Gas control system in crystal growth furnace

Abstract

The utility model discloses a gas control system in a crystal growth furnace, which is characterized in that inert gas is introduced into the crystal growth furnace through a second pipeline, and nitrogen is introduced into the crystal growth furnace through a third pipeline, so that the inert gas and the nitrogen exist in the crystal growth furnace, and normal growth of crystals in the crystal growth furnace is ensured; an output pump and a monitoring module are arranged on the first pipeline, in the crystal growth process, the output pump is started to extract mixed gas in the crystal growth furnace through the first pipeline, and at least one of the nitrogen concentration and the inert gas concentration in the mixed gas is detected through the monitoring module; at least one of the second pipeline and the third pipeline is provided with a control valve, so that the opening degree of the corresponding control valve can be adjusted according to the nitrogen concentration detected by the monitoring module, the gas concentration in the crystal growing furnace can be adjusted, the nitrogen concentration in the crystal growing furnace is stabilized in a specified range, the resistivity uniformity of crystals is improved, and the yield of the crystals is improved. And the qualified rate of the resistivity of the crystal is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crystal preparation, and more particularly to a gas control system and method in a crystal growth furnace. BACKGROUND

[0002] The resistivity of a crystal is an important indicator of its electrical conductivity. In the process of preparing a crystal in a crystal growth furnace, the uniformity of the resistivity of the crystal is poor, and the probability of unqualified resistivity of the crystal is large.

[0003] To sum up, how to improve the uniformity of the resistivity of the crystal and improve the qualified rate of the resistivity of the crystal is a problem to be solved by the technical personnel in the field at present. CONTENT OF THE INVENTION

[0004] Therefore, the purpose of the present application is to provide a gas control system in a crystal growth furnace, which improves the uniformity of the resistivity of the crystal and improves the qualified rate of the resistivity of the crystal.

[0005] In order to achieve the above purpose, the present application provides the following technical scheme:

[0006] A gas control system in a crystal growth furnace, comprising: a first pipeline, an output pump, a monitoring module, a second pipeline, a third pipeline and a control valve; wherein the second pipeline and the third pipeline are both used to communicate with the crystal growth furnace, the second pipeline is used to introduce inert gas into the crystal growth furnace, and the third pipeline is used to introduce nitrogen into the crystal growth furnace; at least one of the second pipeline and the third pipeline is provided with the control valve; the first pipeline is used to communicate with the crystal growth furnace, and the output pump and the monitoring module are arranged on the first pipeline, the output pump is used to extract mixed gas in the crystal growth furnace through the first pipeline, the mixed gas comprising the nitrogen and the inert gas, and the monitoring module is used to acquire at least one of the nitrogen concentration and the inert gas concentration in the mixed gas.

[0007] In some embodiments, the periphery of the crystal growth furnace is provided with a cooling device, and the first pipeline can pass through the cooling device.

[0008] In some embodiments, the monitoring module comprises: at least one gas chromatograph for detecting the nitrogen concentration and the inert gas concentration in the mixed gas; or at least one mass spectrometer for detecting the nitrogen concentration and the inert gas concentration in the mixed gas.

[0009] In some embodiments, the gas chromatograph comprises: a first gas chromatograph configured to detect a nitrogen concentration in the mixed gas; and a second gas chromatograph configured to detect an inert gas concentration in the mixed gas.

[0010] In some embodiments, the mass spectrometer comprises: a first mass spectrometer configured to detect a nitrogen concentration in the mixed gas; and a second mass spectrometer configured to detect an inert gas concentration in the mixed gas.

[0011] In some embodiments, the control valve comprises: a first control valve disposed in the second pipeline; and a second control valve disposed in the third pipeline.

[0012] In some embodiments, the system further comprises a control module connected to the monitoring module, the first control valve, and the second control valve, wherein the control module is configured to control the opening degree of the first control valve and the opening degree of the second control valve.

[0013] In some embodiments, the second pipeline is further provided with a first flow meter configured to detect a flow value of the inert gas in the second pipeline, and the third pipeline is further provided with a second flow meter configured to detect a flow value of the nitrogen in the third pipeline, wherein the first flow meter and the second flow meter are connected to the control module.

[0014] In some embodiments, the first pipeline is further provided with a pressure control valve connected between the crystal growth furnace and the output pump.

[0015] In some embodiments, the inert gas comprises at least one of argon and helium.

[0016] The crystal growth furnace gas control system provided by the application, the second pipeline and the third pipeline are both communicated with the crystal growth furnace, inert gas is introduced into the crystal growth furnace through the second pipeline, and nitrogen is introduced into the crystal growth furnace through the third pipeline, so that the inert gas and the nitrogen exist in the crystal growth furnace, and the normal growth of the crystal in the crystal growth furnace is ensured; the crystal growth furnace is communicated with the first pipeline, the output pump and the monitoring module are arranged on the first pipeline, during the crystal growth process, the output pump is started to extract the mixed gas in the crystal growth furnace through the first pipeline, and at least one of the nitrogen concentration and the inert gas concentration in the mixed gas is detected through the monitoring module; at least one of the second pipeline and the third pipeline is provided with a control valve, so that the opening degree of the corresponding control valve can be adjusted according to the nitrogen concentration detected by the monitoring module, the gas concentration in the crystal growth furnace is adjusted, the nitrogen concentration in the crystal growth furnace is stabilized in a specified range, the uniformity of the resistivity of the crystal is improved, and the qualified rate of the resistivity of the crystal is improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the application, and other drawings can be obtained by the provided drawings without creative labor for those skilled in the art.

[0018] Figure 1 The structure diagram of the crystal growth furnace gas control system provided by the embodiments of the application.

[0019] Mark explanation:

[0020] 10-crystal growth furnace, 11-crucible, 12-heating device, 13-cooling device;

[0021] 21-first flowmeter, 22-first control valve, 23-second pipeline;

[0022] 31-second flowmeter, 32-second control valve, 33-third pipeline;

[0023] 41-first pipeline, 42-pressure control valve, 43-output pump, 44-monitoring module;

[0024] 50-control module. DETAILED DESCRIPTION

[0025] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0026] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. The terms used in the following embodiments are only for the purpose of describing the specific embodiments, and are not intended to be limiting to the present application. As used in the specification and the appended claims of the present application, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0027] In the present specification, the phrase “one embodiment” or “some embodiments” etc. means that a particular feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Therefore, the phrases “in one embodiment”, “in some embodiments”, “in other some embodiments”, “in yet some embodiments” etc. appearing in different places in the present specification are not necessarily all referring to the same embodiment, but mean “one or more but not all embodiments”, unless otherwise specifically emphasized. The terms “comprise”, “include”, “have” and their variations mean “including but not limited to”, unless otherwise specifically emphasized.

[0028] The plurality referred to in the embodiments of the present application means greater than or equal to two. It should be noted that in the description of the embodiments of the present application, the terms “first”, “second” etc. are only used for distinguishing the purpose of description, and cannot be understood as indicating or implying relative importance, nor can be understood as indicating or implying order.

[0029] At present, in the process of preparing silicon carbide crystals in a crystal growth furnace, the nitrogen concentration in the crystal growth furnace will affect the uniformity and size of the resistivity of the silicon carbide crystals. According to research, the increase of the nitrogen concentration will make the uniformity of the resistivity of the silicon carbide crystals more consistent, however, when the nitrogen concentration is greater than 1x10 19 cm -3 -6, it will cause the resistivity of the silicon carbide crystals to be lower than its normal operating range. Therefore, in order to ensure the uniformity and size of the resistivity of the silicon carbide crystals, the nitrogen concentration in the crystal growth furnace needs to be stabilized in a specified range.

[0030] In the existing process of preparing silicon carbide crystals using crystal growth furnaces, the nitrogen concentration inside the furnace cannot be determined, resulting in poor resistivity uniformity of the silicon carbide crystals and a high probability of the resistivity of the silicon carbide crystals failing to meet standards.

[0031] This application provides a gas control system for a crystal growth furnace, which improves the uniformity of the resistivity of the crystal and increases the yield of the crystal resistivity.

[0032] The gas concentration control system for a crystal growth furnace provided in this embodiment includes: a first pipe 41, an output pump 43, a monitoring module 44, a second pipe 23, a third pipe 33, and a control valve. Both the second pipe 23 and the third pipe 33 are connected to the crystal growth furnace 10. The second pipe 23 introduces inert gas into the crystal growth furnace 10, and the third pipe 33 introduces nitrogen gas into the crystal growth furnace 10, thus ensuring the presence of both inert gas and nitrogen gas within the crystal growth furnace 10, thereby guaranteeing the normal growth of silicon carbide crystals within the crystal growth furnace 10.

[0033] During the operation of the crystal growth furnace 10, the second pipe 23 and the third pipe 33 continuously introduce inert gas and nitrogen into the crystal growth furnace, and the crystal growth furnace 10 continuously discharges some inert gas and nitrogen.

[0034] The first pipe 41 connects to the crystal growth furnace 10. An output pump 43 and a monitoring module 44 are installed on the first pipe 41. During the silicon carbide crystal growth process, the output pump 43 is started to draw mixed gas from the crystal growth furnace 10 through the first pipe 41, and the monitoring module 44 detects at least one of the nitrogen concentration and the inert gas concentration in the mixed gas. At least one of the second pipe 23 and the third pipe 33 is equipped with a control valve. In this way, according to the nitrogen concentration detected by the monitoring module 44, the opening degree of the corresponding control valve can be adjusted, thereby regulating the nitrogen concentration in the crystal growth furnace 10 and stabilizing the nitrogen concentration in the crystal growth furnace 10 within a specified range. This improves the uniformity of the crystal resistivity and increases the pass rate of the crystal resistivity.

[0035] It should be noted that in order to ensure the normal growth of the crystal in the crystal growth furnace 10, the crystal growth furnace 10 contains almost only inert gas and nitrogen. Therefore, obtaining the inert gas concentration can also yield a relative nitrogen concentration.

[0036] In practice, such as Figure 1 As shown, a crucible 11 is provided inside the crystal growth furnace 10. The silicon carbide crystal is melted inside the crucible 11 so that the inert gas and nitrogen can isolate the air outside the crystal growth furnace 10 during the silicon carbide crystal growth process, thus ensuring the purity and quality of the silicon carbide crystal. The gas introduced into the crystal growth furnace 10 as described in the embodiments of this application is actually introduced into the crucible 11.

[0037] In some embodiments, the inert gas introduced through the second pipeline 23 can be argon or helium, which can ensure the purity and quality of the silicon carbide crystal, and can maintain the uniformity of the temperature in the crystal growth furnace 10, thereby ensuring the growth of the silicon carbide crystal. Of course, helium and argon can be introduced at the same time, and the embodiments of the present application do not make any limitation in this regard.

[0038] In other embodiments, the inert gas introduced through the second pipeline 23 can be any inert gas or a combination of any two inert gases, and the embodiments of the present application do not make any limitation in this regard.

[0039] It should be noted that, since the silicon carbide crystal needs to be grown in a stable low-pressure environment, in order to ensure the normal growth of the silicon carbide crystal, as shown in FIG. 4, a pressure control valve 42 is further arranged on the first pipeline 41, and the pressure control valve 42 is connected between the crystal growth furnace 10 and the output pump 43, so as to control the frequency of the output pump 43 through the pressure control valve 42, so as to ensure that the crystal growth furnace 10 is in a stable pressure environment. Figure 1

[0040] In some embodiments, the pressure range maintained by the pressure control valve 42 in the crystal growth furnace 10 is 100-500 Pa, and the embodiments of the present application do not make any limitation in this regard.

[0041] Since, as shown in FIG. 4, the crystal growth furnace 10 is provided with a heating device 12 for heating the crucible 11, and the periphery of the crystal growth furnace 10 is provided with a cooling device 13. Therefore, the temperature in the crystal growth furnace 10 is high, and the temperature of the mixed gas is also high. As described above, the first pipeline 41 communicates with the crystal growth furnace 10, and the first pipeline 41 passes through the cooling device 13, so that the mixed gas is extracted through the cooling device 13, so that the mixed gas is cooled under the cooling action of the cooling device 13, so that the monitoring module 44 can withstand the temperature of the mixed gas, thereby realizing the detection of the nitrogen concentration or the inert gas concentration in the crystal growth furnace 10 by the monitoring module 44. In this way, the embodiments of the present application realize the cooling of the high-temperature mixed gas through the structure of the crystal growth furnace 10 itself, so that the monitoring module 44 can detect, without the need for additional cooling equipment, thereby simplifying the overall structure and saving costs. Figure 1 In some embodiments, the cooling device of the crystal growth furnace 10 can be a cooling water system, and a sealing structure is arranged at the connection between the first pipeline 41 and the cooling water system, so as to ensure the sealing operation of the cooling water system and ensure the cooling effect.

[0042]

[0043] ​​In some embodiments, the monitoring module 44 includes at least one gas chromatograph, which can detect the nitrogen concentration and inert gas concentration in the mixed gas. The monitoring module 44 provided in this application embodiment can be a single gas chromatograph, which can test the concentration of multiple gases and reduce costs.

[0044] In some other embodiments, the monitoring module 44 includes a first gas chromatograph and a second gas chromatograph. The first gas chromatograph can detect the nitrogen concentration in the mixed gas, and the second gas chromatograph can detect the inert gas concentration in the mixed gas. In this way, the accuracy of detection is improved by detecting the concentration of the corresponding gas using two gas chromatographs.

[0045] It should be noted that the gas chromatograph can be a packed column gas chromatograph, a capillary gas chromatograph, etc., and the embodiments of this application do not limit it.

[0046] In some other embodiments, the monitoring module 44 includes at least one mass spectrometry and chromatography instrument, which can detect the nitrogen concentration and inert gas concentration in the mixed gas. The monitoring module 44 provided in this application embodiment can be a mass spectrometry and chromatography instrument, which can test the concentration of multiple gases and reduce costs.

[0047] In some other embodiments, the monitoring module 44 includes a first mass spectrometry and chromatography system and a second mass spectrometry and chromatography system. The first mass spectrometry and chromatography system can detect the nitrogen concentration in the mixed gas, and the second mass spectrometry and chromatography system can detect the inert gas concentration in the mixed gas. In this way, the detection accuracy is improved by detecting the concentration of the corresponding gas using two mass spectrometry and chromatography systems.

[0048] like Figure 1 As shown, to improve the convenience of the control process, the control valves include a first control valve 22 and a second control valve 32. The first control valve 22 is located in the second pipeline 23, allowing the flow rate of inert gas entering the crystal growth furnace 10 to be controlled by adjusting the opening degree of the first control valve 22. The second control valve 32 is located in the third pipeline 33, allowing the flow rate of nitrogen entering the crystal growth furnace 10 to be controlled by adjusting the opening degree of the second control valve 32. In this way, based on the nitrogen and inert gas concentrations detected by the monitoring module 44, the flow rates of the corresponding gases can be controlled more directly, improving the convenience of the control process.

[0049] In some embodiments, after the nitrogen concentration or inert gas concentration in the mixed gas inside the crystal growth furnace 10 is known by the monitoring module 44, the opening degree of the first control valve 22 or the second control valve 32 can be manually adjusted so that the operator can observe and control the process, thereby improving the safety of the adjustment process.

[0050] In some other embodiments, such as Figure 1 As shown, to improve the intelligence of gas control, the gas control system in the crystal growth furnace also includes a control module 50. The control module 50 is connected to the monitoring module 44, the first control valve 22, and the second control valve 32. The control module 50 presets the nitrogen concentration in the mixed gas. The control module 50 is connected to the monitoring module 44, the first control valve 22, and the second control valve 32 so that the control module 50 can adjust the opening degree of the corresponding first control valve 22 and second control valve 32 according to the nitrogen concentration determined by the monitoring module 44 and the preset nitrogen concentration. This allows the control module 50 to adjust the nitrogen concentration in the crystal growth furnace 10 more timely, improving the efficiency of gas regulation and further improving the uniformity of resistivity and the pass rate of resistivity of silicon carbide crystals.

[0051] For example, if the detected nitrogen concentration is greater than the preset nitrogen concentration, it indicates that the nitrogen concentration in the crystal growth furnace 10 is higher than the preset value, and the nitrogen concentration should be reduced. The control module 50 can control the opening degree of the first control valve 22 on the second pipe 23 to increase the flow rate of the inert gas entering the crystal growth furnace 10, thereby reducing the nitrogen concentration in the crystal growth furnace 10. Alternatively, the control module 50 can control the opening degree of the second control valve 22 on the third pipe 33 to decrease the flow rate of nitrogen entering the crystal growth furnace 10, thereby reducing the nitrogen concentration in the crystal growth furnace 10. Of course, the control module 50 can also simultaneously increase the opening degree of the first control valve 22 and decrease the opening degree of the second control valve 32 to accelerate the rate of nitrogen concentration reduction in the crystal growth furnace 10 and improve the efficiency of gas regulation.

[0052] If the detected nitrogen concentration is equal to the preset nitrogen concentration, it means that the nitrogen concentration in the crystal growth furnace 10 is equal to the preset value, which meets the set growth conditions of silicon carbide crystal. The control module 50 does not need to be adjusted, and the opening degree of the first control valve 22 and the second control valve 32 remains unchanged.

[0053] In the case that the detected nitrogen concentration is less than the preset nitrogen concentration, it indicates that the nitrogen concentration in the crystal growth furnace 10 is lower than the preset value, and the nitrogen concentration should be increased. The opening degree of the first control valve 22 on the second pipeline 23 can be reduced by the control module 50 to reduce the flow of inert gas into the crystal growth furnace 10, so as to increase the nitrogen concentration in the crystal growth furnace 10. Alternatively, the opening degree of the second control valve 32 on the third pipeline 33 can be increased by the control module 50 to increase the flow of nitrogen into the crystal growth furnace 10, so as to increase the nitrogen concentration in the crystal growth furnace 10. Of course, the opening degree of the first control valve 22 can be reduced and the opening degree of the second control valve 32 can be increased at the same time by the control module 50 to accelerate the increasing rate of the nitrogen concentration in the crystal growth furnace 10 and improve the efficiency of gas regulation.

[0054] It should be noted that the regulation process of the control module 50 on the first control valve 22 and the second control valve 32 is a conventional means that can be realized by those skilled in the art, and the principle does not involve program improvement, which will not be described here.

[0055] It should be noted that the detected inert gas concentration can also be compared with the preset value, which can be a preset inert gas concentration. The preset value can also be a preset nitrogen concentration, and the corresponding nitrogen concentration can be obtained by detecting the inert gas concentration, which is not limited in the embodiments of the present application.

[0056] As shown in Figure 1 The second pipeline 23 is also provided with a first flow meter 21, which can detect the flow value of the inert gas in the second pipeline 23. The third pipeline 33 is also provided with a second flow meter 31, which can detect the flow value of the nitrogen in the third pipeline 33, and the first flow meter 21 and the second flow meter 31 are connected to the control module 50. In this way, the control module 50 can detect the inert gas flow in the second pipeline 23 and the nitrogen flow in the third pipeline 33, and determine whether the opening degree of the corresponding control valve meets the requirements through the corresponding gas flow.

[0057] In some embodiments, the first flow meter 21 and the second flow meter 22 can be volume flow meters, mass flow meters, etc., which can be selected according to actual needs, and the embodiments of the present application are not limited thereto.

[0058] The crystal growth furnace gas control system provided by the embodiments of the present application works as follows: first, the inert gas and the nitrogen gas are continuously introduced into the crystal growth furnace 10 through the second pipeline 23 and the third pipeline 33 respectively, so as to ensure the normal growth environment of the silicon carbide crystal; during the growth of the silicon carbide crystal, the output pump 43 is started to extract the mixed gas in the crystal growth furnace 10 through the first pipeline 41, the nitrogen concentration in the mixed gas is obtained through the monitoring module 44, and the detected nitrogen concentration and the preset value, the opening degree of the first control valve 22 or the second control valve 32 adjusted by the control module 50 are compared, so as to adjust the flow of the inert gas or the flow of the nitrogen gas introduced into the crystal growth furnace 10, the nitrogen concentration in the crystal growth furnace 10 is adjusted, the nitrogen concentration in the crystal growth furnace 10 is stabilized in a specified range, the uniformity of the resistivity of the silicon carbide crystal is improved, and the qualified rate of the resistivity of the silicon carbide crystal is improved.

[0059] The above description of disclosed embodiments enables one skilled in the art to make or use the application. Numerous modifications to these embodiments will be apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gas control system in a crystal growth furnace, characterized by, include: First pipeline (41), output pump (43), monitoring module (44), second pipeline (23), third pipeline (33) and control valve; The second pipe (23) and the third pipe (33) are both used to connect the crystal growth furnace (10). The second pipe (23) is used to introduce inert gas into the crystal growth furnace (10), and the third pipe (33) is used to introduce nitrogen into the crystal growth furnace (10). The control valve is provided on at least one of the second pipe (23) and the third pipe (33); The first pipe (41) is used to connect to the crystal growth furnace (10). The first pipe (41) is equipped with the output pump (43) and the monitoring module (44). The output pump (43) is used to extract the mixed gas in the crystal growth furnace (10) through the first pipe (41). The mixed gas includes the nitrogen and the inert gas. The monitoring module (44) is used to obtain at least one of the nitrogen concentration and the inert gas concentration in the mixed gas.

2. The gas control system for a crystal growing furnace according to claim 1, wherein A cooling device (13) is provided around the crystal growth furnace (10), and the first pipe (41) can pass through the cooling device (13).

3. The gas control system for a crystal growing furnace according to claim 1, wherein The monitoring module (44) includes: At least one gas chromatograph, the gas chromatograph being used to detect the nitrogen concentration and the inert gas concentration in the mixed gas; Alternatively, at least one mass spectrometry-chromatography (MS / GC) instrument is used to detect the nitrogen and inert gas concentrations in the gas mixture.

4. The gas control system for a crystal growing furnace according to claim 3, wherein The gas chromatograph includes: A first gas chromatograph is used to detect the nitrogen concentration in the mixed gas; A second gas chromatograph is used to detect the concentration of inert gas in the mixed gas.

5. The gas control system for a crystal growing furnace according to claim 3, wherein The mass spectrometry-chromatography system includes: A first mass spectrometry and chromatography instrument is used to detect the nitrogen concentration in the mixed gas; A second mass spectrometry and chromatography instrument is used to detect the concentration of inert gas in the mixed gas.

6. The gas control system for a crystal growing furnace according to claim 1, wherein The control valve includes: The first control valve (22) is disposed in the second pipeline (23); The second control valve (32) is disposed in the third pipeline (33).

7. The gas control system for a crystal growing furnace according to claim 6, wherein It also includes a control module (50), which is connected to the monitoring module (44), the first control valve (22) and the second control valve (32). The control module (50) can control the opening degree of the first control valve (22) and the opening degree of the second control valve (32).

8. The gas control system for a crystal growing furnace according to claim 7, wherein The second pipe (23) is also equipped with a first flow meter (21), which is used to detect the flow rate of the inert gas in the second pipe (23); The third pipe (33) is also equipped with a second flow meter (31), which is used to detect the flow rate of nitrogen in the third pipe (33); The first flow meter (21) and the second flow meter (31) are connected to the control module (50).

9. The crystal growth furnace atmosphere control system of any one of claims 1-8, wherein, The first pipeline (41) is further provided with a pressure control valve (42), and the pressure control valve (42) is connected between the crystal growth furnace (10) and the output pump (43).

10. The gas control system for a crystal growth furnace according to any one of claims 1 to 8, wherein The inert gas includes one of argon and helium.

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