A method for surface treatment of silicon carbide and its application

Abstract

The present invention provides a method for surface treatment of silicon carbide materials and its application. The method for surface treatment of silicon carbide materials in the present invention includes the following steps: placing the silicon carbide material with a surface to be treated in a vacuum chamber; performing hydrothermal oxidation treatment on the silicon carbide material to form an oxide layer; performing pickling treatment and ultrasonic cleaning treatment on the oxide layer. The present invention provides a method for surface treatment of silicon carbide materials and the application of the method for surface treatment of silicon carbide materials in the field of wafer etching. The method for surface treatment of silicon carbide materials in the present invention can eliminate the stress damage layer generated on the surface of the silicon carbide material during the processing, and can significantly improve the surface flatness and smoothness of the silicon carbide material, extend the service life of the silicon carbide material, meet the requirements for assisting chip production, provide an environment for uniform etching of the wafer, and effectively improve the effect of wafer etching.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and particularly to a surface treatment method for silicon carbide and its application. Background Art

[0002] Silicon carbide (SiC) ceramics have the characteristics of high temperature resistance, high hardness, excellent oxidation and chemical corrosion resistance, wear resistance, and thermal shock resistance, and are an important structural material. In addition, SiC ceramics also have advantages such as a thermal expansion coefficient similar to that of Si, a relatively high thermal conductivity, a higher critical breakdown voltage, and a negative resistance temperature coefficient, which enable them to be widely used in semiconductor components serving in high-frequency, high-temperature, and high-pressure environments, and gradually replace silicon materials to become the main application material in the etching process. Silicon carbide materials need to undergo grinding and polishing processes during machining. In these processes, due to the imperfect rotational speed and types of tools, the surface layer of the material will be damaged during machining, resulting in the stress damage layer formed on the surface of the silicon carbide material being preferentially etched during the etching process, affecting the service life of the silicon carbide material. And because the stress damage layer on the surface of the silicon carbide material is preferentially etched, unevenness of the etching stage will occur during production, that is, the wafer is unevenly etched, resulting in a sharp drop in the etching effect. To prepare a wafer material with good etching effect and excellent properties on the surface of the silicon carbide material, it is necessary to treat the surface of the silicon carbide material, that is, to etch the surface of the silicon carbide material to remove the uneven stress damage layer on the surface, so as to obtain an ordered surface topography, which is beneficial to the growth of high-quality wafer materials. However, due to the excellent physical and chemical stability of silicon carbide, it can only be etched under special conditions and cannot completely and effectively eliminate the surface damage of the material.

[0003] Traditional surface treatment methods for silicon carbide materials include: 1. Wet etching, which corrodes silicon carbide in molten alkali or salt at a temperature below 1000°C; 2. Dry etching, which etches using hydrogen, halogen-containing gas or a mixed gas at a temperature above 1000°C; 3. Oxygen plasma bombardment etching followed by simple wet cleaning with HF; among them, wet etching has the advantages of high removal efficiency, simple operation and low cost, but poor controllability, and will produce corrosion and impurities that are difficult to remove on the surface; while general dry etching has good controllability and a clean substrate surface, but has high usage cost, strong gas corrosiveness and high equipment requirements; oxygen plasma bombardment etching is different from the first two methods. It will first form an oxide film, and then use HF for simple wet cleaning to remove the newly formed oxide film, so as to achieve the purpose of removing processing traces. Although this method can form an oxide film relatively quickly, oxygen ion bombardment is likely to cause deeper damage to the wafer surface. While removing the processing traces, the surface roughness of the wafer will also increase accordingly, which will affect the etching uniformity. Moreover, subsequent simple wet cleaning of the oxide layer formed on the silicon carbide surface will also introduce contamination of other impurities;

[0004] In addition, some existing technologies also use thermal oxidation to treat the silicon carbide surface. This method will also generate an oxide layer first, but it is gentler than the oxygen plasma bombardment method and will not cause deep damage. However, since there are still some relatively protruding stress damage points in the stress damage layer on the surface of the silicon carbide material, after surface treatment by the thermal oxidation method, some stress damage points cannot be completely removed and there will still be residues, so it will still lead to an increase in the surface roughness of the silicon carbide material, resulting in poor etching uniformity of the wafer. Therefore, there is an urgent need for a new silicon carbide surface treatment method to improve the removal effect of the stress damage layer on the silicon carbide material surface. Summary of the Invention

[0005] In order to improve the above problems existing in the prior art, the present invention provides a surface treatment method for silicon carbide materials and the application of the surface treatment method for silicon carbide materials in the field of wafer etching. The surface treatment method for silicon carbide materials of the present invention can eliminate the stress damage layer generated on the surface of the silicon carbide material during the processing, and can significantly improve the surface flatness and smoothness of the silicon carbide material. While eliminating the stress damage layer on its surface, it can also prevent the silicon carbide material from being concentratedly etched at the stress damage points due to the residue of some relatively protruding stress damage points in the stress loss layer during the etching process, thereby significantly improving the service life of the silicon carbide material, further meeting the requirements of assisting chip production, providing an environment for uniform etching of the wafer, and effectively improving the wafer etching effect.

[0006] To achieve the above object, the first aspect of the present invention provides a silicon carbide surface treatment method, including the following steps:

[0007] Place the silicon carbide material with the surface to be processed in a vacuum chamber;

[0008] Perform hydrothermal oxidation treatment on the silicon carbide material to form an oxide layer;

[0009] Perform pickling treatment and ultrasonic cleaning treatment on the oxide layer;

[0010] Among them, the hydrothermal oxidation treatment of the silicon carbide material includes performing a first heat treatment on the surface of the silicon carbide material using a first gas;

[0011] The first gas includes water vapor and oxygen, and the gas flow ratio of water vapor to oxygen ranges from (5:1) to (10:1);

[0012] The temperature of the first heat treatment is controlled at 1200 °C to 1500 °C and maintained for 1 h to 5 h;

[0013] During the hydrothermal oxidation treatment of the silicon carbide material, the pressure in the vacuum chamber ranges from 60 kPa to 120 kPa.

[0014] The second aspect of the present invention provides an application of the silicon carbide surface treatment method described in the first aspect of the present invention in the field of wafer etching.

[0015] Through the above technical solutions, the present invention has at least the following advantages compared with the prior art:

[0016] (1) By the method of first oxidizing and then removing, the present invention can eliminate the stress damage layer generated on the surface of the silicon carbide material during the processing, and by using the first gas mixed with water vapor and oxygen as the oxygen source gas for forming the oxide layer, the surface flatness and smoothness of the silicon carbide material can be significantly improved, successfully improving the service life of the silicon carbide material and providing a uniform etching environment for the subsequent wafer etching process.

[0017] (2) The present invention performs hydrothermal oxidation treatment on the surface of the silicon carbide material under vacuum conditions, which is gentler than the oxygen plasma bombardment method and will not cause deep damage to the wafer surface. When using this method to treat the surface of the silicon carbide material, the relatively protruding stress damage points can preferentially contact with water vapor and thus be preferentially eliminated, and then the stress damage layer with processing traces is eliminated, so as to avoid the residue of the stress damage layer after the surface treatment of the silicon carbide material, further meeting the requirements of assisting chip production, providing a uniform etching environment for the wafer, and improving the service life of the silicon carbide material.

[0018] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. Description of the Drawings

[0019] Figure 1 It is a process step flowchart of the surface treatment method of the silicon carbide material of the present invention;

[0020] Figure 2 It is an SEM image of the silicon carbide material provided by an embodiment of the present invention before surface treatment;

[0021] Figure 3 It is an SEM image of the silicon carbide material provided by an embodiment of the present invention after surface treatment. Detailed Description of the Invention

[0022] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0023] The first aspect of the present invention provides a method for treating the surface of silicon carbide, as Figure 1 shown, including the following steps:

[0024] Place the silicon carbide material with a surface to be treated in a vacuum chamber;

[0025] Perform hydrothermal oxidation treatment on the silicon carbide material to form an oxide layer;

[0026] Perform pickling treatment and ultrasonic cleaning treatment on the oxide layer;

[0027] Among them, the hydrothermal oxidation treatment of the silicon carbide material includes using a first gas to perform a first heat treatment on the surface of the silicon carbide material;

[0028] The first gas includes water vapor and oxygen, and the gas flow ratio range of water vapor to oxygen is (5:1) to (10:1);

[0029] The temperature of the first heat treatment is controlled at 1200°C to 1500°C and maintained for 1h to 5h;

[0030] During the hydrothermal oxidation treatment of the silicon carbide material, the pressure range in the vacuum chamber is 60 kPa to 120 kPa.

[0031] SEM image of the silicon carbide material before surface treatment, as Figure 2 shown. It can be observed from Figure 2 that the surface of the silicon carbide material has a stress damage layer, and the stress damage layer also includes some relatively protruding stress damage points. By means of the method of first oxidizing and then removing, the present invention can eliminate the stress damage layer generated on the surface of the above-mentioned silicon carbide material during the processing. Moreover, since the present invention uses a first gas mixture of water vapor and oxygen as the oxygen source gas for forming the oxide layer and performs a first heat treatment under high temperature conditions, silicon carbide will react rapidly with water vapor and oxygen to generate a layer of silicon dioxide oxide layer. The reaction equations occurring in this process include:

[0032] SiC + 2O2 → SiO2 + CO2;

[0033] SiC + 2H2O → Si(OH)4 + CH4;

[0034] Si(OH)4 + 2O2 → SiO2 + 2H2O;

[0035] Si(OH)4 is an unstable intermediate product, and the generation of CH4 gas will also promote the reaction. Therefore, mixing water vapor with a higher temperature on the basis of oxygen can promote the formation of the SiO2 oxide layer from SiC. Moreover, water vapor molecules are prone to aggregate on the irregular surface. This is because the convex part usually has a higher surface free energy than the flat part, which makes the convex part have a stronger adsorption ability for water vapor. Therefore, the relatively protruding stress damage points in the stress damage layer will preferably contact and react with water vapor, and thus will preferentially and rapidly react to generate the SiO2 oxide layer, avoiding the problem that stress damage points still remain after surface treatment. More importantly, when the irregular convex part is covered by the oxide layer, due to the very strong fluidity of water vapor, the coverage rate of the flat part of the stress damage layer will also be particularly high, making the reaction degrees at different positions of the flat part close to being consistent, improving the uniformity of the SiO2 oxide layer formed on the surface of the silicon carbide material. Thereby, it can ensure that the surface flatness and smoothness of the silicon carbide material are significantly improved after subsequent pickling treatment and ultrasonic cleaning treatment, improving the service life of the silicon carbide material, and also ensuring the uniformity of the sheath voltage at the edge of the wafer, thereby ensuring the uniformity of the wafer etching and providing a uniform etching environment for subsequent wafer etching.

[0036] In a specific embodiment, the gas flow ratio range of water vapor to oxygen is (5:1) to (10:1). In a specific embodiment, the gas flow ratio of water vapor to oxygen can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1. When the gas flow ratio range of water vapor to oxygen is less than 5:1, the gas flow of water vapor is too small, which will lead to a decrease in the amount of water vapor inside the reaction furnace tube of the vacuum chamber and an excessive oxygen content. Oxygen will directly react with silicon carbide to form silicon dioxide. First, an intermediate product Si(OH)4 is formed, and then the silicon carbide that forms silicon dioxide will decrease accordingly. This will cause the oxidation process to become too intense, easily causing damage to the newly formed oxide layer. Even when the oxygen content is excessive, deeper oxidation will continue, thus damaging the surface of the silicon carbide material. When the gas flow ratio range of water vapor to oxygen is greater than 10:1, the gas flow of water vapor is too large, which will lead to an excessive amount of water vapor and a too small amount of oxygen inside the reaction furnace tube of the vacuum chamber. This will cause incomplete oxidation of the stress damage layer, and the flatness and smoothness of the surface of the silicon carbide material will decrease. Moreover, by adjusting the gas flow ratio of water vapor and oxygen in the oxygen source gas, the oxidation depth of the oxide layer can also be adjusted, avoiding damage to the surface of the silicon oxide material and also avoiding a decrease in the uniformity of the surface of the oxidized silicon carbide material due to insufficient oxidation depth. In a preferred embodiment, the gas flow ratio range of water vapor to oxygen is (5:1) to (7:1).

[0037] In a specific embodiment, the pressure range in the vacuum chamber is 60 kPa to 120 kPa. Exemplarily, the pressure in the vacuum chamber can be 60 kPa, 70 kPa, 80 kPa, 90 kPa, 100 kPa, 110 kPa, 120 kPa. During the hydrothermal oxidation treatment, the pressure setting in the vacuum chamber will affect the reaction rate and reaction uniformity of the oxidation reaction. When the pressure in the vacuum chamber is less than 60 kPa, this will lead to insufficient numbers of water vapor molecules and oxygen molecules actually participating in the oxidation reaction, and may also cause uneven distribution of these two types of molecules in the reaction chamber, thus affecting the formation depth and thickness uniformity of the generated oxide layer. When the pressure in the vacuum chamber is greater than 120 kPa, the collision rate of water vapor molecules and oxygen molecules with the stress damage layer will increase with the increase in pressure, which will also lead to insufficient numbers of water vapor molecules and oxygen molecules actually participating in the oxidation reaction, affecting the uniformity of the oxidation reaction of the stress damage layer. Therefore, by setting the pressure range in the vacuum chamber within a suitable range in the present invention, the occurrence of the above problems can be avoided. In a preferred embodiment, the pressure range in the vacuum chamber is 80 kPa to 100 kPa.

[0038] In a specific embodiment, during the hydrothermal oxidation treatment, the temperature of the first heat treatment is controlled within the range of 1200°C to 1500°C and maintained for 1 h to 5 h. Specifically, the internal temperature of the vacuum chamber should be raised to 1200°C to 1500°C at a heating rate of 10 - 20°C / min and maintained for 1 - 5 h. Exemplarily, the temperature range of a heat treatment can be 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, 1450°C, 1500°C, or any range composed of any two values. When the temperature of the first heat treatment is lower than 1100°C, the oxidation will be incomplete, the oxidation depth of the oxide layer will decrease, the stress damage layer will not be completely oxidized, resulting in a decrease in the surface uniformity of the silicon carbide material. When the temperature of the first heat treatment is higher than 1500°C, the oxidation process of water vapor and oxygen will become intense, leading to damage to the oxide layer and even deeper oxidation, damaging the surface of the silicon carbide material. Therefore, by adjusting the temperature range of the first heat treatment within an appropriate range, an oxide layer with appropriate oxidation degree and depth can be obtained. In a preferred embodiment, the temperature of the first heat treatment is controlled within the range of 1200°C to 1300°C.

[0039] Exemplarily, the holding time of the first heat treatment can be 1 h, 2 h, 3 h, 4 h, 5 h, or any range composed of any two values. When the holding time of the hydrothermal oxidation treatment is too short, the oxidation will be incomplete, the oxidation depth of the oxide layer will decrease, and after the next pickling process, it is easy to cause certain corrosion on the surface of the silicon carbide material, resulting in a decrease in surface uniformity. When the holding time of the hydrothermal oxidation treatment is too long, the depth of the oxide layer will increase, and the surface of the silicon carbide material is also easily damaged and corroded by the oxygen source gas. Therefore, adjusting the holding time of the hydrothermal oxidation treatment can also avoid the decrease in the surface uniformity of the silicon carbide material and improve the flatness and smoothness of the material surface after surface treatment. In a preferred embodiment, the holding time of the first heat treatment is 2 - 3 h.

[0040] Furthermore, by observing the cross-sectional SEM of the silicon carbide material after the hydrothermal oxidation treatment, the thickness range of the oxide layer formed by the hydrothermal oxidation treatment can be measured. This thickness can reflect the elimination depth of the stress damage layer. Therefore, in order to avoid over-eliminating the surface of the silicon carbide material, it can be achieved by controlling the thickness of the oxide layer. In a specific embodiment, after the hydrothermal oxidation treatment of the silicon carbide material, the thickness of the oxide layer is 500 nm to 1000 nm. Exemplarily, the thickness of the oxide layer can be 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, or any range composed of any two values. In a preferred embodiment, the thickness of the oxide layer can be 600 nm to 800 nm.

[0041] In a specific embodiment, the pickling treatment includes using a mixed solution of HF and pure water to clean the oxide layer and remove the oxide layer formed on the surface. HF and pure water are mixed to form a hydrofluoric acid solvent. During the pickling treatment using this hydrofluoric acid solvent, due to its certain corrosion resistance, the silicon carbide material can effectively avoid damage to the internal silicon carbide material after the oxide layer is removed during the reaction between the oxide layer and hydrofluoric acid.

[0042] In a specific embodiment, during the pickling treatment, the mass ratio range of the mixed solution of HF and pure water is (1:50) to (1:100), the pickling temperature is 20°C to 35°C, and the pickling time is 10 to 30 minutes.

[0043] Exemplarily, during the pickling treatment, the mass ratio of the mixed solution of HF and pure water can be 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, 1:85, 1:90, 1:95, 1:100 or a range composed of any two values. In a preferred embodiment, the mass ratio range of the mixed solution of HF and pure water is (1:70) to (1:90).

[0044] Exemplarily, during the pickling treatment, the pickling temperature can be 20°C, 25°C, 30°C, 35°C.

[0045] Exemplarily, during the pickling treatment, the pickling time can be 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes.

[0046] In a specific embodiment, the concentration of HF is 30% to 50%. Exemplarily, the concentration of HF can be 30%, 40%, 50% or a range composed of any two values.

[0047] In a specific embodiment, the ultrasonic cleaning treatment includes using deionized water to remove the residual impurity components on the surface and complete the surface treatment of silicon carbide. Through the ultrasonic cleaning treatment, the residual impurity components after the pickling treatment and the water oxygen oxidation treatment can be removed. Therefore, in order to further improve the surface treatment effect of the silicon carbide material, it is necessary to perform ultrasonic cleaning on the surface of the silicon carbide material that has undergone Step 1 and Step 2.

[0048] In a specific embodiment, during the ultrasonic cleaning process, the ultrasonic cleaning time ranges from 10 min to 60 min. Exemplarily, the ultrasonic cleaning time can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or any range composed of two values. In a specific embodiment, the ultrasonic cleaning time ranges from 10 min to 30 min.

[0049] In a specific embodiment, during the ultrasonic cleaning process, the ultrasonic cleaning temperature ranges from 20°C to 50°C, preferably from 30°C to 40°C.

[0050] In a specific embodiment, after the pickling treatment and ultrasonic cleaning treatment of the oxide layer, it further includes using a second gas to perform a second heat treatment on the surface of the silicon carbide material;

[0051] In a preferred embodiment, the second gas includes water vapor and hydrogen, and the gas flow ratio of the water vapor to the hydrogen ranges from (3:1) to (5:1);

[0052] In a preferred embodiment, the temperature of the second heat treatment is controlled at 900°C to 1100°C and maintained for 30 min to 90 min.

[0053] On the surface of the silicon carbide material with the oxide layer removed, after pickling treatment and ultrasonic cleaning treatment, there may still be residual fluorine-containing substances that are not cleaned thoroughly and a small amount of oxide layer residue on the surface. Therefore, in order to further remove the impurities on the surface of the silicon carbide material, water vapor and hydrogen can be further used to perform a defouling treatment on the surface of the silicon carbide material. Some fluorine-containing substances that are soluble in water will be removed with the combination with water vapor molecules under high-temperature conditions, and other oxide layer residual impurities will react with hydrogen under high-temperature conditions, thereby further improving the flatness and smoothness of the surface of the silicon carbide material.

[0054] The third aspect of the present invention provides an application of the silicon carbide surface treatment method described in the first aspect of the present invention in the field of wafer etching.

[0055] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0056] Unless otherwise specified, the materials and instruments used in the following embodiments are all commercially available.

[0057] Example 1

[0058] For surface treatment of silicon carbide materials, the process flow chart is as Figure 1 shown, and specifically includes the following steps:

[0059] Step 1: Place the silicon carbide material with the surface to be treated (the SEM image of which is as Figure 2 shown) in the reaction furnace tube, and evacuate the reaction furnace tube.

[0060] Step 2: Perform hydrothermal oxidation treatment on the silicon carbide material to generate an oxide layer: After the silicon carbide material is processed, place the silicon carbide material with the surface to be treated in the reaction furnace tube under vacuum for hydrothermal oxidation treatment, keep the pressure in the reaction furnace tube at 90 kPa, then introduce the first gas: water vapor and oxygen into the vacuum reaction furnace tube, the gas flow ratio of the two gases is 6:1, the temperature range is 1300 °C, and the time is 5 h, so that the silicon carbide material reacts fully in the reaction furnace tube.

[0061] Step 3: Perform pickling treatment and ultrasonic cleaning treatment on the surface of the oxide layer to complete the surface treatment of silicon carbide:

[0062] Perform pickling treatment on the silicon carbide material after hydrothermal oxidation treatment in Step 2. Specifically, use an HF solution (concentration of 40%) and pure water solution to treat the surface of the silicon carbide material with an oxide layer grown. The mass ratio of the HF and pure water mixed solution is 1:80, the pickling treatment time is 30 min, and the temperature is 30 °C;

[0063] Then, perform ultrasonic cleaning treatment on the pickled silicon carbide material. Specifically, ultrasonically clean the pickled silicon carbide material with deionized water for 20 min to remove the impurity components on the surface.

[0064] Step 4: Perform a second heat treatment on the surface of the silicon carbide material using water vapor and hydrogen, including: Continue to place the silicon carbide material obtained in Step 3 in the vacuum chamber reaction furnace tube, use water vapor and hydrogen with a gas flow ratio of 4:1, and under the condition of a temperature of 1000 ± 100 °C, continue to perform heat treatment on the surface of the silicon carbide material obtained in Step 3, the treatment time is 1 h, and finally complete the treatment of the material. The SEM image of the surface of the treated silicon carbide material is as Figure 3 shown;

[0065] From Figure 2 and Figure 3 comparison, it can be clearly seen that the surface of the silicon carbide material treated by the above method is smoother, brighter, and more uniform.

[0066] Example 2

[0067] For surface treatment of silicon carbide materials, the process flow chart is asFigure 1 As shown in the figure, it specifically includes the following steps:

[0068] Step 1: Place the silicon carbide material with the surface to be processed in the reaction furnace tube and evacuate the reaction furnace tube.

[0069] Step 2: Perform hydrothermal oxidation treatment on the silicon carbide material to generate an oxide layer. After the silicon carbide material is processed, place the silicon carbide material with the surface to be processed in the reaction furnace tube in a vacuum state for hydrothermal oxidation treatment. Keep the pressure in the reaction furnace tube at 100 kPa, and then introduce the first gas, water vapor and oxygen, into the vacuum reaction furnace tube. The gas flow ratio of the two gases is 5:1, the temperature range is 1250 °C, and the time is 6 h, so that the silicon carbide material reacts fully in the reaction furnace tube.

[0070] Step 3: Perform pickling treatment and ultrasonic cleaning treatment on the surface of the oxide layer to complete the surface treatment of silicon carbide:

[0071] Perform pickling treatment on the silicon carbide material that has undergone hydrothermal oxidation treatment in Step 2. Specifically, use an HF solution (concentration 30%) and pure water solution to treat the surface of the silicon carbide material with an oxide layer grown. The mass ratio of the HF and pure water mixed solution is 1:70, the pickling treatment time is 25 min, and the temperature is 25 °C.

[0072] Then, perform ultrasonic cleaning treatment on the pickled silicon carbide material. Specifically, ultrasonically clean the pickled silicon carbide material with deionized water for 30 min to remove the impurity components on the surface.

[0073] Step 4: Perform a second heat treatment on the surface of the silicon carbide material using water vapor and hydrogen, including: continue to place the silicon carbide material obtained in Step 3 in the reaction furnace tube of the vacuum chamber, use water vapor and hydrogen with a gas flow ratio of 4:1, and continue to heat-treat the surface of the silicon carbide material obtained in Step 3 at a temperature of 1000 ± 100 °C for 1 h to finally complete the treatment of the material.

[0074] Example 3

[0075] For surface treatment of silicon carbide materials, the process step flow chart is as Figure 1 shown, and it specifically includes the following steps:

[0076] Step 1: Place the silicon carbide material with the surface to be processed in the reaction furnace tube and evacuate the reaction furnace tube.

[0077] Step 2. Perform hydrothermal oxidation treatment on the silicon carbide material to generate an oxide layer: After the silicon carbide material is processed, place the silicon carbide material with the surface to be treated into the reaction furnace tube under vacuum for hydrothermal oxidation treatment. Keep the pressure in the reaction furnace tube at 80 kPa, and then introduce the first gas, water vapor and oxygen, into the vacuum reaction furnace tube. The gas flow ratio of the two gases is 7:1, the temperature range is 1200 °C, and the time is 4 h, so that the silicon carbide material reacts fully in the reaction furnace tube.

[0078] Step 3. Perform pickling treatment and ultrasonic cleaning treatment on the surface of the oxide layer to complete the surface treatment of silicon carbide:

[0079] Perform pickling treatment on the silicon carbide material that has undergone hydrothermal oxidation treatment in Step 2. Specifically, use an HF solution (concentration of 50%) and pure water solution to treat the surface of the silicon carbide material with an oxide layer grown. The mass ratio of the HF and pure water mixed solution is 1:90, the pickling treatment time is 20 min, and the temperature is 35 °C;

[0080] Then, perform ultrasonic cleaning treatment on the pickled silicon carbide material. Specifically, ultrasonically clean the pickled silicon carbide material with deionized water for 10 min to remove the impurity components on the surface.

[0081] Step 4. Perform a second heat treatment on the surface of the silicon carbide material using water vapor and hydrogen, including: Continue to place the silicon carbide material obtained in Step 3 in the reaction furnace tube of the vacuum chamber, and use water vapor and hydrogen with a gas flow ratio of 4:1 to continue heat-treat the surface of the silicon carbide material obtained in Step 3 at a temperature of 1000 ± 100 °C for 1 h, and finally complete the treatment of the material.

[0082] 4 groups of examples

[0083] 4 groups of examples are carried out with reference to Example 1. The only difference is that the gas flow ratio of water vapor and oxygen in the first gas in Step 2 is changed, specifically as follows:

[0084] Example 4-1, change the gas flow ratio of water vapor and oxygen in the first gas in Step 2 to 5:1;

[0085] Example 4-2, change the gas flow ratio of water vapor and oxygen in the first gas in Step 2 to 7:1;

[0086] Example 4-3, change the gas flow ratio of water vapor and oxygen in the first gas in Step 2 to 10:1.

[0087] 5 groups of examples

[0088] Example 5 was carried out with reference to Example 1. The only difference was that the temperature of the first heat treatment in Step 2 was adjusted as follows:

[0089] In Example 5-1, the temperature of the first heat treatment in Step 2 was changed to 1200 °C;

[0090] In Example 5-2, the temperature of the first heat treatment in Step 2 was changed to 1500 °C.

[0091] Example 6 group

[0092] Example 6 was carried out with reference to Example 1. The only difference was that during the hydrothermal oxidation treatment of the silicon carbide material in Step 2, the pressure range in the reaction furnace tube was changed as follows:

[0093] In Example 6-1, the pressure in the reaction furnace tube in Step 2 was changed to 60 kPa;

[0094] In Example 6-2, the pressure in the reaction furnace tube in Step 2 was changed to 120 kPa.

[0095] Comparative Example 1

[0096] Comparative Example 1 was carried out with reference to Example 1. The only difference was that the first gas used in Step 2 did not include water vapor.

[0097] Comparative Example 2

[0098] Comparative Example 2 was carried out with reference to Example 1. The only difference was that Step 4 was not carried out, that is, the silicon carbide material surface was not subjected to the second heat treatment with water vapor and hydrogen at the end.

[0099] Comparative Example 3 group

[0100] Comparative Example 3 was carried out with reference to Example 1. The only difference was that the gas flow ratio of water vapor and oxygen in the first gas in Step 2 was changed as follows:

[0101] In Comparative Example 3-1, the gas flow ratio of water vapor and oxygen in the first gas in Step 2 was changed to 2:1;

[0102] In Comparative Example 3-2, the gas flow ratio of water vapor and oxygen in the first gas in Step 2 was changed to 15:1.

[0103] Comparative Example 4 group

[0104] Comparative Example 4 was carried out with reference to Example 1. The only difference was that the temperature of the first heat treatment in Step 2 was adjusted as follows:

[0105] Comparative Example 4-1: Adjust the temperature of the first heat treatment in Step 2 to 800 °C;

[0106] Comparative Example 4-2: Adjust the temperature of the first heat treatment in Step 2 to 1800 °C.

[0107] Comparative Example 5 group

[0108] The Comparative Example 5 group was carried out with reference to Example 1. The only difference was that during the hydrothermal oxidation treatment of the silicon carbide material in Step 2, the pressure range in the reaction furnace tube was changed, specifically as follows:

[0109] Comparative Example 5-1: Change the pressure in the reaction furnace tube in Step 2 to 30 kPa;

[0110] Comparative Example 5-2: Change the pressure in the reaction furnace tube in Step 2 to 150 kPa.

[0111] Test Example

[0112] The silicon carbide materials that had been surface-treated in the above Examples and Comparative Examples were tested as follows: 1. Roughness detection: Using the optical measurement method, the surface profile of the surface-treated silicon carbide material was converted into an optical signal, and then the Rq value was obtained through computer processing. The calculation results were recorded in Table 1; 2. SEM-EDS test: The surface of the surface-treated silicon carbide material was analyzed by a scanning electron microscope attached with an X-ray energy dispersive spectrometer (SEM-EDS). Ten different position points with uniform distribution on the surface were taken for compositional analysis. If the percentage ratio of C atoms to Si atoms at these 10 points was all between 1.00 and 1.10, it indicated that the compositional distribution on the surface of the silicon carbide material prepared in the above Examples or Comparative Examples was relatively uniform, and the SiC purity on the surface of the silicon carbide material was relatively high. Therefore, the passing rate of the percentage ratio of C atoms to Si atoms at 10 position points being between 1.00 and 1.10 could be used to represent its uniformity and purity. A percentage between 1.00 and 1.10 was considered passed, otherwise it was considered failed. Calculate A (number of passes) / A0 (number of tests) and record it in Table 1.

[0113] Table 1

[0114]

[0115]

[0116] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for treating the surface of silicon carbide, characterized in that: The steps include: placing a silicon carbide material having a surface to be processed in a vacuum chamber; Performing water-oxygen oxidation treatment on the silicon carbide material to form an oxide layer; The oxide layer is pickled and ultrasonically cleaned; Wherein, the water-oxygen oxidation treatment of the silicon carbide material comprises performing a first heating treatment on the surface of the silicon carbide material using a first gas; The first gas includes water vapor and oxygen, and the gas flow ratio of the water vapor to the oxygen is in the range of (5:1) to (10:1); The temperature of the first heating treatment is controlled at 1200° C. to 1500° C. and maintained for 1 h to 5 h; During the water-oxygen oxidation treatment of the silicon carbide material, the pressure in the vacuum chamber ranges from 60 kPa to 120 kPa.

2. The method for treating the surface of silicon carbide according to claim 1, characterized in that: The gas flow ratio of the water vapor to the oxygen is in the range of (5:1) to (7:1); And / or, the temperature of the first heating treatment is controlled at 1200° C. to 1300° C. and maintained for 2 h to 3 h; And / or, during the water-oxygen oxidation treatment of the silicon carbide material, the pressure in the vacuum chamber ranges from 80 kPa to 100 kPa.

3. The method for surface treatment of silicon carbide according to claim 1, characterized in that: After the silicon carbide material is subjected to water-oxygen oxidation treatment, the thickness of the oxide layer is 500nm-1000nm.

4. The method for treating the surface of silicon carbide according to claim 1, characterized in that: The pickling treatment includes using a mixed solution of HF and pure water to clean the oxide layer and remove the oxide layer generated on the surface.

5. The method for surface treatment of silicon carbide according to claim 4, characterized in that: During the pickling process, the mass ratio of the mixed solution of HF and pure water is in the range of (1:50) to (1:100), the pickling temperature is 20° C. to 35° C., and the pickling time is 10 to 30 minutes.

6. The method for surface treatment of silicon carbide according to claim 5, characterized in that: The concentration of HF is 30% to 50%.

7. The method for treating the surface of silicon carbide according to claim 1, characterized in that: The ultrasonic cleaning process includes using deionized water to remove impurities remaining on the surface to complete the surface treatment of silicon carbide.

8. The method for treating the surface of silicon carbide according to claim 7, characterized in that: In the ultrasonic cleaning process, the ultrasonic cleaning time ranges from 10 min to 60 min, and the ultrasonic cleaning temperature ranges from 20° C. to 50° C.

9. The method for treating the surface of silicon carbide according to claim 1, characterized in that: After the oxide layer is pickled and ultrasonically cleaned, the surface of the silicon carbide material is subjected to a second heating treatment using a second gas; The second gas includes water vapor and hydrogen, and the gas flow ratio of the water vapor to the hydrogen is in the range of (3:1) to (5:1); The temperature of the second heating treatment is controlled at 900° C. to 1100° C. and maintained for 30 min to 90 min.

10. Application of the silicon carbide surface treatment method according to any one of claims 1 to 9 in the field of wafer etching.

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