Method for depositing ultra-pure silicon carbide film on surface of silicon carbide ceramic

Abstract

The invention relates to the field of ceramics, in particular to a method for depositing an ultra-pure silicon carbide film on the surface of silicon carbide ceramic, which comprises the following steps: cleaning a silicon carbide ceramic substrate with a polished single surface, and then drying to obtain a pretreated substrate; a high-purity SiC target material is installed on a magnetron sputtering target located in a vacuum bin, the pretreated substrate is placed on a rotary heating table located in the vacuum bin in the mode that the polishing face is upward, and a corresponding magnetron sputtering environment is set; performing ionization cleaning and reverse sputtering cleaning on the polished surface of the silicon carbide ceramic substrate, then performing magnetron sputtering, and depositing a SiC film on the polished surface of the cleaned substrate; therefore, the ultra-high-purity silicon carbide ceramic membrane is formed on the surface of the silicon carbide ceramic. The ultra-pure silicon carbide film obtained by the method has the technical advantages of high strength, smooth surface and the like.

Description

Technical Field

[0001] The invention relates to the field of ceramics, in particular to a method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramics. Background Art

[0002] Wafer boats are an indispensable part of semiconductor manufacturing technology, mainly as carrier devices involved in the transportation and processing of wafers. Since wafer processing has extremely high requirements for its precision and cleanliness, the surface of the wafer boat needs to be smooth, have high chemical stability, and be free of impurity metal ions that will react with the wafer, that is, high purity. Silicon carbide ceramic wafer boats that can fully meet the various performance requirements of wafer boats have gradually become the development focus of this field. At present, conventional silicon carbide ceramic materials cannot meet the application standards of wafer boats in terms of purity. In practical applications, it is necessary to deposit a dense layer of high-purity silicon carbide ceramic film on the surface of silicon carbide ceramic wafer boats. Therefore, the current field of wafer boat manufacturing urgently needs a method for preparing a high-purity, stable-performance, high-density silicon carbide ceramic film on the surface of silicon carbide ceramics.

[0003] Silicon carbide ceramics, as a special ceramic material commonly used in industry, have excellent properties such as high strength, high hardness, high temperature resistance, wear resistance, and thermal shock resistance. High-purity silicon carbide films not only retain their high mechanical properties, but also inherit the high chemical stability of silicon carbide materials. They are suitable for devices such as crystal boats that need to work under extreme chemical and physical conditions. At present, the preparation of ultra-high purity silicon carbide ceramic coatings usually uses methods such as chemical vapor deposition, magnetron sputtering or atomic layer deposition. Among them, chemical vapor deposition is the most widely used in the preparation of silicon carbide coatings due to its advantages such as high purity, density and easy preparation of the silicon carbide coatings produced. However, due to the different reaction conditions of chemical vapor deposition, the performance of the ultra-high purity silicon carbide films produced varies greatly.

[0004] As a physical vapor deposition method, magnetron sputtering can obtain coatings with good quality, good uniformity, and fast deposition speed while ensuring the quality of the target material. The film surface is smooth, the particle size is uniform, and it has high high-temperature oxidation resistance. However, the current research on magnetron sputtering is mostly used to prepare amorphous silicon carbide coatings with good optoelectronic properties. There are not many studies on high-purity silicon carbide coatings used in crystal boats, and there are only some studies in similar directions. For example, the patent with publication number CN118053615A discloses a method for depositing a silicon carbide layer on the surface of an organic flexible substrate. This method uses a vacuum magnetron sputtering device to deposit a silicon carbide layer while ensuring the transparency of the substrate. It can be applied to semiconductor touch screen devices, but the patent only involves structural design and does not focus on specific process flows and performance indicators. The patent with publication number CN118422140A discloses a process for depositing a metal copper layer on the surface of a silicon carbide ceramic substrate. By means of magnetron sputtering, it can solve the problems of loose metal layer structure, poor conductivity, low bonding strength between the metal layer and the ceramic substrate, and poor reliability of the metallized ceramic substrate in the traditional deposition technology. The patent with publication number CN118326365A discloses a method for forming a silicon carbide coating on a substrate by chemical vapor deposition process. The method mainly utilizes an organic silicon source gas to react with the surface of the silicon carbide substrate at high temperature to generate a layer of silicon carbide coating on the surface of the substrate. Since the chemical vapor deposition reaction requires a high temperature and a long reaction time, and due to poor controllability, there are certain microcracks and internal stress problems, so the application of high-quality silicon carbide films is limited. The above patents have achieved valuable results in the deposition of silicon carbide thin films, but there is still a lack of in-depth research on the bonding between silicon carbide ceramic substrates and silicon carbide thin films. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for forming an ultra-high purity silicon carbide film on the surface of a silicon carbide ceramic substrate by magnetron sputtering; the ultra-high purity silicon carbide film obtained by the method of the present invention has the technical advantages of high strength and smooth surface.

[0006] In order to solve the above technical problems, the present invention provides a method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramics, comprising the following steps:

[0007] 1) Substrate pretreatment:

[0008] The single-side polished (surface roughness Ra < 1.6 μm) silicon carbide ceramic substrate is cleaned and then dried to obtain a pre-treated substrate;

[0009] 2) Setting of magnetron sputtering environment:

[0010] A high-purity SiC (purity ≥ 99.99%) target material is mounted on a magnetron sputtering target in a vacuum chamber; the pre-treated substrate obtained in step 1) is placed on a rotating heating table in the vacuum chamber with the polished surface facing upward; the vacuum chamber is first evacuated, and then the temperature in the vacuum chamber is adjusted to a set magnetron sputtering temperature (the temperature in the vacuum chamber can be controlled to be the set magnetron sputtering temperature by adjusting the heating lamp group), and then Ar gas is introduced as a protective atmosphere, and the pressure in the vacuum chamber is adjusted to 2-5 Pa, thereby achieving the setting of the magnetron sputtering environment in the vacuum chamber;

[0011] 3) Substrate cleaning:

[0012] The polished surface of the silicon carbide ceramic substrate is subjected to ionization cleaning and reverse sputtering cleaning to obtain a cleaned substrate;

[0013] 4) Magnetron sputtering:

[0014] At the set magnetron sputtering temperature, the pressure in the vacuum chamber is controlled to be 2.5-3.5Pa when depositing the film (preferably the magnetron sputtering pressure is 3Pa, which is controlled by adjusting the Ar gas flow rate), the ionization power supply is started, the current density is controlled, and the sputtering power is adjusted, and the high-purity SiC target is bombarded by plasma, thereby depositing the SiC film on the polished surface of the cleaned substrate; thereby forming an ultra-high purity silicon carbide ceramic film on the surface of the silicon carbide ceramic.

[0015] Note: After the film deposition is completed, turn off all power supplies and take out the sample after the deposition chamber temperature returns to room temperature.

[0016] As an improvement to the method of depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramics of the present invention: the silicon carbide ceramic substrate is a single-sided polished high-purity silicon carbide ceramic with a purity of >99.9% (mass %).

[0017] The dimensions are, for example: thickness 10 mm, diameter 1 inch.

[0018] As a further improvement of the method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramics of the present invention: in the step 2):

[0019] First, evacuate the vacuum chamber until the vacuum degree is 2.0×10 -4 ~1.0×10 -4 Pa;

[0020] The magnetron sputtering temperature is set at 450°C to 500°C (preferably 500°C), and then Ar gas is introduced to adjust the pressure in the vacuum chamber to a range of 2 to 5Pa.

[0021] As a further improvement of the method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramic of the present invention: the substrate cleaning in step 3) is as follows:

[0022] After the magnetron sputtering environment setting of step 2 is completed, the ionization power supply is started to perform ionization cleaning on the polished surface of the silicon carbide ceramic substrate (ionization cleaning time is 3 to 5 minutes); after the ionization cleaning is completed, the ionization power supply is turned off; the RF power supply is started again, a negative bias voltage is applied to the substrate, and the polished surface of the silicon carbide ceramic substrate is reversely sputtered and cleaned (reverse sputtering cleaning time is 10 to 20 minutes), thereby ensuring that the polished surface of the substrate is free of contamination, and a cleaned substrate is obtained; after the reverse sputtering cleaning is completed, the RF power supply is turned off.

[0023] As a further improvement of the method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramics of the present invention: the voltage of the negative bias in the step 3) is -80V.

[0024] As a further improvement of the method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramics of the present invention: Step 4): Control the current density to 20±2 mA / cm 2 , adjust the sputtering power to 100-200 W (preferably 150 W) and the sputtering time to 13-17 min (preferably 15 min).

[0025] Note: The high-purity SiC (purity ≥ 99.99%) target material used may be, for example, 50 mm in diameter and 3 mm in thickness.

[0026] As a further improvement of the method for depositing ultra-high purity silicon carbide film on the surface of silicon carbide ceramic of the present invention: the cleaning of step 1) is: the single-side polished silicon carbide ceramic substrate is cleaned in sequence with hydrofluoric acid solution with a mass concentration of 8-12%, acetone, ethanol and deionized water.

[0027] As a further improvement of the method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramics of the present invention: in the step 1):

[0028] The silicon carbide ceramic substrate is immersed in a hydrofluoric acid solution with a mass concentration of 8-12% and cleaned for 9-11 minutes, then taken out, immersed in acetone, ultrasonically cleaned for 14-16 minutes, then taken out, and then ultrasonically cleaned with ethanol with a purity of ≥99% for 14-16 minutes; then rinsed with deionized water for 2-3 times, and finally blown dry until there is no water stain on the surface to obtain a pretreated substrate.

[0029] The main raw materials of the method of the present invention are SiC target material with a purity of 99.99% (e.g., diameter 50mm, thickness 3mm), single-sided polished silicon carbide ceramic substrate (e.g., diameter 1 inch, thickness 10mm), and Ar gas as a protective atmosphere.

[0030] The technical advantage of the present invention is that a layer of ultra-high purity silicon carbide ceramic material is successfully prepared on the surface of a silicon carbide substrate by using a magnetron sputtering method. The magnetron sputtering method has achieved high practical value in the field of preparing ultra-high purity ceramic films on the surface of crystal boats due to its advantages such as fast speed, low temperature, and little impact on substrate performance. That is, the method for preparing silicon carbide film by magnetron sputtering provided by the present invention can obtain an ultra-high purity silicon carbide film on the surface of silicon carbide ceramics, which can significantly improve the purity of silicon carbide on the surface of ceramic materials and improve mechanical properties (hardness, etc.), overcoming the problem of insufficient surface purity faced by traditional silicon carbide ceramic materials when used in the semiconductor field, and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0032] Figure 1 Scanning electron microscope images of ultra-high purity silicon carbide ceramic films and polished high-purity silicon carbide ceramics;

[0033] Figure 1 middle:

[0034] The scanning electron microscope images of the ultra-high purity silicon carbide ceramic films on the polished surface of the silicon carbide ceramic substrate obtained after sputtering in Examples 1-1, 1-2, and 1-3 (i.e., obtained in step 4) are shown as 100W film, 150W film, and 200W film, respectively;

[0035] The scanning electron microscope images of the polished surface of the silicon carbide ceramic substrate of Examples 1-1, 1-2, and 1-3 before sputtering (i.e., after cleaning in step 3) are shown as 100W sub, 150W sub, and 200W sub, respectively;

[0036] pass Figure 1 , the changes in the surface morphology of the silicon carbide substrate before and after sputtering can be intuitively seen.

[0037] Figure 2 The morphology of the silicon carbide film obtained in each embodiment under an atomic force microscope (AFM) is shown in FIG. Figure 2 By analyzing, we can get the difference of surface roughness of films made under different conditions. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0039] Example 1-1: A method for preparing an ultra-high purity silicon carbide ceramic film, comprising the following steps in sequence:

[0040] 1) Substrate pretreatment:

[0041] A single-sided polished (surface roughness Ra < 1.6 μm), 10 mm thick, 1 inch in diameter, and purity > 99.9% (mass%) high-purity silicon carbide ceramic was used as a substrate, and the morphology of the substrate was obtained by scanning electron microscopy;

[0042] The substrate is immersed in a 10% (mass %) hydrofluoric acid solution for ultrasonic cleaning for 10 minutes, then taken out, immersed in acetone for ultrasonic cleaning for about 15 minutes, then taken out again, and then ultrasonically cleaned with ethanol with a purity of ≥99% for 15 minutes; the cleaned substrate is rinsed with deionized water for 2 to 3 times, and finally blown dry (until there is no water stain on the surface) to complete the pretreatment; and the pretreated silicon carbide ceramic substrate is obtained.

[0043] The power of the above ultrasonic cleaning is 300-600W.

[0044] 2) Magnetron sputtering environment settings:

[0045] The vacuum chamber is equipped with a magnetron sputtering target and a rotating heating table, and the center distance between the magnetron sputtering target and the rotating heating table is 60 mm;

[0046] A SiC target (purity 99.99%, diameter 50 mm, thickness 3 mm) was mounted on the magnetron sputtering target;

[0047] The pretreated silicon carbide ceramic substrate was placed in a magnetron sputtering vacuum chamber, and the pretreated silicon carbide ceramic substrate was placed with the polished surface facing upward at the center of the rotating heating table in the vacuum chamber, and then the vacuum chamber was sealed; the vacuum chamber was evacuated by a vacuum pump until the vacuum degree was 2.0×10 -4 ~1.0×10 -4 Pa; then start the heating lamp group and heat to the preset sputtering temperature of 450°C; after determining that the temperature in the vacuum chamber has reached the set temperature, introduce Ar gas to increase the pressure in the vacuum chamber to 2-5Pa, and complete the setting of the magnetron sputtering environment.

[0048] Therefore, the distance between the polished surface of the silicon carbide ceramic substrate and the SiC target is 60 mm.

[0049] 3) Substrate cleaning:

[0050] After completing the settings, start the ionization power supply and perform ionization cleaning (cleaning power is 1000W) on the polished surface of the substrate for 3 to 5 minutes; after the ionization cleaning is completed, turn off the ionization power supply; then start the RF power supply and apply a negative bias voltage of -80V to the substrate, so as to use the RF power supply to perform reverse sputtering cleaning (cleaning power is 200W) on the polished surface of the silicon carbide ceramic substrate, and the reverse sputtering cleaning time is 10 to 20 minutes; after the reverse sputtering cleaning is completed, turn off the RF power supply.

[0051] The purpose of this step 3) cleaning is to ensure that the polished surface of the substrate is free of contamination.

[0052] 4) Magnetron sputtering:

[0053] The pressure in the vacuum chamber can be controlled to be between 3Pa during film deposition by adjusting the Ar gas flow rate, starting the ionization power supply, and controlling the current density to 20mA / cm 2 , adjust the voltage, control the sputtering power to 100W, bombard the high-purity SiC target with plasma, and the sputtered atoms hit the polished surface of the substrate, so that the SiC film begins to be deposited on the polished surface of the cleaned substrate, and the deposition time is 15 minutes; a silicon carbide ceramic with a SiC film (highly densified ultra-high purity silicon carbide film) coated on the surface is obtained.

[0054] Then the power of the entire instrument is turned off, and after the temperature of the deposition chamber returns to room temperature, the silicon carbide ceramic with the SiC film coated on the surface is taken out, and the surface morphology of the film is obtained by scanning electron microscopy.

[0055] The present invention obtains a highly densified ultra-high purity silicon carbide film on the surface of a silicon carbide ceramic substrate (the polished surface of a silicon carbide ceramic substrate) by magnetron sputtering. Compared with the original silicon carbide substrate, the hardness of the surface is greatly improved.

[0056] Example 1-2: A method for preparing an ultra-high purity silicon carbide ceramic film:

[0057] The sputtering power in step 4) of Example 1-1 was changed from 100 W to 150 W; the rest was the same as Example 1-1.

[0058] Example 1-3: A method for preparing an ultra-high purity silicon carbide ceramic film:

[0059] The sputtering power in step 4) of Example 1-1 was changed from 100 W to 200 W; the rest was the same as Example 1-1.

[0060] Example 2-1: A method for preparing an ultra-high purity silicon carbide ceramic film,

[0061] The sputtering temperature in step 2) of Example 1-1 was changed from 450° C. to 500° C.; the rest was the same as Example 1-1.

[0062] Example 2-2: A method for preparing an ultra-high purity silicon carbide ceramic film:

[0063] The sputtering power in step 4) of Example 2-1 was changed from 100 W to 150 W, and the rest was the same as Example 2-1.

[0064] Example 2-3: A method for preparing an ultra-high purity silicon carbide ceramic film:

[0065] The sputtering power in step 4) of Example 2-1 was changed from 100 W to 200 W, and the rest was the same as Example 2-1.

[0066] Table 1. Properties of silicon carbide ceramic films in various examples

[0067]

[0068] Compared with Example 1-1, the surface hardness of the ultra-high purity silicon carbide film obtained in Example 1-2 is further improved, and the surface roughness of the film is reduced, making it smoother. This means that when the sputtering power is 150W, a more uniform ultra-high purity silicon carbide film can be stably prepared.

[0069] Compared with Example 1-2, the surface hardness of the ultra-high purity silicon carbide film obtained in Example 1-3 is further improved, which means that the higher the sputtering power, the more stable the structure of the film; however, the flatness of Example 1-3 is not as good as that of Example 1-2.

[0070] Compared with Example 1-1, the ultra-high purity silicon carbide film obtained in Example 2-1 has higher surface hardness and lower surface roughness, which means that high temperature is conducive to the preparation of higher quality ultra-high purity silicon carbide films.

[0071] Compared with Example 2-1, the ultra-high purity silicon carbide film obtained in Example 2-2 has achieved the best performance in all aspects.

[0072] Compared with Example 2-2, the hardness of the ultra-high purity silicon carbide film obtained in Example 2-3 reaches the highest value, but the surface roughness is improved to a certain extent, that is, the flatness of Example 2-3 is not as good as that of Example 2-2.

[0073] Comparative Example 1-1: A method for preparing an ultra-high purity silicon carbide ceramic film:

[0074] The sputtering power was changed to 150 W and the sputtering temperature was changed to 600° C.; the rest was the same as in Example 1-1.

[0075] Comparative Example 1-2: A method for preparing an ultra-high purity silicon carbide ceramic film:

[0076] The sputtering power was changed to 150 W and the sputtering temperature was 400° C.; the rest was the same as in Example 1-1.

[0077] Comparative Example 2-1: The deposition time in step 4) of Example 2-2 was changed from 15 min to 20 min, and the rest was the same as Example 2-2.

[0078] Comparative Example 2-2: The deposition time in step 4) of Example 2-2 was changed from 15 min to 10 min, and the rest was the same as Example 2-2.

[0079] Finally, it should be noted that the above examples are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for depositing an ultra-high purity silicon carbide film on a silicon carbide ceramic surface, characterized in that The following steps are involved: 1) Substrate pretreatment: The single-side polished silicon carbide ceramic substrate is cleaned and then dried to obtain a pre-treated substrate; 2) Setting of magnetron sputtering environment: The high-purity SiC target material is mounted on a magnetron sputtering target in a vacuum chamber; the pre-treated substrate obtained in step 1) is placed on a rotating heating table in the vacuum chamber with the polished surface facing upward; the vacuum chamber is first evacuated, and then the temperature in the vacuum chamber is adjusted to the set magnetron sputtering temperature, and then Ar is introduced as a protective atmosphere, and the pressure in the vacuum chamber is adjusted to 2-5 Pa, thereby achieving the setting of the magnetron sputtering environment in the vacuum chamber; 3) Substrate cleaning: The polished surface of the silicon carbide ceramic substrate is subjected to ionization cleaning and reverse sputtering cleaning to obtain a cleaned substrate; 4) Magnetron sputtering At the set magnetron sputtering temperature, the pressure in the vacuum chamber is controlled to be 2.5-3.5 Pa when depositing the film, the ionization power supply is started, the current density is controlled and the sputtering power is adjusted, and the high-purity SiC target is bombarded by plasma, thereby depositing the SiC film on the polished surface of the cleaned substrate; thereby forming an ultra-high purity silicon carbide ceramic film on the surface of the silicon carbide ceramic.

2. The method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramic according to claim 1, characterized in that: The silicon carbide ceramic substrate is a single-sided polished high-purity silicon carbide ceramic with a purity greater than 99.9%.

3. The method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramic according to claim 1 or 2, characterized in that In the step 2): First, evacuate the vacuum chamber until the vacuum degree is 2.0×10 -4 ~1.0×10 -4 Pa; The magnetron sputtering temperature is set at 450°C to 500°C, and Ar gas is introduced to adjust the pressure in the vacuum chamber within a range of 2 to 5 Pa.

4. The method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramic according to any one of claims 1 to 3, characterized in that The substrate cleaning in step 3) is as follows: After the magnetron sputtering environment setting of step 2 is completed, the ionization power supply is started to perform ionization cleaning on the polished surface of the silicon carbide ceramic substrate; after the ionization cleaning is completed, the ionization power supply is turned off; and the radio frequency power supply is started again to apply a negative bias voltage to the substrate to perform reverse sputtering cleaning on the polished surface of the silicon carbide ceramic substrate to obtain a cleaned substrate.

5. The method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramic according to claim 4, characterized in that: The negative bias voltage in step 3) is -80V.

6. The method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramic according to any one of claims 1 to 5, characterized in that Step 4): Control the current density to 20±2 mA / cm 2 , adjust the sputtering power to 100-200 W and the sputtering time to 13-17 min.

7. The method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramic according to any one of claims 1 to 6, characterized in that The cleaning of step 1) is as follows: The single-side polished silicon carbide ceramic substrate is cleaned in sequence using a hydrofluoric acid solution with a mass concentration of 8-12%, acetone, ethanol and deionized water.

8. The method for depositing an ultra-high purity silicon carbide film on the surface of silicon carbide ceramic according to claim 7, characterized in that In the step 1): The silicon carbide ceramic substrate is immersed in a hydrofluoric acid solution with a mass concentration of 8-12% and cleaned for 9-11 minutes, then taken out, immersed in acetone, ultrasonically cleaned for 14-16 minutes, then taken out, and then ultrasonically cleaned with ethanol with a purity of ≥99% for 14-16 minutes; then rinsed with deionized water for 2-3 times, and finally blown dry until there is no water stain on the surface to obtain a pretreated substrate.

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