Metal content control method for epitaxial furnace cavity

Abstract

The invention relates to a metal content control method for an epitaxial furnace cavity, which comprises the following stages: a cleaning stage: removing residual substances in the cavity; gas is introduced into the cavity to remove dust and impurity residues, then the heating element is used for removing organic matter and moisture on the surface of the substrate, the temperature and pressure in the cavity are kept stable after the steps are completed, and finally residual matter on the surface of the substrate is removed in the etching step; a coating stage: growing a silicon layer with controllable thickness on the surface of the base; gas is introduced into the cavity to remove residual substances, the temperature and the pressure in the cavity are kept stable after the steps are completed, and finally a silicon layer with the controllable thickness is generated on the surface of the base in the coating step; in the cooling stage, the temperature of the cavity is ensured to be 25 DEG C; the method comprises the following steps: firstly, introducing gas into a cavity to remove residual substances, and then reducing the temperature of a substrate to 25 DEG C; by optimizing the etching step and the coating step, the problem that the metal of the epitaxial wafer exceeds the standard is solved, so that the quality of the epitaxial wafer is improved.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a method for controlling the metal content of an epitaxial furnace cavity. Background Art

[0002] The epitaxial furnace uses the reduction reaction of trichlorosilane or silicon chloride with hydrogen to grow single crystal epitaxy on a single crystal substrate silicon wafer. As the number of epitaxial wafers produced increases, the reaction chamber of the epitaxial furnace needs to be shut down for cleaning and maintenance. During the replacement of accessories, metal pollutants are introduced from the outside, causing the metal pollutant content in the epitaxial furnace chamber to increase. Even if the concentration is very low, it will reduce the quality of the epitaxial wafer and ultimately lead to a decrease in device performance. The existing method for cleaning the reaction chamber is mainly to introduce hydrogen chloride gas into the chamber, etch the silicon oxide remaining in the chamber, and then discharge it through tail gas treatment to improve the chamber environment.

[0003] Traditional cleaning methods have poor effects on improving metal content and cannot remove metal impurities remaining on the substrate surface, causing the metal impurities to penetrate into the epitaxial wafer, causing the metal content of the epitaxial wafer to exceed the standard, thereby reducing the quality of the epitaxial wafer and adversely affecting the performance of components. Summary of the invention

[0004] The present invention aims to solve the problems existing in the above-mentioned prior art and provides a method for controlling the metal content of an epitaxial furnace cavity. By optimizing the etching process and coating process in the scheme, the problem of excessive metal content in epitaxial wafers is improved, thereby improving the quality of epitaxial wafers.

[0005] The present invention solves the technical problem by adopting a technical method: a method for controlling the metal content of an epitaxial furnace cavity, comprising the following stages: S100, the first stage of cleaning, removing residual substances in the cavity; firstly, gas is introduced into the cavity to remove dust and impurities, and then the heating element is gradually raised to a certain temperature to remove organic matter and moisture on the surface of the substrate. After the organic matter and moisture on the surface of the substrate are completely evaporated, etching gas is used to remove residual substances on the surface of the substrate; S200, the second stage of coating, growing a silicon layer with controllable thickness on the surface of the base; firstly, introducing gas into the cavity to remove residual substances on the surface, then using temperature and pressure detection devices to monitor the temperature and pressure to ensure the stability of the temperature and pressure in the cavity, and then using reaction gas for coating to form a silicon layer with controllable thickness on the surface of the base; S300, the third stage of cooling, ensure that the cavity temperature is 25°C; first, gas is introduced into the cavity to remove residual substances on the surface, and then the substrate temperature is reduced to 25°C.

[0006] In this scheme, the residual substances on the surface of the substrate can be effectively removed through the first stage of cleaning; then, a silicon layer with controllable thickness is formed on the surface of the base through the second stage of coating. The silicon layer has a stable structure and good adhesion with the metal material, which reduces the outward diffusion of metal contaminants attached to the surface of the substrate.

[0007] Preferably, the first stage of cleaning specifically includes the following steps: S110, purging, using inert gas as the cleaning gas, moving the nozzle to clean, ensuring that there is no visible dust and impurities remaining in the cavity, and then using an optical microscope to check the inner surface of the cavity to confirm that there are no residual particles; S120, heating, gradually raising the temperature from room temperature to 1000°C by means of a heating element, and ensuring uniform temperature distribution throughout the process; S130, baking, when the temperature is gradually increased to 1000° C., and then the temperature is kept constant for baking, until the organic matter and water on the surface of the substrate are completely evaporated and the surface is dry, a detection device is used to detect the surface of the substrate to confirm that no organic matter and water remain; S140, stabilization, after the baking is completed, the temperature and pressure in the epitaxial cavity are kept stable, and the temperature and pressure are monitored by a temperature and pressure monitoring device to ensure the stability of the environmental conditions in the cavity; S150, etching, use etching gas to etch, and use a microscope to check the substrate surface to confirm No residual substances.

[0008] In this stage, the dust and impurities on the surface are removed by purging the epitaxial furnace cavity; organic matter and moisture on the substrate surface are removed by high-temperature baking treatment; residual substances can be effectively removed by etching gas; and after the baking treatment, the temperature and pressure in the cavity are stabilized to provide suitable environmental conditions for the implementation of the etching step.

[0009] Preferably, the etching step lasts for 36 seconds to 53 seconds. Prolonging the etching time can completely remove the residual substances on the surface of the base.

[0010] Preferably, the gas used in the etching step is hydrogen chloride, and the etching rate is 0.25 μm / s, which can effectively remove residual substances on the surface of the base.

[0011] Preferably, the second stage coating specifically comprises the following steps: S210, purging, using inert gas as cleaning gas, cleaning by moving the nozzle to ensure that there is no visible dust and impurities remaining in the cavity, and then using an optical microscope to check the inner surface of the cavity to confirm that there are no residual particles; S220, stabilization, maintaining the temperature and pressure in the epitaxial cavity stable, using a temperature and pressure monitoring device to monitor the temperature and pressure, and ensuring the stability of the environmental conditions in the cavity; S230, coating, using a reactive gas for coating, so that a silicon layer with controllable thickness grows on the surface of the base, and a thickness measuring device is used to measure the thickness of the silicon layer to ensure its uniformity and thickness control.

[0012] During this stage, the inside of the epitaxial furnace chamber is purged to remove residues on the surface; the temperature and pressure inside the chamber are stabilized to create good environmental conditions for the subsequent coating steps; in addition, the thickness-controlled silicon layer grown on the surface of the base during the coating step acts as a protective film, which can effectively block the diffusion of metal contaminants into the epitaxial wafer.

[0013] Preferably, the thickness of the silicon layer in the coating step is 1-2 μm. Increasing the thickness of the silicon layer can reduce the impact of metal contaminants on the epitaxial wafer, but if the silicon layer is too thick, the base and the pins of the external support base will be adhered together. After considering the advantages and disadvantages of both, the thickness of the silicon layer is controlled between 1-2 μm.

[0014] Preferably, the reaction gases used in the coating step are trichlorosilane and hydrogen, which are used to grow a silicon layer with controllable thickness on the surface of the base, and the silicon layer acts as a protective film.

[0015] Preferably, the coating step lasts for 45s to 125s. Prolonging the coating step can increase the thickness of the silicon layer on the surface of the base, thereby effectively preventing metal contaminants on the surface of the substrate from diffusing into the epitaxial layer.

[0016] Preferably, argon gas is introduced as a carrier in the coating step, and the argon gas accounts for 10% to 30% of the total gas flow, so that the coating step is further optimized and the uniformity and thickness control of the protective film are ensured.

[0017] Preferably, the third stage cooling specifically comprises the following steps: S310, purging, using inert gas as cleaning gas, cleaning by moving the nozzle to ensure that there is no visible dust and impurities remaining in the cavity, and then using an optical microscope to check the inner surface of the cavity to confirm that there are no residual particles; S320, cooling, first lowering the substrate temperature to room temperature, and using a temperature monitoring device to monitor the temperature to ensure that the temperature is stable at 25°C.

[0018] After completing the first stage of cleaning and the second stage of coating, the epitaxial furnace chamber is still in a high temperature state, so the main purpose of this stage is to cool it down.

[0019] The present invention has the following beneficial effects: 1. Through multi-stage cleaning, coating and cooling steps, the metal content of the epitaxial wafer is effectively reduced, and the purity and quality of the epitaxial wafer are improved, which not only extends the service life of the epitaxial wafer, but also improves the performance and reliability of the epitaxial wafer, making it suitable for the manufacture of high-performance semiconductor devices.

[0020] 2. Through the cleaning steps, including purging, heating, baking, stabilization and etching, the dust, impurities, organic matter and moisture in the cavity, as well as the residual substances on the surface of the substrate are completely removed, ensuring the cleanliness of the cavity, and providing a pure environment for subsequent epitaxial growth, reducing the risk of contamination of the epitaxial wafer.

[0021] 3. In the etching step, hydrogen chloride gas is used for etching, and the etching time is extended to the preset time to ensure that the residual substances on the substrate surface are completely removed and confirm that there are no residual substances on the substrate surface, thereby improving the cleanliness of the substrate surface and providing a high-quality substrate for subsequent epitaxial growth.

[0022] 4. In the coating step, a silicon layer with a thickness of 1-2μm is generated on the surface of the base through purging, stabilization and coating. Trichlorosilane and hydrogen are used as reaction gases, and the coating time is extended to the preset time to ensure the uniform growth and thickness control of the silicon layer. In addition, the introduction of argon as a carrier further improves the transmission efficiency of the reaction gas, ensures the uniformity and thickness control of the silicon layer, and effectively blocks the diffusion of metal contaminants on the surface of the substrate to the epitaxial layer. Through the cooling step, the substrate temperature is reduced to the preset temperature, ensuring the stability of the cavity temperature, providing a reliable environment for subsequent processes, and improving the quality and reliability of epitaxial wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of the scheme of the present invention; Figure 2 The metal test result after the preventive maintenance of the cavity in the present invention; Figure 3 This is the metal test result of the cavity after 60s of coating in the present invention. DETAILED DESCRIPTION

[0024] The following is combined with Figures 1 to 3 The present invention will be further described: Combination Figure 1 As shown, the present invention provides a method for controlling the metal content in an epitaxial furnace chamber. The design method is generally divided into three stages: cleaning, coating and cooling.

[0025] S100, the first stage of cleaning, removes residual substances in the cavity. First, inert gas is introduced into the cavity to remove dust and impurities. After completion, an optical microscope is used to check the inner surface of the cavity to confirm that there are no residual particles; then the heating element is gradually raised to a certain temperature to remove organic matter and moisture on the surface of the substrate. After the organic matter and moisture on the surface of the substrate are completely evaporated, the surface of the substrate is detected using a detection device to confirm that there is no organic matter and moisture remaining; then the temperature and pressure detection device is used to monitor the temperature and pressure to ensure the stability of the temperature and pressure in the cavity; finally, etching gas is used to remove residual substances on the surface of the base, and the surface of the base is checked with a microscope to ensure that there are no residual substances.

[0026] In this embodiment, the heating element can be set as a resistance wire or an infrared lamp to achieve temperature control during the cleaning process, thereby achieving precise heating or baking.

[0027] The cleaning of the residual substances in the cavity at this stage ensures the cleanliness of the cavity of the epitaxial furnace, providing a good foundation for the subsequent epitaxial growth. In addition, the etching in this stage can effectively remove the residual substances on the surface of the base, ensuring the cleanliness of the surface of the base and reducing the impact of the residual substances on the subsequent processes.

[0028] S200, the second stage of coating, grows a silicon layer with controllable thickness on the surface of the base. First, inert gas is introduced into the cavity to remove dust and impurities. After completion, an optical microscope is used to check the inner surface of the cavity to confirm that there are no residual particles; then the temperature and pressure detection device is used to monitor the temperature and pressure to ensure the stability of the temperature and pressure in the cavity; then the reaction gas is used for coating to generate a silicon layer with controllable thickness on the surface of the base, and the thickness of the silicon layer is measured using a thickness measuring device to ensure its uniformity and controllable thickness.

[0029] In this stage, a silicon layer with controllable thickness is grown on the surface of the base. The silicon acts as a protective film, which can prevent metal contaminants from diffusing into the epitaxial wafer.

[0030] S300, the third stage of cooling, ensure that the cavity temperature is 25℃. First, inert gas is introduced into the cavity to remove dust and impurities. After completion, the inner surface of the cavity is checked with an optical microscope to confirm that there are no residual particles; then the substrate temperature is lowered to room temperature, and the temperature is monitored using a temperature monitoring device to ensure that the temperature drops to 25℃.

[0031] After removing the metal residues in the cavity, the temperature in the cavity is still at a high temperature. Therefore, the main function of this stage is to cool down.

[0032] In order to further illustrate the effect of the first stage cleaning, the first stage cleaning is further explained. The specific steps to achieve the first stage cleaning include: S110, purge, use high-purity nitrogen as the cleaning gas, and move the nozzle in a large-angle circular swing to clean, ensuring that there is no visible dust and impurities remaining in the cavity. At this time, the swing angle of the nozzle is 120°, the swing frequency is 1Hz, the nozzle is 10cm away from the epitaxial cavity wall, the gas flow rate is 500-1000sccm, and the purge should make the air flow rate in the epitaxial cavity reach 1-2m / s. The entire purge process takes 5s. After purging, use an optical microscope to check the inner surface of the cavity to confirm that there are no residual particles. In this step, the dust and impurities on the surface of the cavity can be effectively removed by purging the epitaxial furnace cavity.

[0033] S120, heating, heating by infrared lamp, so that the temperature in the cavity is heated at a rate of 10℃ / s, so that the temperature in the cavity gradually rises from room temperature (about 25℃) to 1000℃. The entire heating process lasts for 30s. During this process, the temperature distribution should be uniform to avoid local overheating. In order to ensure that the temperature deviation does not exceed ±5℃, a thermocouple is used to monitor the temperature in the cavity. In this step, the main purpose of heating is to make the temperature in the epitaxial furnace cavity meet the requirements of the subsequent process environment.

[0034] S130, baking. When the temperature rises to 1000°C, stop heating and keep the temperature at 1000°C. In order to remove organic matter and moisture on the surface of the substrate, keep the temperature in the chamber constant for 45 seconds for baking. When the organic matter and moisture on the surface of the substrate are completely evaporated and the surface is dry, use an infrared spectrometer to detect the surface of the substrate to confirm that there is no organic matter and moisture remaining.

[0035] S140, stability, after the baking is completed, the temperature and pressure in the chamber need to be kept stable. The duration of the stabilization process is 10s, so that the environmental conditions in the chamber are suitable for the subsequent etching steps. In order to ensure that the temperature and pressure fluctuate within the set value range by no more than ±1%, the temperature and pressure in the chamber are monitored using thermocouples and pressure sensors.

[0036] S150, etching, using hydrogen chloride gas for etching, the entire etching process takes 43 seconds, the gas flow rate during the etching process is 1000sccm, the etching rate is 0.25μm / s, and the etching temperature is 1000°C. During this process, the residual substances (such as oxides, metal particles, etc.) on the surface of the base will be completely removed. In order to confirm that there are no residual substances, the surface of the base is checked using a scanning electron microscope.

[0037] In this step, hydrogen chloride gas is used as the etching gas, and the etching rate is controlled at 0.25μm / s, which can effectively remove the residual substances on the surface of the base. The etching time is optimized and controlled to 43s. On the one hand, the residual substances on the surface of the base can be completely removed, and on the other hand, the surface of the base will not be corroded due to excessive etching time, thereby causing damage to the equipment and products. The optimization of the etching step effectively removes the residual substances on the surface of the base, reduces metal contamination, and improves the quality and purity of the epitaxial wafer.

[0038] In order to further illustrate the effect achieved by the second stage coating, the second stage coating is further explained. The specific steps for achieving the second stage coating include: S210, purge, use high-purity nitrogen as the cleaning gas, and move the nozzle in a large-angle circular swing to clean, ensuring that there is no visible dust and impurities remaining in the cavity. At this time, the swing angle of the nozzle is 120°, the swing frequency is 1Hz, the nozzle is 10cm away from the epitaxial cavity wall, the gas flow rate is 500-1000sccm, and the purge should make the air flow rate in the epitaxial cavity reach 1-2m / s. The entire purge process takes 30s. After purging, use an optical microscope to check the inner surface of the cavity to confirm that there are no residual particles. In this step, the residues on the surface of the cavity can be effectively removed by purging the epitaxial furnace cavity.

[0039] S220, stability. After baking, the temperature and pressure in the cavity need to be kept stable. The duration of the stabilization process is 15 seconds, so that the environmental conditions in the cavity are suitable for the subsequent coating steps. In order to ensure that the temperature and pressure fluctuate within the set value range by no more than ±1%, the temperature and pressure in the cavity are monitored using thermocouples and pressure sensors.

[0040] S230, coating, using trichlorosilane and hydrogen for coating, so that a layer of silicon layer with controllable thickness grows on the surface of the base. The silicon layer acts as a protective film and can effectively block the diffusion of metal pollutants to the epitaxial wafer. The entire coating process takes 60s, the flow rate of trichlorosilane is 100-500sccm, the flow rate of hydrogen is 1000-5000sccm, and the coating temperature is 1000℃. During the coating process, precise control of gas flow and reaction time should be ensured to generate a uniform and thickness-controlled silicon layer. The thickness range of the silicon layer should be controlled to be 1-2μm. During this process, an ellipsometer is needed to measure the thickness of the silicon layer to ensure its uniformity and thickness control.

[0041] In this step, silicon trichloride gas and hydrogen will be used to react to generate silicon. Trichlorosilane and hydrogen undergo a chemical vapor deposition reaction at high temperature, which can form a uniform silicon layer with controllable thickness on the surface of the base. Trichlorosilane is a commonly used silicon source gas with high reactivity. At high temperatures, trichlorosilane can decompose and release silicon atoms, which react with hydrogen to generate a silicon layer. Hydrogen, as a reducing agent, can promote the decomposition of trichlorosilane and improve the growth rate and quality of the silicon layer. At the same time, hydrogen can also remove oxides on the surface of the substrate to ensure the purity and uniformity of the silicon layer.

[0042] In addition, introducing an appropriate amount of argon as a carrier in the coating step improves the uniformity and controllability of the coating process and ensures the consistent thickness of the protective film. The total proportion of argon in the total gas flow should be between 10% and 30%.

[0043] Table 1 Combined with Figure 2 , Attachment Figure 3 As shown in the figure, the body metal test value after preventive maintenance of the cavity is 2.68e12. The body metal content in the cavity is required to be less than 5e10, so the body metal content is seriously exceeded. Comparing the body metal content in the cavity at different coating times in Table 1, it can be concluded that the longer the coating time, the lower the body metal content in the cavity. However, if the coating time is too long, the base and the pins of the external support base will stick together, affecting the service life of the cavity, so the coating time needs to be controlled within a reasonable range. After the experiment, it was decided to optimize the time of the coating step, and finally the time of the coating stage was controlled at 60s. On the one hand, this optimization scheme effectively blocked the diffusion of metal contaminants to the epitaxial wafer, and on the other hand, it avoided the adhesion of the base and the pins of the external support base, thereby improving the reliability and stability of the process.

[0044] The introduction of argon as a carrier improves the uniformity and controllability of the coating process, ensures the consistent thickness of the protective film, and effectively blocks the diffusion of metal contaminants. Through annealing treatment, the structure of the epitaxial wafer is further improved, stress is eliminated, and the crystallization quality and electrical properties of the epitaxial layer are improved. These optimization measures further reduce the metal content of the epitaxial wafer, improve the purity and reliability of the epitaxial wafer, and meet the manufacturing needs of high-performance semiconductor devices.

[0045] As shown in Table 2, S1: purging, the time is 5 seconds. This step removes dust and impurities on the surface by purging the epitaxial furnace cavity. S2: heating, the time is 30 seconds. This step heats the substrate to a certain temperature to prepare for subsequent processes. S3: baking, the time is 45 seconds. Through high temperature treatment, organic matter and moisture on the surface of the substrate are removed. S4: stabilization, the time is 10 seconds. This step ensures that the substrate temperature is stable and provides stable conditions for subsequent processes. S5: etching, the time is 36 seconds to 53 seconds. Chemical gases are used to remove the surface of the substrate. Residual substances on the surface, S6: Purge, time is 30 seconds, purge the epitaxial furnace cavity again to remove the residues on the surface, S7: Stabilize, time is 15 seconds, ensure the stability of the substrate temperature, and provide stable conditions for subsequent processes, S8: Coating, time is 45 seconds to 125 seconds, the function is to grow a protective film on the surface of the substrate to effectively block metal pollution, S9: Purge, time is 15 seconds, this step purges the epitaxial furnace cavity again to remove the residues on the surface, S10: Cooling, time is 5 seconds, cool the substrate to room temperature, prepare for the next process.

[0046] Table 2 As shown in Table 3 below, the coating step time is 60 seconds to balance the metal content control and avoid the adhesion of the base to the pins of the external support base. By optimizing the coating time, the thickness of the protective film is ensured to be moderate, which not only effectively blocks metal contamination, but also avoids the adhesion of the base to the pins of the external support base, thereby improving the reliability and stability of the process; the etching step time is 43 seconds to ensure the removal of residual substances on the base. By precisely controlling the etching time, it is ensured that the residual substances on the substrate surface are completely removed, thereby improving the purity and quality of the epitaxial wafer.

[0047] Table 3 In order to further illustrate the role of the third stage cooling, the third stage cooling is further explained. The specific steps for achieving the third stage cooling include: S310, purge, use high-purity nitrogen as the cleaning gas, and move the nozzle in a large-angle circular swing to clean, ensuring that there is no visible dust and impurities remaining in the cavity. At this time, the swing angle of the nozzle is 120°, the swing frequency is 1Hz, the nozzle is 10cm away from the epitaxial cavity wall, the gas flow rate is 500-1000sccm, and the purge should make the air flow rate in the epitaxial cavity reach 1-2m / s. The entire purge process takes 15s. After purging, use an optical microscope to check the inner surface of the cavity to confirm that there are no residual particles. In this step, the residues on the surface of the cavity can be effectively removed by purging the epitaxial furnace cavity.

[0048] S320, cooling, using nitrogen as the atmosphere protection, quickly lowering the temperature in the chamber to room temperature, the entire cooling process takes 5 seconds, and the gas flow rate is 1000 sccm. In order to avoid stress caused by temperature gradient, a thermocouple is used to detect the temperature.

[0049] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0050] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for controlling the metal content of an epitaxial furnace cavity, characterized in that: The following phases are included: S100, the first stage of cleaning, removing residual substances in the cavity; firstly, gas is introduced into the cavity to remove dust and impurities, and then the heating element is gradually raised to a certain temperature to remove organic matter and moisture on the surface of the substrate. After the organic matter and moisture on the surface of the substrate are completely evaporated, etching gas is used to remove residual substances on the surface of the substrate; S200, the second stage of coating, growing a silicon layer with controllable thickness on the surface of the base; firstly, introducing gas into the cavity to remove residual substances on the surface, then using temperature and pressure detection devices to monitor the temperature and pressure to ensure the stability of the temperature and pressure in the cavity, and then using reaction gas for coating to form a silicon layer with controllable thickness on the surface of the base; S300, the third stage of cooling, ensure that the cavity temperature is 25°C; first, gas is introduced into the cavity to remove residual substances on the surface, and then the substrate temperature is reduced to 25°C.

2. The method for controlling the metal content of an epitaxial furnace cavity according to claim 1, characterized in that: The first stage of cleaning specifically includes the following steps: S110, purging, using inert gas as the cleaning gas, moving the nozzle to clean, ensuring that there is no visible dust and impurities remaining in the cavity, and then using an optical microscope to check the inner surface of the cavity to confirm that there are no residual particles; S120, heating, gradually raising the temperature from room temperature to 1000°C by means of a heating element, and ensuring uniform temperature distribution throughout the process; S130, baking, when the temperature is gradually increased to 1000° C., and then the temperature is kept constant for baking, until the organic matter and water on the surface of the substrate are completely evaporated and the surface is dry, a detection device is used to detect the surface of the substrate to confirm that no organic matter and water remain; S140, stabilization, after the baking is completed, the temperature and pressure in the epitaxial cavity are kept stable, and the temperature and pressure are monitored by a temperature and pressure monitoring device to ensure the stability of the environmental conditions in the cavity; S150, etching: etching with an etching gas, and inspecting the substrate surface with a microscope to confirm that there is no residual material.

3. The method for controlling the metal content of an epitaxial furnace cavity according to claim 2, characterized in that: The etching step takes 36 to 53 seconds to remove residual substances on the surface of the base.

4. The method for controlling the metal content of an epitaxial furnace cavity according to claim 2, characterized in that: The gas used in the etching step is hydrogen chloride, and the etching rate is 0.25 μm / s.

5. The method for controlling the metal content of an epitaxial furnace cavity according to claim 1, characterized in that: The second stage coating specifically includes the following steps: S210, purging, using inert gas as cleaning gas, cleaning by moving the nozzle to ensure that there is no visible dust and impurities remaining in the cavity, and then using an optical microscope to check the inner surface of the cavity to confirm that there are no residual particles; S220, stabilization, maintaining the temperature and pressure in the epitaxial cavity stable, using a temperature and pressure monitoring device to monitor the temperature and pressure, and ensuring the stability of the environmental conditions in the cavity; S230, coating, using a reactive gas for coating, so that a silicon layer with controllable thickness grows on the surface of the base, and a thickness measuring device is used to measure the thickness of the silicon layer to ensure its uniformity and thickness control.

6. The method for controlling the metal content of an epitaxial furnace cavity according to claim 1, characterized in that: The thickness of the silicon layer in the coating step is 1-2 μm.

7. The method for controlling the metal content of an epitaxial furnace cavity according to claim 6, characterized in that: The reaction gases used in the coating step are trichlorosilane and hydrogen, which are used to grow a silicon layer with controllable thickness on the surface of the base.

8. The method for controlling the metal content of an epitaxial furnace cavity according to claim 6, characterized in that: The coating step lasts for 45 seconds to 125 seconds, which is used to prevent metal pollutants on the surface of the substrate from diffusing into the epitaxial layer.

9. The method for controlling the metal content of an epitaxial furnace cavity according to claim 6, characterized in that: Argon gas is introduced as a carrier in the coating step, and the argon gas accounts for 10% to 30% of the total gas flow.

10. The method for controlling the metal content of an epitaxial furnace cavity according to claim 1, characterized in that: The third stage cooling specifically includes the following steps: S310, purging, using inert gas as cleaning gas, cleaning by moving the nozzle to ensure that there is no visible dust and impurities remaining in the cavity, and then using an optical microscope to check the inner surface of the cavity to confirm that there are no residual particles; S320, cooling, first lowering the substrate temperature to room temperature, and using a temperature monitoring device to monitor the temperature to ensure that the temperature is stable at 25°C.

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