A process for cleaning silicon carbide furnace tubes

Abstract

The application discloses a silicon carbide furnace tube cleaning process and relates to the technical field of silicon carbide furnace tube cleaning. The cleaning process comprises the following steps: sequentially cleaning the silicon carbide furnace tube in pure water, a hydrofluoric acid solution and a cleaning solution; washing with water, drying, detecting the number of surface particles, and achieving the standard, and the cleaning of the silicon carbide furnace tube is completed. The application can effectively and quickly clean organic impurities, heavy metal ions and alkali metal ions on the surface of the silicon carbide furnace tube.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide furnace tube cleaning technology, and more specifically to a silicon carbide furnace tube cleaning process. Background Technology

[0002] When impurity ions are implanted into a semiconductor chip, the high-energy incident ions collide with atoms on the semiconductor lattice, causing some lattice atoms to shift and creating numerous vacancies. This results in disordered atomic arrangement or amorphous regions in the implanted area. Therefore, annealing is necessary after ion implantation, where the semiconductor is annealed at a specific temperature to restore the crystal structure and eliminate defects. Annealing also activates the functions of donor and acceptor impurities, allowing impurity atoms in interstitial positions to move into their substituted sites. Silicon carbide is a material with high strength, high hardness, good wear resistance, high temperature resistance, corrosion resistance, good thermal shock resistance, high thermal conductivity, and good oxidation resistance. It is mainly used in medium-frequency smelting, various electric heat treatment furnaces, metallurgy, chemical industry, and non-ferrous metal processing. Furnace tubes made from silicon carbide have advantages such as high strength, high hardness, good wear resistance, good thermal shock resistance, high thermal conductivity, good oxidation resistance, and non-reaction with strong acids and alkalis.

[0003] During long-term operation, existing annealing furnace tubes can accumulate metal impurities due to etching solutions and incomplete post-cleaning processes. These impurities can remain in the furnace tubes during normal production. In such cases, trace amounts of metal ions from the contaminated furnace tubes can circulate and contaminate the semiconductors being produced. This invention discloses a novel cleaning process suitable for cleaning annealing furnace tubes, possessing significant practical value. Summary of the Invention

[0004] The purpose of this invention is to provide a silicon carbide furnace tube cleaning process to solve the following technical problems:

[0005] Existing cleaning processes are ineffective at removing organic impurities, heavy metal ions, and alkali metal ions from furnace tube surfaces, and are highly corrosive.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A silicon carbide furnace tube cleaning process, comprising the following steps:

[0008] S1: Immerse the silicon carbide furnace tube in pure water;

[0009] S2: Immerse the silicon carbide furnace tube in hydrofluoric acid;

[0010] S3: After soaking in hydrofluoric acid solution, place the silicon carbide furnace tube in the cleaning solution for cleaning;

[0011] S4: Wash and dry. Cleaning complete.

[0012] As a further aspect of the present invention, the cleaning solution comprises the following raw materials by weight percentage: 3-12% tetramethylammonium hydroxide, 5-15% fatty alcohol polyoxyethylene ether ammonium sulfate, 1-5% additives, and the balance being water.

[0013] As a further aspect of the present invention, the method for preparing the additive includes the following steps:

[0014] S1: Mix macroporous chloromethyl polystyrene resin and tetrahydrofuran evenly, add ethylenediamine, heat to 40-50℃, keep warm for 24-36h, filter, wash and dry to obtain ethylenediamine modified resin.

[0015] S2: In a nitrogen atmosphere, the ethylenediamine modified resin is added to a mixed solution of dichloromethane and ethylenediaminetetraacetic acid, thionyl chloride is added, and the reaction is carried out for 3-6 hours to obtain the modified resin.

[0016] S3: Add the modified resin and inositol hexaphosphate to the reactor, stir at room temperature for 24-30 hours, wash with water and dry to obtain the additive.

[0017] As a further aspect of the present invention, the preparation method of the macroporous chloromethyl polystyrene resin includes the following steps:

[0018] A1: Add 10 mL of styrene and 5 mL of divinylbenzene to a reaction flask, then add 0.1 g of BPO and stir until completely dissolved. Add 2 g of porogen and 500 mL of distilled water, then add 0.5 g of polyvinyl alcohol and 0.1 mL of 1 wt% methylene blue aqueous solution. Heat to 75 °C and react for 2 h, then heat to 80 °C and react for 2 h. Maintain at 95-100 °C for 6 h. Filter, wash, and dry to obtain component one.

[0019] A2: Add 10g of component one and 50g of chloromethyl ether to the reaction flask, stir well, add 1g of anhydrous zinc chloride, heat to 50-52℃, keep the temperature for 6-9h, filter, wash and dry to obtain the carrier.

[0020] As a further aspect of the present invention, the mass ratio of macroporous chloromethyl polystyrene resin: tetrahydrofuran: ethylenediamine is 1:1-2:4-8.

[0021] As a further aspect of the present invention: the mass ratio of the ethylenediamine modified resin: dichloromethane: ethylenediaminetetraacetic acid: dichloro sulfoxide is 1:100-200:10-15:3-6.

[0022] As a further aspect of the present invention: the mass ratio of the modified resin to inositol hexaphosphate is 1:0.01-0.1.

[0023] As a further aspect of the present invention: the cleaning conditions for S3 are: heating to 50-60℃ and ultrasonic cleaning at 20-40kHz.

[0024] As a further aspect of the present invention: the hydrofluoric acid is a hydrofluoric acid solution with a mass percentage of 40-60%, and the soaking time is 12-24 hours.

[0025] As a further aspect of the present invention: the specific drying step in S4 is as follows: the surface of the silicon carbide furnace tube is dried by blowing nitrogen gas with a purity greater than 99.99% and then placed in an oven for drying.

[0026] As a further aspect of the present invention: the specific steps of water washing in S4 are as follows: after ultrapure water spray washing, place it in an overflow rinsing tank, change the water three times continuously, and then perform a fourth overflow rinsing for 12 hours.

[0027] As a further aspect of the present invention: the sample is immersed in hydrofluoric acid and rotated once every 3 hours.

[0028] The beneficial effects of this invention are:

[0029] 3-12% Tetramethylammonium hydroxide, 5-15% Fatty alcohol polyoxyethylene ether ammonium sulfate, 1-5% Additives

[0030] (1) This application utilizes water washing followed by hydrofluoric acid washing to remove the oxide film on the surface of the silicon nitride furnace tube, thereby facilitating the removal of metal and organic contaminants embedded in the oxide layer. After hydrofluoric acid washing, the furnace tube is immersed in the cleaning solution. The organic contaminants on the surface of the furnace tube expand, and the interaction force between the organic contaminants and the furnace tube weakens. Fatty alcohol polyoxyethylene ether ammonium sulfate carries the organic contaminants away from the surface of the furnace tube. Its polyoxyethylene chains undergo hydration in the water and form hydrogen bonds with hydrogen in the water. As the water temperature rises, the hydrogen bonds weaken, the hydration decreases, and the capacity for organic contaminants increases, making it easier to wash away.

[0031] (2) In this application, tetramethylammonium hydroxide is added to the cleaning solution. Tetramethylammonium hydroxide is water-stable and can effectively dissolve organic impurities. Fatty alcohol polyoxyethylene ether ammonium sulfate can reduce surface tension and has wetting and penetrating effects, which can remove heavy metal particles and alkali metal ions remaining on the surface of the furnace tube from the surface of the furnace tube. Tetramethylammonium hydroxide also has a certain complexing effect, which can convert metal ions into complexes and remove them during cleaning. Ammonium fatty alcohol polyoxyethylene ether sulfate reduces the surface energy of the furnace tube surface, disrupting the environment for adsorbing impurity particles and reducing secondary adsorption. Ammonium fatty alcohol polyoxyethylene ether sulfate also has a penetrating effect; osmotic pressure causes free surfactant molecules in the solvent, as well as the unadsorbed free portions on the hydrophilic groups of adsorbed surfactant molecules, to penetrate into the contact gap between the furnace tube and impurity particles. These molecules attract and combine with the remaining free bonds on the furnace tube surface and impurity particles, reducing the force bonds between the furnace tube and impurity particles and promoting the separation of impurity particles from the furnace tube surface. The additive has excellent chelating effects on metal ions, removing metal ion and atomic contamination. The components of this cleaning agent, when used in combination, have the advantages of excellent cleaning performance, low residue and low corrosiveness, and high surface smoothness of the cleaned furnace tube. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] The preparation method of macroporous chloromethyl polystyrene resin includes the following steps:

[0035] A1: Add 10 mL of styrene and 5 mL of divinylbenzene to a reaction flask, then add 0.1 g of BPO and stir until completely dissolved. Add 2 g of porogen and 500 mL of distilled water, then add 0.5 g of polyvinyl alcohol and 0.1 mL of 1 wt% methylene blue aqueous solution. Heat to 75 °C and react for 2 h, then heat to 80 °C and react for 2 h. Maintain at 95-100 °C for 6 h. Filter, wash, and dry to obtain component one.

[0036] A2: Add 10g of component one and 50g of chloromethyl ether to the reaction flask, stir well, add 1g of anhydrous zinc chloride, heat to 50-52℃, keep the temperature for 6h, filter, wash and dry to obtain the carrier.

[0037] Example 2

[0038] The preparation method of the additive includes the following steps:

[0039] S1: Mix 1g of macroporous chloromethyl polystyrene resin prepared in Example 1 with 1g of tetrahydrofuran and stir until uniform. Add 4g of ethylenediamine, heat to 40°C, keep warm for 24h, filter, wash and dry to obtain ethylenediamine modified resin.

[0040] S2: In a nitrogen atmosphere, 1g of ethylenediamine modified resin was added to a mixed solution of 100g dichloromethane and 10g ethylenediaminetetraacetic acid, and 3g of thionyl chloride was added. The mixture was reacted for 3 hours to obtain the modified resin.

[0041] S3: Add 1g of modified resin and 0.01g of inositol hexaphosphate to the reactor, stir at room temperature for 24h, wash with water and dry to obtain the additive.

[0042] Example 3

[0043] The preparation method of the additive includes the following steps:

[0044] S1: Mix 1g of macroporous chloromethyl polystyrene resin prepared in Example 1 and 1.5g of tetrahydrofuran until homogeneous, add 6g of ethylenediamine, heat to 45°C, keep warm for 30h, filter, wash and dry to obtain ethylenediamine modified resin.

[0045] S2: In a nitrogen atmosphere, 1g of ethylenediamine modified resin was added to a mixed solution of 150g dichloromethane and 12g ethylenediaminetetraacetic acid, and 4g dichlorosulfoxide was added. The mixture was reacted for 6 hours to obtain the modified resin.

[0046] S3: Add 1g of modified resin and 0.05g of inositol hexaphosphate to the reactor, stir at room temperature for 30h, wash with water and dry to obtain the additive.

[0047] Example 4

[0048] The preparation method of the additive includes the following steps:

[0049] S1: Mix 1g of macroporous chloromethyl polystyrene resin prepared in Example 1 with 2g of tetrahydrofuran, add 8g of ethylenediamine, heat to 50°C, keep warm for 36h, filter, wash and dry to obtain ethylenediamine modified resin.

[0050] S2: In a nitrogen atmosphere, 1g of ethylenediamine modified resin was added to a mixed solution of 200g dichloromethane and 15g ethylenediaminetetraacetic acid, and 6g of thionyl chloride was added. The mixture was reacted for 6 hours to obtain the modified resin.

[0051] S3: Add 1g of modified resin and 0.1g of inositol hexaphosphate to the reactor, stir at room temperature for 36h, wash with water and dry to obtain the additive.

[0052] Example 5

[0053] The cleaning solution comprises the following raw materials by weight percentage: 5% tetramethylammonium hydroxide, 15% fatty alcohol polyoxyethylene ether ammonium sulfate, 2% additive prepared in Example 2, and 78% water.

[0054] Example 6

[0055] The cleaning solution comprises the following raw materials by weight percentage: 5% tetramethylammonium hydroxide, 15% fatty alcohol polyoxyethylene ether ammonium sulfate, 2% additive prepared in Example 3, and 78% water.

[0056] Example 7

[0057] The cleaning solution comprises the following raw materials by weight percentage: 5% tetramethylammonium hydroxide, 15% fatty alcohol polyoxyethylene ether ammonium sulfate, 2% additive prepared in Example 4, and 78% water.

[0058] Example 8

[0059] A silicon carbide furnace tube cleaning process, comprising the following steps:

[0060] S1: Soak the silicon carbide furnace tube in pure water for 30 minutes;

[0061] S2: Immerse the silicon carbide furnace tube in a 49wt% hydrofluoric acid solution for 12 hours, rotating it once every 3 hours;

[0062] S3: The silicon carbide furnace tube, after being soaked in hydrofluoric acid solution, is placed in the cleaning solution prepared in Example 5, heated to 50°C, and ultrasonically cleaned at 20 kHz.

[0063] S4: After being sprayed with ultrapure water, the tube is placed in an overflow rinsing tank and the water is changed three times. The fourth overflow rinsing lasts for 12 hours. After the surface of the silicon carbide furnace tube is dried with nitrogen gas with a purity greater than 99.99%, it is placed in an oven at 150°C for 6 hours to dry. The cleaning is then complete.

[0064] Example 8

[0065] A silicon carbide furnace tube cleaning process, comprising the following steps:

[0066] S1: Soak the silicon carbide furnace tube in pure water for 30 minutes;

[0067] S2: Immerse the silicon carbide furnace tube in a 49wt% hydrofluoric acid solution for 12 hours, rotating it once every 3 hours;

[0068] S3: The silicon carbide furnace tube, after being soaked in hydrofluoric acid solution, is placed in the cleaning solution prepared in Example 6, heated to 50°C, and ultrasonically cleaned at 20 kHz.

[0069] S4: After being sprayed with ultrapure water, the tube is placed in an overflow rinsing tank and the water is changed three times. The fourth overflow rinsing lasts for 12 hours. After the surface of the silicon carbide furnace tube is dried with nitrogen gas with a purity greater than 99.99%, it is placed in an oven at 150°C for 6 hours to dry. The cleaning is then complete.

[0070] Example 10

[0071] A silicon carbide furnace tube cleaning process, comprising the following steps:

[0072] S1: Soak the silicon carbide furnace tube in pure water for 30 minutes;

[0073] S2: Immerse the silicon carbide furnace tube in a 49wt% hydrofluoric acid solution for 12 hours, rotating it once every 3 hours;

[0074] S3: The silicon carbide furnace tube, after being soaked in hydrofluoric acid solution, is placed in the cleaning solution prepared in Example 7, heated to 50°C, and ultrasonically cleaned at 20 kHz.

[0075] S4: After being sprayed with ultrapure water, the tube is placed in an overflow rinsing tank and the water is changed three times. The fourth overflow rinsing lasts for 12 hours. After the surface of the silicon carbide furnace tube is dried with nitrogen gas with a purity greater than 99.99%, it is placed in an oven at 150°C for 6 hours to dry. The cleaning is then complete.

[0076] Comparative Example 1

[0077] The preparation method of the additive includes the following steps:

[0078] S1: Mix 1g of macroporous chloromethyl polystyrene resin prepared in Example 1 with 1g of tetrahydrofuran, stir until uniform, add 4g of ethylenediamine, heat to 40°C, keep warm for 24h, filter, wash and dry to obtain the additive.

[0079] Comparative Example 2

[0080] The preparation method of the additive includes the following steps:

[0081] S1: Mix 1g of macroporous chloromethyl polystyrene resin prepared in Example 1 with 1g of tetrahydrofuran and stir until uniform. Add 4g of ethylenediamine, heat to 40°C, keep warm for 24h, filter, wash and dry to obtain ethylenediamine modified resin.

[0082] S2: In a nitrogen atmosphere, 1g of ethylenediamine modified resin was added to a mixed solution of 100g dichloromethane and 10g ethylenediaminetetraacetic acid, and 3g of thionyl chloride was added. The reaction was carried out for 3 hours to obtain the additive.

[0083] Comparative Example 3

[0084] The cleaning solution comprises the following raw materials by weight percentage: 5% tetramethylammonium hydroxide, 15% fatty alcohol polyoxyethylene ether ammonium sulfate, 2% additive prepared in Comparative Example 1, and 78% water.

[0085] Comparative Example 4

[0086] The cleaning solution comprises the following raw materials by weight percentage: 5% tetramethylammonium hydroxide, 15% fatty alcohol polyoxyethylene ether ammonium sulfate, 2% additive prepared in Comparative Example 2, and 78% water.

[0087] Comparative Example 5

[0088] Compared with Example 8, Comparative Example 5 only replaced the cleaning solution prepared in Example 5 with the cleaning solution prepared in Comparative Example 3 in an equal amount, and the other steps were completely the same.

[0089] Comparative Example 6

[0090] Compared with Example 8, Comparative Example 6 only replaced the cleaning solution prepared in Example 5 with the cleaning solution prepared in Comparative Example 4 in an equal amount, and the other steps were completely the same.

[0091] Performance testing

[0092] (1) The surface roughness of the furnace tube after cleaning was detected using an Agilent 5600LS atomic force microscope (AFM) manufactured by Agilent Technologies, USA.

[0093] (2) The surface condition of the furnace tube was observed with the aid of an OLYMPUS BX60M metallographic microscope to detect the removal effect of particles with a particle size of 0.1 μm and above.

[0094] Table 1: Performance Test Data Statistics of Examples 8-10 and Comparative Examples 5-6

[0095]

[0096]

[0097] As shown in Table 1, the cleaning process of this application has the advantages of good cleaning ability and low corrosion resistance.

[0098] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A silicon carbide furnace tube cleaning process, characterized in that, The process includes the following steps: S1: Immerse the silicon carbide furnace tube in pure water; S2: Immerse the silicon carbide furnace tube in hydrofluoric acid; S3: After soaking in hydrofluoric acid solution, place the silicon carbide furnace tube in the cleaning solution for cleaning; S4: Wash and dry; cleaning complete. The cleaning solution comprises the following raw materials by weight percentage: 3-12% tetramethylammonium hydroxide, 5-15% fatty alcohol polyoxyethylene ether ammonium sulfate, 1-5% additives, and the balance being water; The preparation method of the additive includes the following steps: S1: Mix macroporous chloromethyl polystyrene resin and tetrahydrofuran evenly, add ethylenediamine, heat to 40-50℃, keep warm for 24-36h, filter, wash and dry to obtain ethylenediamine modified resin. S2: In a nitrogen atmosphere, the ethylenediamine modified resin is added to a mixed solution of dichloromethane and ethylenediaminetetraacetic acid, thionyl chloride is added, and the reaction is carried out for 3-6 hours to obtain the modified resin. S3: Add the modified resin and inositol hexaphosphate to the reactor, stir at room temperature for 24-36 hours, wash with water and dry to obtain the additive; The mass ratio of macroporous chloromethyl polystyrene resin: tetrahydrofuran: ethylenediamine is 1:1-2:4-8; The mass ratio of the ethylenediamine-modified resin, dichloromethane, ethylenediaminetetraacetic acid, and thionyl chloride is 1: 100-200: 10-15: 3-6. The mass ratio of the modified resin to inositol hexaphosphate is 1:0.01-0.

1.

2. The silicon carbide furnace tube cleaning process according to claim 1, characterized in that, The cleaning conditions for S3 are: heating to 50-60℃ and ultrasonic cleaning at 20-40kHz.

3. The silicon carbide furnace tube cleaning process according to claim 1, characterized in that, The hydrofluoric acid is a hydrofluoric acid solution with a mass percentage of 40-60%, and the soaking time is 12-24 hours.

4. The silicon carbide furnace tube cleaning process according to claim 1, characterized in that, The specific drying steps in S4 are as follows: the surface of the silicon carbide furnace tube is dried by blowing nitrogen gas with a purity greater than 99.99%, and then placed in an oven for drying.

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