Silicon carbide surface treatment method and application thereof

Abstract

The invention provides a silicon carbide material surface treatment method and application, and the silicon carbide material surface treatment method comprises the following steps: placing a silicon carbide material with a to-be-treated surface in a vacuum cavity; performing water-oxygen oxidation treatment on the silicon carbide material to form an oxide layer; and carrying out acid pickling treatment and ultrasonic cleaning treatment on the oxide layer. The invention provides a silicon carbide material surface treatment method and application of the silicon carbide material surface treatment method in the field of wafer etching. According to the surface treatment method for the silicon carbide material, a stress damage layer generated on the surface of the silicon carbide material in the machining process can be eliminated, the surface flatness and smoothness of the silicon carbide material can be remarkably improved, the service life of the silicon carbide material is prolonged, the requirement for auxiliary chip production is met, and the production cost is reduced. And an environment for uniformly etching the wafer is provided, so that the wafer etching effect is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic materials, in particular to a silicon carbide surface treatment method and application thereof. Background Art

[0002] Silicon carbide (SiC) ceramics are an important structural material with the characteristics of high temperature resistance, high hardness, excellent oxidation and chemical corrosion resistance, wear resistance, and thermal shock resistance. In addition, SiC ceramics also have advantages such as a thermal expansion coefficient similar to Si, higher thermal conductivity, higher critical breakdown voltage, and negative resistance temperature coefficient, which makes it 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 go through the process of grinding and polishing during machining. In these processes, due to the imperfect rotation speed and type of the tool, the surface layer of the material will be damaged during the processing, resulting in the stress damage layer formed on the surface of the silicon carbide material being etched first 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 etched first, it will cause uneven etching of the etching base during the production process, that is, the wafer will be unevenly etched, resulting in a sudden drop in the etching effect. In order to prepare a wafer material with good etching effect and excellent performance on the surface of silicon carbide material, it is necessary to process the surface of silicon carbide material, that is, to etch the surface of silicon carbide material to remove the uneven stress damage layer on the surface so that the surface obtains an orderly surface morphology, which is conducive 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 it is impossible to completely and effectively eliminate the surface damage of the material.

[0003] Traditional methods for treating silicon carbide surfaces include: 1. Wet etching, etching silicon carbide in molten alkali or salt at less than 1000°C; 2. Dry etching, etching at a temperature above 1000°C using hydrogen, halogen-containing gas or mixed gas; 3. Simple wet cleaning using HF after oxygen plasma bombardment etching; among them, wet etching has the advantages of high removal efficiency, simple operation and low cost, but poor controllability, and will cause corrosion and impurities that are difficult to remove on the surface; while general dry etching has good controllability and cleans the substrate surface, it is expensive to use and has gas corrosiveness. Strong, high requirements on equipment; 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 marks. Although this method can form an oxide film quickly, oxygen plasma bombardment can easily cause deep damage to the wafer surface. While the processing marks are eliminated, the roughness of the wafer surface will also increase, thereby affecting the uniformity of etching. Moreover, the subsequent simple wet cleaning of the oxide layer formed on the surface of silicon carbide will also introduce contamination from 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 deeper 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, some stress damage points cannot be completely removed after the thermal oxidation surface treatment and will still remain, which will still lead to an increase in the roughness of the silicon carbide material surface, resulting in poor wafer etching uniformity. 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 surface of the silicon carbide material. Summary of the invention

[0005] In order to improve the above-mentioned 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 surface of the silicon carbide material from being concentratedly etched at the stress damage points in the etching ring due to the residual of some relatively protruding stress damage points in the stress loss layer, thereby significantly improving the service life of the silicon carbide material, thereby meeting the requirements of auxiliary chip production, providing an environment for uniform etching of the wafer, and effectively improving the effect of wafer etching.

[0006] In order to achieve the above object, a first aspect of the present invention provides a method for surface treatment of silicon carbide, comprising the following steps:

[0007] placing a silicon carbide material having a surface to be processed in a vacuum chamber;

[0008] Performing water-oxygen oxidation treatment on the silicon carbide material to form an oxide layer;

[0009] The oxide layer is pickled and ultrasonically cleaned;

[0010] 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;

[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 heating treatment is controlled at 1200° C. to 1500° C. and maintained for 1 h to 5 h;

[0013] During the water-oxygen 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 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 solution, the present invention has at least the following advantages compared with the prior art:

[0016] (1) The present invention can eliminate the stress damage layer generated on the surface of the silicon carbide material during the processing process by the method of first oxidation and then removal, and by using a first gas mixed with water vapor and oxygen as an oxygen source gas for forming an oxidation layer, the surface flatness and smoothness of the silicon carbide material can be significantly improved, thereby successfully increasing 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 water-oxygen 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 deeper damage to the wafer surface. In addition, when the method is used to treat the surface of the silicon carbide material, the more protruding stress damage points can be contacted with water vapor first, and thus be eliminated first, and then the stress damage layer with processing traces can be eliminated, thereby avoiding the residual stress damage layer after the surface treatment of the silicon carbide material, thereby better meeting the requirements of auxiliary chip production, providing an environment for the wafer to be uniformly etched, and improving the service life of the silicon carbide material.

[0018] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise 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, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a process flow chart of the surface treatment method of silicon carbide material;

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

[0021] Figure 3 This is a SEM image of the silicon carbide material after surface treatment provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are described in detail below. 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] A first aspect of the present invention provides a method for treating a silicon carbide surface, such as Figure 1 As shown, the following steps are included:

[0024] placing a silicon carbide material having a surface to be processed in a vacuum chamber;

[0025] Performing water-oxygen oxidation treatment on the silicon carbide material to form an oxide layer;

[0026] The oxide layer is pickled and ultrasonically cleaned;

[0027] 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;

[0028] 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);

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

[0030] During the water-oxygen oxidation treatment of the silicon carbide material, the pressure in the vacuum chamber ranges from 60 kPa to 120 kPa.

[0031] SEM image of silicon carbide material before surface treatment, such as Figure 2 As shown, from Figure 2 It can be seen from the observation 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. The present invention can eliminate the stress damage layer generated on the surface of the above-mentioned silicon carbide material during the processing process by the method of first oxidation and then removal. And because the present invention uses a first gas mixed with water vapor and oxygen as the oxygen source gas for forming the oxide layer, the first heating treatment is performed under high temperature conditions, and silicon carbide will react rapidly with water vapor and oxygen to form a silicon dioxide oxide layer. The reaction equations of the reaction 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 high-temperature water vapor with oxygen can promote SiC to form a SiO2 oxide layer, and water vapor molecules tend to gather on irregular surfaces. This is because the convex part usually has a higher surface free energy than the flat part, which makes the convex part more capable of adsorbing water vapor. Therefore, the more protruding stress damage points in the stress damage layer will preferably react with water vapor, thereby reacting quickly to form a SiO2 oxide layer, avoiding the problem of residual stress damage points after surface treatment. More importantly, when the irregular bumps are covered by the oxide layer, the water vapor has a very strong fluidity, so the coverage of the planar part of the stress damage layer will be particularly high, making the reaction degree of different positions of the planar part almost consistent, thereby improving the uniformity of the SiO2 oxide layer formed on the surface of the silicon carbide material, thereby ensuring that the surface flatness and smoothness of the silicon carbide material after subsequent acid pickling and ultrasonic cleaning are significantly improved, thereby increasing the service life of the silicon carbide material and ensuring the uniformity of the wafer edge sheath voltage, thereby ensuring the uniformity of the wafer etching and providing a uniform etching environment for subsequent wafer etching.

[0036] In one embodiment, the gas flow ratio of water vapor to oxygen is in the range of (5:1) to (10:1). In one embodiment, the gas flow ratio of water vapor to oxygen can be 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1. When the gas flow ratio range of water vapor to oxygen is less than 5:1, the gas flow rate of water vapor is too small, which will lead to a decrease in the amount of water vapor inside the vacuum chamber reaction furnace tube. If the oxygen content is too high, oxygen will directly react with silicon carbide to generate silicon dioxide, first generating Si(OH)4 intermediate products, and then the silicon carbide that generates silicon dioxide will be reduced accordingly, which will cause the oxidation process to become too intense, easily causing damage to the newly generated oxide layer. Even when the oxygen content is excessive, deeper oxidation will continue, thereby destroying 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 rate of water vapor is too large, which will lead to an excessive amount of water vapor inside the vacuum chamber reaction furnace tube and an excessive amount of oxygen, which will cause the stress damage layer to be incompletely oxidized, 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 be adjusted to avoid damaging the surface of the silicon oxide material, and to avoid insufficient oxidation depth causing the uniformity of the surface of the oxidized silicon carbide material to decrease. In a preferred embodiment, the gas flow ratio of water vapor to oxygen is in the range of (5:1) to (7:1).

[0037] In a specific embodiment, the pressure range in the vacuum chamber is 60kpa to 120kpa. Exemplarily, the pressure in the vacuum chamber can be 60kpa, 70kpa, 80kpa, 90kpa, 100kpa, 110kpa, and 120kpa. In the process of water-oxygen oxidation treatment, the pressure setting of 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 60kpa, this will lead to insufficient number of water vapor molecules and oxygen molecules actually participating in the oxidation reaction, and may also cause these two molecules to be unevenly distributed in the reaction chamber, thereby affecting the formation depth and thickness uniformity of the generated oxide layer; when the pressure in the vacuum chamber is greater than 120kpa, the collision rate of water vapor molecules and oxygen molecules with the stress damage layer will increase with the increase of pressure, which will also lead to insufficient number 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, the present invention can avoid the occurrence of the above problems by setting the pressure range in the vacuum chamber within an appropriate range. In a preferred embodiment, the pressure in the vacuum chamber ranges from 80 kPa to 100 kPa.

[0038] In a specific embodiment, during the water-oxygen oxidation treatment, the temperature of the first heat treatment is controlled at 1200°C to 1500°C and maintained for 1h to 5h. Specifically, the internal temperature of the vacuum chamber is increased to 1200°C to 1500°C at a heating rate of 10 to 20°C / min and maintained for 1 to 5h. 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 a range consisting 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, and the uniformity of the surface of the silicon carbide material will decrease. When the temperature of the first heat treatment is higher than 1500°C, the oxidation process of water vapor and oxygen will become intense, resulting in damage to the oxide layer, and even continuing to oxidize at a deeper level, destroying the surface of the silicon carbide material. Therefore, by adjusting the temperature range of the first heat treatment within a suitable range, an oxide layer with a suitable oxidation degree and depth can be obtained. In a preferred embodiment, the temperature of the first heat treatment is controlled at 1200°C to 1300°C.

[0039] Exemplarily, the maintenance time of the first heat treatment can be 1h, 2h, 3h, 4h, 5h or a range consisting of any two values. When the maintenance time of the water-oxygen oxidation treatment is too short, the oxidation will not be complete, and the oxidation depth of the oxide layer will decrease. After the next step of pickling, it is easy to cause certain corrosion on the surface of the silicon carbide material, resulting in a decrease in the uniformity of the surface. When the maintenance time of the water-oxygen oxidation treatment is too long, the depth of the oxide layer is increased, and the surface of the silicon carbide material is also easily damaged and corroded by the oxygen source gas. Therefore, adjusting the maintenance time of the water-oxygen oxidation treatment can also avoid the decrease in the uniformity of the surface of the silicon carbide material and improve the flatness and smoothness of the surface of the material after surface treatment. In a preferred embodiment, the maintenance time of the first heat treatment is 2 to 3h.

[0040] Furthermore, by observing the cross-sectional SEM of the silicon carbide material after water-oxygen oxidation treatment, the thickness range of the oxide layer formed by the water-oxygen oxidation treatment can be measured. The thickness can reflect the elimination depth of the stress damage layer. Therefore, in order to avoid excessive elimination of 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 silicon carbide material is subjected to water-oxygen oxidation treatment, the thickness of the oxide layer is 500nm to 1000nm. Exemplarily, the thickness of the oxide layer can be 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm or a range consisting of any two values. In a preferred embodiment, the thickness of the oxide layer can be 600nm to 800nm.

[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 generated on the surface. HF is mixed with pure water to form a hydrofluoric acid solvent. During the pickling treatment using the hydrofluoric acid solvent, the silicon carbide material has a certain corrosion resistance. During the reaction between the oxide layer and the hydrofluoric acid, it can effectively avoid damage to the internal silicon carbide material after the oxide layer is removed.

[0042] In a specific embodiment, 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 min.

[0043] For example, during the pickling process, 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 consisting of any two values. In a preferred embodiment, the mass ratio of the mixed solution of HF and pure water ranges from (1:70) to (1:90).

[0044] Illustratively, during the pickling treatment, the pickling temperature may be 20°C, 25°C, 30°C, or 35°C.

[0045] Illustratively, during the pickling treatment, the pickling time may be 10 min, 15 min, 20 min, 25 min, or 30 min.

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

[0047] In a specific embodiment, the ultrasonic cleaning treatment includes using deionized water to remove impurities remaining on the surface to complete the surface treatment of silicon carbide. The ultrasonic cleaning treatment can remove impurities remaining after the pickling treatment and the water-oxygen oxidation treatment. Therefore, in order to further improve the treatment effect of the silicon carbide material surface, it is necessary to perform ultrasonic cleaning on the surface of the silicon carbide material after 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. For example, the ultrasonic cleaning time can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or a range consisting of any 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 oxide layer is subjected to the pickling treatment and the ultrasonic cleaning treatment, the second step further includes using a second gas to perform a second heating 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 is in the range of (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] After the surface of the silicon carbide material with the oxide layer removed is treated with acid pickling and ultrasonic cleaning, there may still be some F-containing substances that have not been cleaned and a small amount of oxide layer residue on the surface. Therefore, in order to further remove impurities on the surface of the silicon carbide material, water vapor and hydrogen can be used to further remove impurities on the surface of the silicon carbide material. Some water-soluble F-containing substances will be removed as they combine with water vapor molecules under high temperature conditions, and other residual impurities in the oxide layer 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 application of the silicon carbide surface treatment method described in the first aspect of the present invention in the field of wafer etching.

[0055] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0057] Example 1

[0058] Used for surface treatment of silicon carbide materials, the process flow chart is as follows Figure 1 As shown, the specific steps include:

[0059] Step 1: Prepare a silicon carbide material having a surface to be processed (SEM image, such as Figure 2 The device is placed in a reaction furnace tube and the reaction furnace tube is evacuated;

[0060] Step 2, the silicon carbide material is subjected to water-oxygen oxidation treatment to generate an oxide layer: after the silicon carbide material is processed, the silicon carbide material with the surface to be processed is placed in a reaction furnace tube under a vacuum state for water-oxygen oxidation treatment, the pressure in the reaction furnace tube is maintained at 90 kPa, and then the first gas: water vapor and oxygen are introduced 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 hours, so that the silicon carbide material is fully reacted in the reaction furnace tube.

[0061] Step 3: The surface of the oxide layer is pickled and ultrasonically cleaned to complete the surface treatment of silicon carbide:

[0062] The silicon carbide material after the water-oxygen oxidation treatment in step 2 is pickled. Specifically, the surface of the silicon carbide material with an oxide layer is treated with an HF solution (with a concentration of 40%) and a pure water solution. The mass ratio of the mixed solution of HF and pure water is 1:80. The pickling treatment time is 30 minutes and the temperature is 30°C.

[0063] Then, the acid-washed silicon carbide material is subjected to ultrasonic cleaning. Specifically, the acid-washed silicon carbide material is ultrasonically cleaned using deionized water for 20 minutes to remove impurities on the surface.

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

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

[0066] Example 2

[0067] Used for surface treatment of silicon carbide materials, the process flow chart is as follows Figure 1 As shown, the specific steps include:

[0068] Step 1, placing the silicon carbide material with the surface to be processed in a reaction furnace tube, and performing a vacuum treatment on the reaction furnace tube;

[0069] Step 2, the silicon carbide material is subjected to water-oxygen oxidation treatment to generate an oxide layer: after the silicon carbide material is processed, the silicon carbide material with the surface to be processed is placed in a reaction furnace tube under a vacuum state for water-oxygen oxidation treatment, the pressure in the reaction furnace tube is maintained at 100 kPa, and then the first gas: water vapor and oxygen are introduced 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 hours, so that the silicon carbide material is fully reacted in the reaction furnace tube.

[0070] Step 3: The surface of the oxide layer is pickled and ultrasonically cleaned to complete the surface treatment of silicon carbide:

[0071] The silicon carbide material after the water-oxygen oxidation treatment in step 2 is pickled. Specifically, the surface of the silicon carbide material with an oxide layer is treated with an HF solution (with a concentration of 30%) and a pure water solution. The mass ratio of the mixed solution of HF and pure water is 1:70. The pickling treatment time is 25 minutes and the temperature is 25°C.

[0072] Then, the acid-washed silicon carbide material is subjected to ultrasonic cleaning. Specifically, the acid-washed silicon carbide material is ultrasonically cleaned using deionized water for 30 minutes to remove impurities on the surface.

[0073] Step 4, using water vapor and hydrogen to perform a second heat treatment on the surface of the silicon carbide material, including: continuing to place the silicon carbide material obtained in step 3 in a vacuum chamber reaction furnace tube, using water vapor and hydrogen with a gas flow ratio of 4:1, at a temperature of 1000±100°C, continuing to heat the surface of the silicon carbide material obtained in step 3, the treatment time is 1 hour, and finally completing the treatment of the material.

[0074] Example 3

[0075] Used for surface treatment of silicon carbide materials, the process flow chart is as follows Figure 1 As shown, the specific steps include:

[0076] Step 1, placing the silicon carbide material with the surface to be processed in a reaction furnace tube, and performing a vacuum treatment on the reaction furnace tube;

[0077] Step 2, the silicon carbide material is subjected to water-oxygen oxidation treatment to generate an oxide layer: after the silicon carbide material is processed, the silicon carbide material with the surface to be processed is placed in a reaction furnace tube under a vacuum state for water-oxygen oxidation treatment, the pressure in the reaction furnace tube is maintained at 80 kPa, and then the first gas: water vapor and oxygen are introduced 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 hours, so that the silicon carbide material is fully reacted in the reaction furnace tube.

[0078] Step 3: The surface of the oxide layer is pickled and ultrasonically cleaned to complete the surface treatment of silicon carbide:

[0079] The silicon carbide material after the water-oxygen oxidation treatment in step 2 is pickled. Specifically, the surface of the silicon carbide material with an oxide layer is treated with an HF solution (concentration of 50%) and a pure water solution. The mass ratio of the mixed solution of HF and pure water is 1:90. The pickling treatment time is 20 minutes and the temperature is 35°C.

[0080] Then, the acid-washed silicon carbide material is subjected to ultrasonic cleaning. Specifically, the acid-washed silicon carbide material is ultrasonically cleaned using deionized water for 10 minutes to remove impurities on the surface.

[0081] Step 4, using water vapor and hydrogen to perform a second heat treatment on the surface of the silicon carbide material, including: continuing to place the silicon carbide material obtained in step 3 in a vacuum chamber reaction furnace tube, using water vapor and hydrogen with a gas flow ratio of 4:1, at a temperature of 1000±100°C, continuing to heat the surface of the silicon carbide material obtained in step 3, the treatment time is 1 hour, and finally completing the treatment of the material.

[0082] Example 4 Group

[0083] The fourth embodiment was carried out with reference to the first embodiment, except that the gas flow ratio of water vapor and oxygen in the first gas in step 2 was changed, as shown below:

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

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

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

[0087] Example 5 Group

[0088] Example 5 was carried out in accordance with Example 1, except that the temperature of the first heating treatment in step 2 was adjusted as follows:

[0089] In Example 5-1, the temperature of the first heat treatment in step 2 is adjusted to 1200° C.

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

[0091] Example 6 Group

[0092] The sixth embodiment was carried out with reference to the first embodiment, except that the pressure range in the reaction furnace tube during the water-oxygen oxidation treatment of the silicon carbide material in step 2 was changed to be as follows:

[0093] Example 6-1, changing the pressure in the reaction furnace tube in step 2 to 60 kPa;

[0094] Example 6-2, the pressure in the reaction furnace tube in step 2 is changed to 120 kPa.

[0095] Comparative Example 1

[0096] Comparative Example 1 is carried out with reference to Example 1, except that the first gas used in step 2 does not include water vapor.

[0097] Comparative Example 2

[0098] Comparative Example 2 is carried out with reference to Example 1, except that step 4 is not performed, that is, water vapor and hydrogen are not used to perform a second heat treatment on the surface of the silicon carbide material.

[0099] Comparative Example 3

[0100] Comparative Example 3 was carried out with reference to Example 1, except that the gas flow ratio of water vapor and oxygen in the first gas in step 2 was changed, as shown below:

[0101] Comparative Example 3-1, the gas flow ratio of water vapor and oxygen in the first gas in step 2 is 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 is changed to 15:1.

[0103] Comparative Example 4

[0104] Comparative Example 4 was carried out in accordance with Example 1, except that the temperature of the first heating treatment in step 2 was adjusted as follows:

[0105] In comparative example 4-1, the temperature of the first heating treatment in step 2 was adjusted to 800° C.;

[0106] In Comparative Example 4-2, the temperature of the first heat treatment in step 2 was adjusted to 1800°C.

[0107] Comparative Example 5

[0108] Comparative Example 5 was carried out with reference to Example 1, except that the pressure range in the reaction furnace tube during the water-oxygen oxidation treatment of the silicon carbide material in step 2 was changed, as shown below:

[0109] Comparative Example 5-1, the pressure in the reaction furnace tube in step 2 was changed to 30 kPa;

[0110] In comparative example 5-2, the pressure in the reaction furnace tube in step 2 is changed to 150 kPa.

[0111] Test Case

[0112] The silicon carbide materials subjected to surface treatment in the above-mentioned embodiments and comparative examples were subjected to the following tests: 1. Roughness detection: using an optical measurement method, the surface profile of the above-mentioned surface-treated silicon carbide materials was converted into an optical signal, and then the Rq value was obtained by computer processing, and 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 with an X-ray energy dispersive spectrometer (SEM-EDS), and 10 evenly distributed positions on the surface were taken for component composition analysis. If the 1 If the percentage ratios of C atoms to Si atoms at 0 points are all between 1.00 and 1.10, it means that the composition distribution on the surface of the silicon carbide material prepared in the above embodiment or comparative example is relatively uniform, and the SiC purity on the surface of the silicon carbide material is relatively high. Therefore, the pass rate of whether the percentage ratios of C atoms to Si atoms at 10 position points are between 1.00 and 1.10 can be used to represent its uniformity and purity. The percentages between 1.00 and 1.10 are considered to be passed, otherwise they are considered to be failed. A (pass times) / A0 (test times) are calculated and recorded in Table 1.

[0113] Table 1

[0114]

[0115]

[0116] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to 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 to 1000nm.

4. The method for surface treatment 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 treating the surface 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 treating the surface 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 surface treatment 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; Preferably, 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); Preferably, the temperature of the second heat 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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