Microwave plasma chemical vapor deposition system

Abstract

The microwave plasma chemical vapor deposition system comprises a deposition chamber provided with a water cooling table; the device comprises a microwave plasma excitation mechanism and a seed source, and is characterized by further comprising a hydrogen fuel cell, a power supply end of which is connected with the seed source and is used for supplying power to the seed source; the heat absorption and refrigeration module is arranged between the hydrogen fuel cell and the water cooling table, a heat absorption loop is communicated between the heat absorption and refrigeration module and the hydrogen fuel cell, and the heat absorption loop inputs waste heat generated by the hydrogen fuel cell into the heat absorption and refrigeration module and converts the waste heat into energy required by refrigeration; a condensation loop is communicated between the water cooling table and the deposition chamber, the condensation loop is partially located in a heat absorption refrigeration module, and water in the condensation loop is cooled through the heat absorption refrigeration module in a heat exchange mode and condensed water is provided for the water cooling table. According to the system, the hydrogen fuel cell is used for directly providing energy for the seed source, the process of converting alternating current into direct current is not needed, and loss in the alternating current and direct current conversion process in the prior art is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical vapor deposition technology using microwave discharge, in particular to a microwave plasma chemical vapor deposition system. Background Art

[0002] Microwave plasma chemical vapor deposition system (hereinafter referred to as MPCVD) is widely used in the field of diamond production. From upstream to downstream, it mainly includes a microwave source, a microwave transmission unit, a mode conversion module and a plasma discharge unit connected in sequence. When microwaves are excited, they will also generate a large amount of heat energy, which reduces the conversion efficiency and increases energy consumption.

[0003] In response to the above technical problems, a Chinese invention patent with patent number CN202310156432.2 (publication number CN116043196B) entitled "A microwave source with adjustable working point, adjustment method and MPCVD equipment" discloses a microwave source adjustment method with adjustable working point. The DC-microwave conversion efficiency of the magnetron is automatically adjusted to the target efficiency through a three-pin regulator. This method enables different magnetrons to achieve a working state of high DC-microwave conversion efficiency, thereby minimizing energy waste.

[0004] However, the output power of the microwave source requires energy excitation from a seed source, and the seed source requires direct current to provide energy. High DC power supplies generally use a rectifier to convert AC power from the mains into DC power for use in microwaves. In this process, about 2%-5% of power loss is generated, reducing power utilization. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a microwave plasma chemical vapor deposition system with high power utilization rate in view of the above-mentioned existing technical status.

[0006] The technical solution adopted by the utility model to solve the above technical problems is: the microwave plasma chemical vapor deposition system includes:

[0007] Deposition chamber, equipped with a water-cooling stage;

[0008] A microwave plasma excitation mechanism, disposed above the deposition chamber, for generating microwaves;

[0009] A seed source, disposed upstream of the microwave plasma excitation mechanism, for providing energy to excite the microwaves of the microwave plasma excitation mechanism;

[0010] It is characterized by also including:

[0011] A hydrogen fuel cell, whose power supply end is connected to the seed source and is used to supply power to the seed source;

[0012] A heat absorption refrigeration module is provided between the hydrogen fuel cell and the water cooling stage, and is connected to the hydrogen fuel cell via a heat absorption circuit, which inputs waste heat generated by the hydrogen fuel cell into the heat absorption refrigeration module and converts it into energy required for refrigeration;

[0013] A condensation circuit is connected to the deposition chamber, and part of the condensation circuit is located in the heat absorption refrigeration module. The heat absorption refrigeration module is used to cool water in the condensation circuit in the form of heat exchange and provide condensed water to the water cooling stage.

[0014] In order to improve the waste heat transportation efficiency of the hydrogen fuel cell, preferably, the cathode chamber of the hydrogen fuel cell has a water outlet and a water inlet; the heat absorption refrigeration module has a heat source inlet and a water return port, a heat absorption pipeline is connected between the heat source inlet and the water outlet, and a return water pipeline is connected between the return water inlet and the water inlet, and the return water pipeline and the heat absorption pipeline constitute the heat absorption loop. The high-temperature water heated by the waste heat in the cathode chamber of the hydrogen fuel cell is transported to the heat source inlet through the heat absorption pipeline, and after the heat absorption process of the heat absorption refrigeration module, the temperature is reduced to become low-temperature water and flows back to the cathode chamber of the hydrogen fuel cell through the return water pipeline, thereby avoiding the overheating of the hydrogen fuel cell. At the same time, the heat absorption loop between the cathode chamber and the heat absorption refrigeration module continuously transports the waste heat to the heat absorption refrigeration module for refrigeration.

[0015] In order to reduce the amount of water used to provide condensed water to the water-cooling table, preferably, the heat-absorbing refrigeration module also has a condensation inlet and a condensation outlet, and has a condensation channel for heat exchange that connects the condensation inlet and the condensation outlet inside, a condensation water inlet pipe is connected between the condensation inlet and the water-cooling pipe inside the water-cooling table, a condensation water outlet pipe is connected between the condensation outlet and the water-cooling pipe, and a condensation circuit is formed with the condensation channel, the water-cooling pipe, the condensation water inlet pipe and the condensation water outlet pipe, and the heat-absorbing refrigeration module can absorb the heat of the water in the heat-absorbing pipe to cool the water in the condensation circuit. The setting of the condensation circuit keeps the water volume in the water flow constant in the circuit, and there is no need to continuously input condensed water to the water-cooling table from the outside during the operation of the microwave plasma chemical vapor deposition system, thereby saving water.

[0016] Furthermore, the heat absorption refrigeration module is a lithium bromide refrigeration unit, and the lithium bromide refrigeration unit includes:

[0017] Generator, the heat source inlet and the water return port are arranged on the generator;

[0018] a condenser, located downstream of and in communication with the generator;

[0019] An evaporator, located downstream of and connected to the condenser, having the condensation channel inside, and the condensation inlet and the condensation outlet are arranged on the evaporator;

[0020] The absorber is located downstream of the evaporator and is connected to the evaporator and the generator. The water return port is arranged on the absorber. The lithium bromide refrigeration unit uses lithium bromide as the absorbent and water as the refrigerant, which is a perfect match with the product water of the hydrogen fuel cell. After the high-temperature water flows from the cathode of the hydrogen fuel cell into the lithium bromide refrigeration unit, the heat is just absorbed by the generator. After that, it passes through the condenser, evaporator, and absorber in sequence and becomes low-temperature liquid water and flows back to the cathode chamber. The product water of the hydrogen fuel cell is used as a medium for transporting waste heat, and no additional water is required, which further saves water consumption.

[0021] In order to improve the utilization rate of the tail gas in the deposition chamber, the hydrogen fuel cell further has a hydrogen inlet, the deposition chamber has a tail gas outlet, a return gas pipeline is connected between the hydrogen inlet and the tail gas outlet, and a gas pump and a purifier are sequentially arranged on the return gas pipeline, the gas pump is used to transport the tail gas in the deposition chamber to the hydrogen inlet, and the purifier is used to purify the tail gas to increase the proportion of hydrogen. The input amount of hydrogen in the deposition chamber is generally much greater than that of methane, so there will inevitably be residual hydrogen after the reaction, and the hydrogen fuel cell requires hydrogen input, so the setting of the return gas pipeline uses tail gas purification to provide part of the hydrogen for the hydrogen fuel cell, reducing the additional input amount of hydrogen.

[0022] Furthermore, the hydrogen inlet is connected to the hydrogen supply station as the hydrogen source by a hydrogen supply pipeline, the access point of the hydrogen supply pipeline and the return gas pipeline is between the purifier and the hydrogen inlet, and the hydrogen supply pipeline branches out a branch to communicate with the deposition chamber. This technical solution makes full use of the return gas pipeline to lay the hydrogen input pipeline from the hydrogen supply station to the deposition chamber, reducing the pipeline laying cost.

[0023] Compared with the prior art, the advantages of the utility model are:

[0024] 1. This system uses hydrogen fuel cells to directly provide energy for the seed source without the need for an AC to DC conversion process, thus avoiding the loss in the AC to DC conversion process of the prior art;

[0025] 2. This system absorbs the waste heat generated by the hydrogen fuel cell through the heat absorption circuit and uses it for the heat absorption refrigeration module to cool the water in the condensation circuit, thereby continuously and cyclically providing condensed water to the water cooling table to control the temperature of diamond growth in the deposition chamber, thereby improving the hydrogen fuel cell and reducing the water consumption of condensed water;

[0026] 3. This system cleverly utilizes the property that the product of hydrogen fuel cells is water to transport waste heat to the heat absorption refrigeration module for absorption and then return it to the hydrogen fuel cell, thus avoiding the phenomenon that the hydrogen fuel cell is in a high temperature state for a long time and causes abnormal operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1It is the principle diagram of the gas circuit and water circuit of the embodiment of the utility model; DETAILED DESCRIPTION

[0028] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0029] As shown in Figure 1, it is a preferred embodiment of the utility model. The microwave plasma chemical vapor deposition system of this embodiment is mainly used for the growth of diamonds. The seed source of the system requires a DC power supply. The conventional power supply mode for the seed source is AC to DC conversion of the mains. There will be power loss in this process. Therefore, it will be beneficial to provide a microwave plasma chemical vapor deposition system with high power utilization rate. The structure of the microwave plasma chemical vapor deposition system will be described in detail below:

[0030] See also Figure 1 The microwave plasma chemical vapor deposition system includes a deposition chamber 1, a microwave plasma excitation mechanism 2, a seed source 3, a hydrogen fuel cell 4 and an endothermic refrigeration module 5, wherein the deposition chamber 1 is provided with a water cooling stage 11, the microwave plasma excitation mechanism 2 is arranged above the deposition chamber 1, and is used to generate microwaves; the seed source 3 is arranged upstream of the microwave plasma excitation mechanism 2, and is used to provide energy to excite the microwaves of the microwave plasma excitation mechanism 2; the power supply end of the hydrogen fuel cell 4 is connected to the seed source 3, and is used to supply power to the seed source 3; the endothermic refrigeration module 5 is arranged between the hydrogen fuel cell 4 and the water cooling stage 11, and is connected to the hydrogen fuel cell 4 with an endothermic loop 40, and the endothermic loop 40 inputs the waste heat generated by the hydrogen fuel cell 4 into the endothermic refrigeration module 5 and converts it into energy required for refrigeration; the endothermic refrigeration module 5 is connected to the deposition chamber 1 with a condensation loop 10, and the condensation loop 10 is partially located in the endothermic refrigeration module 5, and the water in the condensation loop 10 is cooled in the form of heat exchange by the endothermic refrigeration module 5 and condensed water is provided to the water cooling stage 11. A delivery pump for delivering liquid may be additionally provided on the heat absorption circuit 40 and the condensation circuit 10 to promote the flow of water in the circuit.

[0031] The cathode chamber of the hydrogen fuel cell 4 has a water outlet O1 and a water inlet I1; the heat absorption refrigeration module 5 has a heat source inlet I2 and a water return port O2. A heat absorption pipeline 51 is connected between the heat source inlet I2 and the water outlet O1, and a water return pipeline 52 is connected between the water return port O2 and the water inlet I1. The water return pipeline 52 and the heat absorption pipeline 51 constitute a heat absorption loop 40. The high-temperature water heated by the waste heat in the cathode chamber of the hydrogen fuel cell is transported to the heat source inlet I2 through the heat absorption pipeline 51. After the heat absorption process of the heat absorption refrigeration module 5, the temperature is reduced to become low-temperature water and flows back to the cathode chamber of the hydrogen fuel cell through the water return pipeline 52, thereby avoiding the phenomenon of overheating of the hydrogen fuel cell. At the same time, the heat absorption loop between the cathode chamber and the heat absorption refrigeration module 5 continuously transports the waste heat to the heat absorption refrigeration module 5 for refrigeration, thereby improving the waste heat transportation efficiency of the hydrogen fuel cell 4.

[0032] The heat-absorbing refrigeration module 5 also has a condensation inlet I3 and a condensation outlet O3, and has a condensation channel for heat exchange inside that connects the condensation inlet I3 with the condensation outlet O3. A condensation water inlet pipe 12 is connected between the condensation inlet I3 and the water-cooling pipe in the water-cooling stage 11, and a condensation water outlet pipe 13 is connected between the condensation outlet O3 and the water-cooling pipe. A condensation circuit 10 is formed with the condensation channel, the water-cooling pipe, the condensation water inlet pipe 12 and the condensation water outlet pipe 13. The heat-absorbing refrigeration module 5 can absorb the heat of the water in the heat-absorbing pipe 51 to cool the water in the condensation circuit 10. The setting of the condensation circuit 10 keeps the water volume in the water flow constant in the circuit, and it is not necessary to continuously input condensation water from the outside to the water-cooling stage 11 during the operation of the microwave plasma chemical vapor deposition system, which saves water and reduces the amount of water used to provide condensation water to the water-cooling stage 11.

[0033] The heat absorption refrigeration module 5 is a lithium bromide refrigeration unit, which includes a generator 53, a condenser 54, an evaporator 55 and an absorber 56, wherein the heat source inlet I2 and the return water inlet O2 of the generator 53 are arranged on the generator 53; the condenser 54 is located downstream of the generator 53 and is connected; the evaporator 55 is located downstream of the condenser 54 and is connected, and has a condensation channel inside, and the condensation inlet I3 and the condensation outlet O3 are arranged on the evaporator 55; the absorber 56 is located downstream of the evaporator 55 and is connected to the evaporator 55 and the generator 53, and the return water inlet O2 is arranged on the absorber 56. The lithium bromide refrigeration unit uses lithium bromide as the absorbent and water as the refrigerant, which is a perfect match for the product water of the hydrogen fuel cell. After the high-temperature water flows from the cathode of the hydrogen fuel cell into the lithium bromide refrigeration unit, the heat is just absorbed by the generator 53, and then passes through the condenser 54, the evaporator 55, and the absorber 56 in sequence to become low-temperature liquid water and return to the cathode chamber. The product water of the hydrogen fuel cell 4 is used as a medium for transporting waste heat, and there is no need to introduce additional water, which further saves water consumption.

[0034] The hydrogen fuel cell 4 also has a hydrogen inlet I4, and the deposition chamber 1 has a tail gas outlet O4. A return gas pipeline 6 is connected between the hydrogen inlet I4 and the tail gas outlet O4. A gas pump 61 and a purifier 62 are sequentially arranged on the return gas pipeline 6. The gas pump 61 is used to transport the tail gas in the deposition chamber 1 to the hydrogen inlet I4, and the purifier 62 is used to purify the tail gas to increase the proportion of hydrogen. The input amount of hydrogen in the deposition chamber 1 is generally much greater than that of methane, so there will inevitably be residual hydrogen after the reaction, and the hydrogen fuel cell requires hydrogen input. Therefore, the setting of the return gas pipeline uses tail gas purification to provide part of the hydrogen for the hydrogen fuel cell, which reduces the additional input amount of hydrogen and improves the utilization rate of the tail gas in the deposition chamber 1.

[0035] The hydrogen inlet I4 is connected to the hydrogen supply station 7 as a hydrogen source by a hydrogen supply pipeline 71. The access point of the hydrogen supply pipeline 71 and the return gas pipeline 6 is between the purifier 62 and the hydrogen inlet I4. A branch 72 of the hydrogen supply pipeline 71 is connected to the deposition chamber 1. This technical solution makes full use of the return gas pipeline to lay the hydrogen input pipeline from the hydrogen supply station 7 to the deposition chamber 1, reducing the pipeline laying cost.

[0036] The working principle of the microwave plasma chemical vapor deposition system is as follows: the hydrogen fuel cell 4 provides electrical energy for the seed source to excite the microwaves of the microwave plasma excitation mechanism 2, and the microwaves provide a heat source for the growth of diamonds in the deposition chamber 1. The hydrogen fuel cell generates waste heat while generating direct current. The waste heat is absorbed by the water in the cathode chamber of the hydrogen fuel cell 4 and then enters the lithium bromide refrigeration unit through the heat absorption pipeline 51 for refrigeration. In the lithium bromide refrigeration unit, water is used as a refrigerant and lithium bromide is used as a heat absorber. Water flows from the generator 53 through the condenser 54, the evaporator 55, and the absorber 56. 6 After that, the water temperature is reduced and flows back to the cathode chamber of the hydrogen fuel cell 4, and then absorbs the waste heat of the hydrogen fuel cell 4 and transports it to the lithium bromide refrigeration unit for heat absorption and refrigeration, and the cycle is repeated; at the same time, the growth platform needs continuous condensation water cooling in the water-cooling pipe. The evaporator 55 inside the lithium bromide refrigeration unit absorbs heat and cools the water in the condensation channel, and then flows from the condensation outlet O3 through the condensation outlet pipe 13 into the water cooling pipe, absorbs the heat of the growth platform, and then flows into the condensation inlet I3 through the condensation inlet pipe 12, and absorbs heat and cools again to produce condensed water, thereby circulating cooling the growth platform in the deposition chamber.

Claims

1. A microwave plasma chemical vapor deposition system, comprising: A deposition chamber (1) is provided with a water cooling stage (11); A microwave plasma excitation mechanism (2), disposed above the deposition chamber (1) and used for generating microwaves; A seed source (3) is arranged upstream of the microwave plasma excitation mechanism (2) and is used to provide energy to excite the microwaves of the microwave plasma excitation mechanism (2); It is characterized in that Also included are: A hydrogen fuel cell (4), whose power supply end is connected to the seed source (3) and is used to supply power to the seed source (3); A heat absorption refrigeration module (5) is arranged between the hydrogen fuel cell (4) and the water cooling stage (11), and is connected to the hydrogen fuel cell (4) via a heat absorption circuit (40). The heat absorption circuit (40) inputs waste heat generated by the hydrogen fuel cell (4) into the heat absorption refrigeration module (5) and converts it into energy required for refrigeration; A condensation circuit (10) is connected to the deposition chamber (1), and part of the condensation circuit (10) is located in the heat absorption refrigeration module (5). The heat absorption refrigeration module (5) cools the water in the condensation circuit (10) in the form of heat exchange and provides condensed water to the water cooling stage (11).

2. The microwave plasma chemical vapor deposition system according to claim 1, characterized in that: The cathode chamber of the hydrogen fuel cell (4) has a water outlet (O1) and a water inlet (I1); the heat absorption refrigeration module (5) has a heat source inlet (I2) and a water return port (O2); a heat absorption pipeline (51) is connected between the heat source inlet (I2) and the water outlet (O1); a water return pipeline (52) is connected between the water return port (O2) and the water inlet (I1); the water return pipeline (52) and the heat absorption pipeline (51) constitute the heat absorption circuit (40).

3. The microwave plasma chemical vapor deposition system according to claim 2, characterized in that: The heat absorption refrigeration module (5) also has a condensation inlet (I3) and a condensation outlet (O3), and has a condensation channel for heat exchange inside the condensation inlet (I3) and the condensation outlet (O3). A condensation water inlet pipe (12) is connected between the condensation inlet (I3) and the water cooling pipe provided in the water cooling table (11), and a condensation water outlet pipe (13) is connected between the condensation outlet (O3) and the water cooling pipe. The condensation channel, the water cooling pipe, the condensation water inlet pipe (12) and the condensation water outlet pipe (13) form a condensation circuit (10). The heat absorption refrigeration module (5) can absorb the heat of water in the heat absorption pipeline (51) to cool the water in the condensation circuit (10).

4. The microwave plasma chemical vapor deposition system according to claim 3, characterized in that: The heat absorption refrigeration module (5) is a lithium bromide refrigeration unit, and the lithium bromide refrigeration unit comprises: Generator (53), the heat source inlet (I2) and the water return port (O2) are arranged on the generator (53); a condenser (54), located downstream of and in communication with the generator (53); an evaporator (55), located downstream of and connected to the condenser (54), having the condensation channel therein, and the condensation inlet (I3) and the condensation outlet (O3) are arranged on the evaporator (55); The absorber (56) is located downstream of the evaporator (55) and is connected to the evaporator (55) and the generator (53). The water return port (O2) is arranged on the absorber (56).

5. The microwave plasma chemical vapor deposition system according to any one of claims 1 to 4, characterized in that: The hydrogen fuel cell (4) also has a hydrogen inlet (I4), and the deposition chamber (1) has an exhaust gas outlet (O4). A return gas pipeline (6) is connected between the hydrogen inlet (I4) and the exhaust gas outlet (O4). A gas pump (61) and a purifier (62) are sequentially arranged on the return gas pipeline (6). The gas pump (61) is used to transport the exhaust gas in the deposition chamber (1) to the hydrogen inlet (I4), and the purifier (62) is used to purify the exhaust gas to increase the proportion of hydrogen.

6. The microwave plasma chemical vapor deposition system according to claim 5, characterized in that: The hydrogen inlet (I4) is connected to a hydrogen supply station (7) serving as a hydrogen source via a hydrogen supply pipeline (71). The connection point between the hydrogen supply pipeline (71) and the return gas pipeline (6) is between the purifier (62) and the hydrogen inlet (I4). A branch (72) is branched from the hydrogen supply pipeline (71) and connected to the deposition chamber (1).

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