Gas mixing and heating system for silicon carbide growth

Abstract

The utility model discloses a gas mixing and heating system for silicon carbide growth, and belongs to the technical field of silicon carbide crystal growth. Comprising a plurality of doped gas pipelines, a gas mixing tank, a gas flow divider and a mixed gas temperature control system, a plurality of doped gas pipelines are connected with the inlet end of a gas transmission pipeline through a gas mixing joint, the gas transmission pipeline is sequentially connected with the gas mixing tank and the gas flow divider, and the outlet end of the gas transmission pipeline is connected with a silicon carbide growth device; each doped gas pipeline is sequentially connected with a pneumatic diaphragm valve, a gas flowmeter and a check valve along the gas transmission direction; the mixed gas temperature control system is connected with the gas transmission pipeline and is used for performing constant-temperature heating control on gas in the gas transmission pipeline; according to the utility model, the influence of environment temperature change on mixed gas in the pipeline can be eliminated; and meanwhile, the uniformity of the mixed gas is effectively improved through multi-stage fusion.

Description

Technical Field

[0001] The utility model belongs to the technical field of silicon carbide crystal growth, in particular to a gas mixing heating system for silicon carbide growth. Background Art

[0002] Doping is required during the growth process of silicon carbide. Some elements such as S and P are doped into the silicon carbide material to make it have the conductivity type and resistivity required for manufacturing resistors, PN junctions, buried layers, etc. The gas used in the doping process is called doping gas. Usually, the doping gas and the carrier gas are mixed in advance, and the mixed gas is continuously injected into the silicon carbide crystal growth device. The gas diffuses in the growth device and surrounds the crystal, and finally deposits in the crystal.

[0003] Depending on the process requirements, the types and proportions of doping gases vary; if the various doping gases are not mixed evenly, the uniformity of doping inside the crystal will deteriorate, and the uniformity of the crystal resistivity will deteriorate. The resistivity of the crystal is closely related to the performance of semiconductor devices. Parameters such as the breakdown voltage of the transistor are directly affected by the resistivity of the crystal.

[0004] At the same time, the pressure and other characteristics of the mixed gas will also change with the change of the external ambient temperature. If the temperature of the mixed gas is not accurately controlled, it will inevitably affect the mixing uniformity of the gas and affect the growth of the crystal. Utility Model Content

[0005] The utility model overcomes the shortcomings of the prior art and proposes a gas mixing heating system for silicon carbide growth, thereby solving the problem that various doping gases are mixed unevenly and are easily affected by the ambient temperature during the silicon carbide growth process.

[0006] In order to achieve the above purpose, the utility model is implemented through the following technical solutions.

[0007] A gas mixing and heating system for silicon carbide growth comprises a plurality of doped gas pipelines, a gas mixing tank, a gas splitter, and a mixed gas temperature control system; the plurality of doped gas pipelines are connected to the inlet end of a gas transmission pipeline via a gas mixing joint, the gas transmission pipeline is sequentially connected to the gas mixing tank and the gas splitter, and the outlet end of the gas transmission pipeline is connected to a silicon carbide growth device; each doped gas pipeline is sequentially connected to a pneumatic diaphragm valve, a gas flow meter, and a check valve along the gas transmission direction; the mixed gas temperature control system is connected to the gas transmission pipeline and is used for performing constant temperature heating control on the gas in the gas transmission pipeline.

[0008] Furthermore, the outlet end of the gas transmission pipeline is sequentially connected with a check valve and a one-way controllable valve along the gas transmission direction.

[0009] Furthermore, the mixed gas temperature control system includes a temperature control device, a circulating liquid system and a temperature measuring device, the circulating liquid system is in contact with and connected to the outer wall of the gas transmission pipeline, the temperature control device is connected to the circulating liquid system, and the temperature measuring device is arranged at the outlet end of the gas transmission pipeline.

[0010] Furthermore, the gas transmission pipeline is a spiral gas transmission pipeline, and the spiral gas transmission pipeline is coiled on the circulation pipeline of the circulating liquid system.

[0011] Furthermore, the temperature measuring device is a gas temperature detector, and the gas temperature detector is linked to the temperature control device.

[0012] Furthermore, the air inlet of the gas mixing tank is at the lower part, the air outlet is at the upper part, and a plurality of baffles are alternately arranged inside the tank cavity of the gas mixing tank.

[0013] Furthermore, there are several gas tube bundles inside the cavity of the gas splitter, the tail end of the gas tube bundle is closed, and there are several holes on the tail end tube wall, and the gas enters the mixing chamber at the rear end of the gas splitter through the holes.

[0014] The beneficial effects of the utility model compared with the prior art are:

[0015] The utility model gradually improves the uniformity of the mixed gas in two stages; at the same time, the temperature of the mixed gas is controlled throughout the whole process to ensure that the gas temperature meets the process requirements and is stable.

[0016] The utility model can eliminate the influence of ambient temperature changes on the mixed gas inside the pipeline; at the same time, the multi-stage fusion also effectively improves the uniformity of the mixed gas. In this environment, the semiconductor can obtain a precise doping depth without damaging the semiconductor surface. High-quality semiconductor materials can not only improve the performance of semiconductor devices, but also reduce the manufacturing cost of semiconductor devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of the gas mixing heating system for silicon carbide growth according to the utility model;

[0018] Figure 2 It is a schematic diagram of the structure of a gas mixing joint;

[0019] Figure 3 It is a structural schematic diagram of a gas mixing tank;

[0020] Figure 4 is a schematic diagram of the structure of a gas splitter;

[0021] In the figure:

[0022] 1-doping gas pipeline; 2-gas mixing tank; 3-gas diverter; 4-gas mixing joint; 5-gas transmission pipeline; 6-silicon carbide growth device; 7-pneumatic diaphragm valve; 8-gas flow meter; 9-one-way controllable valve; 10-temperature control device; 11-circulation pipeline; 12-gas temperature detector; 13-check valve; 21-blocking plate; 31-gas tube bundle; 32-hole; 33-mixing chamber. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail in combination with the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The technical solution of the present invention is described in detail below in combination with the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0024] like Figure 1-4 As shown, this embodiment provides a gas mixing and heating system for silicon carbide growth, which includes two doping gas pipelines 1, a gas mixing tank 2, a gas diverter 3, and a mixed gas temperature control system; the two doping gas pipelines 1 are connected to the inlet end of the gas transmission pipeline 5 through a gas mixing joint 4, the gas transmission pipeline 5 is sequentially connected to the gas mixing tank 2 and the gas diverter 3, and the outlet end of the gas transmission pipeline 5 is connected to the silicon carbide growth device 6; each doping gas pipeline 1 is sequentially connected to a pneumatic diaphragm valve 7, a gas flow meter 8 and a check valve 13 along the gas transmission direction; the mixed gas temperature control system is connected to the gas transmission pipeline 5, and is used to perform constant temperature heating control on the gas in the gas transmission pipeline 5. And the check valve 13 and the one-way controllable valve 9 are sequentially connected to the outlet end of the gas transmission pipeline 5 along the gas transmission direction.

[0025] The mixed gas temperature control system includes a temperature control device 10, a circulating liquid system and a temperature measuring device. The circulating liquid system is in contact with and connected to the outer wall of the gas transmission pipeline 5. The temperature control device 10 is connected to the circulating liquid system, and the temperature measuring device is arranged at the outlet end of the gas transmission pipeline 5. The temperature measuring device is a gas temperature detector 12, and the gas temperature detector 12 is linked to the temperature control device 10. The gas transmission pipeline 5 is a spiral gas transmission pipeline, which is coiled on the circulation pipeline 11 of the circulating liquid system. The spiral pipeline can extend the gas transmission distance to increase the mixing uniformity of the gas. At the same time, the repeated collision of the gas with the inner wall of the pipeline during the transmission process can further deepen the uniformity of the gas mixing.

[0026] The temperature control device 10 can manually set the control temperature, and can also automatically control the temperature of the circulating liquid according to the feedback of the gas temperature detector 12; the circulating liquid system is composed of a circulating pipe 11 and a circulating liquid, and the circulating pipe 11 is connected to the temperature control device 10. The circulating liquid circulates continuously in it to ensure that the temperature of the circulating liquid is constant and uniform. At the same time, the spiral gas transmission pipe is coiled on the circulating pipe to ensure that the mixed gas is heated uniformly; the gas temperature detector 12 detects the temperature of the mixed gas entering the silicon carbide growth device 6 and feeds back to the temperature control device 10, and the temperature control device 10 will control the temperature of the circulating liquid according to its feedback signal.

[0027] The two gases to be doped enter the gas mixing joint 4 through two doping gas pipelines 1 for primary mixing, and the gas source of the selected gas is connected by controlling the pneumatic diaphragm valve 7; the gas flow rate is controlled by the gas flow meter 8 according to the process requirements; the check valve 13 connected to the doping gas pipeline 1 is a protection device, which is used to prevent gas backflow caused by pipeline blockage or pressure changes in the cavity, and ensure that the gas source is not polluted. The check valve 13 is installed at multiple locations of the system to improve the reliability of the system; the gas mixing joint 4 can perform primary mixing of the gas, and its internal structure is as follows Figure 2 As shown, different mixing joints can be selected according to the amount of input gas, which provides convenient conditions for adding or reducing input pipelines in the later system.

[0028] The two gases that are initially mixed enter the gas mixing tank 2 for deep mixing. The gas inlet of the gas mixing tank 2 is at the bottom, the gas outlet is at the top, and a plurality of baffles 21 are alternately arranged inside the tank cavity of the gas mixing tank 2. The mixed gas fills the tank cavity from bottom to top, and the baffles 21 arranged inside the tank cavity slow down the rising speed of the lighter gas in the mixed gas, ensuring that the mixed gas simultaneously fills the tank body to deepen the uniformity of gas mixing.

[0029] The cavity of the gas splitter 3 has a plurality of dense gas tube bundles 31, the tail end of the gas tube bundle 31 is closed, and there are a plurality of holes 32 on the wall of the tail end tube, and the gas enters the mixing chamber 33 at the rear end of the gas splitter 3 through the holes 32. The gas splitter 3 has dense thin tubes inside to divide the mixed gas into a plurality of gas bundles, the tail end of the thin tube is closed and there are a plurality of small holes on the wall of the tail end tube, and the gas bundle can enter the mixing chamber at the rear end of the splitter through the small holes, and the internal structure is as follows: Figure 4 As shown in the figure, after multiple splitting and mixing of the mixed gas, the gas mixing uniformity is higher.

[0030] This device can eliminate the impact of ambient temperature changes on the mixed gas inside the pipeline; at the same time, the multi-stage fusion also maximizes the uniformity of the mixed gas. In this environment, the semiconductor can obtain a precise doping depth without damaging the semiconductor surface. High-quality semiconductor materials can not only improve the performance of semiconductor devices, but also reduce the manufacturing cost of semiconductor devices, bringing momentum to the development of the semiconductor industry.

[0031] The above content is a further detailed description of the utility model in combination with a specific preferred implementation method. It cannot be determined that the specific implementation methods of the utility model are limited to this. For ordinary technicians in the technical field to which the utility model belongs, they can make several simple deductions or substitutions without departing from the utility model, which should be regarded as belonging to the utility model and the scope of patent protection determined by the submitted claims.

Claims

1. A gas mixing heating system for silicon carbide growth, characterized in that: The invention comprises a plurality of doping gas pipelines (1), a gas mixing tank (2), a gas splitter (3), and a mixed gas temperature control system; the plurality of doping gas pipelines (1) are connected to the inlet end of a gas transmission pipeline (5) via a gas mixing joint (4); the gas transmission pipeline (5) is connected to the gas mixing tank (2) and the gas splitter (3) in sequence; the outlet end of the gas transmission pipeline (5) is connected to a silicon carbide growth device (6); each doping gas pipeline (1) is connected to a pneumatic diaphragm valve (7), a gas flow meter (8), and a check valve in sequence along the gas transmission direction; the mixed gas temperature control system is connected to the gas transmission pipeline (5) and is used to perform constant temperature heating control on the gas in the gas transmission pipeline (5).

2. A gas mixing heating system for silicon carbide growth according to claim 1, characterized in that: The outlet end of the gas transmission pipeline (5) is connected in sequence with a check valve and a one-way controllable valve (9) along the gas transmission direction.

3. A gas mixing heating system for silicon carbide growth according to claim 1, characterized in that: The mixed gas temperature control system comprises a temperature control device (10), a circulating fluid system and a temperature measuring device, wherein the circulating fluid system is in contact with and connected to the outer wall of a gas transmission pipeline (5), the temperature control device (10) is connected to the circulating fluid system, and the temperature measuring device is arranged at the outlet end of the gas transmission pipeline (5).

4. A gas mixing heating system for silicon carbide growth according to claim 3, characterized in that: The gas transmission pipeline (5) is a spiral gas transmission pipeline, and the spiral gas transmission pipeline is coiled on the circulation pipeline (11) of the circulating liquid system.

5. A gas mixing heating system for silicon carbide growth according to claim 3, characterized in that: The temperature measuring device is a gas temperature detector (12), and the gas temperature detector (12) is linked to the temperature control device (10).

6. A gas mixing heating system for silicon carbide growth according to claim 1, characterized in that: The gas inlet of the gas mixing tank (2) is at the bottom, and the gas outlet is at the top. A plurality of baffles (21) are alternately arranged inside the tank cavity of the gas mixing tank (2).

7. A gas mixing heating system for silicon carbide growth according to claim 1, characterized in that: A plurality of gas tube bundles (31) are arranged inside the cavity of the gas splitter (3); the tail end of the gas tube bundle (31) is closed, and a plurality of holes (32) are arranged on the tube wall at the tail end; gas enters a mixing chamber (33) at the rear end of the gas splitter (3) through the holes (32).

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