Surface treatment process method for preparing silicon carbide material by CVD (Chemical Vapor Deposition) method
By forming an oxide layer on the surface of silicon carbide material and removing defects, the problem of surface defects in silicon carbide material prepared by CVD method is solved, which improves the stability of the material and the service life and yield of the etching ring and spray head.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG LIUFANG CARBON TECH CO LTD
- Filing Date
- 2025-12-19
- Publication Date
- 2026-05-12
AI Technical Summary
Silicon carbide materials prepared by CVD have processing defects on their surface, such as chipping and microcracks, which make them prone to particulate contaminants during etching, affecting the stability and lifespan of the etching ring and spray head.
An oxide layer is formed on the surface of silicon carbide material using an oxidation process. By controlling the oxygen flow rate, segmented heating and cooling rates, and temperature, a dense silicon dioxide film is formed to cover surface defects. The oxide layer is then removed by chemical cleaning.
It significantly improves the lifespan of silicon carbide materials and the stability of the etching process, reduces surface defects, and enhances the lifespan and yield of etching rings and spray heads.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of silicon carbide materials, and in particular to a surface treatment process for preparing silicon carbide materials by CVD. Background Technology
[0002] In the etching process of integrated circuits, the etching ring and spray head are continuously bombarded and corroded by etching ions in the reaction chamber, making them critical consumables that directly determine the product stability and yield of the etching process. Silicon carbide (SiC) material has high thermal conductivity, high density, and high purity, offering better corrosion resistance and stability than silicon, and a lifespan approximately three times longer. Therefore, SiC is the preferred material for fabricating etching rings and spray head components in advanced manufacturing processes.
[0003] Silicon carbide prepared by CVD is extremely hard and brittle, making it very difficult to machine. Furthermore, the machined surface often exhibits defects (mainly chipping and microcracks). These defects are more easily etched during etching due to high stress, leading to particulate contaminants at the defect sites and ultimately causing wafer scrap and yield loss. Therefore, addressing surface defects in silicon carbide is currently a key aspect of improving the lifespan and stability of etching rings and spray heads for silicon carbide materials. Summary of the Invention
[0004] This invention provides a surface treatment process for preparing silicon carbide materials by CVD, in order to remove defects and improve the lifespan of components during etching.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: A surface treatment process for preparing silicon carbide materials by CVD includes the following steps: The silicon carbide material prepared by CVD method is placed in an oxidation furnace for oxidation treatment to form an oxide layer on the surface of the silicon carbide material. Remove the oxide layer.
[0006] Preferably, the oxidation treatment includes the following steps: Oxygen is introduced, and the temperature is raised from room temperature to the first preset temperature at a rate of 3-5℃ / min, and then kept warm. Continue heating at a rate of 2-3℃ / min to the second preset temperature, then heat at a rate of 0.8-1.2℃ / min to the target process temperature, and perform heat preservation oxidation; The temperature is lowered to the first preset temperature at a rate of 2.5-3.5℃ / min, then lowered to the third preset temperature at a rate of 1.3-1.8℃ / min, and finally cooled naturally.
[0007] Preferably, the oxygen flow rate is 16-24 l / min.
[0008] Preferably, there are 8 oxygen nozzles evenly distributed inside the oxidation furnace, and the flow rate of each oxygen nozzle is 2-3 l / min.
[0009] Preferably, the first preset temperature is 750-850℃, and the heat preservation time is 1-2 hours.
[0010] Preferably, the second preset temperature is 1200-1300℃.
[0011] Preferably, the target process temperature is 1350-1450°C and the oxidation process time is 25-35 hours.
[0012] Preferably, the third preset temperature is 550-650℃.
[0013] Preferably, the oxide layer has a thickness of 1 μm and is removed by chemical cleaning.
[0014] Preferably, after heating to the second preset temperature, oxygen is stopped, and nitrogen gas is introduced at a flow rate of 16-24 L / min, and the temperature is maintained for 60-120 min; then nitrogen gas is stopped, oxygen gas is introduced again, and the temperature is increased to the target process. Silicon carbide has many defects at grain boundaries, which diffuse rapidly and oxidize quickly, easily forming defects along the grain boundaries. By introducing nitrogen gas before oxidation, nitrogen atoms preferentially diffuse to the grain boundaries to form SiCN, significantly inhibiting the rapid diffusion of oxygen along the grain boundaries during subsequent oxidation.
[0015] Preferably, during the oxidation process, multi-point thermocouples are used to monitor the temperature inside the oxidation furnace, and the temperature uniformity is controlled within ±5℃. The oxidation of silicon carbide is extremely sensitive to temperature; even slight temperature differences can directly lead to differences in the oxidation rate, resulting in significantly different oxidation depths in different areas, forming "oxidation corrosion pits." Therefore, this invention requires temperature uniformity to be controlled within ±5℃.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: By treating silicon carbide materials through an oxidation process, the defect layer is uniformly oxidized to form an oxide layer (silicon dioxide film) on its surface. The oxide layer is then removed, thereby eliminating surface defects and significantly improving the lifespan of SiC materials and the stability and yield of the etching process. The key to this invention lies in achieving consistency and uniformity in the oxidation depth by controlling oxygen concentration, reaction temperature, and reaction time. Otherwise, oxidation pits will appear on the SiC surface after oxidation, rendering the oxidation process ineffective. Therefore, this invention first employs a segmented, slow heating process, with each segment approaching the target temperature at a slower rate. Specifically, the temperature is first increased to a first preset temperature at a rate of 3-5°C / min, allowing sufficient time for heat to transfer from the surface of the silicon carbide material to its interior. This ensures that the temperature of the entire component rises as synchronously as possible, reducing thermal stress. The component is then held at the first preset temperature to release microscopic stresses (such as machining stress and growth stress) within the silicon carbide material, preventing stress buildup and cracking at higher temperatures. Next, the temperature is increased to a second preset temperature at a rate of 2-3°C / min to reduce the stress risk caused by thermal expansion of silicon carbide at high temperatures. Finally, the target process is then carried out. The material undergoes a heat preservation oxidation treatment at a specific temperature to form a dense silicon dioxide film, which covers surface micro-defects (such as microcracks and chipping), forming a continuous and dense oxide layer. Finally, the material is cooled in stages at a rate of 2.5-3.5℃ / min to the first preset temperature, allowing sufficient time for the atoms inside the material to rearrange themselves, eliminating new thermal stress and phase transformation stress generated during the high-temperature oxidation process. This ensures uniform shrinkage inside and outside the component and avoids brittle cracking caused by excessive temperature difference. Since the material is more brittle at lower temperatures, a gentler cooling method is used, i.e., cooling at a rate of 1.3-1.8℃ / min to the third preset temperature, followed by natural cooling. Detailed Implementation
[0017] The present invention will now be described in more detail. It should be noted that the description of the present invention is illustrative only and not restrictive. Various embodiments can be combined with each other to form other embodiments not shown in the following description.
[0018] Example 1
[0019] A surface treatment process for preparing silicon carbide materials by CVD includes the following steps: The silicon carbide material prepared by CVD was placed in an oxidation furnace, oxygen was introduced for 16 min, and the temperature was increased from room temperature to 1350℃ at a rate of 4℃ / min for 30 h to form a 0.9 μm oxide layer on the surface of the silicon carbide material. The oxide layer was removed by cleaning with 49% HF at a temperature of 20°C for 25 minutes.
[0020] Example 2
[0021] A surface treatment process for preparing silicon carbide materials by CVD includes the following steps: The silicon carbide material prepared by CVD was placed in an oxidation furnace, oxygen was introduced at a rate of 24 l / min, and the temperature was increased from room temperature to 1400℃ at a rate of 5℃ / min for 32 h to form a 1 μm oxide layer on the surface of the silicon carbide material. The oxide layer was removed by cleaning with 49% HF at a temperature of 25°C for 30 minutes.
[0022] Example 3
[0023] A surface treatment process for preparing silicon carbide materials by CVD includes the following steps: The silicon carbide material prepared by CVD was placed in an oxidation furnace, and oxygen was introduced at a rate of 24 L / min. The temperature was increased from room temperature to 800℃ at a rate of 3℃ / min and held for 1 h. The temperature was then increased to 1200℃ at a rate of 2℃ / min, and then increased to 1350℃ at a rate of 0.8℃ / min and held for oxidative treatment for 25 h. The temperature was then decreased to 800℃ at a rate of 2.5℃ / min, and then decreased to 600℃ at a rate of 1.3℃ / min. Finally, the temperature was allowed to cool naturally, forming a 1 μm oxide layer on the surface of the silicon carbide material. The oxide layer was removed by cleaning with 49% HF at a temperature of 20°C for 25 minutes.
[0024] Example 4
[0025] A surface treatment process for preparing silicon carbide materials by CVD includes the following steps: The silicon carbide material prepared by CVD was placed in an oxidation furnace, and oxygen was introduced at a rate of 24 L / min. The temperature was increased from room temperature to 800℃ at a rate of 5℃ / min and held for 2 hours. The temperature was then increased to 1200℃ at a rate of 3℃ / min, and then increased to 1350℃ at a rate of 1.2℃ / min and held for 35 hours. The temperature was then decreased to 800℃ at a rate of 3.5℃ / min, and then decreased to 600℃ at a rate of 1.8℃ / min. Finally, the temperature was allowed to cool naturally, forming a 1.1 μm oxide layer on the surface of the silicon carbide material. The oxide layer was removed by cleaning with 49% HF at a temperature of 20°C for 25 minutes.
[0026] Example 5
[0027] A surface treatment process for preparing silicon carbide materials by CVD includes the following steps: The silicon carbide material prepared by CVD was placed in an oxidation furnace, and oxygen was introduced at a rate of 24 L / min. The temperature was increased from room temperature to 750°C at a rate of 4°C / min and held for 2 h. The temperature was then increased to 1300°C at a rate of 2°C / min, and then increased to 1350°C at a rate of 1°C / min and held for 30 h. The temperature was then decreased to 750°C at a rate of 3°C / min, and then decreased to 600°C at a rate of 1.5°C / min. Finally, the temperature was allowed to cool naturally, forming a 1.1 μm oxide layer on the surface of the silicon carbide material. The oxide layer was removed by cleaning with 49% HF at a temperature of 20°C for 25 minutes.
[0028] Example 6
[0029] A surface treatment process for preparing silicon carbide materials by CVD includes the following steps: The silicon carbide material prepared by CVD was placed in an oxidation furnace, and oxygen was introduced at a rate of 24 L / min. The temperature was increased from room temperature to 850°C at a rate of 4°C / min and held for 2 h. The temperature was then increased to 1300°C at a rate of 2°C / min, and then increased to 1450°C at a rate of 1°C / min and held for 30 h. The temperature was then decreased to 850°C at a rate of 3°C / min, and then decreased to 600°C at a rate of 1.5°C / min. Finally, the temperature was allowed to cool naturally, forming a 1.1 μm oxide layer on the surface of the silicon carbide material. The oxide layer was removed by cleaning with 49% HF at a temperature of 20°C for 25 minutes.
[0030] Example 7
[0031] A surface treatment process for preparing silicon carbide materials by CVD includes the following steps: The silicon carbide material prepared by CVD was placed in an oxidation furnace, and oxygen was introduced at a rate of 24 L / min. The temperature was increased from room temperature to 850°C at a rate of 4°C / min and held. The temperature was then increased to 1300°C at a rate of 2°C / min, oxygen was stopped, nitrogen was introduced at a rate of 16 L / min, and the temperature was held for 60 min. Then, nitrogen was stopped, oxygen was introduced, and the temperature was increased to 1450°C at a rate of 1°C / min and held for oxidation. The temperature was then decreased to 850°C at a rate of 3°C / min, then decreased to 600°C at a rate of 1.5°C / min, and finally allowed to cool naturally, forming a 1 μm oxide layer on the surface of the silicon carbide material. The oxide layer was removed by cleaning with 49% HF at a temperature of 20°C for 25 minutes.
[0032] Example 8
[0033] A surface treatment process for preparing silicon carbide materials by CVD includes the following steps: The silicon carbide material prepared by CVD was placed in an oxidation furnace, and oxygen was introduced at a rate of 24 L / min. The temperature was increased from room temperature to 850°C at a rate of 4°C / min and held. The temperature was then increased to 1300°C at a rate of 2°C / min, oxygen was stopped, nitrogen was introduced at a rate of 24 L / min, and the temperature was held for 120 min. Then, nitrogen was stopped, oxygen was introduced, and the temperature was increased to 1450°C at a rate of 1°C / min and held for oxidation. The temperature was then decreased to 850°C at a rate of 3°C / min, then decreased to 600°C at a rate of 1.5°C / min, and finally allowed to cool naturally, forming a 1.1 μm oxide layer on the surface of the silicon carbide material. The oxide layer was removed by cleaning with 49% HF at a temperature of 20°C for 25 minutes.
[0034] Comparative Example High-density SiC materials were prepared by CVD without surface treatment.
[0035] Testing: The product obtained in Example 1 was scanned using SEM. For the products obtained in Examples 1-8 and the comparative examples, a laser scattering particle counter (detection limit 0.1 μm) was used to scan the entire surface after treatment. The content of surface metal impurities was detected using TXRF (total internal reflection X-ray fluorescence) technology. The results are detailed in Table 1.
[0036] Table 1
[0037] As shown in Table 1, the products prepared in Examples 1-8 have significantly lower total content and number of metal impurities on their surface than the comparative examples.
[0038] 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 surface treatment process for preparing silicon carbide materials by CVD, characterized in that, Includes the following steps: The silicon carbide material prepared by CVD method is placed in an oxidation furnace for oxidation treatment to form an oxide layer on the surface of the silicon carbide material. Remove the oxide layer.
2. The surface treatment process according to claim 1, characterized in that, The oxidation treatment includes the following steps: Oxygen is introduced, and the temperature is raised from room temperature to the first preset temperature at a rate of 3-5℃ / min, and then kept warm. Continue heating at a rate of 2-3℃ / min to the second preset temperature, then heat at a rate of 0.8-1.2℃ / min to the target process temperature, and perform heat preservation oxidation; The temperature is lowered to the first preset temperature at a rate of 2.5-3.5℃ / min, then lowered to the third preset temperature at a rate of 1.3-1.8℃ / min, and finally cooled naturally.
3. The surface treatment process according to claim 2, characterized in that, The oxygen flow rate is 16-24 L / min.
4. The surface treatment process method according to claim 2 or 3, characterized in that, The oxidation furnace has 8 oxygen nozzles evenly distributed inside, with each oxygen nozzle having a flow rate of 2-3 L / min.
5. The surface treatment process according to claim 2, characterized in that, The first preset temperature is 750-850℃, and the heat preservation time is 1-2 hours.
6. The surface treatment process according to claim 2, characterized in that, The second preset temperature is 1200-1300℃.
7. The surface treatment process according to claim 2, characterized in that, The target process temperature is 1350-1450°C, and the oxidation process time is 25-35 hours.
8. The surface treatment process according to claim 2, characterized in that, The third preset temperature is 550-650℃.
9. The surface treatment process according to claim 1, characterized in that, The oxide layer was 1 μm thick and was removed by chemical cleaning.
10. The surface treatment process according to claim 1, characterized in that, After heating to the second preset temperature, stop the oxygen supply and introduce nitrogen at a flow rate of 16-24 L / min, and hold for 60-120 min; then stop the nitrogen supply, continue to introduce oxygen, and heat to the target process temperature.