CN112030226A

CN112030226A - Diamond growth process control method and device based on PLC

Info

Publication number: CN112030226A
Application number: CN202010774593.2A
Authority: CN
Inventors: 张金风; 苏凯; 任泽阳; 张进成; 何琦; 邢雨菲; 郝跃
Original assignee: Xidian University
Current assignee: Xidian University
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2020-12-04
Anticipated expiration: 2040-08-04
Also published as: CN112030226B

Abstract

The invention relates to a diamond growth process control method and a device based on PLC, the control method comprises the following steps: controlling the air pumping flow according to the air pumping flow starting signal, the feedback signal of each element in the air pumping system and the vacuum gauge pressure analog quantity signal fed back by the vacuum cavity, so that the pressure in the vacuum cavity reaches the target pressure; controlling the process flow according to the process flow starting signal, the feedback signal of each element of the air pumping system and the vacuum gauge pressure analog quantity signal fed back by the vacuum cavity to realize the growth control of the diamond; the exhaust flow control is carried out according to the process stop signal, the feedback signal of each element of the air pumping system and the pressure analog quantity signal of the vacuum gauge, so that the pressure in the vacuum cavity is recovered to the normal pressure. The control method can keep each element in the final state in each stage, and the elements except the process are locked, so that dangerous accidents caused by manual misoperation are avoided, and the stability and the safety of diamond growth are improved.

Description

Diamond growth process control method and device based on PLC

Technical Field

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

Background

Diamond, as a wide band gap semiconductor material, has many unusual properties, such as a large forbidden band width, a low dielectric constant, a high breakdown voltage, a high electron-hole mobility, a high thermal conductivity, and an excellent radiation resistance, and is chemically stable. All of these physical, chemical and electrical properties have led to the wide application of diamond in many areas of industry and civilian use.

At present, in the process of diamond growth by Chemical Vapor Deposition (CVD), the quality of the diamond growth result is greatly influenced by the vacuum environment. However, in the existing diamond growth process, an operator needs to perform manual overall operation on air suction and exhaust in a vacuum environment according to experience; the manual overall operation error rate is high, dangerous accidents caused by manual misoperation are easy to happen, and the safety is low.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a diamond growth process control method and a diamond growth process control device 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 diamond growth process control method based on a PLC (programmable logic controller), which comprises the following steps of:

controlling the air pumping flow according to the air pumping flow starting signal, the feedback signal of each element in the air pumping system and the vacuum gauge pressure analog quantity signal fed back by the vacuum cavity, so that the pressure in the vacuum cavity reaches the target pressure;

carrying out process flow control according to a process flow starting signal, a feedback signal of each element of the air pumping system and a vacuum gauge pressure analog quantity signal fed back by the vacuum cavity to realize diamond growth control;

and controlling the exhaust flow according to the process stop signal, the feedback signal of each element of the air pumping system and the pressure analog quantity signal of the vacuum gauge, so that the pressure in the vacuum cavity is recovered to the normal pressure.

In an embodiment of the present invention, performing pumping process control according to a pumping process start signal, a feedback signal of each element in a pumping system, and a vacuum gauge pressure analog signal fed back by a vacuum cavity to make the pressure in the vacuum cavity reach a target pressure, includes:

controlling a dry pump to operate according to the pumping flow starting signal, and receiving a dry pump operation signal fed back by the dry pump;

controlling the molecular pump angle valve to be opened according to the dry pump operation signal so as to vacuumize the outlet of the molecular pump, and receiving a molecular pump angle valve opening state signal fed back by the molecular pump angle valve;

controlling the molecular pump to operate according to the dry pump operation signal and the molecular pump angle valve opening state signal, and receiving a molecular pump rotating speed analog quantity signal fed back by the molecular pump;

controlling the molecular pump angle valve to close according to the dry pump running signal and the molecular pump rotating speed analog quantity signal so as to keep the pressure of the outlet of the molecular pump, and receiving a molecular pump angle valve closing state signal fed back by the molecular pump angle valve;

controlling a straight-through angle valve to be opened according to the dry pump running signal and the molecular pump angle valve closing state signal so as to vacuumize the vacuum cavity, and receiving the vacuum gauge pressure analog quantity signal;

controlling the through angle valve to close 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, and receiving a through angle valve closing signal fed back by the through angle valve;

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

and controlling a gate valve to be opened according to the dry pump operation signal, the molecular pump angle valve opening state signal, 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 receiving the gate valve opening state signal fed back by the gate valve so that the pressure in the vacuum cavity reaches a target pressure.

In one embodiment of the invention, the molecular pump rotating speed analog quantity signal is 5-10V.

In an embodiment of the present invention, the method for controlling the growth of the diamond according to the process flow starting signal, the feedback signal of each element of the pumping system and the vacuum gauge pressure analog quantity signal fed back by the vacuum cavity includes:

judging whether the air pumping flow control is executed or not according to the process flow starting signal, the dry pump running signal, the gate valve opening state signal and the vacuum gauge pressure analog quantity signal, if not, continuing the air pumping flow control, and if so, controlling the process flow;

controlling the gate valve to close according to the process flow starting signal, receiving a gate valve closing state signal, and simultaneously controlling a radio frequency power supply to start;

controlling the molecular pump to stop running according to the gate valve closing state signal, and receiving a molecular pump running stop signal;

controlling the molecular pump angle valve to be closed according to the molecular pump stop signal and the gate valve closing state signal, and receiving the molecular pump angle valve closing state signal;

controlling the opening of a proportional valve angle valve according to the molecular pump stop operation signal, the gate valve closing state signal and the molecular pump angle valve closing state signal;

and controlling the vacuum pressure, the glow and the growth position according to the growth information formula table to realize the growth control of the diamond.

In one embodiment of the present invention, performing an exhaust flow control to restore the pressure in the vacuum chamber to a normal pressure according to a process stop signal, feedback signals of components of the pumping system, and the vacuum gauge pressure analog signal comprises:

judging whether the air pumping flow control is executed or not according to the process stopping signal, the dry pump running signal, the gate valve opening state signal and the vacuum gauge pressure analog quantity signal, if not, continuing the air pumping flow control, and if so, performing exhaust flow control;

controlling the gate valve to close according to the process stop signal, and receiving a gate valve closing state signal;

and controlling an exhaust valve to be opened according to the closing state signal of the gate valve so as to restore the pressure in the vacuum cavity to normal pressure.

In one embodiment of the present invention, the process stop signal includes a process flow interrupt signal or a growth flow complete signal.

In one embodiment of the invention, the target pressure is equal to or less than 300 mbar.

Another embodiment of the present invention provides a diamond growth process control apparatus based on a PLC, including:

the pumping flow control module is used for controlling the pumping flow according to pumping flow starting signals, feedback signals of all elements in the pumping system and vacuum gauge pressure analog quantity signals fed back by the vacuum cavity so as to enable the pressure in the vacuum cavity to reach a target pressure;

the process flow control module is used for controlling the process flow according to a process flow starting signal, a feedback signal of each element of the air pumping system and a vacuum gauge pressure analog quantity signal fed back by the vacuum cavity so as to realize the growth control of the diamond;

and the exhaust flow control module is used for controlling the exhaust flow according to the process stop signal, the feedback signal of each element of the air exhaust system and the vacuum gauge pressure analog quantity signal so as to restore the pressure in the vacuum cavity to the normal pressure.

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

the control method comprises three stages of air exhaust flow control, process flow control and exhaust flow control, wherein in each stage, the PLC controls each stage according to a feedback signal of an air exhaust system and a vacuum pressure gauge analog quantity signal fed back by the vacuum cavity, so that each element in each stage can be kept in a final state, and elements except the flow are locked, thereby avoiding dangerous accidents caused by manual misoperation, and further improving the stability and the safety of diamond growth.

Drawings

Fig. 1 is a schematic flow chart of a method for controlling a diamond growth flow based on a PLC according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a PLC-based diamond growth system according to an embodiment of the present invention;

fig. 3 is a schematic block diagram of a diamond growth process control device 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 and 2, fig. 1 is a schematic flow chart of a method for controlling a PLC-based diamond growth process according to an embodiment of the present invention, and fig. 2 is a schematic structural diagram of a PLC-based diamond growth system according to an embodiment of the present invention. In this embodiment, the control method in fig. 1 is performed based on the diamond growth system in fig. 2.

Specifically, the diamond growth system of fig. 2 includes pumping system 10, vacuum chamber 20, rf power supply 30, seed crystal movement system 40, PLC controller 50, router 60, upper computer 70, analog input/output module 80, and exhaust valve 90. Wherein the pumping system 10 is connected to the sidewall of the vacuum chamber 20 for evacuating the vacuum chamber 20 before diamond growth. A generator of a radio frequency power supply 30 is disposed above the vacuum chamber 20 for providing glow power to the vacuum chamber 20 during diamond growth. Seed crystal load movement system 40 extends through the bottom of vacuum chamber 20 and is used to control the lifting of the seed crystal load plate within vacuum chamber 20 during diamond growth. PLC controller 50 is electrically connected with air pumping system 10, radio frequency power supply 30 and seed crystal carrying moving system 40; the router 60 is connected between the PLC controller 50 and the upper computer 70; PLC 50 is connected to corresponding components of pumping system 10, rf power supply 30, and seed crystal carrier moving system 40 through analog input/output module 80, so as to receive analog signals fed back from corresponding components of pumping system 10, rf power supply 30, and seed crystal carrier moving system 40.

Further, the air exhaust system 10 comprises a dry pump 11, a molecular pump angle valve 12, a molecular pump 13, a gate valve 14, a proportional valve 15, a proportional valve angle valve 16 and a through angle valve 17. The dry pump 11, the molecular pump angle valve 12, the molecular pump 13 and the gate valve 14 are sequentially connected, the dry pump 11, the molecular pump angle valve 12, the molecular pump 13 and the gate valve 14 are all electrically connected with the PLC 50, one end of the gate valve 14 is connected to the vacuum cavity 20, and meanwhile, the molecular pump 13 is also connected with the PLC 50 through an analog input and output module 80; the proportional valve 15 is connected with a proportional valve angle valve 16, one end of the proportional valve 15 is connected between the dry pump 11 and the molecular pump angle valve 12, and one end of the proportional valve angle valve 16 is connected to the vacuum cavity 20; the straight-through angle valve 17 has one end connected between the dry pump 11 and the molecular pump angle valve 12 and the other end connected to the vacuum chamber 20. The vacuum chamber 20 is provided with a pirani gauge 21 (i.e. a vacuum gauge), and the pirani gauge 21 is connected with the PLC controller 50 through an analog input/output module 80.

In this embodiment, the method for controlling the diamond growth process based on the PLC includes three stages, i.e., an air pumping process control stage, a process flow control stage, and an exhaust flow control stage, and specifically includes the following steps:

and S1, controlling the air exhaust flow according to the air exhaust flow starting signal, the feedback signal of each element in the air exhaust system and the vacuum gauge pressure analog quantity signal fed back by the vacuum cavity, so that the pressure in the vacuum cavity reaches the target pressure. Wherein, each element in the air extraction system is a dry pump 11, a molecular pump angle valve 12, a molecular pump 13, a gate valve 14, a proportional valve 15, a proportional valve angle valve 16 and a straight-through angle valve 17.

Step S1 specifically includes:

and S11, controlling the operation of the dry pump according to the air pumping flow starting signal, and receiving a dry pump operation signal fed back by the dry pump.

Specifically, the operator gives the air suction flow starting signal through the upper computer 70, and the PLC controller 50 controls the dry pump relay to be electrically operated according to the air suction flow starting signal, so that the operation input contact of the dry pump 11 is closed, the dry pump 11 starts to operate, and meanwhile, the PLC controller 50 receives the dry pump operation signal.

It can be understood that the PLC controller 50 outputs contacts to power up the dry pump relay coil, so that the dry pump relay normally open contacts are closed; the closing of the dry pump relay normally open contact causes the dry pump run signal to remain high, whereby the dry pump 11 run is initiated.

And S12, controlling the molecular pump angle valve to be opened according to the dry pump running signal so as to vacuumize the outlet of the molecular pump, and receiving a molecular pump angle valve opening state signal fed back by the molecular pump angle valve.

Specifically, the PLC controller 50 energizes the molecular pump angle valve relay according to the dry pump operation signal, the molecular pump angle valve relay further controls the molecular pump angle valve 12 to open, and the outlet of the molecular pump 13 is vacuumized, and meanwhile, the PLC controller 50 receives a molecular pump angle valve opening state signal fed back by the molecular pump angle valve 12.

It will be appreciated that when the dry pump 11 is running, the operating status indicates that the contacts are closed, thereby keeping the PLC controller 50 input signal high. After receiving the signal, the PLC controller 50 considers that the opening condition of the molecular pump angle valve 12 is satisfied, and then the PLC controller 50 outputs a contact to electrify the molecular pump angle valve relay coil, so that the normally open contact of the molecular pump angle valve relay is closed, the molecular pump angle valve 12 is electrified, the molecular pump angle valve 12 is opened, and the outlet of the molecular pump 13 is vacuumized.

And S13, controlling the molecular pump to operate according to the dry pump operation signal and the molecular pump angle valve opening state signal, and receiving the molecular pump rotating speed analog quantity signal fed back by the molecular pump.

Specifically, the PLC controller 50 closes the operation input contact of the molecular pump 13 through the molecular pump relay according to the dry pump operation signal and the molecular pump angle valve open state signal, and the molecular pump 13 starts to operate, and at the same time, the PLC controller 50 receives the molecular pump rotation speed analog quantity signal fed back by the molecular pump 13.

It will be appreciated that when the dry pump 11 is running, the PLC controller 50 input signal remains high. After the molecular pump angle valve 12 is opened, the normally open contact is closed, so that the PLC input signal is kept at a high level (the high level is a molecular pump angle valve open state signal). After receiving the two signals, the PLC controller 50 determines that the operating conditions of the molecular pump 13 are satisfied; then, the PLC controller 50 outputs a contact to electrify 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, thereby the molecular pump 13 is started to operate.

And S14, controlling the molecular pump angle valve to close according to the dry pump running signal and the molecular pump rotating speed analog quantity signal to keep the pressure of the outlet of the molecular pump, and receiving a molecular pump angle valve closing state signal fed back by the molecular pump angle valve.

Specifically, the PLC controller 50 switches off the relay of the molecular pump angle valve according to the dry pump operation signal and the molecular pump rotation speed analog signal, so as to close the molecular pump angle valve 12 and maintain the outlet pressure of the molecular pump 13, and meanwhile, the PLC controller 50 receives the molecular pump angle valve closing state signal fed back by the molecular pump angle valve 12.

It will be appreciated that when the dry pump 11 is running, the PLC controller 50 input signal remains high. When the molecular pump 13 runs, the molecular pump rotating speed analog quantity signal is a voltage signal, and the range of the voltage signal is 0-10V; the PLC 50 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 50 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 50 determines that the condition of the molecular pump angle valve 12 is satisfied; then the PLC 50 outputs a contact to disconnect 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 disconnected, the molecular pump angle valve 12 is closed, and the outlet pressure of the molecular pump 13 is kept lower than the standard atmospheric pressure.

And S15, controlling the straight-through angle valve to be opened according to the dry pump running signal and the molecular pump angle valve closing state signal so as to vacuumize the vacuum cavity, and receiving a vacuum gauge pressure analog quantity signal.

Specifically, the PLC controller 50 energizes the direct angle valve relay according to the dry pump operation signal and the molecular pump angle valve off state signal, and the direct angle valve relay controls the direct angle valve 17 to open, starts to vacuumize the vacuum chamber 20, and receives the vacuum gauge pressure analog quantity signal fed back by the pirani gauge 21 on the vacuum chamber 20.

It will be appreciated that when the dry pump 11 is running, the PLC controller 50 input signal remains high. The normally open contact of the molecular pump angle valve 12 is opened after closing, so that the PLC controller 50 input signal is kept at a low level (i.e., the molecular pump angle valve closed state signal). When the PLC controller 50 receives the above two signals, it is considered that the opening condition of the straight-through angle valve 17 is satisfied; then, the output contact of the PLC controller 50 energizes the straight-through angle valve relay coil to close the normally open contact of the straight-through angle valve relay, so that the straight-through angle valve 17 is energized, the straight-through angle valve 17 is opened, and the vacuum chamber 20 starts to be vacuumized.

And S16, controlling the straight-through angle valve to be closed according to the dry pump running signal and the vacuum gauge pressure analog quantity signal to enable the vacuum cavity to keep pressure, and receiving a straight-through angle valve closing signal fed back by the straight-through angle valve.

Specifically, the PLC controller 50 switches off the direct angle valve relay according to the dry pump operation signal and the vacuum gauge pressure analog quantity signal, closes the direct angle valve 17, and maintains the cavity pressure, and at the same time, the PLC controller 50 receives a direct angle valve closing signal fed back by the direct angle valve 17.

It will be appreciated that when the dry pump 11 is running, the PLC controller 50 input signal remains high. Pirani gauge 21 gathers the pressure value in the vacuum cavity 20 in real time, sends PLC controller 50 through the analog signal, and PLC controller 50 receives this vacuum gauge pressure analog signal, and this vacuum gauge pressure analog signal is a voltage signal to obtain the pressure in the vacuum cavity 20 according to this voltage signal, wherein, voltage signal range 0 ~ 10V corresponds pressure value 0 ~ 1333mbar, for example, PLC controller 50 is according to receiving 6.38V voltage signal, and it reaches 200mbar to obtain the vacuum cavity 20 internal pressure. When the PLC controller 50 receives the above two signals, it is considered that the closing condition of the straight-through angle valve 17 is satisfied; subsequently, the output contact of the PLC 50 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 17 is closed, and the vacuum cavity 20 stops being vacuumized.

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

Specifically, the PLC controller 50 energizes the molecular pump angle valve relay according to the dry pump operation signal, the direct connection angle valve closing signal, and the vacuum gauge pressure analog signal, the molecular pump angle valve relay controls the molecular pump angle valve 12 to open, and vacuums the outlet of the molecular pump 13, and meanwhile, the PLC controller 50 receives the molecular pump angle valve opening state signal fed back by the molecular pump angle valve 12.

It will be appreciated that when the dry pump 11 is running, the PLC controller 50 input signal remains high. The normally open contact of the direct-connection angle valve 17 is disconnected after being closed, so that the input signal of the PLC 50 keeps a low level (the low level is a direct-connection angle valve closing signal); the Pirani gauge 21 collects the pressure value in the vacuum cavity 20 in real time and sends the pressure value to the PLC 50 through an analog quantity signal, the PLC 50 receives the pressure analog quantity signal of the vacuum gauge, and the pressure analog quantity signal of the vacuum gauge is a voltage signal; the PLC 50 obtains the pressure in the vacuum cavity 20 according to the voltage signal, wherein the voltage signal range is 0-10V, and the corresponding pressure value is 0-1333 mbar, for example, the PLC 50 obtains the pressure in the vacuum cavity 20 reaching 200mbar according to the received 6.38V voltage signal. When the PLC controller 50 receives the above three signals, it is considered that the opening condition of the molecular pump angle valve 12 is satisfied. Then, the PLC controller 50 outputs a contact to electrify 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, thereby electrifying the molecular pump angle valve 12, opening the molecular pump angle valve 12, and continuously vacuumizing the molecular pump 13.

S18, controlling the opening of the gate valve according to the dry pump operation signal, the molecular pump angle valve opening state signal, the straight-through angle valve closing signal and the vacuum gauge pressure analog quantity signal to perform vacuum purification on the vacuum cavity, and receiving the gate valve opening state signal fed back by the gate valve to enable the pressure in the vacuum cavity to reach the target pressure.

Specifically, the PLC controller 50 energizes the gate valve relay according to the dry pump operation signal, the molecular pump angle valve open state signal, the direct connection angle valve close signal, and the vacuum gauge pressure analog quantity signal, the gate valve relay controlling the gate valve 14 to open, the cavity performing high vacuum purification, and receiving the gate valve open state signal fed back by the gate valve 14.

It is understood that when the dry pump 11 is running, the PLC controller 50 input signal remains high; after the molecular pump angle valve 12 is opened, the normally open contact is closed, so that the PLC input signal keeps high level; the normally open contact of the direct-connection angle valve 17 is disconnected after being closed, so that the input signal of the PLC 50 keeps a low level (the low level is a direct-connection angle valve closing signal); pirani gauge 21 gathers the pressure value in the vacuum cavity 20 in real time, send PLC controller 50 through the analog signal, PLC controller 50 receives this vacuum gauge pressure analog signal, this vacuum gauge pressure analog signal is for using voltage signal, PLC controller 50 reachs the pressure in the vacuum cavity 20 according to this voltage signal, wherein, voltage signal range 0 ~ 10V corresponds pressure value 0 ~ 1333mbar, for example, PLC controller 50 reachs vacuum cavity 20 internal pressure and reaches 200mbar according to receiving 6.38V voltage signal. After the PLC controller 50 receives the above four signals, it is considered that the opening condition of the gate valve 14 is satisfied. Then the PLC 50 outputs a contact to electrify the solenoid of the gate valve relay, so that the normally open contact of the gate valve relay is closed, the gate valve 14 is electrified, the gate valve 14 is opened, and the cavity is purified in high vacuum.

When the air pumping is finished, the PLC 50 controls each element in the process to keep the final state, so that a safe, stable and clean growth environment is formed, and necessary environmental support is provided 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, controlling the process flow according to the process flow starting signal, the feedback signal of each element of the air exhaust system and the vacuum gauge pressure analog quantity signal fed back by the vacuum cavity, and realizing the growth control of the diamond. Step S2 specifically includes:

s21, judging whether the air exhaust flow control is executed or not according to the process flow starting signal, the dry pump running signal, the gate valve opening state signal and the vacuum gauge pressure analog quantity signal, if not, continuing the air exhaust flow control, and if so, carrying out the process flow control.

Specifically, an operator issues a process flow starting signal through the upper computer 70, and after receiving the signal, the PLC controller 50 firstly judges whether the system has executed the air exhaust process control through the dry pump operation signal, the gate valve opening state, and the vacuum gauge pressure analog quantity signal, and if not, automatically operates the air exhaust process control, and if so, performs the process flow control.

It is understood that when the dry pump 11 is running, the PLC controller 50 input signal remains high; after the gate valve 14 is opened, the normally open contact is closed, so that the input signal of the PLC 50 keeps a high level (the high level is a gate valve opening state signal); after the direct current angle valve 17 is closed, the normally open contact of the direct current angle valve is disconnected, so that the input signal of the PLC 50 keeps low level; the Pirani gauge 21 collects the pressure value in the vacuum cavity 20 in real time and sends the pressure value to the PLC 50 through an analog quantity signal, the PLC 50 receives the pressure analog quantity signal of the vacuum gauge, and the pressure analog quantity signal of the vacuum gauge is a voltage signal; the PLC 50 obtains the pressure in the vacuum cavity 20 according to the voltage signal, wherein the voltage signal range is 0-10V, and the corresponding pressure value is 0-1333 mbar, for example, the PLC 50 receives a voltage signal smaller than 6.38V, and the pressure in the vacuum cavity 20 is smaller than 200 mbar. When the PLC controller 50 receives the above three signals, the system is considered to have executed the air extraction process, and the PLC controller 50 performs the process control. If any one of the three signals is not satisfied, the PLC 50 determines that the system does not execute the air extraction process, the program automatically jumps out of the process flow control, and then automatically triggers an air extraction process operation signal to start executing the air extraction process; 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, controlling the gate valve to close according to the process flow starting signal, receiving a gate valve closing state signal, and simultaneously controlling the radio frequency power supply to start.

Specifically, the PLC controller 50 switches off the gate valve relay according to the process flow start signal, and the gate valve relay controls the gate valve 14 to be closed and receives the gate valve closing state signal; meanwhile, the preheating input contact of the radio frequency power supply 30 is closed through the radio frequency power supply relay, so that the preheating function of the radio frequency power supply 30 is started.

It can be understood that the PLC 50 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 14 is powered off, and the gate valve 14 is closed; meanwhile, another output contact of the PLC controller 50 energizes the rf power relay coil, so that the normally open contact of the rf power relay is closed, and the contact is closed, which may cause the preheating start signal of the rf power supply 30 to maintain a high level, so that the rf power supply 30 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 according to the gate valve closing state signal, and receiving a molecular pump stop running signal.

Specifically, the PLC controller 50 opens the molecular pump operation input contact through the molecular pump relay, stops the operation of the molecular pump 13, and receives the molecular pump stop signal fed back from the molecular pump 13.

It will be appreciated that the normally open contact of the gate valve 14 will open after it is closed, thereby keeping the PLC controller 50 input signal low. When the PLC 50 receives the signal, the system is considered to meet the condition that the molecular pump 13 stops running; subsequently, the PLC controller 50 outputs a contact to disconnect the solenoid of the molecular pump relay, so that the normally open contact of the molecular pump relay is disconnected, and the disconnection of the contact will cause the operation start signal of the molecular pump 13 to be kept at a low level, so that the molecular pump 13 stops starting.

And S24, controlling the molecular pump angle valve to close according to the molecular pump stop signal and the gate valve closing state signal, and receiving the molecular pump angle valve closing state signal.

Specifically, the PLC controller 50 cuts off the molecular pump angle valve closing relay according to the molecular pump operation signal and the gate valve closing state signal, so that the molecular pump angle valve 12 is closed, and high vacuum is stopped, and at the same time, the PLC controller 50 receives the molecular pump angle valve closing state signal fed back by the molecular pump angle valve 12.

It will be appreciated that when the molecular pump 13 is stopped, the operation status display contacts will be opened, thereby keeping the PLC controller 50 input signal low. After the gate valve 14 is closed, the normally open contact is opened, so that the input signal of the PLC 50 keeps low level. After the PLC 50 receives the two signals, the system is considered to meet the closing condition of the angle valve 12 of the molecular pump; then the PLC 50 outputs a contact to disconnect 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 disconnected, the molecular pump angle valve 12 is closed, and the cavity stops high vacuum purification.

And S25, controlling the proportional valve angle valve to be opened according to the molecular pump stop operation signal, the gate valve closing state signal and the second molecular pump angle valve closing state signal.

Specifically, the PLC 50 energizes the proportional valve angle valve relay, and the proportional valve angle valve relay controls the proportional valve angle valve 16 to be opened, so that the pipeline between the proportional valve 15 and the dry pump 11 is ensured to be smooth.

It can be understood that when the molecular pump 11 stops operating, the operating status display contact will be opened, so that the PLC controller 50 input signal will be kept at a low level; after the gate valve 14 is closed, the normally open contact is disconnected, so that the input signal of the PLC 50 keeps low level; the normally open contact of the molecular pump angle valve 12 will open after closing, thereby keeping the PLC controller 50 input signal low. After the PLC 50 receives the three signals, the system is considered to meet the opening condition of the proportional valve angle valve 16; then the PLC 50 outputs a contact to electrify 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 16 is electrified, the proportional valve angle valve 16 is opened, and the smooth pipeline among the dry pump 11, the proportional valve 15 and the vacuum cavity 20 is ensured.

And S26, controlling the vacuum pressure, the glow and the growth position according to the growth information formula table, and realizing the growth control of the diamond.

Specifically, when the diamond growth is performed, the PLC controller 50 performs the diamond growth according to the growth information recipe table obtained from the upper computer 70. 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 50 reads the parameters from the first column, compares the above pressure, flow, temperature, power and position parameters with the read gauge pressure analog signal (gauge, i.e., vacuum gauge), process gas mass flow meter flow analog signal (process gas mass flow meter is represented by MFC in fig. 2), infrared thermometer temperature modulus signal (infrared thermometer is represented by T in fig. 2), radio frequency power supply current power analog signal and stepper motor encoder position digital signal (stepper motor is represented by M in fig. 2) in a one-to-one correspondence, and in combination with the internal timer of the PLC controller 50, the PLC controller 50 sends the following signals within the timer set time: and the PID controller is matched to send an opening degree analog quantity signal to the proportional valve, send a set power analog quantity signal to the radio frequency power supply and send 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 50 reads the time of the next column of parameters, and if the time is not zero, the PLC controller 50 continues to perform corresponding growth control according to such parameters. If the time is zero, the PLC controller 50 considers the growth control to be completed and the process stops.

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.

And S3, controlling the exhaust flow according to the process stop signal, the feedback signal of each element of the air exhaust system and the pressure analog quantity signal of the vacuum gauge, so that the pressure in the vacuum cavity is recovered to the 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 50 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 S3 specifically includes the steps of:

s31, judging whether the air exhaust flow control is finished or not according to the process stop signal, the dry pump running signal, the gate valve opening state signal and the vacuum gauge pressure analog quantity signal, if not, continuing the air exhaust flow control, and if so, performing the exhaust flow control.

Specifically, when an operator issues a process stop signal through the upper computer 70, after receiving the signal, the PLC controller 50 first determines whether the system has executed the pumping process control through the dry pump operation signal, the gate valve open state, and the vacuum gauge pressure analog signal, and if not, automatically operates the pumping process control, and if so, performs the exhaust process control.

It is understood that when the dry pump 11 is running, the PLC controller 50 input signal remains high; after the gate valve 14 is opened, the normally open contact of the gate valve is closed, so that the input signal of the PLC 50 keeps high level; after the direct current angle valve 17 is closed, the normally open contact of the direct current angle valve is disconnected, so that the input signal of the PLC 50 keeps low level; the Pirani gauge 21 collects the pressure value in the cavity in real time and sends the pressure value to the PLC 50 through an analog quantity signal, the PLC 50 receives the vacuum gauge pressure analog quantity signal, and the vacuum gauge pressure analog quantity signal is a voltage signal; the PLC 50 obtains the pressure in the vacuum cavity 20 according to the voltage signal, wherein the voltage signal range is 0-10V, and the corresponding pressure value is 0-1333 mbar, for example, the PLC 50 receives a voltage signal smaller than 6.38V, and the pressure in the vacuum cavity 20 is smaller than 200 mbar. When the PLC controller 50 receives the above three signals and receives the process stop signal, the PLC controller 50 recognizes that the system has performed the exhaust flow, and the PLC controller 50 performs the exhaust flow control. If any one of the three signals is not satisfied, and the PLC 50 receives the process stop signal, the PLC 50 determines that the system does not execute the air extraction process, the program automatically jumps out of the air exhaust flow control, and then automatically triggers an air extraction process starting signal to start executing the air extraction process. When the air extraction flow control is finished, the flow control is automatically started to the exhaust flow control and the step S31 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 S32, controlling the gate valve to close according to the process stop signal, and receiving a gate valve closing state signal.

Specifically, the PLC controller 50 switches off the gate valve relay according to the process stop signal, and the gate valve relay controls the gate valve 14 to be closed, thereby protecting the molecular pump 12 from atmospheric pressure impact, and simultaneously receiving a gate valve closing state signal fed back by the gate valve 14. It can be understood that the PLC controller 50 outputs contacts to power off the solenoid of the gate valve relay, so that the normally open contact of the gate valve relay is turned off, and thus the gate valve 14 is powered off and the gate valve 14 is closed.

And S33, controlling 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.

Specifically, the PLC controller 50 energizes the exhaust valve relay according to the gate valve closing signal, and the exhaust valve 90 relay controls the exhaust valve to open, so that the vacuum chamber 20 recovers to the normal atmospheric pressure. It will be appreciated that the normally open contact of the gate valve 14 will open after it is closed, thereby keeping the PLC controller 50 input signal low. When the PLC controller 50 receives the above signals, the system is considered to satisfy the open condition of the exhaust valve 90; then, the PLC controller 50 outputs a contact to energize the exhaust valve relay coil, so that the normally open contact of the exhaust valve relay is closed, thereby energizing the exhaust valve 90, opening the exhaust valve 90, communicating the vacuum chamber 20 with the atmosphere, and recovering the vacuum chamber 20 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.

The control method of the embodiment comprises three stages of air exhaust flow control, process flow control and exhaust flow control, wherein in each stage, the PLC controls each element according to a feedback signal of an air exhaust system and a vacuum pressure gauge analog quantity signal fed back by the vacuum cavity, so that each element in each stage can keep the final state, and elements except the flow are locked, thereby avoiding dangerous accidents caused by manual misoperation, and further improving the stability and the safety of diamond growth.

Example two

On the basis of the first embodiment, please refer to fig. 3, and fig. 3 is a schematic block diagram of a PLC-based diamond growth process control apparatus according to an embodiment of the present invention. This diamond growth flow control device based on PLC includes: an extraction flow control module 31, a process flow control module 32, an exhaust flow control module 33.

The pumping flow control module 31 is configured to perform pumping flow control according to a pumping flow start signal, a feedback signal of each element in the pumping system, and a vacuum gauge pressure analog signal fed back from the vacuum cavity, so that the pressure in the vacuum cavity reaches a target pressure. The process flow control module 32 is used for controlling the process flow according to the process flow starting signal, the feedback signal of each element of the air pumping system and the vacuum gauge pressure analog quantity signal fed back by the vacuum cavity, so as to realize the growth control of the diamond. The exhaust flow control module 33 is used for controlling the exhaust flow according to the process stop signal, the feedback signal of each element of the air pumping system and the vacuum gauge pressure analog quantity signal, so that the pressure in the vacuum cavity is recovered to the normal pressure.

In particular, the target pressure is equal to or less than 300 mbar.

For the specific steps executed by the pumping flow control module 31, the process flow control module 32, and the exhaust flow control module 33, please refer to the first embodiment, which will not be described again.

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 diamond growth process control method based on PLC is characterized by comprising the following steps:

2. A PLC-based diamond growth process control method according to claim 1, wherein the pumping process control is performed according to a pumping process start signal, a feedback signal of each element in the pumping system, and a vacuum gauge pressure analog signal fed back from the vacuum chamber, so that the pressure in the vacuum chamber reaches a target pressure, and the method includes:

3. The PLC-based diamond growth process control method according to claim 2, wherein the molecular pump rotation speed analog quantity signal is 0-10V.

4. A PLC-based diamond growth process control method according to claim 2, wherein the process control is performed according to a process start signal, a feedback signal of each element of the pumping system, and a vacuum gauge pressure analog signal fed back from the vacuum chamber, so as to realize diamond growth control, and the method includes:

5. The PLC-based diamond growth process control method according to claim 2, wherein performing exhaust flow control to restore the pressure in the vacuum chamber to a normal pressure according to a process stop signal, feedback signals of the components of the pumping system, and the vacuum gauge pressure analog quantity signal comprises:

6. The PLC-based diamond growth process control method according to claim 5, wherein the process stop signal includes a process flow interrupt signal or a growth flow complete signal.

7. The PLC-based diamond growth process control method according to claim 1, wherein the target pressure is 300mbar or less.

8. A diamond growth flow control device based on PLC is characterized by comprising:

9. The PLC-based diamond growth flow control device of claim 8, wherein the target pressure is 300mbar or less.