Silicon carbide epitaxial wafer uniformity in-situ detection system

Abstract

The invention provides a silicon carbide epitaxial wafer uniformity in-situ detection system. The in-situ detection system for the uniformity of the silicon carbide epitaxial wafer comprises a distance measuring sensor, a temperature sensor and a controller, the distance measuring sensor is arranged above the graphite tray base, deviates from the circle center of the graphite tray base and is used for detecting the distance between the distance measuring sensor and the graphite tray base before epitaxial temperature rise and sending detected distance data to the controller; the temperature sensor is arranged above the graphite tray base, deviates from the circle center of the graphite tray base and is used for detecting the temperature of the graphite tray base after epitaxial temperature rise and sending detected temperature data to the controller; the controller is used for determining whether the silicon carbide epitaxy is abnormal according to the distance data and the temperature data. Monitoring is carried out in the epitaxial growth processing stage through the distance measuring sensor and the temperature sensor, the abnormity in epitaxial growth can be found in time, further epitaxial process growth is prevented, and adverse effects are prevented.

Description

Technical Field

[0001] The invention relates to the technical field of silicon carbide epitaxial production, and in particular to an in-situ detection system for uniformity of a silicon carbide epitaxial wafer. Background Art

[0002] Silicon carbide epitaxy belongs to the third generation of semiconductors and is widely used in discrete devices such as MOSFET, SBD, JBS, and JFET. Silicon carbide epitaxial growth refers to growing a layer of silicon carbide single crystal with a specific thickness and carrier concentration on the surface of a silicon carbide substrate at high temperature to obtain products that can be used in MOSFET, JBS, SBD, JFET and other fields.

[0003] During the silicon carbide epitaxial growth process, due to the flatness deviation of the rotating base installation, the transmission error during the robot transmission process, the failure of the rotating component, etc., the key characteristic parameters of the epitaxial product, such as thickness and carrier concentration, will deviate and become scrapped.

[0004] In the prior art, abnormalities can usually only be discovered during the product inspection stage after the silicon carbide epitaxial growth is completed, and intervention and regulation cannot be performed during the epitaxial growth process, which seriously affects the product qualification rate and production and processing efficiency. Summary of the invention

[0005] The embodiment of the present invention provides an in-situ detection system for uniformity of silicon carbide epitaxial wafers to solve the problem in the prior art that abnormalities can only be discovered after the epitaxial growth is completed, which affects the product qualification rate and production and processing efficiency.

[0006] In a first aspect, an embodiment of the present invention provides an in-situ detection system for uniformity of a silicon carbide epitaxial wafer, comprising: a distance sensor, a temperature sensor and a controller;

[0007] The distance measuring sensor is arranged above the graphite tray base and deviates from the center of the graphite tray base, and is used to detect the distance between the graphite tray base and the graphite tray base before the epitaxial temperature is increased, and the detected distance data is sent to the controller;

[0008] The temperature sensor is arranged above the graphite tray base and deviates from the center of the graphite tray base, and is used to detect the temperature of the graphite tray base after the epitaxial temperature is increased, and send the detected temperature data to the controller;

[0009] The controller is used to determine whether there is an abnormality in the silicon carbide epitaxy according to the distance data and the temperature data.

[0010] Optionally, determining whether there is an abnormality in the silicon carbide epitaxy based on the distance data and the temperature data includes:

[0011] Determine the angular velocity of the graphite tray base according to the distance data, and if the angular velocity of the graphite tray base is greater than a preset angular velocity, it is determined that the silicon carbide epitaxy is abnormal;

[0012] The surface flatness of the graphite tray base is determined based on the distance data. If the surface of the graphite tray base is not flat, it is determined that the silicon carbide epitaxy is abnormal.

[0013] The surface flatness of the graphite tray base is determined based on the temperature data. If the surface of the graphite tray base is not flat, it is determined that there is an abnormality in the silicon carbide epitaxy.

[0014] Optionally, a groove or a protrusion is provided on the edge of the graphite tray base; when the graphite tray base rotates, the groove or the protrusion passes through the detection area of ​​the distance measuring sensor.

[0015] Optionally, a groove is provided on an edge of the graphite tray base; and determining the angular velocity of the graphite tray base according to the distance data includes:

[0016] If a first preset number of consecutive distance data is greater than a first preset distance, the time corresponding to the first distance data among the first preset number of consecutive distance data is used as the target time;

[0017] The time interval between two adjacent target moments is taken as the rotation period of the graphite tray base;

[0018] The angular velocity of the graphite tray base is determined based on the rotation period.

[0019] Optionally, determining the angular velocity of the graphite tray base according to the distance data further includes:

[0020] taking an average value of the rotation periods of a plurality of graphite tray bases as a target rotation period;

[0021] Determine the angular velocity of the graphite tray base based on the rotation period, including:

[0022] Determine the angular velocity of the graphite tray base based on the target rotation period.

[0023] Optionally, the surface flatness of the graphite tray base is determined based on the distance data, including:

[0024] For any target moment, the distance data between the target moment and the next target moment adjacent thereto is used as the target data corresponding to the target moment; data greater than a first preset distance from the target data corresponding to the target moment is removed, and a maximum value and a minimum value of the remaining target data are determined; a difference between the maximum value and the minimum value is calculated to obtain a first difference value corresponding to the target moment;

[0025] If the first difference values ​​corresponding to a second preset number of consecutive target moments are all greater than the second preset distance, it is determined that the surface of the graphite tray base is uneven.

[0026] Optionally, the surface flatness of the graphite tray base is determined based on the temperature data, including:

[0027] Calculate the average value of the third preset number of consecutive temperature data to obtain the target temperature value;

[0028] For any temperature data, calculate the difference between the temperature data and the target temperature value to obtain a second difference corresponding to the temperature data;

[0029] If the second difference values ​​corresponding to the third preset number of consecutive temperature data are all greater than the preset temperature, it is determined that the surface of the graphite tray base is uneven.

[0030] Optionally, the sampling time of the third preset number of temperature data is 2 to 3 rotation periods of the graphite tray base.

[0031] Optionally, the third preset number is 1000.

[0032] Optionally, the above-mentioned silicon carbide epitaxial wafer uniformity in-situ detection system further includes: an alarm device;

[0033] The alarm device is connected to the controller and is used to issue an alarm when there is an abnormality in the silicon carbide epitaxy.

[0034] The embodiment of the present invention provides an in-situ detection system for the uniformity of silicon carbide epitaxial wafers. The in-situ detection system for the uniformity of silicon carbide epitaxial wafers includes: a distance sensor, a temperature sensor and a controller; the distance sensor is arranged above a graphite tray base and deviates from the center of the graphite tray base, and is used to detect the distance between the graphite tray base and the graphite tray base before the epitaxial temperature rises, and sends the detected distance data to the controller; the temperature sensor is arranged above the graphite tray base and deviates from the center of the graphite tray base, and is used to detect the temperature of the graphite tray base after the epitaxial temperature rises, and sends the detected temperature data to the controller; the controller is used to determine whether there is an abnormality in the silicon carbide epitaxy according to the distance data and the temperature data. The embodiment of the present invention monitors the epitaxial growth processing stage through the distance sensor and the temperature sensor, and can timely discover the abnormality in the epitaxial growth, prevent further epitaxial process growth, prevent the occurrence of defects, and improve the product qualification rate and production and processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 It is a schematic diagram of a graphite tray base in the prior art;

[0037] Figure 2 It is a schematic diagram of the normal loading of the silicon carbide substrate into the graphite tray base;

[0038] Figure 3 It is a structural schematic diagram of an epitaxial device in the prior art;

[0039] Figure 4 It is a structural schematic diagram of an in-situ detection system for uniformity of silicon carbide epitaxial wafers provided in an embodiment of the present invention;

[0040] Figure 5 is a schematic diagram showing that the silicon carbide substrate is not properly loaded into the graphite tray base;

[0041] Figure 6 It is another schematic diagram that the silicon carbide substrate is not properly loaded into the graphite tray base;

[0042] Figure 7 is a schematic diagram of a graphite tray base provided by an embodiment of the present invention;

[0043] Figure 8 is a distance data diagram when the silicon carbide substrate in the embodiment of the present invention is not normally loaded into the graphite tray base;

[0044] Fig. 9 Temperature data diagram of a silicon carbide substrate when it is normally loaded into a graphite tray base in an embodiment of the present invention;

[0045] Fig.10 A temperature data diagram when the silicon carbide substrate is not properly loaded into the graphite tray base in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0047] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0048] Figure 1 The graphite tray base 1 in the prior art is shown. The silicon carbide substrate 2 is placed in the graphite tray base 1 manually or by a robot arm, and then transferred to the cyclone tray 3 in the reaction chamber by the robot arm. Figure 2 and Figure 3 The carrier gas (usually hydrogen or argon) is blown in through two inclined air inlets under the cyclone tray 3, so that the cyclone tray 3 rotates, thereby driving the graphite tray base 1 on which the silicon carbide substrate 2 is placed to rotate at a high speed.

[0049] Due to the installation flatness deviation of the graphite tray base 1, the transmission error during the robot transmission process, the failure of the rotating component, etc., the epitaxial product parameters may be abnormal and scrapped.

[0050] Based on the above, Figure 4 A schematic diagram of the structure of an in-situ detection system for uniformity of silicon carbide epitaxial wafers provided by an embodiment of the present invention. Figure 4 , the silicon carbide epitaxial wafer uniformity in-situ detection system comprises: a distance sensor 4, a temperature sensor 5 and a controller 6;

[0051] The distance sensor 4 is arranged above the graphite tray base 1 and deviates from the center of the graphite tray base 1, and is used to detect the distance between the graphite tray base 1 and the graphite tray base 1 before the epitaxial temperature is increased, and send the detected distance data to the controller 6;

[0052] The temperature sensor 5 is arranged above the graphite tray base 1 and deviates from the center of the graphite tray base 1, and is used to detect the temperature of the graphite tray base 1 after the epitaxial temperature is increased, and send the detected temperature data to the controller 6;

[0053] The controller 6 is used to determine whether there is any abnormality in the silicon carbide epitaxy according to the distance data and the temperature data.

[0054] refer to Figure 2 When the silicon carbide substrate 2 is normally loaded into the graphite tray base 1, the silicon carbide substrate 2 fits with the graphite tray base 1, and the surface of the silicon carbide substrate 2 is flat (or the surface of the graphite tray base 1 is flat); Figure 5 When the silicon carbide substrate 2 fails to be properly loaded into the graphite tray base 1, the edge of the silicon carbide substrate 2 will be placed on the edge of the graphite tray base 1. Figure 6, the lower surface of the silicon carbide substrate 2 cannot be attached to the graphite tray base 1, the surface of the silicon carbide substrate 2 is uneven, and the epitaxial heating is uneven.

[0055] Based on this, an embodiment of the present invention provides an in-situ detection system for uniformity of silicon carbide epitaxial wafers, including a distance sensor 4, through which the uneven surface of the silicon carbide substrate 2 and the abnormal angular velocity are detected; at the same time, based on the uneven heating of the silicon carbide substrate 2 when it fails to be normally loaded into the graphite tray base 1, a temperature sensor 5 is used to detect temperature data to determine the abnormality, so that the abnormality can be discovered in time during the epitaxial production stage, further epitaxial process growth can be prevented, and defects can be prevented, thereby improving the product qualification rate and production and processing efficiency.

[0056] In a possible implementation, determining whether there is an abnormality in silicon carbide epitaxy according to distance data and temperature data includes:

[0057] S101: determining the angular velocity of the graphite tray base 1 according to the distance data, and if the angular velocity of the graphite tray base 1 is greater than a preset angular velocity, determining that there is an abnormality in the silicon carbide epitaxy;

[0058] S102: determining the surface flatness of the graphite tray base 1 according to the distance data, and if the surface of the graphite tray base 1 is not flat, determining that the silicon carbide epitaxy is abnormal;

[0059] S103: Determine the surface flatness of the graphite tray base 1 according to the temperature data. If the surface of the graphite tray base 1 is not flat, it is determined that there is an abnormality in the silicon carbide epitaxy.

[0060] If the angular velocity of the graphite tray base 1 is too fast or uneven, it will cause the thickness / concentration of epitaxial growth to be abnormal, resulting in scrapping. Therefore, the embodiment of the present invention can determine the angular velocity of the graphite tray base 1 according to the distance data, determine the abnormality according to the angular velocity; can also determine the abnormal flatness of the surface of the graphite tray base 1 according to the distance data; further, can further determine the abnormal flatness of the surface of the graphite tray base 1 according to the temperature data.

[0061] In a possible implementation manner, a groove or a protrusion is provided on the edge of the graphite tray base 1 ; when the graphite tray base 1 rotates, the groove or the protrusion passes through the detection area of ​​the distance measuring sensor 4 .

[0062] In the embodiment of the present invention, a groove or protrusion may be provided on the edge of the graphite tray base 1. When the graphite tray base 1 rotates, each time the distance sensor 4 passes through the groove or protrusion, the distance data will change suddenly. Therefore, the embodiment of the present invention can determine the angular velocity of the graphite tray based on the law of sudden change of the distance data.

[0063] For example, refer to Figure 7When a groove is provided on the edge of the graphite tray base 1, the distance data increases suddenly each time the distance measuring sensor 4 passes through the groove; when a protrusion is provided on the edge of the graphite tray base 1, the distance data decreases suddenly each time the distance measuring sensor 4 passes through the protrusion.

[0064] In one possible implementation, reference Figure 7 , a groove is provided on the edge of the graphite tray base 1; S101 may include:

[0065] S1011: If a first preset number of consecutive distance data is greater than a first preset distance, taking a time corresponding to a first distance data among the first preset number of consecutive distance data as a target time;

[0066] S1012: taking the time interval between two adjacent target moments as the rotation period of the graphite tray base 1;

[0067] S1013: Determine the angular velocity of the graphite tray base 1 according to the rotation period.

[0068] Based on the above analysis, when a groove is provided on the edge of the graphite tray base 1, the distance data increases suddenly each time the distance sensor 4 passes through the groove. Therefore, if the first preset number of consecutive distance data is greater than the first preset distance, it means that the distance data increases suddenly and the distance sensor 4 reaches the groove. Therefore, the time interval between the moment corresponding to the first distance data of the sudden increase and the first data of the next sudden increase can be used as the rotation period. Then according to ω=2π / T, the angular velocity of the graphite tray base 1 is calculated.

[0069] Specifically, the first preset number can be set according to actual application requirements and is not specifically limited here.

[0070] Furthermore, in a possible implementation manner, S101 may also include:

[0071] S1014: taking the average value of the rotation periods of the plurality of graphite tray bases 1 as the target rotation period;

[0072] S1013 includes: determining the angular velocity of the graphite tray base 1 according to the target rotation period.

[0073] In the embodiment of the present invention, the rotation periods of the graphite tray base 1 obtained by multiple detections can be averaged to improve the detection accuracy, thereby making the calculation of the angular velocity of the graphite tray base 1 more accurate and the abnormality judgment more accurate.

[0074] In a possible implementation, S102 may include:

[0075] S1021: For any target moment, the distance data between the target moment and the next target moment adjacent thereto is used as the target data corresponding to the target moment; data greater than a first preset distance from the target data corresponding to the target moment is removed, and a maximum value and a minimum value of the remaining target data are determined; a difference between the maximum value and the minimum value is calculated to obtain a first difference value corresponding to the target moment;

[0076] S1022: If the first difference values ​​corresponding to a second preset number of consecutive target moments are all greater than the second preset distance, it is determined that the surface of the graphite tray base 1 is uneven.

[0077] Based on the above analysis, reference Figure 2 When the silicon carbide substrate 2 is normally loaded into the graphite tray base 1, the silicon carbide substrate 2 fits with the graphite tray base 1, and the distance data detected by the distance measuring sensor 4 in the non-groove part should be basically consistent; when the silicon carbide substrate 2 is not normally loaded into the graphite tray base 1, the edge of the silicon carbide substrate 2 will be placed on the edge of the graphite tray base 1, refer to Figure 5 and Figure 6 , the distance data detected by the distance measuring sensor 4 in the non-groove part are very different from each other. Figure 8 , the maximum value Zmax and the minimum value Zmin of the distance data within one cycle are very different.

[0078] Based on this, the embodiment of the present invention removes the data greater than the first preset distance in the target data corresponding to the target moment, that is, removes the distance data of the groove part. If the distance data of the non-groove part has a large deviation, it means that the surface of the graphite tray base 1 is uneven.

[0079] In a possible implementation, S103 may include:

[0080] S1031: Calculate the average value of a third preset number of consecutive temperature data to obtain a target temperature value;

[0081] S1032: for any temperature data, calculating the difference between the temperature data and the target temperature value to obtain a second difference corresponding to the temperature data;

[0082] S1033: If the second difference values ​​corresponding to the third preset number of consecutive temperature data are all greater than the preset temperature, it is determined that the surface of the graphite tray base 1 is uneven.

[0083] After the equipment starts to heat up, the temperature sensor 5 starts to work and collects temperature data. During the production process, since the tray base is made of graphite, the graphite base tray is heated by the induction coil, and the temperature is then transferred to the silicon carbide substrate 2 by heat conduction, so that the silicon carbide substrate 2 is heated and the silicon carbide substrate 2 is controlled to be above 1500°C for epitaxial growth. When the silicon carbide substrate 2 is normally loaded into the graphite tray base 1, the silicon carbide substrate 2 is heated relatively evenly, and the temperature data collected by the temperature sensor 5 is relatively stable. Fig. 9 When the silicon carbide substrate 2 fails to be properly loaded into the graphite tray base 1, the edge of the silicon carbide substrate 2 will overlap the edge of the graphite tray base 1, the silicon carbide substrate 2 is heated unevenly, and the temperature of the overlapping area will be lower. Fig.10 , then in one rotation cycle, the temperature data detected by the temperature sensor 5 will have a large deviation. Therefore, in the embodiment of the present invention, the average temperature is calculated, and if the second difference corresponding to the third preset number of temperature data is greater than the preset temperature, it indicates that there is a low temperature area in the silicon carbide substrate 2 and the surface of the graphite tray base 1 is uneven.

[0084] Specifically, the second preset number can be set according to actual application requirements and is not specifically limited here.

[0085] It should be noted that when the graphite tray base 1 rotates, the detection area of ​​the temperature sensor 5 will not pass through the groove or the protrusion.

[0086] In a possible implementation manner, the sampling time of the third preset number of temperature data may be 2 to 3 rotation periods of the graphite tray base 1 .

[0087] In order to improve the accuracy of the average temperature calculation without increasing the amount of data, the temperature data of 2 to 3 rotation cycles of the graphite tray base 1 can be averaged to obtain a relatively accurate average temperature.

[0088] In one possible implementation, the third preset number may be 1000.

[0089] The temperature sensor 5 may collect data in milliseconds, and the third preset number may be 1000.

[0090] In a possible implementation manner, the above system may further include: an alarm device;

[0091] The alarm device is connected to the controller 6 and is used to issue an alarm when there is an abnormality in the silicon carbide epitaxy.

[0092] In the embodiment of the present invention, an alarm device can also be provided to issue an alarm when an abnormality is detected in the silicon carbide epitaxy. At the same time, the alarm device can also timely control the equipment to shut down and stop the epitaxial growth when an abnormality occurs in the silicon carbide epitaxy to prevent the epitaxy from producing defects.

[0093] Furthermore, the above system may also include a database for data storage and data display, which will not be described in detail here.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An in-situ detection system for uniformity of silicon carbide epitaxial wafers, characterized in that: include: Distance measuring sensor, temperature sensor and controller; The distance measuring sensor is arranged above the graphite tray base and deviates from the center of the graphite tray base, and is used to detect the distance between the sensor and the graphite tray base before the epitaxial temperature is increased, and send the detected distance data to the controller; The temperature sensor is arranged above the graphite tray base and deviates from the center of the graphite tray base, and is used to detect the temperature of the graphite tray base after epitaxial heating, and send the detected temperature data to the controller; The controller is used to determine whether there is an abnormality in silicon carbide epitaxy according to the distance data and the temperature data.

2. The silicon carbide epitaxial wafer uniformity in-situ detection system according to claim 1, characterized in that: The determining whether there is an abnormality in silicon carbide epitaxy according to the distance data and the temperature data includes: Determining the angular velocity of the graphite tray base according to the distance data, and if the angular velocity of the graphite tray base is greater than a preset angular velocity, determining that an abnormality exists in the silicon carbide epitaxy; Determine the surface flatness of the graphite tray base according to the distance data, and if the surface of the graphite tray base is not flat, determine that the silicon carbide epitaxy is abnormal; The surface flatness of the graphite tray base is determined according to the temperature data. If the surface of the graphite tray base is not flat, it is determined that there is an abnormality in the silicon carbide epitaxy.

3. The silicon carbide epitaxial wafer uniformity in-situ detection system according to claim 2, characterized in that: The edge of the graphite tray base is provided with a groove or a protrusion; when the graphite tray base rotates, the groove or the protrusion passes through the detection area of ​​the distance measuring sensor.

4. The in-situ detection system for uniformity of silicon carbide epitaxial wafers according to claim 3, characterized in that: The edge of the graphite tray base is provided with a groove; and determining the angular velocity of the graphite tray base according to the distance data comprises: If a first preset number of consecutive distance data is greater than a first preset distance, taking the time corresponding to the first distance data among the first preset number of consecutive distance data as the target time; The time interval between two adjacent target moments is taken as the rotation period of the graphite tray base; The angular velocity of the graphite tray base is determined according to the rotation period.

5. The in-situ detection system for uniformity of silicon carbide epitaxial wafers according to claim 4, characterized in that: The step of determining the angular velocity of the graphite tray base according to the distance data further comprises: taking an average value of the rotation periods of the plurality of graphite tray bases as a target rotation period; Determining the angular velocity of the graphite tray base according to the rotation period includes: The angular velocity of the graphite tray base is determined according to the target rotation period.

6. The in-situ detection system for uniformity of silicon carbide epitaxial wafers according to claim 4, characterized in that: Determining the surface flatness of the graphite tray base according to the distance data includes: For any target moment, the distance data between the target moment and the next target moment adjacent thereto is used as the target data corresponding to the target moment; data greater than the first preset distance in the target data corresponding to the target moment is removed, and the maximum value and the minimum value in the remaining target data are determined; the difference between the maximum value and the minimum value is calculated to obtain a first difference value corresponding to the target moment; If the first differences corresponding to a second preset number of consecutive target moments are all greater than the second preset distance, it is determined that the surface of the graphite tray base is uneven.

7. The in-situ detection system for uniformity of silicon carbide epitaxial wafer according to claim 2, characterized in that: Determining the surface flatness of the graphite tray base according to the temperature data includes: Calculate the average value of the third preset number of consecutive temperature data to obtain the target temperature value; For any temperature data, calculate the difference between the temperature data and the target temperature value to obtain a second difference corresponding to the temperature data; If the second difference values ​​corresponding to the third preset number of consecutive temperature data are all greater than the preset temperature, it is determined that the surface of the graphite tray base is uneven.

8. The in-situ detection system for uniformity of silicon carbide epitaxial wafers according to claim 7, characterized in that: The sampling time of the third preset number of temperature data is 2 to 3 rotation cycles of the graphite tray base.

9. The in-situ detection system for uniformity of silicon carbide epitaxial wafers according to claim 8, characterized in that: The third preset number is 1000.

10. The in-situ detection system for uniformity of silicon carbide epitaxial wafer according to any one of claims 1 to 9, characterized in that: Also includes: Alarm device; The alarm device is connected to the controller and is used to issue an alarm when there is an abnormality in the silicon carbide epitaxy.

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