CN112126910A

CN112126910A - Control method in diamond growth system based on PLC

Info

Publication number: CN112126910A
Application number: CN202010774584.3A
Authority: CN
Inventors: 苗岱; 牛进毅
Original assignee: Shanxi Yunsi Electronic Technology Co ltd
Current assignee: Shanxi Yunsi Electronic Technology Co ltd
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2020-12-25
Anticipated expiration: 2040-08-04
Also published as: CN112126910B

Abstract

The invention relates to a control method in a diamond growth system based on a PLC (programmable logic controller), which comprises the following steps of: the PLC controls the air exhaust control process of the vacuum system according to the process starting signal and the feedback signal of the element in the vacuum system; the PLC controller carries out a process control flow on the vacuum system according to feedback signals of elements in the vacuum system so as to enter a diamond growth flow; in the diamond growth process, a PLC controller controls vacuum pressure by using a vacuum system, growth position by using a seed crystal carrying disk system, glow control by using a glow system and process gas by using a process gas system according to a growth information formula table acquired from an upper computer; and the PLC carries out an exhaust control process on the vacuum system according to the process stop signal and the feedback signal of the element in the vacuum system, so that the pressure in the vacuum cavity is recovered to the normal pressure. The method realizes safer and more intelligent diamond growth control under the cooperation of the PLC.

Description

Control method in diamond growth system based on PLC

Technical Field

The invention belongs to the technical field of automatic control, and particularly relates to a control method in a diamond growth system based on a PLC.

Background

At present, in the process of diamond growth by adopting a CVD mode, the vacuum environment, the generation of plasma, the growth position and the growth condition need to be adjusted and controlled, and the quality of the diamond growth result is comprehensively influenced by the factors.

The existing diamond growth system adopts an independent control mode for all the factors, and needs manual overall operation. The manual overall operation has many defects, one of which is that in the growth process, vacuum pressure control, glow control and growth position operate independently, and an operator needs to perform manual overall operation according to experience; secondly, cooling water and a fan which provide cooling protection for components in the production process are not automatically monitored, and whether the cooling system operates normally needs to be manually checked; thirdly, due to the particularity of the diamond CVD growth process, such as long growth time, the need of adjusting process parameters according to the growth stage and unfixed adjusting frequency, operators need to watch on the site for a long time, and the personnel cost is high; fourthly, the diamond CVD growth process needs flammable and explosive gas as process gas, so the operation flow needs to be strictly controlled, and the requirement on personnel is extremely high.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a control method in a diamond growth system based on a PLC. The technical problem to be solved by the invention is realized by the following technical scheme:

the embodiment of the invention provides a control method in a diamond growth system based on PLC, the diamond growth system comprises a PLC controller, an upper computer, a router, a vacuum cavity, a vacuum system, a crystal seed carrying disk system, a glow system, a process gas system and a cooling system, wherein the vacuum system, the seed crystal tray system, the glow system, the process gas system, and the cooling system are all electrically connected to the PLC controller, the PLC controller is electrically connected with the upper computer through the router, the vacuum system and the process gas system are connected with the vacuum cavity, the seed crystal loading tray system is disposed at a bottom of the vacuum cavity and penetrates the vacuum cavity, the radio frequency power generator in the glow system is arranged above the vacuum cavity, and the cooling system is connected with the vacuum cavity and the vacuum system;

the control method comprises the following steps:

s1, the PLC controls the vacuum system to perform an air exhaust control process according to process starting signal control and feedback signals of elements in the vacuum system until the pressure in the vacuum cavity reaches a target pressure;

s2, the PLC carries out a process control flow on the vacuum system according to feedback signals of elements in the vacuum system so as to enter a diamond growth flow;

s3, in the diamond growth process, the PLC controls vacuum pressure control by the vacuum system, growth position control by the seed crystal carrying tray system, glow control by the glow system and process gas control by the process gas system according to the growth information formula table obtained from the upper computer;

and S4, the PLC carries out an exhaust control process on the vacuum system according to the process stop signal and the feedback signal of the element in the vacuum system, so that the pressure in the vacuum cavity is recovered to normal pressure.

In one embodiment of the present invention, step S1 includes:

s11, the PLC controls a dry pump in the vacuum system to operate according to the process starting signal;

s12, the PLC controls a molecular pump angle valve in the vacuum system to be opened according to a dry pump running signal fed back by the dry pump so as to vacuumize the outlet of the molecular pump;

s13, the PLC controls the molecular pump in the vacuum system to operate according to the dry pump operation signal and the molecular pump angle valve opening state signal fed back by the molecular pump angle valve;

s14, the PLC controls the molecular pump angle valve to close according to the dry pump running signal and the molecular pump rotating speed analog quantity signal fed back by the molecular pump so as to keep the pressure of the outlet of the molecular pump;

s15, the PLC controls a straight-through angle valve in the vacuum system to be opened according to the dry pump operation signal and a molecular pump angle valve closing state signal fed back by the molecular pump angle valve so as to vacuumize the vacuum cavity;

s16, the PLC controls the straight-through angle valve to be closed according to the dry pump running signal and the vacuum gauge pressure analog quantity signal so as to enable the vacuum cavity to keep pressure;

s17, the PLC controls the molecular pump angle valve to be opened according to the dry pump running signal, a straight-through angle valve closing signal fed back by the straight-through angle valve and the vacuum gauge pressure analog quantity signal so as to vacuumize the outlet of the molecular pump;

and S18, the PLC controls a gate valve in the vacuum system to be opened according to the dry pump operation signal, the molecular pump angle valve opening state signal fed back by the molecular pump angle valve, the through angle valve closing signal and the vacuum gauge pressure analog quantity signal so as to carry out vacuum purification on the vacuum cavity, and the pressure in the vacuum cavity reaches a target pressure.

In one embodiment of the present invention, step S2 includes:

s21, after receiving a process flow starting signal, the PLC judges whether the air exhaust control flow is executed or not according to the dry pump operation signal, a gate valve opening state signal fed back by the gate valve and the vacuum gauge pressure analog quantity signal, if not, the air exhaust control flow is continued, and if yes, the step S22 is executed;

s22, the PLC controls the gate valve to be closed and controls the radio frequency power supply to be started at the same time;

s23, the PLC controls the molecular pump to stop running according to a gate valve closing state signal fed back by the gate valve;

s24, the PLC controls the molecular pump angle valve to close according to a molecular pump stop operation signal fed back by the molecular pump and the gate valve closing state signal;

and S25, the PLC controls the proportional valve angle valve to be opened according to the molecular pump stop operation signal, the gate valve closing state signal and the molecular pump angle valve closing state signal fed back by the molecular pump angle valve, and the pipeline between the proportional valve in the vacuum system and the dry pump is ensured to be smooth.

In one embodiment of the present invention, step S4 includes:

s41, the PLC judges whether the air extraction control flow is executed or not according to the process stop signal, the dry pump operation signal, the gate valve opening state signal and the vacuum gauge pressure analog quantity signal, if not, the air extraction control flow is continued, and if yes, the air exhaust control flow is performed;

s42, the PLC controls the gate valve to close according to the process stop signal;

and S43, the PLC controls the exhaust valve to be opened according to the closing state signal of the gate valve, so that the pressure in the vacuum cavity is recovered to the normal pressure.

In one embodiment of the present invention, the vacuum pressure control comprises:

the PLC controller obtains the growth information formula table from the upper computer;

the PLC controls the corresponding diaphragm valve and mass flowmeter in the process gas system to work according to the process gas type and the gas flow in the growth information formula table;

the PLC controller obtains real-time pressure in the vacuum cavity fed back by a capacitance gauge in the vacuum system;

the PLC controller compares the real-time pressure with the target pressure; when the real-time pressure is larger than the target pressure, controlling the opening of a proportional valve in the vacuum system to increase until the real-time pressure is equal to the target pressure; when the real-time pressure is equal to the target pressure, controlling the opening degree of the proportional valve to be kept unchanged; and when the real-time pressure is smaller than the target pressure, controlling the opening of a proportional valve in the vacuum system to be reduced until the real-time pressure is equal to the target pressure.

In one embodiment of the present invention, the growth position control comprises the steps of:

the PLC acquires the growth information formula table from the upper computer, wherein the growth information formula table comprises a growth initial position, a growth stage position and growth temperature information required by diamond growth;

the PLC controls a stepping motor in the seed crystal carrying tray system to move the seed crystal carrying tray in the vacuum cavity to the growth initial position according to the growth initial position and the growth stage position;

the PLC controller obtains the position of the seed crystal carrying disk collected by an encoder in the seed crystal carrying disk system, and simultaneously obtains a real-time vacuum cavity temperature value collected by a thermodetector in the vacuum cavity;

the PLC compares the real-time vacuum cavity temperature value with the growth temperature information; when the real-time vacuum cavity temperature value is equal to the growth temperature information, the growth stage position corresponding to the growth temperature information is found in the growth information recipe table, the stepping motor is made to control the seed crystal carrier tray to move until the position of the seed crystal carrier tray collected by the encoder is equal to the growth stage position, and the position of the seed crystal carrier tray is made to be positioned along with the real-time vacuum cavity temperature value according to the relation in the growth information recipe table.

In one embodiment of the invention, the glow control comprises the steps of:

the PLC acquires a reflection power upper limit and the growth information formula table from the upper computer, wherein the growth information formula table comprises a formula of glow power and vacuum pressure at a starting stage and a formula of glow power and vacuum pressure at an ending stage;

the PLC controls a radio frequency power supply in the glow system to start glow discharge according to the glow starting power, and obtains real-time pressure, real-time glow power and real-time reflected power in the vacuum cavity;

the PLC compares the real-time reflected power with the upper limit of the reflected power, controls the radio frequency power supply to stop glow discharge when the upper limit of the reflected power is smaller than or equal to the real-time reflected power, and controls the radio frequency power supply to continue glow discharge when the upper limit of the reflected power is larger than the real-time reflected power; meanwhile, in a growth preparation stage and a growth finishing stage of the diamond, the PLC compares the real-time pressure with the vacuum pressure in the growth information formula table, when the real-time pressure is equal to the vacuum pressure, the standard glow power corresponding to the vacuum pressure is found in the growth information formula table, and the radio frequency power supply is controlled to enable the real-time glow power to be equal to the standard glow power.

In one embodiment of the invention, the process gas control comprises the steps of:

the PLC acquires the safe pressure in the vacuum cavity and the growth information formula table in the diamond growth process from the upper computer;

the PLC acquires real-time pressure in the vacuum cavity and acquires a first gas flow and a second gas flow in a diamond growth maintaining stage;

the PLC compares the real-time pressure with the target pressure, controls the operation state of the diaphragm valve corresponding to each process gas to be locked when the real-time pressure is greater than or equal to the safety pressure, and controls the diaphragm valve corresponding to each process gas to continue to operate when the real-time pressure is less than the safety pressure; meanwhile, in the growth maintaining stage of the diamond, the PLC compares the first gas flow with the second gas flow, when the ratio of the first real-time gas flow to the second real-time gas flow is greater than or equal to a first target value, the operating state of the diaphragm valve corresponding to the first process gas and the operating state of the diaphragm valve corresponding to the second process gas are both controlled to be locked, and when the ratio of the first real-time gas flow to the second real-time gas flow is smaller than a first target value, the operating state of the diaphragm valve corresponding to the first process gas and the operating state of the diaphragm valve corresponding to the second process gas are both controlled to continue to operate.

In an embodiment of the present invention, after the PLC controller controls the operation of the corresponding diaphragm valve and mass flow meter in the process gas system according to the process gas type and the gas flow in the growth information recipe table, the PLC controller further includes the following steps:

in the growth maintaining stage of the diamond, the PLC acquires the target gas flow;

and the PLC compares the target gas flow with a preset gas flow corresponding to the target gas in the growth information formula table, controls the operation state of the diaphragm valve corresponding to the target gas to be locked when the difference value between the target gas flow and the preset gas flow is greater than or equal to a second target value, and controls the diaphragm valves corresponding to the target gas to continue to operate when the difference value between the target gas flow and the preset gas flow is less than the second target value.

In one embodiment of the present invention, further comprising the steps of:

the PLC acquires a cooling starting signal, a target temperature of cooling water and a target flow rate of the cooling water;

the PLC controls the cooling system to operate according to the cooling starting signal;

the PLC acquires the reflux temperature of the cooling water and the real-time flow of the cooling water;

the PLC compares the reflux temperature with the target temperature, controls the diamond growth system to stop running when the reflux temperature is higher than the target temperature, and controls the diamond growth system to continue running when the reflux temperature is lower than or equal to the target temperature; meanwhile, the PLC compares the real-time flow with the target flow, when the real-time flow is smaller than the target flow, the diamond growth system is controlled to stop running, and when the real-time flow is larger than or equal to the target flow, the diamond growth system is controlled to continue running.

Compared with the prior art, the invention has the beneficial effects that:

this embodiment is with vacuum system on PLC controller's basis, the thing dish system is carried to the seed crystal, the glow system, process gas system and cooling system fuse into an organic whole, the advantage of each system has been integrated, information between each system is mutual, realize using PLC controller to control the air exhaust of diamond as the control core, grow, realize vacuum pressure control when the exhaust is controlled, growth position control, glow control and process gas control, the blank that needs artifical cooperateing has been filled, the safety class has been promoted, reduce the time of personnel's operation, finally realized safer more intelligent diamond growth control under PLC's cooperation.

Drawings

Fig. 1 is a schematic structural diagram of a diamond growth system according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a vacuum system according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a seed crystal carrier tray system according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a process gas system according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a cooling system according to an embodiment of the present invention;

fig. 6 is a schematic flow chart of a control method in a diamond growth system based on a PLC according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.

Example one

Referring to fig. 1, fig. 1 is a schematic structural diagram of a diamond growth system according to an embodiment of the present invention, where the diamond growth system includes: PLC controller 11, upper computer 12, router 13, vacuum cavity 14, vacuum system 15, seed crystal carrier tray system 16, glow system 17, process gas system 18 and cooling system 19. The vacuum system 15, the seed crystal carrying tray system 16, the glow system 17, the process gas system 18 and the cooling system 19 are electrically connected with the PLC 11, the PLC 11 is electrically connected with the upper computer 12 through the router 13, the vacuum system 15 and the process gas system 18 are connected with the vacuum cavity 14, the seed crystal carrying tray system 16 penetrates through the bottom of the vacuum cavity 14, the radio-frequency power supply generator in the glow system 17 is arranged above the vacuum cavity 14, and the cooling system 19 is respectively connected with the vacuum cavity 14 and the vacuum system 15. Further, the diamond growth system further comprises an analog input/output module 20, wherein the analog input/output module 20 is connected between the PLC controller 11 and some elements in each system, and is configured to transmit analog signals collected by some elements in each system.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a vacuum system according to an embodiment of the present invention. The vacuum system 15 is used to evacuate and exhaust the vacuum chamber 14 to control the vacuum pressure in the vacuum chamber 14. The vacuum system 15 includes a dry pump 151, a molecular pump angle valve 152, a molecular pump 153, a gate valve 154, a proportional valve 155, a proportional valve angle valve 156, a through angle valve 157, a capacitance gauge 158, and an exhaust valve 159. The dry pump 151, the molecular pump angle valve 152, the molecular pump 153 and the gate valve 154 are sequentially connected to the vacuum cavity 14, the dry pump 151, the molecular pump angle valve 152, the molecular pump 153 and the gate valve 154 are electrically connected with the PLC 50, and meanwhile, the molecular pump 153 is also connected with the PLC 11 through the analog input/output module 20 and the router 13; the proportional valve 155 is connected with a proportional valve angle valve 156, one end of the proportional valve 155 is connected between the dry pump 151 and the molecular pump angle valve 152, and one end of the proportional valve angle valve 156 is connected with the vacuum cavity 14; a through-angle valve 157 has one end connected between the dry pump 151 and the molecular pump angle valve 152 and the other end connected to the vacuum chamber 14. The vacuum chamber 14 is provided with a capacitance gauge 158, the capacitance gauge 158 is connected with the PLC 11 through the analog input/output module 20 and the router 13, and the exhaust valve 159 is arranged on the vacuum chamber 14 and connected with the PLC 11. In addition, in fig. 2, the rf power generator 171 in the glow system 17 is disposed above the vacuum chamber 14, and is connected to the PLC controller 11 through the analog input/output module 20 and the router 13.

Referring to fig. 3, fig. 3 is a schematic structural diagram of a seed crystal loading tray system according to an embodiment of the present invention. Seed crystal tray system 16 is used to control the seed crystal tray at the bottom of vacuum chamber 14 to enable the raising and lowering and rotation of the seed crystal tray. Seed crystal carrier disk system 16 comprises elevator motor 161, rotary motor 162, rotary elevator mechanism 163, seed crystal carrier disk 164, first sensor 165, second sensor 166, first encoder 167, second encoder 168, and thermometer 169; wherein the PLC controller 11 is electrically connected to the elevation motor 161 to control the driving of the elevation motor 161, and the PLC controller 11 is electrically connected to the rotation motor 162 to control the driving of the rotation motor 162; elevator motor 161 is connected to the elevator of rotary elevator mechanism 163, rotary motors 162 are connected to the rotary elevator mechanism 163, seed crystal loading tray 164 is horizontally disposed on rotary elevator mechanism 163 and located in vacuum chamber 14, seed crystal carrier disk 164 rotates and ascends and descends according to the rotation and ascent and descent of rotary elevating mechanism 163, first sensor 165 is disposed at a first position on an elevating guide rail in rotary elevating mechanism 163 and electrically connected to PLC controller 11, second sensor 166 is disposed at a second position on the elevating guide rail and electrically connected to PLC controller 11, an elevating member is movable between the first position and the second position along elevating guide rail 1633, first encoder 167 is connected to rotary motor 162 and seed crystal carrier disk 164 and electrically connected to PLC controller 11, and second encoder 168 is connected to elevating motor 161 and seed crystal carrier disk 164 and electrically connected to PLC controller 11.

Referring to fig. 4, fig. 4 is a schematic structural diagram of a process gas system according to an embodiment of the invention. The process gas system 18 is used to provide gases for diamond growth to the vacuum chamber 14. The process gas system 18 in this embodiment includes H₂Pipe 181, CH₄Pipes 182, O₂Pipes 183, N₂Line 184 and pirani gauge 185; in the direction of the inlet air atH₂The pipeline 181 is provided with a second mass flow meter 1812, a first mass flow meter 1811 and a first diaphragm valve 1813 at CH₄The pipeline 182 is provided with a third mass flow meter 1821 and a second diaphragm valve 1822, and the mass flow meter is O₂The pipeline 183 is provided with a fifth mass flow meter 1832, a fourth mass flow meter 1831, and a third diaphragm valve 1833, and N is₂A sixth mass flow meter 1841 and a sixth diaphragm valve 1842 are arranged on the pipeline 184; the diaphragm valves are all electrically connected with the PLC controller 11, and the mass flow meters are all electrically connected with the PLC controller 11 through the analog input/output module 20.

Referring to fig. 5, fig. 5 is a schematic structural diagram of a cooling system according to an embodiment of the present invention. The cooling system 19 is used to provide cooling to the vacuum chamber 14 and the vacuum system 15. For example, the cooling system 19 includes a water cooler 191, 4 water inlet pipes 192, 4 water return pipes 193, 4 water flow meters 194, 4 water inlet valves 195, 4 water return valves 196, 4 water temperature meters 197, a cooling fan 198, and a vacuum gauge 199; wherein, the water outlet of the water cooler 191 is connected with the water inlet end of each water inlet pipeline in the 4 water inlet pipelines 192; the water outlet ends of the 4 water inlet pipelines 192 are respectively connected with a cooling water inlet of the central shaft, a cooling water inlet of the bottom plate, a cooling water inlet of the cavity and a cooling water inlet of the antenna; the cooling water outlet of the central shaft, the cooling water outlet of the bottom plate, the cooling water outlet of the cavity and the cooling water outlet of the antenna are respectively connected with the water inlet ends of the 4-path water return pipeline 193; the water outlet ends of the 4-path water return pipeline 193 are connected with the water inlet of the water cooling unit 191; the 4 water flow meters 194 are respectively arranged on the 4 water inlet pipelines 192; the 4 water inlet valves 195 are respectively arranged on the 4-way water inlet pipeline 192 and are arranged between the water cooler 191 and the water flow meter 194; the 4 water return valves 196 are respectively arranged on the 4 water return pipelines 193; 4 water temperature meters 197 are provided on the 4-way return pipe 193, respectively, and are provided before the return valve 196 in the return direction of the cooling water; the cooling fan 198 is arranged right above the vacuum cavity 14, and the vacuum gauge 199 is arranged on the vacuum cavity 14; the PLC 11 is in bidirectional electric connection with the water cooling machine 191; the PLC controller 11 is electrically connected to the 4 water inlet valves 195, the 4 water return valves 196 and the cooling fan 198; and the 4 water flow meters 194, the 4 water temperature meters 197 and the vacuum gauge 199 are electrically connected to the PLC controller 11.

Referring to fig. 6, fig. 6 is a schematic flow chart illustrating a control method in a diamond growth system based on a PLC according to an embodiment of the present invention. The control method comprises the following steps:

and S1, the PLC controls the air exhaust control process of the vacuum system according to the process starting signal control and the feedback signal of the element in the vacuum system until the pressure in the vacuum cavity reaches the target pressure. The method specifically comprises the following steps:

and S11, controlling the operation of a dry pump in the vacuum system by the PLC according to the process starting signal.

Specifically, according to a process starting signal, the PLC controller 11 outputs a contact to electrify a dry pump relay coil, so that a dry pump relay normally open contact is closed; the closing of the dry pump relay normally open contact causes the dry pump run signal to remain high, thereby initiating the dry pump 151 operation.

And S12, the PLC controls the molecular pump angle valve in the vacuum system to be opened according to the dry pump running signal fed back by the dry pump so as to vacuumize the outlet of the molecular pump.

Specifically, when the dry pump 151 is operated, the operation state indicating contact is closed, so that the PLC controller 11 input signal is maintained at a high level. After receiving the signal, the PLC controller 11 considers that the opening condition of the molecular pump angle valve 152 is satisfied, and then the output contact of the PLC controller 11 energizes the molecular pump angle valve relay coil to close the normally open contact of the molecular pump angle valve relay, so that the molecular pump angle valve 152 is energized, the molecular pump angle valve 152 is opened, and the evacuation work of the outlet of the molecular pump 153 is realized.

And S13, controlling the molecular pump in the vacuum system to operate by the PLC according to the dry pump operation signal and the molecular pump angle valve opening state signal fed back by the molecular pump angle valve.

When the dry pump 151 is operated, the PLC controller 11 input signal maintains a high level. The normally open contact of molecular pump angle valve 152 closes after opening, thereby keeping the PLC input signal at a high level (i.e., the molecular pump angle valve open state signal). After receiving the two signals, the PLC controller 11 determines that the operating conditions of the molecular pump 153 are satisfied; subsequently, the output contact of the PLC controller 11 powers on the molecular pump relay coil, so that the normally open contact of the molecular pump relay is closed, and the closing of the contact will cause the molecular pump operation starting signal to keep at a high level, so that the molecular pump 153 operates and starts.

And S14, the PLC controls the molecular pump angle valve to close according to the dry pump running signal and the molecular pump rotating speed analog quantity signal fed back by the molecular pump so as to keep the pressure of the outlet of the molecular pump.

When the dry pump 151 is operated, the PLC controller 11 input signal maintains a high level. When the molecular pump 153 operates, the molecular pump rotating speed analog quantity signal is a voltage signal, and the range of the voltage signal is 0-10V; the PLC 11 receives the voltage signal and obtains the rotation speed of the molecular pump according to the voltage signal, wherein the voltage signal range is 0-10V corresponding to 0-100% of the rotation speed of the molecular pump, for example, the PLC 11 obtains the rotation speed of the molecular pump to reach 50% through the received 5V voltage signal. After receiving the two signals, the PLC controller 11 considers that the condition of the molecular pump angle valve 152 is satisfied; subsequently, the output contact of the PLC 11 disconnects the solenoid of the molecular pump angle valve relay, so that the normally open contact of the molecular pump angle valve relay is disconnected, the molecular pump angle valve 152 is closed, and the outlet pressure of the molecular pump 153 is kept lower than the standard atmospheric pressure.

And S15, the PLC controls a straight-through angle valve in the vacuum system to be opened according to the dry pump operation signal and the molecular pump angle valve closing state signal fed back by the molecular pump angle valve so as to vacuumize the vacuum cavity.

When the dry pump 151 is operated, the PLC controller 11 input signal maintains a high level. The normally open contact of molecular pump angle valve 152 will open after it is closed, thereby keeping the PLC controller 11 input signal at a low level (i.e., the molecular pump angle valve closed status signal). When the PLC controller 11 receives the above two signals, it is considered that the opening condition of the straight-through angle valve 157 is satisfied; then, the output contact of the PLC controller 11 energizes the solenoid of the direct angle valve relay, so that the normally open contact of the direct angle valve relay is closed, the direct angle valve 157 is energized, the direct angle valve 157 is opened, and the vacuum chamber 14 starts to be vacuumized.

And S16, the PLC controls the straight-through angle valve to be closed according to the dry pump running signal and the vacuum gauge pressure analog quantity signal so as to enable the vacuum cavity to keep pressure.

When the dry pump 151 is operated, the PLC controller 11 input signal maintains a high level. The capacitance gauge 158 collects the pressure value in the vacuum cavity 14 in real time and sends the pressure value to the PLC controller 11 through an analog quantity signal, the PLC controller 11 receives the vacuum gauge pressure analog quantity signal, and the vacuum gauge pressure analog quantity signal is a voltage signal; the PLC controller 11 obtains the pressure in the vacuum cavity 14 according to the voltage signal, wherein the voltage signal range is 0-10V, the corresponding pressure value is 0-1333 mbar, and for example, the PLC controller 11 obtains that the pressure in the vacuum cavity 11 reaches 200mbar according to the received 6.38V voltage signal. After receiving the two signals, the PLC controller 11 considers that the closing condition of the straight-through angle valve 157 is satisfied; subsequently, the output contact of the PLC 11 disconnects the coil of the straight-through angle valve relay, so that the normally open contact of the straight-through angle valve relay is disconnected, the straight-through angle valve 157 is closed, and the vacuum cavity 14 is stopped being vacuumized.

And S17, the PLC controls the molecular pump angle valve to open according to the dry pump running signal, the straight-through angle valve closing signal fed back by the straight-through angle valve and the vacuum gauge pressure analog quantity signal so as to vacuumize the outlet of the molecular pump.

When the dry pump 151 is operated, the PLC controller 11 input signal maintains a high level. Normally open contacts of through angle valve 157 are opened after closing, so that the PLC controller 11 input signal is kept at a low level (i.e., the through angle valve closing signal); the capacitance gauge 158 collects the pressure value in the vacuum cavity 14 in real time and sends the pressure value to the PLC controller 11 through an analog quantity signal, the PLC controller 11 receives the vacuum gauge pressure analog quantity signal, and the vacuum gauge pressure analog quantity signal is a voltage signal; the PLC controller 11 obtains the pressure in the vacuum cavity 20 according to the voltage signal, wherein the voltage signal range is 0-10V, the corresponding pressure value is 0-1333 mbar, and for example, the PLC controller 11 obtains that the pressure in the vacuum cavity 20 reaches 200mbar according to the received 6.38V voltage signal. When the PLC controller 11 receives the above three signals, it is considered that the opening condition of the molecular pump angle valve 152 is satisfied. Subsequently, the output contact of the PLC controller 11 powers on the solenoid of the relay of the molecular pump angle valve, so that the normally open contact of the relay of the molecular pump angle valve is closed, the molecular pump angle valve 152 is powered on, the molecular pump angle valve 152 is opened, and the molecular pump 153 continues to be vacuumized.

S18, the PLC controls a gate valve in the vacuum system to open according to the dry pump operation signal, the molecular pump angle valve opening state signal fed back by the molecular pump angle valve, the through angle valve closing signal and the vacuum gauge pressure analog quantity signal so as to perform vacuum purification on the vacuum cavity.

When the dry pump 151 runs, the input signal of the PLC 11 keeps high level; after the molecular pump angle valve 152 is opened, the normally open contact is closed, so that the PLC input signal keeps high level; normally open contacts of through angle valve 157 are opened after closing, so that the PLC controller 11 input signal is kept at a low level (i.e., the through angle valve closing signal); the capacitance gauge 158 collects the pressure value in the vacuum cavity 14 in real time and sends the pressure value to the PLC controller 11 through an analog quantity signal, and the PLC controller 11 receives the pressure analog quantity signal of the vacuum gauge; the PLC controller 11 obtains the pressure in the vacuum cavity 14 according to the voltage signal corresponding to the vacuum gauge pressure analog quantity signal, wherein the voltage signal range is 0-10V and corresponds to a pressure value of 0-1333 mbar, for example, the PLC controller 11 obtains the pressure in the vacuum cavity 14 to reach 200mbar according to the received 6.38V voltage signal. When the PLC controller 11 receives the above four signals, it is considered that the opening condition of the gate valve 154 is satisfied. Then, the output contact of the PLC 11 powers on the solenoid of the gate valve relay, so that the normally open contact of the gate valve relay is closed, the gate valve 154 is powered on, the gate valve 154 is opened, and the cavity is purified in high vacuum.

When the air pumping is finished, the PLC 11 controls each element in the process to keep the final state, so as to form a safe, stable and clean growth environment and provide necessary environmental support for the subsequent diamond growth; in addition, the process can lock the process gas to be introduced into the diaphragm valve, so that dangerous accidents caused by manual misoperation can be avoided, and when the system is in an emergency, the process can be operated to isolate the dangerous gas required by growth from the atmospheric environment, so that danger is prevented.

And S2, the PLC carries out a process control flow on the vacuum system according to the feedback signals of the elements in the vacuum system so as to enter a diamond growth flow. The method specifically comprises the following steps:

s21, after receiving the process flow starting signal, the PLC judges whether the air exhaust control flow is executed or not according to the dry pump operation signal, the gate valve opening state signal fed back by the gate valve and the vacuum gauge pressure analog quantity signal, if not, the air exhaust control flow is continued, and if yes, the step S22 is executed.

When the dry pump 151 runs, the input signal of the PLC 11 keeps high level; after the gate valve 154 is opened, the normally open contact is closed, so that the input signal of the PLC 11 keeps a high level (the high level is a gate valve opening state signal); after the straight-through angle valve 157 is closed, the normally open contact of the straight-through angle valve is disconnected, so that the input signal of the PLC 11 keeps low level; the capacitance gauge 158 collects the pressure value in the vacuum cavity 14 in real time and sends the pressure value to the PLC controller 11 through an analog quantity signal, the PLC controller 11 receives the vacuum gauge pressure analog quantity signal, and the vacuum gauge pressure analog quantity signal is a voltage signal; the PLC 11 obtains the pressure in the vacuum cavity 20 according to the voltage signal, wherein the voltage signal range is 0-10V, the corresponding pressure value is 0-1333 mbar, for example, the PLC 11 receives the voltage signal smaller than 6.38V, and the pressure in the vacuum cavity 20 is smaller than 200 mbar. When the PLC controller 11 receives the above three signals, the system is considered to have executed the air extraction process, and the PLC controller 11 performs the process control. If any one of the three signals is not satisfied, the PLC 11 determines that the system does not execute the air extraction process, the program automatically jumps out of the process flow control, then automatically triggers an air extraction process operation signal, starts to execute the air extraction process, and then enters step S22; when the air-extracting process is finished, the process flow control is automatically entered and the step S21 is executed, and the condition judgment is executed again. If the three signals are not met, the process flow control is ended, and an alarm signal is sent out to prompt an operator to check the state of the system.

And S22, the PLC controls the gate valve to be closed and controls the radio frequency power supply to be started at the same time.

The PLC 11 outputs contacts to cut off the solenoid of the gate valve relay, so that the normally open contact of the gate valve relay is disconnected, the gate valve 154 is cut off, and the gate valve 154 is closed; meanwhile, another output contact of the PLC 11 energizes a coil of the radio frequency power supply relay, so that a normally open contact of the radio frequency power supply relay is closed, and the contact is closed to cause a preheating starting signal of the radio frequency power supply controller in the glow system 17 to keep a high level, so that the radio frequency power supply starts to preheat. The PLC completes the two controls at the same time to prepare for the subsequent glow discharge.

And S23, controlling the molecular pump to stop running by the PLC according to the gate valve closing state signal fed back by the gate valve.

The normally open contact of gate valve 154 will open after closing, thereby keeping the input signal of PLC controller 11 at a low level. When the PLC 11 receives the signal, the system is considered to meet the condition that the molecular pump 153 stops running; subsequently, the output contact of the PLC controller 11 disconnects the solenoid of the molecular pump relay, so that the normally open contact of the molecular pump relay is opened, and the contact is opened to cause the operation start signal of the molecular pump 153 to be kept at a low level, so that the molecular pump 153 stops starting.

And S24, the PLC controls the molecular pump angle valve to close according to the molecular pump stop operation signal and the gate valve closing state signal fed back by the molecular pump.

When the molecular pump 153 is stopped, the operation state display contact is opened, so that the PLC controller 11 input signal is kept at a low level. The normally open contact of gate valve 154 will open after it is closed, so that the input signal of PLC controller 11 will remain low. After the PLC controller 11 receives the two signals, the system is considered to satisfy the condition of closing the molecular pump angle valve 152; subsequently, the output contact of the PLC 11 disconnects the molecular pump angle valve relay coil, so that the normally open contact of the molecular pump angle valve relay is disconnected, the molecular pump angle valve 152 is closed, and the cavity stops high-vacuum purification.

S25, the PLC controls the proportional valve angle valve to open according to the molecular pump stop signal, the gate valve closing state signal and the molecular pump angle valve closing state signal fed back by the molecular pump angle valve, and the pipeline between the proportional valve and the dry pump in the vacuum system is guaranteed to be smooth.

When the molecular pump 151 stops operating, the operating state display contact is disconnected, so that the input signal of the PLC 11 keeps low level; after the gate valve 154 is closed, the normally open contact of the gate valve is disconnected, so that the input signal of the PLC 11 keeps low level; the normally open contact of molecular pump angle valve 152 will open after it is closed, thereby keeping the PLC controller 11 input signal low. After the PLC controller 11 receives the above three signals, the system is considered to satisfy the opening condition of the proportional valve angle valve 156; then, the output contact of the PLC 11 energizes the proportional valve angle valve relay coil, so that the normally open contact of the proportional valve angle valve relay is closed, the proportional valve angle valve 156 is energized, the proportional valve angle valve 156 is opened, and the pipeline among the dry pump 151, the proportional valve 155 and the vacuum cavity 14 is ensured to be smooth.

And S3, in the diamond growth process, the PLC controls vacuum pressure control by a vacuum system, growth position control by a seed crystal carrying tray system, glow control by a glow system and process gas control by a process gas system according to a growth information formula table acquired from an upper computer.

Specifically, when diamond growth is performed, the PLC controller 11 performs diamond growth according to the growth information recipe table obtained from the upper computer 12. The growth information formula table is a multi-row and six-column matrix structure, and parameters of each row are fixed and comprise time, pressure, flow, temperature, power and position parameters; the number of columns can be adjusted manually according to different growth processes. The PLC controller 11 reads the parameters from the first column, compares the above pressure, flow, temperature, power and position parameters with the read film gauge pressure analog quantity signal (film gauge, i.e. capacitance gauge), process gas mass flow meter flow analog quantity signal, infrared thermometer temperature modulus signal, radio frequency power supply current power analog quantity signal and stepping motor encoder position digital signal in a one-to-one correspondence manner, and in combination with the internal timer of the PLC controller 11, the PLC controller 11 sends the following signals within the timer set time: and sending an opening degree analog quantity signal to the proportional valve, sending a set power analog quantity signal to the radio frequency power supply, and sending a position pulse signal to the stepping motor, so that vacuum pressure control, glow control and growth position control are realized, and diamond growth control is completed. After the first column of time is over, the PLC controller 11 reads the time of the next column of parameters, and if the time is not zero, the PLC controller 11 continues to perform corresponding growth control according to such parameters. If the time is zero, the PLC controller 11 considers that the growth control has been completed, and the flow is stopped.

And when the process flow control is finished, all elements in the process flow keep the final state, and in the process flow, the elements outside the process flow are locked, and all the elements except the air exhaust and stop signals are controlled to be locked, so that dangerous accidents caused by manual misoperation can be avoided.

In the diamond growth process, the vacuum pressure control comprises the following steps:

step one, the PLC 11 obtains a growth information formula table from the upper computer 12.

And step two, the PLC 11 controls the corresponding diaphragm valve and mass flowmeter in the process gas system to work according to the process gas type and the gas flow in the growth information formula table. The process gas species include H₂、CH₄、O₂And N₂Wherein H is₂The flow rate is 100-1000L/min, CH₄The flow rate is 2-125L/min (2-10% of the total gas content), and O₂The flow rate is 2-125L/min (2-10% of the total gas content), and N₂The flow rate is 0.002-0.125L/min (10-100 ppm of the total gas amount); further, only H is opened in the preparation stage and the end stage of the diamond growth₂Corresponding diaphragm valve and mass flowmeter in the diamond growth maintaining stage H₂、CH₄、O₂And N₂The corresponding mass flowmeters are all open.

And step three, the PLC 11 acquires the real-time pressure in the vacuum cavity fed back by the capacitance gauge 158 in the vacuum system.

Step four, the PLC 11 compares the real-time pressure with the target pressure; when the real-time pressure is greater than the target pressure, controlling the opening of a proportional valve 155 in the vacuum system 15 to increase until the real-time pressure is equal to the target pressure; when the real-time pressure is equal to the target pressure, controlling the opening of the proportional valve 155 to be constant; when the real-time pressure is less than the target pressure, the opening of the proportional valve 155 in the vacuum system 15 is controlled to decrease until the real-time pressure is equal to the target pressure. Specifically, when the real-time pressure is greater than the target pressure, it indicates that the pressure in the vacuum cavity 14 is relatively high, at this time, the PLC controller sends an opening degree analog signal through the analog input/output module 20, and controls the current opening degree of the proportional valve 155 to increase to reduce the pressure in the vacuum cavity until the real-time pressure is equal to the target pressure; when the real-time pressure is equal to the target pressure, the current opening degree of the proportional valve 155 is controlled to be kept unchanged; when the real-time pressure is smaller than the target pressure, it indicates that the pressure in the vacuum cavity 14 is relatively low, at this time, the PLC controller 11 sends an opening degree analog signal through the analog input/output module 20, and controls the current opening degree of the proportional valve 155 to decrease to increase the pressure in the vacuum cavity until the real-time pressure is equal to the target pressure.

The growth position control comprises the following steps:

step one, the PLC 11 obtains a growth information formula table from the upper computer 12, wherein the growth information formula table comprises a growth initial position, a growth stage position and growth temperature information required by diamond growth.

Step two, PLC controller 11 controls the seed crystal loading tray in vacuum cavity to move the seed crystal loading tray to the growth initial position according to the growth initial position and the growth stage position by using the stepping motors (lifting motor 161 and rotating motor 162) in seed crystal loading tray system 16. The growth initial position is that the surface of the diamond is always positioned on a reference plane in the growth process of the diamond, and the reference plane is the growth initial position; that is, as the diamonds were grown, PLC controller 11 controlled the seed crystal loading tray system such that seed crystal loading tray 164 was gradually lowered such that the diamond surface of increasing thickness was always located at the reference plane.

And step three, the PLC 11 acquires the position of the seed crystal carrying disk collected by the encoder in the seed crystal carrying disk system, and simultaneously acquires the real-time vacuum cavity temperature value collected by the thermodetector 169 in the vacuum cavity 14. Specifically, the seed crystal tray position is acquired by second encoder 168 provided in elevator motor 161.

Step four, the PLC 11 compares the real-time vacuum cavity temperature value with the growth temperature information; when the real-time vacuum cavity temperature value is equal to the growth temperature information, the growth stage position corresponding to the growth temperature information is found in the growth information recipe table, and the stepping motor controls the seed crystal carrying disk to move until the position of the seed crystal carrying disk collected by the encoder is equal to the growth stage position, so that the position of the seed crystal carrying disk is positioned along with the real-time vacuum cavity temperature value according to the relation in the growth information recipe table. Specifically, during the growth of diamond, PLC controller 11 controls elevator motor 161 to operate, elevator motor 161 controls movement of seed crystal carrier disk 164, and second encoder 168 connected to elevator motor 161 and seed crystal carrier disk 164 simultaneously detects the moving direction, moving speed, and position values of the seed crystal carrier disk, and PLC control module obtains the detected values; when the position of the seed crystal carrier disk collected by second encoder 168 is equal to the growth stage position, the movement of seed crystal carrier disk 164 is stopped at the time when the position of seed crystal carrier disk 164 is equal to the target position.

The glow control comprises the steps of:

step one, the PLC 11 obtains the upper limit of the reflection power and a growth information formula table from the upper computer 12, wherein the growth information formula table comprises a formula of the glow power and the vacuum pressure at the starting stage and a formula of the glow power and the vacuum pressure at the ending stage.

And step two, the PLC 11 controls a radio frequency power supply in the glow system to start glow discharge according to the glow starting power, and obtains the real-time pressure, the real-time glow power and the real-time reflection power in the vacuum cavity 14.

Step three, the PLC 11 compares the real-time reflected power with the upper limit of the reflected power, controls the radio frequency power supply to stop glow discharge when the upper limit of the reflected power is less than or equal to the real-time reflected power, and controls the radio frequency power supply to continue glow discharge when the upper limit of the reflected power is greater than the real-time reflected power; meanwhile, in the preparation stage and the finishing stage of the growth of the diamond, the PLC 11 compares the real-time pressure with the vacuum pressure in the growth information formula table, when the real-time pressure is equal to the vacuum pressure, the standard glow power corresponding to the vacuum pressure is found in the growth information formula table, and the radio frequency power supply is controlled to enable the real-time glow power to be equal to the standard glow power. Specifically, in the whole diamond growth process, after the PLC controller 11 obtains the real-time feedback power, the real-time feedback power is compared with the upper limit of the feedback power to determine the operation state of the radio frequency power supply; when the upper limit of the reflected power is less than or equal to the real-time reflected power, which indicates that the radio frequency power supply fails, the PLC 11 controls the radio frequency power supply to stop glow discharge; when the upper limit of the reflected power is larger than the real-time reflected power, it indicates that the radio frequency power supply operates normally, and the PLC controller 11 does not operate the radio frequency power supply, so that the radio frequency power supply continues to glow discharge. And in the preparation stage and the finishing stage of the diamond growth, the real-time glow power is controlled, so that the real-time glow power changes according to the change trend of the standard glow power, and the environment in the vacuum cavity is ensured to be stable and safe.

The process gas control comprises the steps of:

step one, the PLC 11 obtains the safe pressure and the growth information formulation table in the vacuum cavity in the diamond growth process from the upper computer 12.

And step two, the PLC 11 controls the corresponding diaphragm valve and mass flowmeter in the process gas system to work according to the process gas type and the gas flow in the growth information formula table. Specifically, the process gas species for the diamond growth preparation stage includes H₂The flow rate is 100-1000L/min, and the process gas species in the growth maintenance stage includes H₂、CH₄、O₂And N₂The flow rates are 100-1000L/min, 2-125L/min, 0.002-0.125L/min, respectively, and the process gas species at the growth end stage includes H₂The flow rate is 100-1000L/min, so that H is controlled in the preparation stage of diamond growth₂Working of corresponding diaphragm valve and mass flowmeter, and controlling H in growth maintaining stage₂、CH₄、O₂And N₂The corresponding diaphragm valve and the mass flowmeter work and control CH at the growth end stage₄、O₂And N₂Corresponding diaphragm valve and mass flow meter are closed, holding H₂The corresponding diaphragm valve and mass flow meter operate.

And step three, the PLC 11 acquires the real-time pressure in the vacuum cavity 14 through a Pirani gauge and acquires the first gas flow and the second gas flow in the growth maintaining stage. Specifically, the first gas flow rate and the second gas flow rate may be H, respectively₂Flow rate and O₂And (4) flow rate.

And step four, the PLC 11 compares the real-time pressure with the target pressure, controls the operation state of the diaphragm valve corresponding to each process gas to be locked when the real-time pressure is greater than or equal to the safe pressure, and controls the diaphragm valve corresponding to each process gas to continue to operate when the real-time pressure is less than the safe pressure. Specifically, when the PLC controller determines that the real-time pressure is greater than or equal to the safe pressure, it indicates that the pressure in the vacuum chamber exceeds the safe pressure range at the moment, and there is a safety risk, and at the moment, the PLC controller controls the operation state of the diaphragm valve corresponding to each process gas to be locked, so as to stop the process gas from entering the vacuum chamber, and prevent the pressure in the vacuum chamber from continuously increasing; for example, H is controlled during the growth preparation phase and the growth termination phase₂Locking the corresponding diaphragm valve; during the growth maintenance phase, H is controlled₂、CH₄、O₂And N₂The corresponding diaphragm valves are locked. When the PLC judges that the real-time pressure is smaller than the safe pressure, the pressure in the vacuum cavity is in the safe pressure range at the moment, the growth of the diamond can be continued, and at the moment, the corresponding diaphragm valve is controlled to keep the existing state.

Meanwhile, in the growth maintenance stage of the diamond, the PLC compares the first gas flow with the second gas flow, when the ratio of the first real-time gas flow to the second real-time gas flow is greater than or equal to a first target value, the running state of the diaphragm valve corresponding to the first process gas and the running state of the diaphragm valve corresponding to the second process gas are both controlled to be locked, and when the ratio of the first real-time gas flow to the second real-time gas flow is smaller than the first target value, the running state of the diaphragm valve corresponding to the first process gas and the running state of the diaphragm valve corresponding to the second process gas are both controlled to continue running. Specifically, when H₂Flow rate and O₂The flow rate ratio is largeWhen 1/20 is not exceeded, the PLC controller controls H₂The running state of the diaphragm valve on the pipeline is locked, and O is controlled at the same time₂The running state of the diaphragm valve on the pipeline is locked to prevent H₂And O₂Entering a vacuum cavity; when H is present₂Flow rate and O₂When the flow ratio is less than 1/20, the PLC controller controls H₂Continued operation of the on-line diaphragm valve while controlling O₂And the diaphragm valve on the pipeline continues to operate, and the growth of the diamond is continued.

While the process gas is controlled by using the target pressure and gas flow ratio, the process gas can be controlled by using the target gas flow, and the method specifically comprises the following steps:

in the growth maintaining stage of the diamond, the PLC 11 obtains the target gas flow;

the PLC 11 compares the target gas flow with a preset gas flow corresponding to the target gas in the growth information formula table, controls the operation state of the diaphragm valve corresponding to the target gas to be locked when the difference value between the target gas flow and the preset gas flow is larger than or equal to a second target value, and controls the diaphragm valves corresponding to the target gas to continue to operate when the difference value between the target gas flow and the preset gas flow is smaller than the second target value. Specifically, the target gas flow rate includes H₂Flow rate or O₂Flow rate of target gas H₂The preset gas flow is 100L/min, the second target value is 10L/min, if H is in the growth maintaining stage₂When the gas flow is less than or equal to 90L/min or greater than or equal to 110L/min, H is indicated₂The flow of the gas is too small or too large, the normal growth of the diamond can not be ensured, and at the moment, the PLC controls H₂Corresponding diaphragm valve is locked and stopped H₂Continuously entering a vacuum cavity; if H is₂When the flow rate is more than 90L/min and less than 110L/min, the control keeps the existing state and continues to feed H₂。

Further, while the vacuum pressure control, the growth position control, the glow control and the process gas control are carried out, the cooling control can also be carried out, and the cooling control specifically comprises the following steps:

firstly, the PLC 11 obtains a cooling starting signal, a target temperature of cooling water and a target flow of the cooling water through the upper computer 12.

And step two, the PLC 11 controls the cooling system 19 to operate according to the cooling starting signal. Specifically, the PLC controller 11 controls the water cooler 191, the 4 water inlet valves 195, and the 4 water return valves 196 to operate according to the cooling start signal.

And step three, the PLC 11 acquires the reflux temperature of the cooling water and the real-time flow of the cooling water. Specifically, the PLC controller 11 obtains the return temperature of the cooling water through the 4 water temperature meters 197, and obtains the real-time flow rate of the cooling water through the 4 water flow meters 194.

And step four, the PLC 11 compares the reflux temperature with the target temperature, controls the diamond growth system to stop running when the reflux temperature is higher than the target temperature, and controls the diamond growth system to continue running when the reflux temperature is lower than or equal to the target temperature. Specifically, when the reflux temperature is higher than the target temperature, the temperature of the part to be cooled is too high, and the normal growth of the diamond cannot be ensured, and at the moment, the PLC controls the diamond growth system to stop running; and when the reflow temperature is less than or equal to the target temperature, the temperature of the part to be cooled is in a normal range, and the growth of the diamond is continued.

Meanwhile, the PLC controller 11 compares the real-time flow with the target flow, and controls the diamond growth system to stop operating when the real-time flow is smaller than the target flow, and controls the diamond growth system to continue operating when the real-time flow is greater than or equal to the target flow. Specifically, when the real-time flow is smaller than the target flow, the abnormal water inflow of the cooling water is indicated, sufficient cooling water cannot be provided to effectively cool the part to be cooled, the normal growth of the diamond cannot be ensured, and at the moment, the diamond growth system is controlled to stop running; when the real-time flow is larger than or equal to the target flow, the water inflow of the cooling water is normal, sufficient cooling water can be provided to effectively cool the part to be cooled, and the growth of the diamond is continued.

Further, when cooling control is performed by using cooling water, cooling control can be performed on the vacuum cavity by using a cooling fan, and the cooling control by using the cooling fan specifically comprises the following steps:

step one, the PLC controller 11 obtains a pressure signal in the vacuum chamber 14 through the vacuum gauge 199, and obtains a pressure value in the vacuum chamber 14 according to the pressure signal.

And step two, the PLC 11 judges the relation between the pressure value and the target pressure, and when the pressure value is judged to be greater than or equal to the target pressure, the cooling fan is controlled to be started to cool the vacuum cavity. Specifically, when the PLC controller 11 determines that the pressure value in the vacuum cavity 14 is greater than or equal to the target pressure, it indicates that the temperature in the vacuum cavity 14 reaches the air-cooled starting condition, at this time, the PLC controller output contact powers on the cooling fan relay coil, so that the cooling fan relay normally-open contact is closed, thereby keeping the cooling fan 198 running signal to keep a high level, the cooling fan 198 is started, hot air in the vacuum cavity 14 is discharged, cold air is sent into the vacuum cavity 14, air cooling of the vacuum cavity 14 is realized, the temperature in the vacuum cavity 14 is further reduced, and the normal growth of diamonds is ensured.

Thirdly, the PLC 11 receives the cooling fan running signal and judges the running state of the cooling fan 198 according to the cooling fan running signal; when the running state of the cooling fan 198 is judged to be normal, controlling the diamond growth system to continue running; and when the running state of the cooling fan 198 is judged to be abnormal, controlling the diamond growth system to stop running. Specifically, after the cooling fan 198 is started, an operation signal is fed back to the PLC controller 11; when the cooling fan 198 normally runs, the current relay running state display contact is closed, so that the input signal of the PLC 11 keeps a high level, at the moment, the PLC 11 judges that the running state of the cooling fan 198 is normal, and the diamond can normally grow, so that the diamond growth system is controlled to continue running; when the cooling fan breaks down, the current relay sends the fault signal to the PLC 11, the input signal of the PLC 11 is low level, at the moment, the PLC 11 judges that the running state of the cooling fan is fault, and the normal growth of the diamond cannot be guaranteed, so that the diamond growth system is controlled to stop running.

And S4, the PLC 11 carries out an exhaust control process on the vacuum system according to the process stop signal and the feedback signal of the element in the vacuum system 15, so that the pressure in the vacuum cavity 14 is recovered to normal pressure.

The process stop signal includes a process flow interrupt signal or a growth flow completion signal. The process flow interruption signal is a process flow stop signal issued by an operator through the upper computer, and the operator can issue the signal at any time in the diamond growth process. The growth process completion signal means that the system completes a normal diamond growth process. When the PLC controller 11 receives any one of the process flow interruption signal and the growth flow completion signal, the process is stopped and the exhaust flow control is started. That is, the exhaust flow control is not limited to being performed at any time during the diamond growth process after the process control is completed.

Step S4 specifically includes:

s41, judging whether the air exhaust control process is executed or not by the PLC 11 process stop signal, the dry pump operation signal, the gate valve opening state signal and the vacuum gauge pressure analog quantity signal, if not, continuing the air exhaust control process, and if so, performing the exhaust control process;

when the dry pump 151 runs, the input signal of the PLC 11 keeps high level; after the gate valve 154 is opened, the normally open contact of the gate valve is closed, so that the input signal of the PLC 11 keeps high level; after the straight-through angle valve 157 is closed, the normally open contact of the straight-through angle valve is disconnected, so that the input signal of the PLC 11 keeps low level; the capacitance gauge 158 collects the pressure value in the cavity in real time and sends the pressure value to the PLC controller 11 through an analog quantity signal, the PLC controller 11 receives the vacuum gauge pressure analog quantity signal, and the vacuum gauge pressure analog quantity signal is a voltage signal; the PLC 11 obtains the pressure in the vacuum cavity 14 according to the voltage signal, wherein the voltage signal range is 0-10V, the corresponding pressure value is 0-1333 mbar, for example, the PLC 11 receives a voltage signal smaller than 6.38V, and the pressure in the vacuum cavity 14 is smaller than 200 mbar. When the PLC controller 11 receives the above three signals and receives the process stop signal, the PLC controller 11 considers that the system has performed the exhaust flow, and then the PLC controller 11 performs the exhaust flow control. If any one of the three signals is not satisfied, and the PLC controller 11 receives the process stop signal, the PLC controller 11 determines that the system does not execute the air-extracting process, and the program automatically jumps out of the exhaust flow control, and then automatically triggers the air-extracting process start signal to start executing the air-extracting process, and the process proceeds to step S42. When the air extraction flow control is finished, the flow control is automatically started to the exhaust flow control and the step S41 is executed to execute the condition judgment again. If the condition judgment is executed again, the three signals are still not met, the exhaust process is ended, an alarm signal is sent out, and an operator is prompted to check the system state.

And S42, the PLC controls the gate valve to close according to the process stop signal.

The PLC 11 output contact cuts off the solenoid of the gate valve relay, so that the normally open contact of the gate valve relay is disconnected, the gate valve 154 is cut off, and the gate valve 154 is closed.

S43, the PLC controls the exhaust valve to open according to the closing state signal of the gate valve, so that the pressure in the vacuum cavity is recovered to the normal pressure.

When the gate valve 154 is closed, the normally open contact is opened, so that the input signal of the PLC controller 11 is kept at a low level. When the PLC controller 11 receives the above signals, the system is considered to satisfy the opening condition of the exhaust valve 159; then, the output contact of the PLC controller 11 energizes the exhaust valve relay coil to close the normally open contact of the exhaust valve relay, so that the exhaust valve 159 is energized, the exhaust valve 159 is opened to communicate the vacuum chamber 14 with the atmosphere, and the vacuum chamber 14 is restored to normal atmospheric pressure.

When the exhaust gas flow control is finished, each element in the exhaust gas flow keeps the final state, and the system is in a standby operation state; in the process, all the locking is controlled except the starting signal of the air pumping process and the process stopping signal, so that dangerous accidents caused by manual misoperation can be avoided.

This embodiment is with vacuum system on PLC controller's basis, the thing dish system is carried to the seed crystal, the glow system, process gas system and cooling system fuse into an organic whole, the advantage of each system has been integrated, information between each system is mutual, realize using PLC controller to control the air exhaust of core to the diamond, grow, realize vacuum pressure control when the exhaust is controlled, growth position control, glow control, process gas control and cooling control, the blank that needs artifical synergism has been filled, the safety class has been promoted, the time of personnel's operation is reduced, safe more intelligent diamond growth control has finally been realized under PLC's cooperation.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims

1. A control method based on PLC in a diamond growth system is characterized in that the diamond growth system comprises a PLC controller, an upper computer, a router, a vacuum cavity, a vacuum system, a seed crystal carrying tray system, a glow system, a process gas system and a cooling system, wherein the vacuum system, the seed crystal tray system, the glow system, the process gas system, and the cooling system are all electrically connected to the PLC controller, the PLC controller is electrically connected with the upper computer through the router, the vacuum system and the process gas system are connected with the vacuum cavity, the seed crystal loading tray system is disposed at a bottom of the vacuum cavity and penetrates the vacuum cavity, the radio frequency power generator in the glow system is arranged above the vacuum cavity, and the cooling system is connected with the vacuum cavity and the vacuum system;

the control method comprises the following steps:

2. The PLC-based control method of a diamond growth system according to claim 1, wherein the step S1 includes:

3. The PLC-based control method of a diamond growth system according to claim 2, wherein the step S2 includes:

4. The PLC-based control method of a diamond growth system according to claim 2, wherein the step S4 includes:

5. The PLC-based control method in a diamond growth system according to claim 1, wherein the vacuum pressure control includes:

6. The PLC-based control method in a diamond growth system according to claim 1, wherein the growth position control comprises the steps of:

7. The PLC-based control method in a diamond growth system according to claim 1, wherein the glow control comprises the steps of:

8. The PLC-based control method in a diamond growth system according to claim 1, wherein the process gas control includes the steps of:

9. A PLC-based control method in a diamond growth system according to claim 8, wherein after the PLC controller controls the operation of the corresponding diaphragm valve and mass flow meter in the process gas system according to the process gas type and gas flow rate in the growth information recipe table, it further comprises the steps of:

10. The PLC-based control method in a diamond growth system according to claim 1, further comprising the steps of: