Perforated graphite component for SiC epitaxy and processing method thereof
By improving the quality of the inner wall of the hole in the graphite component through multiple shallow cutting, reaming and multi-stage polishing processes, the problems of inner wall roughness and structural damage were solved, particle contamination was significantly reduced, and the yield of epitaxial wafers and the life of the component were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-03-27
AI Technical Summary
In the prior art, the hole processing of perforated graphite components results in rough surfaces and structural damage to the inner walls of the holes, making it impossible to completely remove graphite particles embedded in the gaps within the holes. This leads to severe particle contamination of SiC epitaxial wafers, affecting device performance and yield.
By employing multiple shallow cuts with coated diamond tools, reaming with PCD reamers, and polishing, combined with dry grinding with silicon carbide sandpaper and wet polishing with diamond abrasive paste, the surface roughness of the inner wall of the hole is gradually improved, and the damage to the microstructure is reduced.
The surface roughness of the inner wall of the hole is reduced to Ra≤1μm, the microstructure damage rate is reduced by 90%, particle contamination is reduced by 95%, the yield of epitaxial wafers is increased to 88%-92%, the component life is extended, and the production cost is reduced.
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Figure CN121733709A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a SiC epitaxial use hole graphite component and a processing method thereof. BACKGROUND
[0002] In the SiC epitaxial growth process, the hole graphite component (such as graphite tray, graphite support seat, gas flow guide piece, etc.) is the core component of the process system, and its main functions include bearing SiC substrate, guiding the uniform distribution of process gas, maintaining the temperature stability of the process area, etc. The SiC epitaxial process has very high requirements for environmental cleanliness. Even if a small amount of solid particles (particle size is usually 0.1-1 μm) settles on the surface of the SiC substrate, it will form defects during epitaxial growth, causing the Particle of the epitaxial wafer to exceed the standard, and ultimately causing device failure. One of the main sources of Particle pollution is the quality problem of the hole processing of the hole graphite component.
[0003] In the prior art, the hole processing of the hole graphite component is mostly carried out by conventional mechanical cutting and drilling process. Such process greatly damages the brittle structure of the isostatic pressed graphite, and the inner wall surface of the hole is prone to be rough (the surface roughness Ra is usually greater than 5 μm) during processing, and the microstructure of the graphite in the hole is also severely damaged (such as a large number of loose layers, microcracks and free graphite particles). Although ultrasonic cleaning is performed after the component is processed, due to the roughness and structural damage of the inner wall of the hole, the graphite particles embedded in the gaps and loose layers in the hole cannot be completely removed during the cleaning process; in the SiC epitaxial process, high-temperature process gas continuously flows through the hole at high speed, which continuously erodes the inner wall of the hole, peels off the residual graphite particles and carries them into the process area. These particles eventually settle on the surface of the SiC substrate, directly causing the number of epitaxial wafer particles to increase dramatically, and the yield to decrease from the expected 90% to 60%-70%. This not only greatly increases the production cost, but also seriously affects the performance stability of the downstream device. In the prior art, the surface treatment of the graphite component is mostly concentrated on the polishing of the outer surface, and the processing quality of the special structure in the hole is not optimized; some schemes try to use chemical etching method to improve the smoothness of the hole, but it will introduce new impurity elements, and cannot repair the structural damage caused by processing, and cannot fundamentally solve the Particle pollution problem, so it is urgent to innovate the machining process. SUMMARY
[0004] The application provides a SiC epitaxial graphite component with a hole and a processing method thereof, which is used for improving the roughness of the inner wall surface of the hole of the graphite component, reducing the damage to the microstructure of the graphite component in the hole processing process, and has the characteristics of reducing the particle pollution of the epitaxial wafer in the practical application of the graphite component.
[0005] To achieve the above-mentioned object, the application adopts the following technical scheme: The application provides a processing method of a SiC epitaxial graphite component with a hole, which comprises the following steps: S1, performing multiple shallow cutting on the graphite component by using a tool coated with a diamond layer until an initial hole is cut in the graphite component; S2, reaming the initial hole by using a PCD reamer until a hole with a predetermined size is obtained; S3, polishing the inner wall of the hole by using the PCD reamer again; S4, dry grinding the inner wall of the hole after polishing by using a silicon carbide sandpaper, then applying a diamond grinding paste to a polishing head, wet polishing the inner wall of the hole after dry grinding by using the polishing head, and obtaining the SiC epitaxial graphite component with a hole after ultrasonic cleaning.
[0006] Preferably, in step S1, when the tool cuts the graphite component, the cutting speed of the tool is set to 15-25 m / min, the feed amount of the tool is set to 0.01-0.03 mm / r, and the single shallow cutting depth of the tool is controlled to be 0.05-0.1 mm; high temperature generated by high-speed cutting is avoided to cause thermal deformation and structural embrittlement of the graphite, and the cutting force caused by low-speed cutting is prevented to cause material burst, micro-feeding is adopted to reduce the impact of single cutting on the graphite, the cutting texture of the inner wall surface of the hole is ensured to be uniform and delicate, multiple shallow cutting is adopted to replace single deep cutting, and material is gradually removed to avoid delamination and loose of the inner wall of the hole caused by deep cutting.
[0007] Preferably, in step S1, the cutting edge of the tool is subjected to arc passivation treatment, and the radius of the cutting edge of the tool is set to 0.02-0.05 mm; the arc passivation cutting edge can avoid the edge sharpness of the tool being too high to cause graphite edge burst, the cutting process is more stable, and the risk of structural damage of the inner wall of the hole is reduced.
[0008] Preferably, in step S2, the reaming allowance of the PCD reamer is 0.1 mm-0.25 mm, and the feed amount of the PCD reamer is set to 0.02-0.09 mm / r; the micro-unevenness and size error left on the surface of the initial hole after step S1 can be removed, the hole diameter is not out of control due to too large cutting amount, the "biting" phenomenon caused by too large cutting force is avoided, and micro-cracks, loose layers or material tearing of the hole wall are prevented.
[0009] Preferably, in step S4, the polishing pressure of the wet polishing is set to 0.1-0.3 MPa, and the polishing time is set to 5-15 min according to the hole size; the fine scratches left by dry grinding are eliminated and micro-defects are repaired, thereby achieving a gradual reduction in the roughness of the inner wall surface of the hole. At the same time, this smooth and dense surface can effectively reduce the embedding and residue of graphite particles and reduce the risk of particle peeling under subsequent airflow scouring.
[0010] Preferably, in step S4, the inner wall of the hole is dry-ground using 2000-grit silicon carbide sandpaper; the inner wall of the hole is wet-polished using 5000-grit diamond polishing paste; macroscopic cutting marks, large unevenness and surface microcracks left in step S2 are removed, so that the surface is initially smooth, and then the lubrication and cooling effect of the liquid medium and the micro-cutting effect of the ultrafine abrasive are utilized.
[0011] Preferably, the diamond abrasive paste comprises the following components in parts by weight: 20-30 parts diamond powder, 5-10 parts glycerin, 20-30 parts water, 1-3 parts cationic surfactant, and 2-5 parts hydrogen peroxide solution; hydrogen peroxide can micro-etch and remove graphite particles from the graphite surface, while the cationic compound can be adsorbed onto the abrasive surface through electrostatic interaction, which helps to suspend and remove graphite particles.
[0012] Preferably, the volume concentration of the hydrogen peroxide solution is 10-30%, and the cationic surfactant is a quaternary ammonium salt.
[0013] Preferably, the diamond polishing paste further includes 0.5-2 parts of polyurethane microspheres. The polyurethane microspheres are elastic particles that can act as a micro-buffer and assist in polishing, preventing excessively deep scratches. Their size can be 10-50 micrometers.
[0014] A perforated graphite component for SiC epitaxy is obtained by the processing method for the perforated graphite component for SiC epitaxy.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: Using diamond-coated tools to machine graphite parts, multiple shallow cuts are used instead of a single deep cut, and PCD reamers are used to ream the holes to avoid delamination and porosity of the inner wall of the hole caused by a single deep cut, thereby reducing the microstructure damage rate of graphite parts. Using a PCD reamer, the inner wall of the hole is polished to remove the macroscopic cutting marks remaining on the inner wall after reaming. Then, dry grinding is performed with 2000-grit silicon carbide sandpaper to remove the macroscopic cutting marks on the inner wall surface again. Finally, wet polishing is performed with 5000-grit diamond polishing paste and a polishing head to reduce the surface roughness of the inner wall to Ra≤1μm. Attached Figure Description
[0016] In order to more clearly illustrate the technical solutions of the specific embodiments or the prior art of the present application, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.
[0017] Figure 1 The flow chart of the processing method of the SiC epitaxial hole graphite component provided by the present application. EMBODIMENT
[0018] The technical solutions of the present application will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0019] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0020] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0021] The embodiment of the present application provides a processing method of a SiC epitaxial hole graphite component, comprising the following steps: S1, using a tool coated with a diamond-made coating to perform multiple shallow cutting on the graphite component until an initial hole is cut in the graphite component; S2, using a PCD reamer to ream the initial hole until a predetermined size of a finished hole is obtained; S3, using the PCD reamer to polish the inner wall of the finished hole again; S4. First, dry-grind the inner wall of the hole after polishing with silicon carbide sandpaper. Then, apply diamond polishing paste to the polishing head and wet-polish the inner wall of the hole after dry grinding with the polishing head. After ultrasonic cleaning, a perforated graphite part for SiC epitaxy is obtained.
[0022] Multiple shallow cuts are performed on the graphite component using a diamond-coated tool, or multiple shallow cuts are performed on the graphite component using an ultra-fine grain cemented carbide tool with a grain size of less than or equal to one micrometer. These tools have a Vickers hardness of not less than 1800, high wear resistance, and can reduce material tearing caused by tool wear during machining. An initial hole is cut into the graphite component, equivalent to rough machining the initial hole. In step S2, a PCD reamer is used to ream the initial hole, and then the initial hole is finished to obtain a complete hole. In step S3, the inner wall of the completed hole is polished again using a PCD reamer to remove any remaining macroscopic cutting marks after reaming. In step S4, a combination of dry grinding and wet polishing is used. The combined polishing process involves first dry grinding with 2000-grit silicon carbide sandpaper to remove macroscopic cutting marks from the inner wall surface of the hole. Then, wet polishing is performed with 5000-grit diamond polishing paste and a polishing head. The dedicated polishing head is a flexible polishing head adapted to the hole size, which can gradually reduce the surface roughness of the inner wall of the hole, ultimately achieving a surface roughness of Ra≤1μm and further removing microscopic defects, thereby improving the smoothness of the inner wall of the hole. Finally, after ultrasonic cleaning, a perforated graphite part for SiC epitaxy is obtained, and the number of residual graphite particles in the hole is reduced after ultrasonic cleaning.
[0023] To better remove defects such as graphite particles within the abrasive holes, this invention also improves the composition of the diamond polishing paste by adding 1-3 parts of a cationic surfactant and 2-5 parts of hydrogen peroxide solution. Hydrogen peroxide can micro-etch and remove graphite particles from the graphite surface, while the cationic compound can be adsorbed onto the abrasive surface through electrostatic interaction, helping to suspend and remove graphite particles. Preferably, the diamond polishing paste comprises the following components in parts by weight: 20-30 parts diamond powder, 5-10 parts glycerol, 20-30 parts water, 1-3 parts cationic surfactant, and 2-5 parts hydrogen peroxide solution. Preferably, the volume concentration of the hydrogen peroxide solution is 10-30%, and the cationic surfactant is a quaternary ammonium salt. More preferably, the diamond polishing paste further comprises 0.5-2 parts of polyurethane microspheres. Polyurethane microspheres are elastic particles that can act as micro-buffers and assist in polishing, preventing excessively deep scratches; their size can be 10-50 micrometers.
[0024] In a preferred embodiment, in step S1, when the tool cuts the graphite component, the cutting speed of the tool is set to 15-25 m / min, the tool feed rate is set to 0.01-0.03 mm / r, and the single shallow cutting depth is controlled at 0.05-0.1 mm.
[0025] To avoid the high temperatures generated by high-speed cutting that cause thermal deformation and structural embrittlement of graphite, and to prevent excessive cutting forces caused by low-speed cutting that could lead to material fracture, a micro-feed method is adopted to reduce the impact of a single cut on the graphite, ensuring that the cutting texture on the inner wall surface of the hole is uniform and delicate. Multiple shallow cuts are used instead of a single deep cut to gradually remove material, avoiding delamination and porosity on the inner wall of the hole caused by deep cutting.
[0026] In a preferred embodiment, in step S1, the cutting edge of the tool is rounded and blunted, and the radius of the cutting edge is set to 0.02-0.05mm. The rounded blunt cutting edge can avoid graphite chipping caused by excessively sharp cutting edge, making the cutting process more stable and reducing the risk of damage to the inner wall structure of the hole.
[0027] In a preferred embodiment, in step S2, the reaming allowance of the PCD reamer during reaming is 0.1mm-0.25mm, and the feed rate of the PCD reamer is set to 0.02-0.09mm / r. This can remove the micro-unevenness and dimensional error left on the surface of the initial hole after step S1, and will not cause the hole diameter to become out of control due to excessive cutting amount. It avoids the "biting" phenomenon caused by excessive cutting force, thereby preventing the formation of micro-cracks, loose layers or material tearing in the hole wall.
[0028] In a preferred embodiment, in step S4, the polishing pressure of the wet polishing is set to 0.1-0.3 MPa, and the polishing time is set to 5-15 min according to the hole size. The inner wall of the hole is dry-polished with 2000-grit silicon carbide sandpaper; the inner wall of the hole is wet-polished with 5000-grit diamond polishing paste.
[0029] A gradient polishing process, progressing from coarse to fine and from dry to wet, is employed to progressively process the inner wall surface of the hole. First, the high cutting force of rigid abrasive paper efficiently removes macroscopic cutting marks, significant unevenness, and surface microcracks left in step S2, achieving a preliminary smooth surface. Then, utilizing the lubrication and cooling effects of the liquid medium and the micro-cutting action of the ultrafine abrasive, fine friction is applied for 5-15 minutes under a constant pressure of 0.1-0.3 MPa to eliminate fine scratches left by dry grinding and repair microscopic defects. This results in a gradual reduction in the surface roughness of the inner wall of the hole. Simultaneously, this smooth and dense surface effectively reduces the embedding and residue of graphite particles, lowering the risk of particle stripping under subsequent airflow scouring.
[0030] The following describes in detail the processing method of the perforated graphite component for SiC epitaxy provided by the present invention with reference to the embodiments, taking a hole diameter of 4mm as an example.
[0031] Example 1
[0032] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 15m / min, a feed rate of 0.02mm / r, and a single shallow cut depth controlled at 0.1mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.75mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.25mm and a PCD reamer feed rate of 0.06mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.1 MPa and the polishing time is 5 minutes. After ultrasonic cleaning, a porous graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 25 parts diamond powder, 7.5 parts glycerin, 25 parts water, 3.5 parts hydrogen peroxide solution, and 2 parts cationic surfactant. The mixture is stirred thoroughly after mixing.
[0033] Example 2
[0034] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 20m / min, a feed rate of 0.01mm / r, and a single shallow cut depth controlled at 0.075mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.75mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.25mm and a PCD reamer feed rate of 0.06mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.1 MPa and the polishing time is 5 minutes. After ultrasonic cleaning, a porous graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 25 parts diamond powder, 7.5 parts glycerin, 25 parts water, 3.5 parts hydrogen peroxide solution, and 2 parts cationic surfactant. The mixture is stirred thoroughly after mixing.
[0035] Example 3
[0036] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 25m / min, a feed rate of 0.03mm / r, and a single shallow cut depth controlled at 0.05mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.75mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.25mm and a PCD reamer feed rate of 0.06mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.1 MPa and the polishing time is 5 minutes. After ultrasonic cleaning, a porous graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 25 parts diamond powder, 7.5 parts glycerin, 25 parts water, 3.5 parts hydrogen peroxide solution, and 2 parts cationic surfactant. The mixture is stirred thoroughly after mixing.
[0037] Example 4
[0038] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 15m / min, a feed rate of 0.02mm / r, and a single shallow cut depth controlled at 0.1mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.85mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.15mm and a PCD reamer feed rate of 0.03mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.1 MPa and the polishing time is set to 5 minutes. After ultrasonic cleaning, a porous graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 25 parts diamond powder, 7.5 parts glycerin, 25 parts water, 3.5 parts hydrogen peroxide solution, and 2 parts cationic surfactant. The mixture is stirred thoroughly after mixing.
[0039] Example 5
[0040] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 15m / min, a feed rate of 0.02mm / r, and a single shallow cut depth controlled at 0.1mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.80mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.2mm and a PCD reamer feed rate of 0.09mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.1 MPa and the polishing time is 5 minutes. After ultrasonic cleaning, a porous graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 25 parts diamond powder, 7.5 parts glycerin, 25 parts water, 3.5 parts hydrogen peroxide solution, and 2 parts cationic surfactant. The mixture is stirred thoroughly after mixing.
[0041] Example 6
[0042] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 15m / min, a feed rate of 0.02mm / r, and a single shallow cut depth controlled at 0.1mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.75mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.25mm and a PCD reamer feed rate of 0.06mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.2 MPa and the polishing time is 10 min. After ultrasonic cleaning, a porous graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 25 parts diamond powder, 7.5 parts glycerin, 25 parts water, 3.5 parts hydrogen peroxide solution, and 2 parts cationic surfactant. The mixture is stirred thoroughly after mixing.
[0043] Example 7
[0044] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 15m / min, a feed rate of 0.02mm / r, and a single shallow cut depth controlled at 0.1mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.75mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.25mm and a PCD reamer feed rate of 0.06mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.3 MPa and the polishing time is 15 min. After ultrasonic cleaning, a porous graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 25 parts diamond powder, 7.5 parts glycerin, 25 parts water, 3.5 parts hydrogen peroxide solution, and 2 parts cationic surfactant. The mixture is stirred thoroughly after mixing.
[0045] Example 8
[0046] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 15m / min, a feed rate of 0.02mm / r, and a single shallow cut depth controlled at 0.1mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.75mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.25mm and a PCD reamer feed rate of 0.06mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.1 MPa and the polishing time is 5 minutes. After ultrasonic cleaning, a perforated graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 20 parts diamond powder, 5 parts glycerin, 20 parts water, 2 parts hydrogen peroxide solution, and 1 part quaternary ammonium salt. The mixture is stirred thoroughly after mixing.
[0047] Example 9
[0048] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 15m / min, a feed rate of 0.02mm / r, and a single shallow cut depth controlled at 0.1mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.75mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.25mm and a PCD reamer feed rate of 0.06mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.1 MPa and the polishing time is 5 minutes. After ultrasonic cleaning, a perforated graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 30 parts diamond powder, 10 parts glycerin, 30 parts water, 5 parts hydrogen peroxide solution, and 3 parts quaternary ammonium salt. The mixture is stirred thoroughly after mixing.
[0049] Example 10
[0050] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 15m / min, a feed rate of 0.02mm / r, and a single shallow cut depth controlled at 0.1mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.75mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.25mm and a PCD reamer feed rate of 0.06mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.1 MPa and the polishing time is 5 minutes. After ultrasonic cleaning, a porous graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 25 parts diamond powder, 7.5 parts glycerin, 25 parts water, 3.5 parts hydrogen peroxide solution, 2 parts cationic surfactant, and 2 parts 10-micron polyurethane microspheres. The mixture is stirred thoroughly after mixing.
[0051] Example 11
[0052] S1, a diamond tool with a rounded and blunt cutting edge is selected, with a cutting edge radius of 0.02mm. High-purity graphite is selected as the graphite component. The tool performs multiple shallow cuts on the graphite component, with a cutting speed of 15m / min, a feed rate of 0.02mm / r, and a single shallow cut depth controlled at 0.1mm, until the tool cuts an initial hole in the graphite component with a diameter of 3.75mm. S2, use a PCD reamer to ream the initial hole, with a reaming allowance of 0.25mm and a PCD reamer feed rate of 0.06mm / r, until a hole with a diameter of 4.00mm is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the polished inner wall of the hole using 2000-grit silicon carbide sandpaper. Then, apply 5000-grit diamond polishing paste to the polishing head and wet-polish the dry-grinded inner wall of the hole using the polishing head. The polishing pressure is 0.1 MPa and the polishing time is 5 minutes. After ultrasonic cleaning, a porous graphite part for SiC epitaxy is obtained. The diamond polishing paste includes the following components in parts by mass: 25 parts diamond powder, 7.5 parts glycerin, 25 parts water, 3.5 parts hydrogen peroxide solution, 2 parts cationic surfactant, and 0.5 parts 50-micron polyurethane microspheres. The mixture is stirred thoroughly after mixing.
[0053]
[0054] As shown in the table above, Examples 1 to 3 and 6 to 11 all used an initial hole size of 3.75 mm and a reaming allowance of 0.25 mm. By changing the cutting parameters of S1, the polishing intensity of S4, or the formulation of the final polishing paste, the effects of different conditions on the surface quality of the holes in the graphite components were studied. Examples 4 and 5 used an initial hole size of 3.85 mm and a reaming allowance of 0.15 mm and an initial hole size of 3.80 mm and a reaming allowance of 0.20 mm, respectively, to verify the feasibility of the process under different finishing allowances. All examples were able to achieve a surface roughness Ra ≤ 1 μm in the holes of the graphite components and a reduction of more than 95% in graphite particle residue after ultrasonic cleaning. Among them, Examples 10 and 11 showed significant advantages under the same polishing conditions by adding polyurethane microspheres of different sizes to the diamond polishing paste. This additive played a role in buffering, rolling polishing, and deep cleaning, resulting in lower surface roughness and higher cleanliness in the holes obtained in these two examples, demonstrating better process effects.
[0055] Comparative Example In existing technologies, the machining steps for holes in graphite components are summarized as follows: S1, use drilling or milling to rough-machine the graphite component to create the initial hole; S2, the initial hole of the graphite component is further finished by drilling or milling until the hole is formed; S3, perform preliminary dust removal on the processed graphite parts to remove macroscopic graphite chips and floating powder inside and on the surface of the holes; S4. Immerse the graphite component in the cleaning solution and attempt to clean the hole wall using ultrasonic vibration.
[0056] In the existing technology, the hole processing of perforated graphite parts mostly adopts conventional mechanical cutting and drilling processes. These processes cause significant damage to the brittle structure of isostatic graphite, and the processing process easily leads to roughness of the inner wall surface of the hole, while also causing severe damage to the microstructure of the graphite inside the hole. Although ultrasonic cleaning is performed after the part is processed, due to the roughness of the inner wall of the hole and the existence of structural damage, the cleaning process cannot completely remove the graphite particles embedded in the gaps and loose layers inside the hole.
[0057]
[0058] As shown in the table above, compared with the porous graphite components processed by existing technologies, the porous graphite components processed by the SiC epitaxial method have significantly reduced particle contamination. The surface roughness of the inner wall of the porous graphite component is Ra≤1μm, and the microstructure damage rate is reduced by more than 90%. After ultrasonic cleaning, the number of residual graphite particles in the pores is reduced by more than 95%. In the SiC epitaxial process, the amount of particles carried out by the process gas is greatly reduced, and the number of particles per epitaxial wafer is reduced from 5-10 per wafer in existing technologies to less than 1 per wafer, and the yield of epitaxial wafers is improved to 88%-92%.
[0059] The lifespan of perforated graphite components is extended because the internal structure of the pores is only slightly damaged, and the erosion rate of the pore walls by process gas is slowed down. The lifespan of perforated graphite components is extended from the original 50-80 epitaxial cycles to 150-200 cycles, reducing the component replacement frequency by more than 60% and significantly reducing production costs. Improved process stability, consistent smoothness of the inner wall of the pores, and stable structure ensure uniform flow resistance of process gas within the pores, avoiding local temperature fluctuations and uneven airflow caused by gas eddies, and further enhancing the thickness uniformity and crystal quality of the SiC epitaxial layer. The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.
Claims
1. A method for fabricating a perforated graphite component for SiC epitaxy, characterized in that, Includes the following steps: S1, using a diamond-coated tool to perform multiple shallow cuts on the graphite component until an initial hole is cut out in the graphite component. S2, use a PCD reamer to ream the initial hole until a hole of the predetermined size is obtained; S3, then use the PCD reamer to polish the inner wall of the hole; S4. First, dry-grind the inner wall of the hole after polishing with silicon carbide sandpaper. Then, apply diamond polishing paste to the polishing head and wet-polish the inner wall of the hole after dry grinding with the polishing head. After ultrasonic cleaning, a perforated graphite part for SiC epitaxy is obtained.
2. The method for processing perforated graphite components for SiC epitaxy according to claim 1, characterized in that, In step S1, when the tool cuts the graphite component, the cutting speed of the tool is set to 15-25 m / min, the feed rate of the tool is set to 0.01-0.03 mm / r, and the single shallow cutting depth of the tool is controlled at 0.05-0.1 mm.
3. The method for processing perforated graphite components for SiC epitaxy according to claim 1, characterized in that, In step S1, the cutting edge of the tool is rounded and blunted, and the radius of the cutting edge is set to 0.02-0.05mm.
4. The method for processing perforated graphite components for SiC epitaxy according to claim 1, characterized in that, In step S2, the reaming allowance of the PCD reamer during reaming is 0.1mm-0.25mm, and the feed rate of the PCD reamer is set to 0.02-0.09mm / r.
5. The method for processing perforated graphite components for SiC epitaxy according to claim 1, characterized in that, In step S4, the polishing pressure of the wet polishing is set to 0.1-0.3 MPa, and the polishing time is set to 5-15 min according to the hole size.
6. The method for processing a perforated graphite component for SiC epitaxy according to claim 1, characterized in that, In step S4, the inner wall of the hole is dry-ground using 2000-grit silicon carbide sandpaper; and the inner wall of the hole is wet-polished using 5000-grit diamond polishing paste.
7. The method for processing a perforated graphite component for SiC epitaxy according to claim 1, characterized in that, The diamond polishing paste comprises the following components in parts by weight: 20-30 parts diamond powder, 5-10 parts glycerin, 20-30 parts water, 1-3 parts cationic surfactant, and 2-5 parts hydrogen peroxide solution.
8. The method for processing a perforated graphite component for SiC epitaxy according to claim 7, characterized in that, The volume concentration of the hydrogen peroxide solution is 10-30%, and the cationic surfactant is a quaternary ammonium salt.
9. The method for processing a perforated graphite component for SiC epitaxy according to claim 7, characterized in that, The diamond polishing paste also includes 0.5-2 parts of 10-50 micrometer polyurethane microspheres.
10. A perforated graphite component for SiC epitaxy, characterized in that, It is processed by the processing method of the perforated graphite component for SiC epitaxy as described in any one of claims 1-9.