Method for processing silicon carbide through steel wire gasification
By using steel wire gasification to process silicon carbide, volatile gases are generated through high-temperature chemical reactions and combined with hot iron plate treatment, the problems of low cutting accuracy and low material utilization are solved, achieving efficient and low-cost silicon carbide wafer cutting.
Patent Information
- Application Number
- CN202510983217.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-17
- Publication Date
- 2025-10-31
AI Technical Summary
Existing technologies for cutting silicon carbide wafers suffer from problems such as wide kerfs, severe thermal damage, low material utilization, and high costs. In particular, it is difficult to achieve high precision and thickness uniformity in the processing of large-diameter wafers.
The steel wire gasification process involves electrically heated steel wire in a hydrogen or chlorine atmosphere contacting the edge of a silicon carbide wafer. A high-temperature chemical gasification reaction generates volatile gases SiCl4 or SiH4, and a hot iron plate is used for subsequent surface smoothing, achieving fine cutting and material removal.
It achieves a cutting groove width of less than 100μm, high material utilization, good thickness uniformity, reduces grinding costs and processing losses, and is suitable for efficient cutting of large-diameter wafers.
Abstract
Description
Technical Field
[0001] This invention relates to the field of silicon carbide processing technology, specifically a method for processing silicon carbide by gasification of steel wire. Background Technology
[0002] Silicon wafers are widely used in the manufacture of high-end semiconductor power devices and radio frequency devices due to their high hardness (Mohs hardness above 9.0), high thermal conductivity, and chemical stability. Currently, slicing is commonly done using diamond wire saws or laser cutting.
[0003] However, diamond wire saws rely on nickel-plated micron-sized diamond particles, which have insufficient adhesion and are difficult to handle high-hardness SiC, easily causing particle detachment and poor compatibility. While laser cutting can achieve non-contact removal, it results in wide kerfs, severe thermal damage, and dead zones in the central area of large-diameter wafers (12 inches), making it unsuitable. Conventional cutting leaves wafers with uneven thickness, thicker at the edges and thinner in the center, leading to high subsequent grinding costs and low process efficiency. Clearly, a new cutting and surface-flattening process is urgently needed to improve cutting accuracy, thickness uniformity, material utilization, and reduce costs. Therefore, a method for processing silicon carbide using steel wire vaporization is urgently needed to solve the above technical problems. Summary of the Invention
[0004] The purpose of this invention is to provide a method for processing silicon carbide by gasification of steel wire, so as to solve the technical problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] A method for processing silicon carbide by gasification of steel wire, the method comprising the following steps:
[0007] Step 1: Take an 8-inch SiC wafer and rotate it in a hydrogen or chlorine atmosphere at a speed of 10 RPM. Cut it with a steel wire and press a roll of piano wire onto the wafer and move it in the opposite direction at a speed of about 1 m / min.
[0008] Step 2: The piano wire passes through a quartz dome, which is filled with pressurized chlorine gas. The wire is held by graphite electrodes at both ends and heated to about 900°C. It has a diameter of 30–300 μm, is pressed against the edge of the wafer, and slides in the opposite direction at high speed, causing the silicon carbide edge to vaporize into SiCl4 or SiH4 vapor and be expelled, which is used to completely remove the wafer.
[0009] Preferably, the atmosphere is at least one protective gas selected from hydrogen or chlorine.
[0010] Preferably, the steel wire is made of piano wire, which has high mechanical strength and good electrical conductivity to ensure stable sliding at high temperatures.
[0011] Preferably, the wafer is a silicon carbide wafer with a diameter greater than 200 mm and a dicing groove width of less than 100 μm.
[0012] Preferably, after dicing, the cut wafer is brought into contact with a hot iron plate with cross grooves on its surface and heated in the same atmosphere to remove the micro-protrusions and smooth the surface.
[0013] Preferably, the hot iron plate is energized and induction heated to 300-600°C by nickel-chromium wire or copper tube. The surface of the hot iron plate is machined with a grid-shaped groove with a groove depth of less than 1 mm. During the cutting and heat leveling process, the operating equipment and atmosphere device are equipped with a volatile substance collection device to collect SiCl4 or SiH4 volatile substances and perform safe treatment.
[0014] Compared with existing technologies, this invention has the following advantages: The method for processing silicon carbide using steel wire vaporization involves a steel wire heated by electricity passing at high speed across the edge of a rotating silicon carbide wafer in a hydrogen or chlorine protective atmosphere. This causes the silicon carbide to vaporize, generating volatile products such as SiCl4 or SiH4, thus achieving fine cutting. Subsequently, the slices are selectively thermally removed using a flat hot iron plate in the same atmosphere, rapidly improving the smoothness of the surface. This process can achieve a groove width of less than 100μm, high material utilization, and high thickness uniformity; it eliminates the need for micron-sized drill bits, avoiding wear and particle shedding; the cutting groove is narrow with low processing loss; it can cut wafers of 12 inches or larger across the entire dicing diameter; the cut surface thickness is highly consistent, helping to reduce grinding costs; the process equipment has a simple structure and low cost, allowing for large-scale promotion. Detailed Implementation
[0015] The present application will be further described in detail below with reference to embodiments. It is to be understood that the specific embodiments described herein are only for explaining the relevant invention and are not intended to limit the invention.
[0016] Please refer to a method for processing silicon carbide by gasification of steel wire, the method comprising the following steps:
[0017] Step 1: Take an 8-inch SiC wafer and rotate it in a hydrogen or chlorine atmosphere at a speed of 10 RPM. Cut it with a steel wire and press a roll of piano wire onto the wafer and move it in the opposite direction at a speed of about 1 m / min.
[0018] Step 2: The piano wire passes through a quartz dome, which is filled with pressurized chlorine gas. The wire is held by graphite electrodes at both ends and heated to about 900°C. It has a diameter of 30–300 μm, is pressed against the edge of the wafer, and slides in the opposite direction at high speed, causing the silicon carbide edge to vaporize into SiCl4 or SiH4 vapor and be expelled, which is used to completely remove the wafer.
[0019] The atmosphere is at least one protective gas selected from hydrogen or chlorine.
[0020] The steel wire is made of piano wire, which has high mechanical strength and good electrical conductivity to ensure stable sliding at high temperatures.
[0021] The wafer is a silicon carbide wafer with a diameter greater than 200 mm and a dicing groove width of less than 100 μm.
[0022] This includes, after the dicing is completed, contacting the cut wafer with a hot iron plate with cross grooves on its surface, heating it in the same atmosphere, and removing the micro-protrusions to make the surface smooth.
[0023] The hot iron plate is energized and induction heated to 300-600°C by nickel-chromium wire or copper tube. The surface of the hot iron plate is machined with a grid-shaped groove with a groove depth of less than 1 mm. During the cutting and heat leveling process, the operating equipment and atmosphere device are equipped with a volatile substance collection device to collect SiCl4 or SiH4 volatile substances and handle them safely.
[0024] It should be noted that this method of processing silicon carbide by steel wire vaporization breaks through the technical bottlenecks of traditional mechanical or laser cutting, improves material utilization and cut surface quality, and reduces processing costs. The cutting process of this invention mainly utilizes a chemical vaporization reaction at high temperature to remove material, which differs from traditional mechanical processing methods. Its principle is as follows:
[0025] Heat source: The steel wire heating system generates Joule heat through the graphite electrodes, which rapidly raises the temperature of the steel wire to about 900°C.
[0026] Reaction environment: A sealed reaction chamber is formed by a quartz cover, and a Cl2 or H2 atmosphere is injected to avoid high-temperature oxidation and the formation of a reaction medium.
[0027] Contact reaction: A high-speed moving steel wire presses against the edge of a rotating wafer, inducing a vaporization reaction at high temperature in the contact line area;
[0028] Escape of reaction products: The gaseous products such as SiCl4, CCl4, SiH4, and CH4 generated are immediately removed by the extraction system, leaving no solid particles behind;
[0029] Micro-control: By controlling parameters such as wire tension, moving speed, electrical intensity, and gas flow rate, precise control of cutting depth and speed can be achieved;
[0030] Post-processing: After dicing, a heated iron plate is used to selectively heat and remove the microbumps on the wafer through soft contact, making the surface smoother.
[0031] This method integrates mechanisms such as high-temperature pyrolysis, gasification chemical reaction, and dynamic contact processing, achieving the goals of narrow kerf, no residue, and high material utilization in large-size wafer dicing.
[0032] To achieve the above objectives, the present invention proposes the following technical solution:
[0033] Technical principle: The method of this invention utilizes steel wire as a high-temperature heat source, electrically heated to above 900°C in a reducing or halogen atmosphere such as hydrogen or chlorine, bringing it into contact with the edge of a silicon carbide wafer. Under localized high-temperature conditions, the SiC undergoes the following vaporization reaction:
[0034] SiC + 3Cl₂ → SiCl₄↑ + CCl₄↑
[0035] SiC + 4H₂ → SiH₄↑ + CH₄↑
[0036] The vaporization products are volatile gases, which can be promptly removed through a ventilation and exhaust system to achieve the material removal process. By setting the wafer rotation speed and the wire sliding speed, the reaction zone is stabilized, achieving precise cutting.
[0037] Example 1
[0038] 12-inch SiC wafer precision cutting
[0039] Atmosphere: Chlorine, 99.9% purity;
[0040] Wafer: Φ300mm, thickness 625μm;
[0041] Steel wire: Piano wire, 100μm in diameter;
[0042] Equipment parameters: rotation speed 10RPM, wire speed 0.8m / min, current 4A, heating steel wire to 900±20℃; results: groove width 90±5μm, material loss <2%, wafer passed through intact.
[0043] Example 2
[0044] Example of hot leveling process
[0045] The wafer dicing was completed, and the product from Example 1 was selected.
[0046] The hot iron plate structure is a Φ350mm nickel-chromium wire heating coil;
[0047] Heat the tray to 500°C under a chlorine atmosphere and contact the rotating wafer for 5 minutes.
[0048] Surface roughness changed from R_a 0.8 to 0.2 μm, and cross-sectional thickness uniformity was ±10 μm.
[0049] Example 3
[0050] Hydrogen Atmosphere Comparison Experiment
[0051] With the same configuration but in an atmosphere of H2; wire diameter 200μm, wire speed 1m / min; wire temperature 920℃, and grooving width 110μm; the result was a more uniform grooving depth and higher material utilization.
[0052] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.
Claims
1. A method for processing silicon carbide by gasification of steel wire, characterized in that: The method includes the following steps: Step 1: Take an 8-inch SiC wafer and rotate it in a hydrogen or chlorine atmosphere at a speed of 10 RPM. Cut it with a steel wire and press a roll of piano wire onto the wafer and move it in the opposite direction at a speed of about 1 m / min. Step 2: The piano wire passes through a quartz dome, which is filled with pressurized chlorine gas. The wire is held by graphite electrodes at both ends and heated to about 900°C. It has a diameter of 30–300 μm, is pressed against the edge of the wafer, and slides in the opposite direction at high speed, causing the silicon carbide edge to vaporize into SiCl4 or SiH4 vapor and be expelled, which is used to completely remove the wafer.
2. The method for processing silicon carbide by gasification of steel wire according to claim 1, characterized in that: The atmosphere is at least one protective gas selected from hydrogen or chlorine.
3. The method for processing silicon carbide by gasification of steel wire according to claim 1, characterized in that: The steel wire is made of piano wire, which has high mechanical strength and good electrical conductivity to ensure stable sliding at high temperatures.
4. The method for processing silicon carbide by gasification of steel wire according to claim 1, characterized in that: The wafer is a silicon carbide wafer with a diameter greater than 200 mm and a dicing groove width of less than 100 μm.
5. The method for processing silicon carbide by gasification of steel wire according to claim 1, characterized in that: It also includes contacting the cut wafer with a hot iron plate with cross grooves on the surface after cutting, heating it in the same atmosphere, and removing the micro-protrusions to make the surface smooth.
6. The method for processing silicon carbide by gasification of steel wire according to claim 1, characterized in that: The hot iron plate is energized and induction heated to 300-600°C by nickel-chromium wire or copper tube. The surface of the hot iron plate is machined with a grid-shaped groove with a groove depth of less than 1 mm. During the cutting and heat leveling process, the operating equipment and atmosphere device are equipped with a volatile substance collection device to collect SiCl4 or SiH4 volatile substances and handle them safely.