Wet cleaning method for silicon carbide coating graphite substrate component

Abstract

The invention relates to the technical field of semiconductors. The invention discloses a wet cleaning method for a silicon carbide coating graphite substrate component. The wet cleaning method comprises the following steps: step 1, wiping with isopropanol; folding the dust-free cloth, dipping a proper amount of isopropanol solution, and wiping the surface of the component; 2, soaking in a nitric acid aqueous solution; the part is placed in a clean plastic bag, a nitric acid aqueous solution with the volume percent concentration being 5-20% is added, and the normal-temperature soaking time is 2-3 h; 3, constant-temperature heating in a hot water area; the part is placed in a clean plastic bag, ultrapure water is added into the bag, and then the bag is sealed and then sleeved with a layer of bag for sealing; then the sealed part is placed in water with the constant temperature of 75-95 DEG C, and constant-temperature water bath heating is conducted for 48 h; step 4, ultrasonic cleaning; the parts are carried to a 100-level dust-free room to be subjected to ultrasonic cleaning; step 5, washing with pure water; and washing the part by using ultrapure water, then blow-drying by using nitrogen, and finally carrying out dust-free packaging.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, in particular to a method for cleaning a silicon carbide coated graphite substrate component. Background Art

[0002] Metal-organic chemical vapor deposition (MOCVD) equipment is a crucial component in the semiconductor production process. Representing 70% of the value of the entire industry chain (epitaxial wafers, chips, packaging, and applications), it possesses a high level of technological sophistication. The silicon carbide-coated graphite substrate, serving as both the substrate material carrier and heating element, is a critical component of MOCVD equipment, directly determining the uniformity and purity of the thin film material. The purity of the silicon carbide coating directly impacts the quality of the epitaxial wafers.

[0003] The synthesis process for silicon carbide-coated graphite substrates relies primarily on two mainstream technologies: chemical vapor deposition (CVD) and chemical vapor reaction (CVR). The core process of the CVD process includes the following elements: the reaction system uses trichloromethylsilane as a silicon-carbon source precursor, which is vaporized in a precisely temperature-controlled oil bath. The gaseous precursor is introduced into a high-temperature deposition chamber using the synergistic effects of hydrogen carrier gas and diluent gas. Within the optimized temperature range of 1050-1200°C, the active sites on the graphite substrate surface chemically adsorb with the reaction gas to form a transition state complex. This complex then undergoes a multi-step cracking reaction to generate silicon carbide nuclei. These nuclei continue to grow through surface diffusion, ultimately forming a continuous and dense silicon carbide coating.

[0004] Currently, there is no method for cleaning silicon carbide-coated graphite substrate components. Patent CN113488528A discloses a silicon carbide substrate with high surface cleanliness and a cleaning method therefor. However, this patent primarily describes a cleaning method for silicon carbide substrates produced using production equipment comprised of these components, and is therefore of limited reference value. Current research primarily addresses surface contamination from precipitation of silicon carbide-coated graphite substrate components. A solution to the problem of surface contamination from metallic element precipitation during operation remains unresolved.

[0005] Therefore, developing a new wet cleaning process with high cleaning degree and simple procedure is of great significance to improving the element precipitation problem of silicon carbide coated graphite substrate components. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a wet cleaning method for a silicon carbide coated graphite substrate component to solve at least one of the above technical problems.

[0007] In order to achieve the above object, the present invention provides a wet cleaning method for a silicon carbide coated graphite substrate component, characterized in that it comprises the following steps:

[0008] Step 1: Wipe with isopropyl alcohol;

[0009] Fold the dust-free cloth in half, dip it in an appropriate amount of isopropyl alcohol solution, and wipe the surface of the component;

[0010] Step 2: soaking in nitric acid aqueous solution;

[0011] Place the parts in a clean plastic bag, add 5-20% volume percent nitric acid aqueous solution, and soak at room temperature for 2h-3h;

[0012] Step 3: heating the hot water area at a constant temperature;

[0013] Place the parts in a clean plastic bag, add ultrapure water to the bag, seal the bag, and then put another bag in to seal it;

[0014] Then place the sealed parts in constant temperature water of 75-95℃ and heat in a constant temperature water bath;

[0015] Step 4: ultrasonic cleaning;

[0016] The components were moved to a Class 100 clean room for ultrasonic cleaning at a frequency of 4-10 w / in and a duration of 15 min.

[0017] Step 5: rinse with pure water;

[0018] The parts are rinsed with ultrapure water, blown dry with nitrogen, and finally packaged in a dust-free manner.

[0019] Silicon carbide-coated graphite substrate components are those in which a silicon carbide coating is deposited onto a graphite substrate through a CVD process. These components are used in metal organic chemical vapor deposition equipment. This wet cleaning method for silicon carbide-coated graphite substrate components is only suitable for cleaning newly manufactured silicon carbide-coated graphite substrate components before shipment.

[0020] The silicon carbide coated graphite substrate component includes a graphite substrate, and the outer surface of the graphite substrate is covered with a silicon carbide coating. The silicon carbide coating thickness of the component to which this method is applicable is 100μm. If the thickness of the silicon carbide coating is 100μm, the constant temperature heating time of the hot water water area is 48h. This method is mainly aimed at cleaning the surface of the component. Silicon carbide coatings of different thicknesses can increase or decrease the constant temperature heating time of the hot water water area in step three. If the thickness is less than 50μm, the constant temperature heating time of the hot water water area can be shortened to 24h. If the thickness is greater than 200μm, the constant temperature heating time of the hot water water area can be increased to 72h.

[0021] Further preferably, in step 1, the wiping time is not less than 2 minutes.

[0022] Further preferably, in step 1, the isopropyl alcohol solution is high-purity isopropyl alcohol, preferably one or more of grades G2, G3, G4, and G5.

[0023] Further preferably, in step 2, the plastic bag is a high-purity plastic bag for clean room use, preferably one or more of nylon composite material, LDPE, MDPE, and HDPE.

[0024] Further preferably, in step 2, the volume percentage concentration of the nitric acid aqueous solution is 5%, 10% or 15%.

[0025] More preferably, in step 2, the room temperature is 15-25°C.

[0026] Further preferably, in step three, the temperature of the constant temperature water is one of 75°C, 80°C, 85°C and 90°C.

[0027] Further preferably, in step 4, during ultrasonic cleaning, the overflow rate of pure water in the ultrasonic tank is greater than 250 L / h, the resistance of pure water is greater than 2 MΩ, and the temperature of pure water in the ultrasonic tank is 25-40°C.

[0028] Further preferably, in step five, the ultrapure water is required to have a resistivity greater than 18 MΩ, a content of each element less than 10 ppt, and a TOC content less than 10 ppb.

[0029] This invention provides a wet cleaning process for silicon carbide-coated graphite-based components. The beneficial effects of this process include: through chemical cleaning, it effectively reduces organic contamination and metal ion precipitation in highly corrosive chemical solutions, meeting SEMI F57 standards, without damaging the components themselves, thereby extending component life. The process is simple to operate, low-cost, and suitable for widespread use. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of specific embodiment 1 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] See also Figure 1 A wet cleaning method for a silicon carbide coated graphite substrate component, characterized in that it comprises the following steps:

[0033] Step 1: Wipe with isopropyl alcohol;

[0034] Fold the dust-free cloth in half, dip it in an appropriate amount of isopropyl alcohol solution, and wipe the surface of the component for at least 2 minutes;

[0035] Step 2: soaking in nitric acid aqueous solution;

[0036] Place the parts in a clean plastic bag, add 5% volume percent nitric acid aqueous solution, and soak at room temperature for 2 hours;

[0037] Step 3: heating the hot water area at a constant temperature;

[0038] Place the parts in a clean plastic bag, add ultrapure water to the bag, seal the bag, and then put another bag in to seal it;

[0039] The sealed parts were then placed in 85°C constant temperature water bath and heated for 48 hours;

[0040] Step 4: ultrasonic cleaning;

[0041] The components were moved to a Class 100 clean room for ultrasonic cleaning at a frequency of 4-10 w / in and a duration of 15 min.

[0042] The overflow rate of pure water in the ultrasonic tank is greater than 250L / h, the pure water resistance is greater than 2MΩ, and the pure water temperature in the ultrasonic tank is 25-40℃;

[0043] Step 5: rinse with pure water;

[0044] The parts are rinsed with ultrapure water, then blown dry with nitrogen, and finally packaged in a dust-free manner;

[0045] Ultrapure water requirements are resistivity greater than 18MΩ, content of each element less than 10ppt, and TOC content less than 10ppb.

[0046] The thickness of the silicon carbide coating on the components applied by this method is 100μm.

[0047] The experimental results of the silicon carbide coated graphite substrate component before cleaning and after cleaning of Example 1 are as follows:

[0048]

[0049] From the above table, we can see that this method meets the SEMI F57 standard.

[0050] First, organic cleaning is performed. This step removes organic contaminants and processing oils that may have been contaminated during transportation of the silicon carbide-coated graphite substrate. Utilizing the principle that like dissolves like, isopropyl alcohol is used to dissolve the majority of the organic matter, exposing any remaining metallic impurities trapped within it as a pre-treatment for subsequent metal removal.

[0051] Next, the silicon carbide-coated graphite substrate is immersed in a nitric acid solution for cleaning. Nitric acid is used to concentrate and eliminate metallic elements present in the raw materials and on the surface of the components. After cleaning, the components are rinsed with deionized water to remove any residual solution.

[0052] Use a hot water bath to soak and clean again. Ultrasonic cleaning is used to enhance the cleaning effect and remove common polluting elements in the human body, such as Zn, Ca, K, Na, and Fe. Rinse with deionized water after washing.

[0053] The next step is ultrasonic overflow cleaning. This step uses the vibration effect of ultrasound to remove particles from the surface of the component, achieving a targeted removal effect on particles.

[0054] Finally, rinse with ultrapure water to further remove small amounts of metal residues and particles on the surface.

[0055] The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A wet cleaning method for a silicon carbide coated graphite substrate component, characterized in that: The steps include: Step 1: Wipe with isopropyl alcohol; Fold the dust-free cloth in half, dip it in an appropriate amount of isopropyl alcohol solution, and wipe the surface of the component; Step 2: soaking in nitric acid aqueous solution; Place the parts in a clean plastic bag, add 5-20% volume percent nitric acid aqueous solution, and soak at room temperature for 2h-3h; Step 3: heating the hot water area at a constant temperature; Place the parts in a clean plastic bag, add ultrapure water to the bag, seal the bag, and then put another bag in to seal it; Then place the sealed parts in constant temperature water of 75-95℃ and heat in a constant temperature water bath; Step 4: ultrasonic cleaning; The components were moved to a Class 100 clean room for ultrasonic cleaning at an ultrasonic frequency of 4-10 w / in and for 15 min. Step 5: rinse with pure water; The parts are rinsed with ultrapure water, blown dry with nitrogen, and finally packaged in a dust-free manner.

2. The wet cleaning method for a silicon carbide coated graphite substrate according to claim 1, characterized in that: In step 1, the wiping time should be no less than 2 minutes.

3. The wet cleaning method for a silicon carbide coated graphite substrate according to claim 1, characterized in that: In step 1, the isopropyl alcohol solution is high-purity isopropyl alcohol.

4. The wet cleaning method for a silicon carbide coated graphite substrate according to claim 1, characterized in that: In step 2, the plastic bag is a high-purity plastic bag for clean rooms, which is made of nylon composite material, one or more of LDPE, MDPE, and HDPE.

5. The wet cleaning method for a silicon carbide coated graphite substrate according to claim 1, characterized in that: In step 2, the volume percentage concentration of the nitric acid aqueous solution is 5%, 10% or 15%.

6. The wet cleaning method for a silicon carbide coated graphite substrate according to claim 1, characterized in that: In step 2, the normal temperature is 15-25°C.

7. The wet cleaning method for a silicon carbide coated graphite substrate according to claim 1, characterized in that: In step 3, the temperature of the constant temperature water is one of 75°C, 80°C, 85°C and 90°C.

8. The wet cleaning method for a silicon carbide coated graphite substrate according to claim 1, characterized in that: In step 4, during ultrasonic cleaning, the overflow rate of pure water in the ultrasonic tank is greater than 250 L / h, the resistance of pure water is greater than 2 MΩ, and the temperature of pure water in the ultrasonic tank is 25-40°C.

9. The wet cleaning method for a silicon carbide coated graphite substrate according to claim 1, characterized in that: In step 5, the ultrapure water is required to have a resistivity greater than 18 MΩ, a content of each element less than 10 ppt, and a TOC content less than 10 ppb.

10. A wet cleaning method for a silicon carbide coated graphite substrate component, characterized in that: The steps include: Step 1: Wipe with isopropyl alcohol; Fold the dust-free cloth in half, dip it in an appropriate amount of isopropyl alcohol solution, and wipe the surface of the component for at least 2 minutes; Step 2: soaking in nitric acid aqueous solution; Place the parts in a clean plastic bag, add 5% volume percent nitric acid aqueous solution, and soak at room temperature for 2 hours; Step 3: heating the hot water area at a constant temperature; Place the parts in a clean plastic bag, add ultrapure water to the bag, seal the bag, and then put another bag in to seal it; The sealed parts were then placed in 85°C constant temperature water bath and heated for 48 hours; Step 4: ultrasonic cleaning; The components were moved to a Class 100 clean room for ultrasonic cleaning at an ultrasonic frequency of 4-10 w / in and for 15 min. The overflow rate of pure water in the ultrasonic tank is greater than 250L / h, the pure water resistance is greater than 2MΩ, and the pure water temperature in the ultrasonic tank is 25-40℃; Step 5: rinse with pure water; The parts are rinsed with ultrapure water, then blown dry with nitrogen, and finally packaged in a dust-free manner; Ultrapure water requirements are resistivity greater than 18MΩ, content of each element less than 10ppt, and TOC content less than 10ppb.

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