Method for purifying high-purity silicon carbide powder
By using purification furnaces and high-purity quartz tube heating technology in the production of high-purity silicon carbide powder, the problems of small output, low efficiency and impurity pollution in traditional methods are solved, and high purity and large-scale production are achieved, reducing costs and increasing market share.
Patent Information
- Application Number
- CN202411979622.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-05-02
AI Technical Summary
The traditional high-purity silicon carbide production method is limited by the volume of the muffle furnace, the output is small and the continuous operation cannot be carried out, the efficiency is low, and it cannot meet the needs of large-capacity silicon carbide synthesis. At the same time, due to thermal insulation cotton, there will be impurities in the atmosphere group to cause pollution.
The high-purity silicon carbide powder is purified at a high temperature by using a purification furnace, and the high-purity quartz tube is heated and stirred and heated. Combined with the precise control of heating, insulation, cooling and temperature and time, the excess carbon is removed and the purity of the powder is improved.
It has achieved a purity of more than 99.99995% of high-purity silicon carbide powder, and a large amount of purification in a single time. It is suitable for large-scale commercial applications, reducing production costs, improving market share, and improving work efficiency and safety.
Smart Images
Figure CN119911908A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of high-purity silicon carbide powder purification, and in particular to a high-purity silicon carbide powder purification method. Background Art
[0002] There are three main methods for producing high-purity silicon carbide powder: solid phase method, liquid phase method and gas phase method. Among them, the self-propagating high-temperature synthesis method in the solid phase method is currently the most commonly used method for synthesizing high-purity silicon carbide powder. This method uses high-purity silicon powder and high-purity carbon powder as raw materials, reacts directly at 1800-2200℃, and ensures that the synthesis reaction is carried out continuously and effectively by increasing the synthesis temperature and continuously heating to produce high-purity silicon carbide powder.
[0003] The purity of silicon carbide powder used to grow silicon carbide single crystals is very high, and the impurity content should be at least less than 5ppmw. During the synthesis process of high-purity silicon carbide powder, in order to ensure the complete reaction, the carbon-silicon molar ratio is usually greater than 1 when the raw materials are mixed, resulting in a small amount of carbon remaining after synthesis. In order to ensure the purity requirements of silicon carbide powder, silicon carbide powder is usually purified after synthesis to remove excess carbon. At present, conventional carbon removal methods mainly include chemical carbon removal and physical carbon removal. Chemical carbon removal processes are generally divided into heating oxidation method and chemical oxidation method. Physical carbon removal methods are generally divided into flotation method, heavy liquid separation method, and hydrocyclone method. In the silicon carbide semiconductor manufacturing process, the carbon removal method is to use chemical carbon removal method, put the synthesized silicon carbide powder into a special container and push it into a muffle furnace for high-temperature heating and carbon removal.
[0004] The traditional high-purity silicon carbide production method is limited by the volume of the muffle furnace. The weight of silicon carbide carried each time is about 3 kG, the output is small and cannot be operated continuously. The efficiency is low and cannot meet the needs of large-scale silicon carbide synthesis. In addition, due to the insulation cotton, there will be impurity elements in the atmosphere group causing pollution.
[0005] How to design a method for purifying high-purity silicon carbide powder that is reasonable and feasible, ingenious in design, easy to operate, suitable for large-scale commercial application of high-purity silicon carbide powder, and can reduce production costs and increase the market share of high-purity silicon carbide powder is a problem that needs to be solved at present. Summary of the invention
[0006] In order to solve the technical problems that the existing traditional high-purity silicon carbide production method is limited by the volume of the muffle furnace, the output is small and cannot be operated continuously, the efficiency is low, and it cannot meet the needs of large-scale silicon carbide synthesis. In addition, due to the insulation cotton, there will be impurity elements in the atmosphere group causing pollution, the present invention provides a high-purity silicon carbide powder purification method to achieve a reasonable and feasible method, ingenious design, low operation difficulty, adapt to large-scale commercial application of high-purity silicon carbide powder, reduce production costs, and increase the market share of high-purity silicon carbide powder.
[0007] The technical solution adopted by the present invention to solve the above technical problems is: a method for purifying high-purity silicon carbide powder, comprising the following steps: Step 1: feeding the synthesized high-purity silicon carbide powder semi-finished product into the purification furnace through the feed inlet, and then closing the furnace door; Step 2: introducing protective gas into the furnace body to remove the high humidity and polluted air in the furnace body; Step 3, heating the high-purity quartz tube in the furnace body to a high temperature and maintaining it for a period of time through a temperature control program; Step 4: Control the temperature in the furnace to maintain for a certain period of time, and at the same time start the agitator to stir the material; Step 5: Turn off the temperature control program and let the furnace cool naturally; Step six, pour the purified high-purity silicon carbide powder into the high-purity quartz crucible through the discharge port and enter the next step.
[0008] The above is a basic implementation of the present invention, and further improvements, perfections and limitations can be made on the above basis: for example, the protective gas introduced in step 2 is high-purity oxygen or dry compressed air.
[0009] The above is a basic implementation mode of the present invention, and further improvements, perfections and limitations can be made on the above basis: For example, the purity of the high-purity oxygen is above 99.99%.
[0010] The above is a basic implementation mode of the present invention, and further improvements, perfections and limitations can be made on the above basis: as described in step three, the purity of the high-purity quartz tube is above 99.99%, the heating temperature is increased from room temperature to 850-950°C, the heating time is controlled to 2-2.5h, and the heating power is controlled to 30-35kw.
[0011] The above is a basic implementation of the present invention, and further improvements, perfections and limitations can be made on the above basis: as described in step 4, the temperature control time is 3-3.5h, the control temperature is 850-950℃, the heating power is 10-15kw, and the agitator speed is controlled at 1-5r / min.
[0012] The above is a basic implementation mode of the present invention, and further improvements, perfections and limitations can be made on the above basis: For example, in step 5, the natural cooling time of the furnace body is 9-12 hours.
[0013] The above is a basic implementation of the present invention, and further improvements, perfections and limitations can be made on the above basis: for example, the purity of the high-purity quartz crucible used in step six is above 99.99%.
[0014] Compared with the prior art, the present invention has the following beneficial effects: First, the invention uses a purification furnace to purify high-purity silicon carbide powder at high temperature to remove excess carbon. The high-purity quartz tube and stirring heating ensure the uniformity of the high-purity powder, and the precise control of heating, insulation, cooling and corresponding temperature and time ensures that the purity of the high-purity silicon carbide powder can reach more than 99.99995%.
[0015] Second, the present invention adopts high-purity quartz tube for heating mainly because the quartz tube has the characteristics of high pressure resistance and corrosion resistance, has high chemical stability at high temperature, does not react chemically with other substances, and can ensure that the high-purity silicon carbide powder does not generate other impurities during the purification process.
[0016] Third, the purification technology adopted in the present invention has a large single purification volume, and the output of a single furnace can be adjusted according to the size, which plays a positive role in the large-scale production and commercial use of high-purity silicon carbide powder.
[0017] Fourth, the purification process can be operated continuously and in large quantities. Compared with the traditional muffle furnace calcination process, the single-time production capacity is increased by more than 10-20 times, which greatly improves work efficiency and effectively reduces production costs. Compared with traditional processes, the safety risk factor is increased and the labor intensity of employees is reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is the schematic diagram of the purification furnace; In the figure, 1. purification furnace, 2. high-purity quartz tube, 3. stirring motor, 4. high-purity oxygen, 5. gas outlet. DETAILED DESCRIPTION
[0019] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.
[0020] Example 1 like Figure 1 As shown, Figure 1 It is the schematic diagram of the purification furnace; A method for purifying high-purity silicon carbide powder comprises the following steps: Step 1: feeding the synthesized high-purity silicon carbide powder semi-finished product into the purification furnace through the feed inlet, and then closing the furnace door; Step 2: introducing high-purity oxygen into the furnace body to remove the high-humidity and polluted air in the furnace body; the purity of the high-purity oxygen is above 99.99%; Step 3, heating the high-purity quartz tube in the furnace body to 850° C. through a temperature control program; the purity of the high-purity quartz tube is above 99.99%, the heating temperature rises from room temperature to 850° C., the heating time is controlled to be 2 hours, and the heating power is controlled to be 30 kW; Step 4: Control the temperature in the furnace for a certain period of time, and start the agitator to stir the material at the same time; the temperature control time is 3 hours, the control temperature is 850°C, the heating power is 10kw, and the agitator speed is controlled at 1r / min; Step 5, turn off the temperature control program and let the furnace cool naturally. The cooling time is 9 hours; Step six, pour the purified high-purity silicon carbide powder into a high-purity quartz crucible through the discharge port and enter the next step of operation. The purity of the high-purity quartz crucible is above 99.99%.
[0021] Example 2 A method for purifying high-purity silicon carbide powder comprises the following steps: Step 1: feeding the synthesized high-purity silicon carbide powder semi-finished product into the purification furnace through the feed inlet, and then closing the furnace door; Step 2: introducing high-purity oxygen into the furnace body to remove the high-humidity and polluted air in the furnace body; the purity of the high-purity oxygen is above 99.99%; Step 3: heat the high-purity quartz tube in the furnace body to 900° C. through a temperature control program; the purity of the high-purity quartz tube is above 99.99%, the heating temperature rises from room temperature to 900° C., the heating time is controlled to be 2.2 hours, and the heating power is controlled to be 33kw; Step 4: Control the temperature in the furnace for a certain period of time, and start the agitator to stir the material at the same time; the temperature control time is 3.2 hours, the control temperature is 900°C, the heating power is 12kw, and the agitator speed is controlled at 3r / min; Step 5, turn off the temperature control program and let the furnace cool naturally. The cooling time is 10 hours. Step six, pour the purified high-purity silicon carbide powder into a high-purity quartz crucible through the discharge port and enter the next step of operation. The purity of the high-purity quartz crucible is above 99.99%.
[0022] Example 3 like Figure 1 As shown, Figure 1 A method for purifying high-purity silicon carbide powder comprises the following steps: Step 1: feeding the synthesized high-purity silicon carbide powder semi-finished product into the purification furnace through the feed inlet, and then closing the furnace door; Step 2: introducing high-purity oxygen into the furnace body to remove the high-humidity and polluted air in the furnace body; the purity of the high-purity oxygen is above 99.99%; Step 3, heating the high-purity quartz tube in the furnace body to 950° C. through a temperature control program; the purity of the high-purity quartz tube is above 99.99%, the heating temperature rises from room temperature to 950° C., the heating time is controlled to be 2.5 hours, and the heating power is controlled to be 35kw; Step 4: Control the temperature in the furnace for a certain period of time, and start the agitator to stir the material at the same time; the temperature control time is 3.5 hours, the control temperature is 950°C, the heating power is 15kw, and the agitator speed is controlled at 5r / min; Step 5, turn off the temperature control program and let the furnace cool naturally. The cooling time is 12 hours. Step six, pour the purified high-purity silicon carbide powder into a high-purity quartz crucible through the discharge port and enter the next step of operation. The purity of the high-purity quartz crucible is above 99.99%.
[0023] The method of the present invention is reasonable and feasible, ingeniously designed, and easy to operate. It is suitable for large-scale commercial application of high-purity silicon carbide powder, reduces production costs, and increases the market share of high-purity silicon carbide powder. It solves the problems that the existing traditional high-purity silicon carbide production method is limited by the volume of the muffle furnace, the output is small, and continuous operation cannot be performed, the efficiency is low, and the needs of large-capacity silicon carbide synthesis cannot be met. In addition, due to the insulation cotton, there will be impurity elements in the atmosphere group causing pollution and other technical problems. Compared with the existing technology, it has good market prospects and development space.
[0024] The preferred specific implementation modes and embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes and embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the concept of the present invention.
Claims
1. A method for purifying high-purity silicon carbide powder, characterized in that: The following steps are included: Step 1: feeding the synthesized high-purity silicon carbide powder semi-finished product into the purification furnace through the feed inlet, and then closing the furnace door; Step 2: introducing protective gas into the furnace body to remove the high humidity and polluted air in the furnace body; Step 3, heating the high-purity quartz tube in the furnace body to a high temperature and maintaining it for a period of time through a temperature control program; Step 4: Control the temperature in the furnace to maintain for a certain period of time, and at the same time start the agitator to stir the material; Step 5: Turn off the temperature control program and let the furnace cool naturally; Step six, pour the purified high-purity silicon carbide powder into the high-purity quartz crucible through the discharge port and enter the next step.
2. A method for purifying high-purity silicon carbide powder according to claim 1, characterized in that: The protective gas introduced in step 2 is high-purity oxygen or dry compressed air.
3. A method for purifying high-purity silicon carbide powder according to claim 2, characterized in that: The purity of the high-purity oxygen is above 99.99%.
4. A method for purifying high-purity silicon carbide powder according to claim 1, characterized in that: The purity of the high-purity quartz tube in step three is above 99.99%, the heating temperature rises from room temperature to 850-950° C., the heating time is controlled to be 2-2.5 hours, and the heating power is controlled to be 30-35 kw.
5. A method for purifying high-purity silicon carbide powder according to claim 1, characterized in that: The temperature control time in step 4 is 3-3.5h, the controlled temperature is 850-950°C, the heating power is 10-15kw, and the stirrer speed is controlled at 1-5r / min.
6. A method for purifying high-purity silicon carbide powder according to claim 1, characterized in that: The natural cooling time of the furnace body in step 5 is 9-12 hours.
7. A method for purifying high-purity silicon carbide powder according to claim 1, characterized in that: The purity of the high-purity quartz crucible used in step six is above 99.99%.