Cleaning method of silicon carbide epitaxial wafer

Abstract

The invention discloses a silicon carbide epitaxial wafer cleaning method which can be used in the field of semiconductor manufacturing, and the method comprises the steps: firstly, immersing a silicon carbide epitaxial wafer in a first SPM bubbling along with nitrogen, and carrying out the HQDR of the silicon carbide epitaxial wafer after a first preset time is reached; the temperature of the first SPM is a first temperature; then, the silicon carbide epitaxial wafer is soaked in a second SPM along with internal circulation of the solution, and HQDR is carried out on the silicon carbide epitaxial wafer after a second preset duration is reached; the temperature of the second SPM is a second temperature, and the second temperature is higher than the first temperature; then, the silicon carbide epitaxial wafer is soaked in DHF which circulates along with the solution, and QDR is carried out on the silicon carbide epitaxial wafer after a third preset duration is reached; and finally, immersing the silicon carbide epitaxial wafer in the SC1 which circulates along with the solution, and performing QDR on the silicon carbide epitaxial wafer after a fourth preset time length is reached. Therefore, mercury residues and capillary tube indentations are cleaned in a targeted mode, and the cleaning effect is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a cleaning method of a silicon carbide epitaxial wafer. BACKGROUND

[0002] With the increasing application of silicon carbide semiconductors in the fields of power electronics and new energy, the demand for large-size silicon carbide epitaxial wafers such as 6-inch and 8-inch continues to grow.

[0003] Currently, after the silicon carbide epitaxial process, contact tests such as carrier concentration detection are required to test the electrical properties of the silicon carbide epitaxial wafer. However, such detection will cause pollutants such as mercury residues on the surface of the silicon carbide epitaxial wafer, and will also cause capillary indentation. The standard RCA cleaning process (RCA Clean) used in traditional silicon wafer cleaning cannot effectively remove mercury residues and capillary indentation, resulting in an increase in product rework frequency, limited cleaning yield, and difficulty in meeting the high-quality production requirements of large-size silicon carbide epitaxial wafers.

[0004] Therefore, how to improve the cleaning effect of the silicon carbide epitaxial wafer becomes a problem to be solved. SUMMARY

[0005] Based on the above problems, the present application provides a cleaning method of a silicon carbide epitaxial wafer, which can improve the cleaning effect of the silicon carbide epitaxial wafer.

[0006] The embodiments of the present application disclose the following technical solutions:

[0007] In a first aspect, the embodiments of the present application provide a cleaning method of a silicon carbide epitaxial wafer, which comprises:

[0008] immersing the silicon carbide epitaxial wafer in a first sulfuric acid-hydrogen peroxide mixed solution accompanied by nitrogen bubbling, and performing hot rapid pouring flushing on the silicon carbide epitaxial wafer after a first preset time length; the temperature of the first sulfuric acid-hydrogen peroxide mixed solution is a first temperature;

[0009] immersing the silicon carbide epitaxial wafer in a second sulfuric acid-hydrogen peroxide mixed solution accompanied by internal circulation of the solution, and performing hot rapid pouring flushing on the silicon carbide epitaxial wafer after a second preset time length; the temperature of the second sulfuric acid-hydrogen peroxide mixed solution is a second temperature, and the second temperature is higher than the first temperature;

[0010] immersing the silicon carbide epitaxial wafer in a diluted hydrogen fluoride-hydrogen peroxide mixed solution accompanied by internal circulation of the solution, and performing rapid pouring flushing on the silicon carbide epitaxial wafer after a third preset time length;

[0011] The silicon carbide epitaxial wafer is immersed in the ammonia-hydrogen peroxide mixed solution with internal solution circulation, and the silicon carbide epitaxial wafer is quickly poured and washed after a fourth preset time length.

[0012] Optionally, the first temperature is selected from the range of 40℃ to 60℃.

[0013] Optionally, the second temperature is selected from the range of 120℃ to 150℃.

[0014] Optionally, the internal solution circulation flow rate of the second sulfuric acid-hydrogen peroxide mixed solution is 15L / min to 20L / min.

[0015] Optionally, the first preset time length is selected from the range of 8min to 15min.

[0016] Optionally, the second preset time length is selected from the range of 10min to 20min.

[0017] Optionally, the hot quick pouring and washing comprises:

[0018] The silicon carbide epitaxial wafer is placed in a pure water tank with a water temperature of a target temperature, and a first washing process of spraying first, then water filling, and finally water draining is cyclically performed for multiple times.

[0019] A second washing process of spraying first, then water filling, and then bubbling, overflowing, and finally water draining is performed.

[0020] Optionally, the quick pouring and washing comprises:

[0021] The silicon carbide epitaxial wafer is placed in a pure water tank at room temperature, and a third washing process of overflowing first, then bubbling, spraying, and finally water draining is cyclically performed for multiple times.

[0022] Optionally, the temperature of the diluted hydrogen fluoride acid-hydrogen peroxide mixed solution is selected from the range of 20℃ to 30℃.

[0023] Optionally, the temperature of the ammonia-hydrogen peroxide mixed solution is selected from the range of 30℃ to 50℃.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] The embodiment of the present application provides a cleaning method of a silicon carbide epitaxial wafer, in the method, first, the silicon carbide epitaxial wafer is immersed in a first sulfuric acid-hydrogen peroxide mixture solution accompanied by nitrogen bubbling, and after a first preset time length, the silicon carbide epitaxial wafer is subjected to hot rapid pouring flushing; the temperature of the first sulfuric acid-hydrogen peroxide mixture solution is a first temperature; then, the silicon carbide epitaxial wafer is immersed in a second sulfuric acid-hydrogen peroxide mixture solution accompanied by internal circulation of the solution, and after a second preset time length, the silicon carbide epitaxial wafer is subjected to hot rapid pouring flushing; the temperature of the second sulfuric acid-hydrogen peroxide mixture solution is a second temperature, and the second temperature is higher than the first temperature; then, the silicon carbide epitaxial wafer is immersed in a diluted hydrogen fluoride-hydrogen peroxide mixture solution accompanied by internal circulation of the solution, and after a third preset time length, the silicon carbide epitaxial wafer is subjected to rapid pouring flushing; finally, the silicon carbide epitaxial wafer is immersed in an ammonia water-hydrogen peroxide mixture solution accompanied by internal circulation of the solution, and after a fourth preset time length, the silicon carbide epitaxial wafer is subjected to rapid pouring flushing.

[0026] Therefore, the first SPM pretreatment of low-temperature nitrogen bubbling is combined with the second SPM deep treatment of high-temperature internal circulation, the low-temperature environment is combined with nitrogen bubbling to loosen impurities in capillary indentation and preliminarily dissociate mercury residues, the high-temperature environment and internal circulation of the solution strengthen oxidation, and mercury can be completely oxidized into a soluble form and the adsorption structure of the indentation is damaged, so that the problem that mercury residues and capillary indentations cannot be removed in the traditional process is solved from the root, and the cleaning effect on the silicon carbide epitaxial wafer is improved; the combination of DHF and SC1 and internal circulation of the solution can make the surface of the large-size silicon carbide epitaxial wafer and the solution uniformly contact, and the cleaning effect on the edge area of the silicon carbide epitaxial wafer is improved.

[0027] In the embodiment of the present application, the low-temperature SPM pretreatment, the high-temperature SPM deep treatment, the DHF chemical etching, the SC1 cleaning and the multiple flushing are combined, on the one hand, a closed loop of preliminary dissociation, oxidation and removal is formed, and the removal effect on the mercury residues is improved; on the other hand, the low-temperature SPM accompanied by nitrogen bubbling, the high-temperature SPM and the multiple flushing are combined, the capillary indentation is first physically loosened, then the structure of the capillary indentation is damaged, and finally the impurities are flushed and removed, so that the capillary indentation can be completely eliminated. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0029] Figure 1 A cleaning method of a silicon carbide epitaxial wafer is provided in the embodiment of the present application;

[0030] Figure 2 A cleaning effect schematic diagram provided by an embodiment of the present application;

[0031] Figure 3 A cleaning equipment structure diagram of a silicon carbide epitaxial wafer provided by an embodiment of the present application. DETAILED DESCRIPTION

[0032] The cleaning method of the silicon carbide epitaxial wafer provided by the present application can be used in the field of semiconductor manufacturing. The above is only an example and does not limit the application field of the cleaning method of the silicon carbide epitaxial wafer provided by the present application.

[0033] The terms “first”, “second”, “third”, and “fourth” and the like in the specification of the present application and the description of the drawings are used to distinguish different objects, and are not intended to limit a specific order.

[0034] In the embodiments of the present application, the words “as an example” or “for example” are used to represent an example, illustration or description. Any embodiment or design scheme described as “as an example” or “for example” in the embodiments of the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the words “as an example” or “for example” are used to present the relevant concept in a specific manner.

[0035] The terms used in the implementation part of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0036] In order to enable persons skilled in the art to better understand the technical scheme of the present application, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative labor are within the scope of protection of the present application.

[0037] Referring to Figure 1 The figure is a cleaning method flow chart of a silicon carbide epitaxial wafer provided by an embodiment of the present application, the method comprising:

[0038] S101: immerse the silicon carbide epitaxial wafer in a first sulfuric acid-peroxide mixture solution accompanied by nitrogen bubbling, and perform hot rapid pouring flushing on the silicon carbide epitaxial wafer after reaching a first preset time length.

[0039] The temperature of the first sulfuric acid-peroxide mixture (SPM) is a first lower temperature. Specifically, the first temperature is selected from the range of 40℃-60℃, for example, the first temperature can be set to 50±5℃.

[0040] As an example, the first SPM can be a mixture of concentrated sulfuric acid and hydrogen peroxide, with a mixing ratio of 2:1 to 5:1. The concentrated sulfuric acid can be an ultra-pure reagent (UPS) with a mass percentage of 98%, and the hydrogen peroxide can be an ultra-pure semiconductor-grade reagent (UPSS) with a mass percentage of 31%. The use of high-purity acid reagents such as UPS can greatly reduce the introduction of metal impurities such as sodium, magnesium, or iron during the strong oxidation process, reducing the metal residue on the surface of the silicon carbide epitaxial wafer. The use of UPSS reagents not only meets the purity requirements, but also controls the mobile ions such as alkali metals and volatile organic impurities in the solution, which can be more stably mixed with concentrated sulfuric acid, reducing the risk of local overheating or concentration fluctuations.

[0041] By immersing the silicon carbide epitaxial wafer in the first SPM at a first temperature, the strong oxidizing property of the low-temperature SPM can be used to break the bond between mercury and the surface of the silicon carbide, allowing the mercury to transition from an attached state to a free state, laying the foundation for subsequent removal of mercury residues using high-temperature SPM.

[0042] The first SPM is accompanied by uniform nitrogen bubbling, which can penetrate into the tiny gaps of the capillary indentation, loosening the adsorbed contaminants in the indentation, and preventing the solidification of impurities in the indentation during subsequent high-temperature processing.

[0043] As an example, the first preset time can be selected from the range of 8 minutes to 15 minutes.

[0044] After the silicon carbide epitaxial wafer is immersed in the first SPM for a first preset time, a hot quick dump rinse (HQDR) can be performed on the silicon carbide epitaxial wafer.

[0045] In this step, the process of HQDR can be as follows: placing the silicon carbide epitaxial wafer in a pure water tank with a target temperature of 40°C to 60°C; then, performing a first rinse process of spraying, then filling water, and finally draining water, and repeating this process multiple times, such as 1 to 3 times; then, performing a second rinse process of spraying, then filling water, then bubbling, then overflowing, and finally draining water.

[0046] Thus, the first SPM remaining on the surface of the silicon carbide epitaxial wafer can be quickly removed by multiple rapid water drainage, avoiding the generation of new compounds such as sulfates by long-term contact between the first SPM and the surface of the silicon carbide epitaxial wafer; the warm water at 40-60°C combined with bubbling can not only flush away the loosened indentation contaminants, but also maintain the surface temperature, thereby reducing temperature fluctuations and improving reaction stability in the subsequent high-temperature SPM step.

[0047] For example, in step S101, the duration of the entire HQDR process can be selected from the range of 10-20 min.

[0048] S102: immerse the silicon carbide epitaxial wafer in a second sulfuric acid-peroxide mixture solution with internal circulation, and perform hot rapid pouring flushing on the silicon carbide epitaxial wafer after a second preset duration.

[0049] The temperature of the second sulfuric acid-peroxide mixture (SPM) is a second temperature higher than the first temperature. Specifically, the second temperature is selected from the range of 120-150°C, for example, the second temperature can be set to 140±5°C.

[0050] As an example, the second SPM can be a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a mixing ratio of 2:1-5:1; wherein the concentrated sulfuric acid can be UPS concentrated sulfuric acid with a mass percentage concentration of 98%, and the hydrogen peroxide can be UPSS hydrogen peroxide with a mass percentage concentration of 31%.

[0051] Under high-temperature conditions, the oxidizing property of SPM is significantly enhanced, and by immersing the silicon carbide epitaxial wafer in the second SPM at the second temperature, the free-state mercury can be completely oxidized into mercury ions that are easily soluble in water.

[0052] The second SPM is accompanied by internal circulation of the solution, for example, the internal circulation flow rate of the second SPM can be 15-20 L / min, to improve the uniformity of the second SPM concentration and avoid incomplete cleaning due to local solution consumption.

[0053] In addition, in the high-temperature second SPM, the capillary indentation expands due to high temperature, the gap expands, and the physical adsorption structure of the capillary indentation is destroyed, and the solution with internal circulation can quickly flush away the mercury residues and other impurities in the capillary indentation, thereby removing the capillary indentation.

[0054] As an example, the second preset duration can be selected from the range of 10-20 min.

[0055] After the silicon carbide epitaxial wafer is immersed in the second SPM for a second preset time length, the silicon carbide epitaxial wafer can be subjected to a second HQDR.

[0056] In this step, the process of the HQDR can be specifically as follows: the silicon carbide epitaxial wafer is placed in a pure water tank with a water temperature of a target temperature, where the target temperature can be between 50°C and 70°C; then, a first rinsing process of first spraying, then water feeding, and finally water draining is cyclically performed for multiple times, for example, the first rinsing process can be cyclically performed for 1 to 3 times; and then, a second rinsing process of first spraying, then water feeding, and then bubbling, and then overflow, and finally water draining is performed.

[0057] Therefore, the second SPM remaining on the surface of the silicon carbide epitaxial wafer can be quickly taken away through multiple rapid water draining, and the pure water at a high temperature (50°C to 70°C) can accelerate the dissolution and rinsing of the oxidized mercury such as mercury ions (Hg 2+ ) in the form, and avoid the re-attachment of the mercury ions on the surface of the silicon carbide epitaxial wafer. In addition, the overflow and bubbling functions can be simultaneously started in the process of the HQDR, to further rinse away the possible tiny particles generated after the treatment by the second SPM, and improve the rinsing effect.

[0058] The HQDR in step S102 and the HQDR in step S101 can be performed in different pure water tanks to avoid cross contamination, prevent the secondary attachment of pollutants on the surface of the silicon carbide epitaxial wafer, and ensure that the cleanliness of the surface of the silicon carbide epitaxial wafer after each HQDR meets the requirements of subsequent processes.

[0059] In addition, the two HQDRs are performed in different pure water tanks, and the temperatures of the two HQDRs can be independently adjusted more accurately, to avoid the inaccurate temperature control caused by the repeated temperature adjustment of a single tank, and to ensure the stability of the process parameters in the rinsing process. The HQDR in step S101 is used after the cleaning of the low-temperature first SPM, and therefore the temperature of the pure water in step S101 can be in the same temperature range as the temperature of the first SPM, to avoid the stress damage to the silicon carbide epitaxial wafer caused by the sudden change of the temperature, and to efficiently dissolve the residual solution of the low-temperature first SPM with warm water; the temperature of the pure water in step S102 can be higher than the temperature of the pure water in step S101, to adapt to the dissolution characteristics of the oxidation products after the high-temperature reaction, and to strengthen the cleaning effect.

[0060] For example, in step S102, the time length of the entire HQDR process can be selected from the range of 10 minutes to 20 minutes.

[0061] S103: The silicon carbide epitaxial wafer is immersed in a dilute hydrofluoric acid-hydrogen peroxide mixture solution with internal circulation of the solution, and the silicon carbide epitaxial wafer is subjected to a rapid dump rinse after a third preset time length.

[0062] The temperature of the diluted hydrofluoric acid-peroxide mixture (DHF) can be selected from a range of 20°C to 30°C.

[0063] As an example, the DHF can be a mixture of hydrofluoric acid, hydrogen peroxide and pure water in a ratio of 1:2:50 to 1:2:100. The hydrofluoric acid can be UPS hydrofluoric acid with a mass percentage concentration of 49%, the hydrogen peroxide can be UPSS hydrogen peroxide with a mass percentage concentration of 31%, and the pure water can be ultra-pure water supplied directly from a factory.

[0064] The oxidation layer on the surface of the silicon carbide epitaxial wafer is the main carrier of mercury ions and metal impurities. By immersing the silicon carbide epitaxial wafer in the DHF with internal circulation, on the one hand, the extremely thin oxidation layer on the surface of the silicon carbide epitaxial wafer can be etched by hydrofluoric acid, so that the mercury ions and metal impurities attached to the surface of the oxidation layer fall off with the oxidation layer; on the other hand, the residual trace of mercury can be further oxidized to a more soluble form by hydrogen peroxide, further improving the cleaning effect; in addition, diluting the hydrofluoric acid with pure water can reduce the damage of the hydrofluoric acid to the silicon carbide epitaxial wafer.

[0065] The DHF is internally circulated, for example, the internal circulation flow rate of the DHF can be 15 L / min to 20 L / min, to improve the uniformity of the DHF concentration and reduce the metal residue at the edge of the silicon carbide epitaxial wafer.

[0066] As an example, the third predetermined time period can be selected from a range of 10 min to 20 min.

[0067] After the silicon carbide epitaxial wafer is immersed in the DHF for the third predetermined time period, the silicon carbide epitaxial wafer can be subjected to a quick dump rinse (QDR).

[0068] In this step, the process of the QDR can be as follows: the silicon carbide epitaxial wafer is placed in a pure water tank at room temperature, and a third rinsing process of overflow, then bubbling, then spraying, and finally draining is repeatedly performed for multiple times, for example, 7 to 15 times.

[0069] In this way, the QDR including 7 to 15 times of the third rinsing process can thoroughly rinse the DHF residue and the fallen impurities, prevent the residual DHF from corroding the surface of the silicon carbide epitaxial wafer and causing appearance defects of the silicon carbide epitaxial wafer, and prevent the residual hydrofluoric acid from reacting with ammonia to generate NH4F and increase surface particle contamination in subsequent steps. In addition, performing the QDR at room temperature can reduce the stress change caused by temperature fluctuation and protect the structural stability of the large-size silicon carbide epitaxial wafer.

[0070] For example, in step S103, the duration of the entire QDR process can be selected from the range of 800s-1800s.

[0071] S104: immerse the silicon carbide epitaxial wafer in an ammonia-hydrogen peroxide mixture solution with internal solution circulation, and perform a quick dump rinse on the silicon carbide epitaxial wafer after a fourth preset duration.

[0072] The temperature of the ammonia-hydrogen peroxide mixture (APM, also known as Standard Clean 1, SC1) can be selected from the range of 30-50°C, which can ensure a high dissolution efficiency of the metal hydroxide in the solution and reduce the concentration fluctuations of the solution caused by ammonia evaporation at high temperatures.

[0073] As an example, the SC1 can be a mixed solution of ammonia, hydrogen peroxide, and pure water with a mixing ratio of 1:2:20-1:2:60. The ammonia can be UPSS-grade ammonia, the hydrogen peroxide can be UPSS hydrogen peroxide with a mass percentage concentration of 31%, and the pure water can be ultra-pure water supplied directly by the factory.

[0074] The ammonia (NH3·H2O) can adjust the solution to be alkaline, the metal impurities react with the alkaline solution to form soluble hydroxides, which are removed with the SC1 solution circulating inside the solution, and the internal circulation flow rate of the SC1 solution can be 15-20 L / min. The hydrogen peroxide has enhanced oxidation under alkaline conditions, which can oxidize and remove residual organic contaminants such as oil residues in carrier concentration detection, and can also act synergistically with ammonia to disperse small particles and prevent particles from re-depositing on the surface of the silicon carbide epitaxial wafer.

[0075] As an example, the fourth preset duration can be selected from the range of 10-20 min.

[0076] After the silicon carbide epitaxial wafer is immersed in the SC1 for the fourth preset duration, the silicon carbide epitaxial wafer can be subjected to a quick dump rinse (QDR) again.

[0077] In this step, the QDR process can be as follows: the silicon carbide epitaxial wafer is placed in a pure water tank at room temperature, and a third rinsing process of overflow, then bubbling, then spraying, and finally draining is performed repeatedly, for example, 7-15 times.

[0078] Therefore, QDR, which includes 7 to 15 third rinse cycles, thoroughly removes residual ammonia and metal hydroxides from the surface of the silicon carbide epitaxial wafer, preventing white spots from forming on the surface after drying. Furthermore, performing QDR at room temperature allows for a gentle temperature transition from low-temperature SC1 to room-temperature QDR, reducing thermal stress on the silicon carbide epitaxial wafer and lowering the risk of warpage.

[0079] For example, in step S103, the duration of the entire QDR process can be selected from the range of 800s to 1800s.

[0080] It is understandable that the QDR process in step S103 and step S104 can be exactly the same, or different QDR processes can be set according to actual cleaning needs.

[0081] After the cleaning process is completed, the silicon carbide epitaxial wafer also needs to be dried. As an example, the silicon carbide epitaxial wafer can be transferred to a spin dryer for rinsing and spin drying, while simultaneously undergoing nitrogen heating, chamber heating, and electrostatic elimination. Thus, nitrogen heating prevents watermarks from forming on the surface of the silicon carbide epitaxial wafer, ensuring surface cleanliness; chamber heating maintains a constant temperature within the spin dryer chamber, preventing stress damage to the silicon carbide epitaxial wafer due to uneven temperature; and electrostatic elimination prevents the silicon carbide epitaxial wafer from adsorbing tiny particles from the environment during the drying process due to static electricity, further improving the cleanliness of the cleaned silicon carbide epitaxial wafer.

[0082] See Figure 2 This figure is a schematic diagram of a cleaning effect provided in an embodiment of this application, wherein, Figure 2 As can be seen in (a), there are obvious capillary indentations on the surface of the silicon carbide epitaxial wafer before cleaning. After cleaning and drying using the cleaning method provided in this application, as shown in (a), the surface of the silicon carbide epitaxial wafer is cleaned and dried. Figure 2 As shown in (b), the capillary indentation has been removed at the same location, and the surface of the silicon carbide epitaxial wafer is clean. After numerous experiments, the concentration of metallic impurities on the surface of the silicon carbide epitaxial wafer after cleaning using the cleaning method provided in this application is less than 5E10 Atoms / cm². 2 The criteria for inclusion are: particulate contaminant size less than 150 nm, maximum diameter of a single white surface carbonitride defect (SCN) less than or equal to 8 mm, and total number of point defects (P+LP) per unit area on the epitaxial wafer surface and near-surface region less than or equal to 150 / cm. 2The surface of the silicon carbide epitaxial wafer is cleaned by the cleaning method, and the surface qualification rate of the silicon carbide epitaxial wafer is greater than 97%.

[0083] Therefore, the first SPM pretreatment of low-temperature nitrogen bubbling is combined with the second SPM deep treatment of high-temperature internal circulation, and the low-temperature environment is matched with nitrogen bubbling to loosen impurities in the capillary indentation and preliminarily dissociate mercury residues, the high-temperature environment and the internal circulation of the solution strengthen the oxidation effect, and the mercury can be completely oxidized into a soluble form and the adsorption structure of the indentation is destroyed, thereby fundamentally solving the problems that the mercury residues and the capillary indentation cannot be removed in the traditional process, and the cleaning effect on the silicon carbide epitaxial wafer is improved; the internal circulation of the solution combined with the DHF and the SC1 can make the surface of the large-size silicon carbide epitaxial wafer uniformly contact with the solution, and the cleaning effect on the edge area of the silicon carbide epitaxial wafer is improved.

[0084] In the embodiment, the low-temperature SPM pretreatment, the high-temperature SPM deep treatment, the DHF chemical etching, the SC1 cleaning and the multiple rinsing are combined, on the one hand, a closed loop of dissociation first, oxidation second and removal last is formed, and the removal effect on the mercury residues is improved; on the other hand, the low-temperature SPM is combined with the nitrogen bubbling, the high-temperature SPM and the multiple rinsing, the capillary indentation is physically loosened first, the structure of the capillary indentation is destroyed second, and the impurities are finally rinsed and removed, and the capillary indentation can be completely eliminated.

[0085] Referring to Figure 3 The figure is a structure diagram of a cleaning equipment for a silicon carbide epitaxial wafer provided in the embodiment, and the equipment includes a memory 301 and a processor 302.

[0086] The memory 301 is used for storing program codes and transmitting the program codes to the processor.

[0087] The processor 302 is used for executing the steps of the cleaning method for the silicon carbide epitaxial wafer according to the instructions in the program codes.

[0088] In addition, the application further provides a computer readable storage medium, and the computer readable storage medium stores computer instructions, when the computer instructions run on the cleaning equipment for the silicon carbide epitaxial wafer, the cleaning equipment for the silicon carbide epitaxial wafer executes the steps of the cleaning method for the silicon carbide epitaxial wafer.

[0089] It should be noted that each of the embodiments of the present specification is described in a progressive manner, and the same or similar parts between the embodiments can be mutually referred to, and each of the embodiments focuses on the differences from other embodiments. In particular, for the device and storage medium embodiments, since they are basically similar to the method embodiments, they are described more simply, and the relevant parts can be referred to the part of the description of the method embodiments. The above-described device and storage medium embodiments are only illustrative, and the units described as separate components can or can not be physically separated, and the components indicated as units can or can not be physical units, that is, they can be located in one place, or distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiments according to the actual needs. Those skilled in the art can understand and implement it without creative labor.

[0090] The above describes only one specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A cleaning method of a silicon carbide epitaxial wafer, characterized by, The method comprises: immersing the silicon carbide epitaxial wafer in a first sulfuric acid-hydrogen peroxide mixed solution with nitrogen bubbling, and performing hot rapid pouring flushing on the silicon carbide epitaxial wafer after a first preset time length; the temperature of the first sulfuric acid-hydrogen peroxide mixed solution is a first temperature; immersing the silicon carbide epitaxial wafer in a second sulfuric acid-hydrogen peroxide mixed solution with internal solution circulation, and performing hot rapid pouring flushing on the silicon carbide epitaxial wafer after a second preset time length; the temperature of the second sulfuric acid-hydrogen peroxide mixed solution is a second temperature, and the second temperature is higher than the first temperature; immersing the silicon carbide epitaxial wafer in a diluted hydrogen fluoride-hydrogen peroxide mixed solution with internal solution circulation, and performing rapid pouring flushing on the silicon carbide epitaxial wafer after a third preset time length; immersing the silicon carbide epitaxial wafer in an ammonia-hydrogen peroxide mixed solution with internal solution circulation, and performing rapid pouring flushing on the silicon carbide epitaxial wafer after a fourth preset time length.

2. The method of claim 1, wherein, The first temperature is selected from the range of 40℃ to 60℃.

3. The method of claim 1, wherein, The second temperature is selected from the range of 120℃ to 150℃.

4. The method of claim 1, wherein, The internal solution circulation flow rate of the second sulfuric acid-hydrogen peroxide mixed solution is 15L / min to 20L / min.

5. The method of claim 1, wherein, The first preset time length is selected from the range of 8min to 15min.

6. The method of claim 1, wherein, The second preset time length is selected from the range of 10min to 20min.

7. The method of claim 1, wherein, The hot rapid pouring flushing comprises: placing the silicon carbide epitaxial wafer in a pure water tank with a water temperature of a target temperature, and cyclically performing a first flushing process of multiple times of first spraying, then water filling, and finally water draining; performing a second flushing process of first spraying, then water filling, then bubbling, then overflow, and finally water draining.

8. The method of claim 1, wherein, The rapid pouring flushing comprises: placing the silicon carbide epitaxial wafer in a pure water tank at room temperature, and cyclically performing a third flushing process of multiple times of first overflow, then bubbling, then spraying, and finally water draining.

9. The method of claim 1, wherein, The temperature of the diluted hydrogen fluoride-hydrogen peroxide mixed solution is selected from the range of 20℃ to 30℃.

10. The method of claim 1, wherein, The temperature of the ammonia-hydrogen peroxide mixed solution is selected from the range of 30℃ to 50℃.

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