the quartz fixture meets this condition, wear during processing can be reduced, service life can be extended, and high-precision processing, low workpiece deformation, no surface scratches, and no stress accumulation can be achieved when processing silicon rings with the quartz fixture. This ensures stable product quality, reduces processing costs, extends tooling life, and improves the safety of the processing.

[0017] In this application, the surface roughness can be tested using a contact surface roughness tester.

[0018] Secondly, this application provides an application of a quartz jig in silicon ring processing, comprising the following steps: A silicon ring is coated with wax on the quartz fixture and then bonded to the quartz fixture. A quartz jig with a silicon ring is placed in a CNC grinding machine for grinding. After grinding, the quartz jig is heated to remove the wax, melting the wax layer and separating the silicon ring from the quartz jig.

[0019] This application enables high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation while performing integrated machining of silicon rings using quartz fixtures. This, in turn, ensures stable product quality, reduces processing costs, extends tooling life, and improves the safety of the machining process.

[0020] In some embodiments, during heat dewaxing, the difference in the coefficients of thermal expansion between the quartz fixture and the silicon ring is ≤2.5×10⁻⁶. -6 / ℃; the temperature for heating and dewaxing is 80~120℃. When this condition is met, the thermal expansion coefficients of the quartz fixture and the silicon ring are matched, which can achieve high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation during heating and dewaxing without internal stress, abnormal noise, or workpiece damage. This ensures stable product quality, reduces processing costs, extends tooling life, and improves the safety of the processing. Attached Figure Description

[0021] Figure 1 This is a partial structural schematic diagram of a quartz jig for processing silicon rings according to this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0023] Example 1 The quartz jig used for silicon ring processing in this application includes: a disc-shaped body; The disc-shaped main body is made of fused silica with a SiO2 mass content of ≥99.9%. Fused silica is an amorphous glass formed by rapidly cooling high-purity silicon dioxide after melting. The quartz fixture has a centrally symmetrical structure to ensure uniform heating and no distortion or deformation. The disc-shaped main body has a central through hole at its axis for positioning and clearance of the shaft system. The chamfered corner of the central through hole has a rounded chamfer with a radius R of 2mm, which can eliminate stress concentration and prevent the hole from cracking. The radially inner region of the disc-shaped main body includes an inner annular support surface with a flatness of 0.005. The inner annular support surface has eight threaded holes evenly spaced along the same circumference for bonding and positioning with the silicone ring through a wax layer. The stepped edge of the inner annular support surface is provided with a rounded chamfer with a radius of 2mm to avoid stress concentration. The inner annular support surface protrudes axially from the outer mounting flange surface, forming a stepped structure between the two. The radially outer region of the disc-shaped body includes an outer mounting flange surface. This outer mounting flange surface is used for mounting and fixing the disc-shaped body. A concentric annular reinforcing rib is provided on the back of the outer mounting flange surface, located on the inner side of the outer mounting flange surface. The inner edge of the annular reinforcing rib coincides with the projection of the outer edge of the silicon ring onto the axial direction of the disc-shaped body. The outer mounting flange surface includes mounting holes, the inner sides of both the upper and lower openings of which are countersunk. The depth of the countersunk structure is equal to the axial thickness of the bolt head, used for... The mounting hole accommodates the bolt head, ensuring that it does not protrude from the inner annular support surface or the outer mounting flange surface after assembly. The hole opening edge features a rounded transition structure, with the countersunk head structure and the rounded transition structure working together to disperse bolt tightening stress and prevent the quartz fixture hole wall from cracking. The outer mounting flange surface has a 2mm radius rounded chamfer at its corner position, located at the maximum radial outer diameter of the quartz fixture. This completely eliminates stress concentration at sharp corners and improves the quartz fixture's resistance to breakage. After testing, the coefficient of thermal expansion of the quartz jig was found to be 5 × 10⁻⁶. -7 / ℃, surface roughness Ra is 0.2μm.

[0024] This application also includes the application of quartz jigs in silicon ring processing, comprising the following steps: A silicon ring is coated with wax on a quartz fixture and then bonded to the quartz fixture. A quartz jig with a silicon ring is placed in a CNC grinding machine for grinding. After grinding, the quartz jig is dewaxed by heating at 100℃ for 30 minutes to melt the wax layer and separate the silicon ring from the quartz jig. During the dewaxing process, the quartz jig and silicon ring are tested; the difference in their coefficients of thermal expansion is 2.5 × 10⁻⁶. -6 / ℃.

[0025] Example 2 The difference from Example 1 is that the radius R of the rounded chamfer is 5mm.

[0026] Comparative Example 1 The fixture for silicon ring processing in this comparative example differs from that in Example 1 in that it uses a metal tooling.

[0027] Comparative Example 2 The fixture for processing silicon rings in this comparative example differs from that in Example 1 in that the central through hole does not have a rounded chamfer, the inner annular support surface does not have a rounded chamfer, and the outer mounting flange surface does not have a countersunk structure, a rounded transition structure, or a rounded chamfer.

[0028] Test case Accuracy inspection, thermal deformation detection, surface roughness testing, non-destructive stress testing, and tooling wear testing were performed on the silicon ring workpieces of each embodiment and comparative example. Accuracy inspection process: A high-precision coordinate measuring machine was used to measure the dimensions of the silicon ring workpieces after machining with the fixture. The measured dimensional data were compared one by one with the theoretical design reference value of the workpiece, and the average dimensional deviation was calculated as the accuracy evaluation index. The smaller the deviation value, the higher the machining accuracy of the workpiece. Thermal deformation detection process: The silicon ring workpieces were processed at 180℃ for 2 hours, and then cooled to room temperature. The dimensional changes of the silicon ring workpieces during processing were measured using an optical profilometer, and the average deformation was statistically analyzed as the thermal deformation evaluation index. The lower the average deformation, the better the dimensional stability of the workpiece under high-temperature conditions. Surface roughness testing process: A contact surface roughness meter is used. Three test points are randomly selected in each of the four regions of the silicon ring workpiece: the inner working surface, the outer assembly surface, and the upper and lower end faces. A uniform sampling length and evaluation length are set, and the roughness values ​​at each point are measured. The average roughness Ra of the workpiece is calculated by summing all the data. The smaller the Ra value, the higher the surface finish of the workpiece, which represents better wear resistance and assembly compatibility. Non-destructive stress testing process: An X-ray residual stress non-destructive testing instrument is used to detect the residual internal stress along the circumferential and axial directions of the workpiece without damaging the silicon ring workpiece. Eight test points are evenly set along the circumference of the silicon ring, and the residual stress values ​​at each test point are collected. The residual stress values ​​include residual tensile stress values ​​and residual compressive stress values. The average residual stress value of the workpiece is calculated. The lower the average residual stress value, the less internal stress accumulation in the workpiece, and the lower the risk of cracking and deformation during subsequent use. Tooling wear test process: The tooling to be tested and the silicon ring workpiece are batch-processed on the processing equipment, and the same cutting parameters are set; after processing 100 silicon ring workpieces, the tooling wear is measured with a high-precision micrometer, and the total tooling wear after processing 1000 silicon ring workpieces is counted. The average single-time wear of the tooling corresponding to a single piece is calculated; the smaller the average single-time wear of the tooling, the stronger the tooling durability and the lower the production consumable cost under this process.

[0029] Table 1

[0030] As shown in the table above, the quartz fixture for silicon ring machining according to the embodiments of this application can achieve high-precision machining, low workpiece deformation, no surface scratches, and no stress accumulation, thereby ensuring stable product quality, reducing processing costs, extending tooling life, and improving the safety of the machining process. When the radius R of the chamfer is controlled to be ≥ 5mm, the dimensional deviation and deformation of the silicon ring workpiece can be reduced, as well as the roughness and residual stress of the silicon ring workpiece can be reduced, and the wear of the quartz fixture can be reduced, thereby ensuring stable product quality, reducing processing costs, extending tooling life, and improving the safety of the machining process.

[0031] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the principles of this application should be included within the protection scope of this application.

Claims

1. A quartz jig for machining silicon rings, characterized in that, include: The main body is disc-shaped; The material of the disc-shaped body includes fused silica with a SiO2 mass content ≥ 99.9%; The disc-shaped main body has a central through hole at its axis; the central through hole is used for the positioning and avoidance of the axis system of the disc-shaped main body; The radially inner region of the disc-shaped body includes an inner annular support surface, which is used to bond and position the silicone ring with a wax layer; the flatness of the inner annular support surface is ≤0.005mm. The radially outer region of the disc-shaped main body includes an outer mounting flange surface; the outer mounting flange surface is used for mounting and fixing the disc-shaped main body; the outer mounting flange surface and the inner annular support surface are coaxially arranged; the inner annular support surface protrudes axially from the outer mounting flange surface, forming a stepped structure between them; the outer mounting flange surface includes a mounting hole, the upper and lower openings of the mounting hole are countersunk structures, and the edge of the mounting hole opening is provided with an arc transition structure; The central through hole, the stepped edge of the inner annular support surface, and the chamfered position of the outer mounting flange surface are all provided with rounded chamfers, and the radius of the rounded chamfers R≥2mm; The quartz fixture has a centrally symmetrical structure and is used for grinding and dewaxing silicon rings.

2. The quartz fixture according to claim 1, characterized in that, The inner annular support surface is provided with multiple threaded holes that are evenly spaced along the same circumference, and the number of threaded holes is 4 to 8.

3. The quartz fixture according to claim 2, characterized in that, The radius R of the chamfer is ≥ 5 mm.

4. The quartz fixture according to claim 3, characterized in that, The back of the outer mounting flange surface is provided with at least one annular reinforcing rib concentric with the outer mounting flange surface.

5. The quartz fixture according to claim 4, characterized in that, The depth of the countersunk head structure is greater than or equal to the axial thickness of the bolt head, and is used to accommodate the bolt head so that the bolt head does not protrude from the inner annular support surface or the outer mounting flange surface after assembly.

6. The quartz fixture according to claim 5, characterized in that, The coefficient of thermal expansion of the quartz fixture is ≤5×10. -7 / ℃.

7. The quartz fixture according to claim 6, characterized in that, The surface roughness Ra of the quartz fixture is ≤0.2μm.

8. The quartz fixture according to claim 6, characterized in that, The surface roughness Ra of the quartz fixture is ≤0.1μm.

9. The application of the quartz jig according to any one of claims 1 to 8 in the machining of silicon rings, characterized in that, Includes the following steps: A silicon ring is coated with wax on the quartz fixture and then bonded to the quartz fixture. A quartz jig with a silicon ring is placed in a CNC grinding machine for grinding. After grinding, the quartz jig is heated to remove the wax, melting the wax layer and separating the silicon ring from the quartz jig.

10. The application according to claim 9, characterized in that, During heat dewaxing, the difference in the coefficients of thermal expansion between the quartz fixture and the silicon ring is ≤2.5×10⁻⁶. -6 / ℃; the temperature for heating and dewaxing is 80~120℃.

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