Vacuum measurement and control system and method for precision instrument based on FPGA reconfigurable parallel architecture

Abstract

The application discloses a precision instrument vacuum measurement and control system and method based on an FPGA reconfigurable parallel architecture, and the system comprises a parallel main control module, a multi-channel synchronous analog-digital acquisition module, a multi-channel voltage division analog conditioning circuit, a multi-channel voltage division DI protection circuit, a pump valve isolation relay drive array, an Ethernet module, an upper computer and a general-purpose IO expansion module. The parallel main control module is an FPGA main control chip, and is internally provided with a multi-channel vacuum fitting unit, a molecular pump power calculation unit, double hardware locks and a vacuum air source multi-dimensional interlocking unit; the synchronous acquisition of multi-channel vacuum, air source pressure and pump electrical parameters has no sampling time sequence deviation; a pre-evacuation communication valve and a main cavity isolation valve are unlocked by vacuum standard hardware, the vacuum drops to be turned off in microseconds, and the software cannot be opened by force; high-pressure interlocking is synchronously included in the multi-dimensional determination of the vacuum, the air source and the pump power, and is instantaneously cut off in an abnormal state. The system is fully hardware-parallel, responds in microseconds, does not need to change a PCB, can switch process adaptation different equipment by only updating firmware, and significantly improves safety and universality.

Description

Technical Field

[0001] This invention relates to the field of precision instrument hardware control technology, and in particular to a precision instrument vacuum measurement and control system and method based on an FPGA reconfigurable parallel architecture. Background Technology

[0002] Precision instruments such as scanning electron microscopes, transmission electron microscopes, vacuum probe stages, and vacuum coating equipment have stringent requirements for cavity vacuum levels, gas isolation protection, and high-voltage interlocking protection. Existing vacuum controllers suffer from several inherent technical defects that are difficult to overcome simultaneously: First, the gas path topology is fixed and lacks dual-topology compatibility. Existing vacuum controllers have fixed factory-installed control logic, only compatible with a single cavity structure. When a pre-evacuation chamber needs to be added, the PCB circuit board must be redesigned and the entire hardware acquisition and drive circuitry replaced, resulting in high hardware modification costs. Furthermore, the pre-evacuation chamber, main chamber, and electron gun cavity share the same vacuum judgment logic, lacking a graded interlocking mechanism, making it extremely easy for low-vacuum gas in the pre-evacuation chamber to backflow into the 10... -10 The ultra-high vacuum chamber of the Torr electron gun caused permanent cathode burnout, resulting in irreversible damage to the equipment.

[0003] Second, the time-division multiplexing of analog signals results in timing discrepancies in the acquired data. Traditional PLCs and low-end MCU controllers employ a cyclic time-division sampling mechanism, leading to inconsistent acquisition times for parameters such as the pre-evacuation chamber, main chamber, electron gun vacuum, gas source pressure, and pump electrical parameters. This inconsistency in threshold determination criteria causes frequent false triggering of valve actions and high-pressure interlocks. Furthermore, the lack of a standardized and unified voltage divider conditioning circuit makes the vacuum gauge output signal prone to overvoltage damage that could break down the acquisition chip.

[0004] Third, the existing solution only implements on / off control of the vacuum pump and lacks quantitative monitoring of the pump's operating status. The existing solution only outputs start / stop switch signals to the vacuum pump and cannot collect pump voltage and current signals for real-time load calculation; vacuum pump no-load, stall, and pumping speed decay faults cannot be predicted in advance, and long-term operation can easily lead to vacuum process failure and unexpected shutdown of the entire machine.

[0005] Fourth, the interlocking logic is executed serially, resulting in a delay of tens of milliseconds in protective actions. Vacuum and gas source data rely on serial cyclic calculations by software. When a vacuum drop fault occurs, the isolation valve shut-off and high-pressure cut-off actions are delayed, posing a significant safety hazard of discharge damage to the electron gun.

[0006] Fifth, the safety judgment logic is incomplete, and the gas source interlock condition is not introduced. The existing technology relies solely on vacuum values ​​to complete the high-pressure interlock judgment, ignoring that insufficient nitrogen and total gas source pressure can also lead to cavity contamination and process failure, indicating a significant loophole in the safety judgment condition.

[0007] Sixth, the hardware and software are deeply integrated, and the functions of the I / O ports are fixed at the factory. The signal acquisition, driving I / O ports and control logic hardware are strongly bound together. Modifying the pneumatic circuit structure and adapting to new equipment models requires modifying the PCB hardware. The control logic cannot be reconstructed by firmware alone, resulting in poor hardware reusability of the equipment.

[0008] In summary, there is currently no integrated parallel measurement and control solution that can achieve single-hardware compatibility with dual topologies (with and without pre-evacuation chambers), synchronous acquisition of multiple vacuum and gas sources, inter-sectional nonlinear vacuum calculation, online monitoring of multi-channel pump power, hardware interlocking of dual isolation valves, instantaneous high-pressure interlocking of vacuum and gas sources in two dimensions, and firmware without hardware reconfiguration. Therefore, developing an improved, general-purpose intelligent vacuum measurement and control solution for precision instruments has become an urgent technical problem to be solved in this field. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing vacuum controllers, such as fixed topology, asynchronous data acquisition, lack of pump power quantification monitoring, interlocking serial lag, lack of gas source safety judgment, and deep binding and solidification of software and hardware. It provides a precision instrument vacuum measurement and control system and method based on an FPGA-based reconfigurable parallel architecture. Through the FPGA hardware parallel computing architecture, it achieves synchronous acquisition of multiple vacuum and gas source channels. Relying on the underlying dual isolation valve hardware lock and high-pressure interlocking of the vacuum and gas source, it supports firmware-free switching of dual gas path topology, online pump power monitoring, and microsecond-level safety protection. This significantly improves the operational safety of vacuum equipment, ensures process reliability, reduces hardware iteration and modification costs, and enhances hardware reuse and adaptability.

[0010] To achieve the above objectives, the present invention provides the following solution: A precision instrument vacuum measurement and control system based on an FPGA-reconfigurable parallel architecture is adapted to two types of scanning electron microscope vacuum topologies: one without a pre-evacuation chamber and the other with an independent pre-evacuation chamber. The upper and lower electron gun chambers are physically isolated and each is equipped with an ion pump. The lower electron gun chamber is connected to the main sample chamber via a main chamber isolation valve. The pre-evacuation chamber is connected to the main sample chamber via a pre-evacuation connection valve. The measurement and control system includes: Parallel main control module: It is an FPGA main control chip, which integrates a multi-channel vacuum parallel fitting unit, a molecular pump real-time power calculation unit, a dual hardware lock unit for the pre-evacuation connecting valve and the main cavity isolation valve, a vacuum air source multi-dimensional high-pressure instantaneous interlock unit, and a firmware dynamic reconstruction logic unit. The parallel main control module is used to perform vacuum acquisition control, vacuum value calculation, pump power calculation, valve hardware lock management, high-pressure interlock determination, and firmware reconstruction control in parallel. Multi-channel voltage divider analog conditioning circuit: used to uniformly divide and condition multiple vacuum gauge signals, gas source pressure signals and molecular pump analog signals, and output analog signals that meet the input range of the multi-channel synchronous analog-to-digital acquisition module; Multi-channel synchronous analog-to-digital acquisition module: used to perform synchronous analog-to-digital conversion on all input analog signals at the same time, and transmit the conversion results to the parallel main control module via SPI bus; Multi-channel voltage divider DI protection circuit: used to perform unified voltage divider protection on all valve limit signals and pump limit signals, and input the voltage-divided digital signals into the parallel main control module; Pump and valve isolation relay drive array: connected to the output of the parallel main control module, receiving control signals from the parallel main control module, and driving the opening and closing actions of vacuum pumps and various vacuum valves; the parallel main control module also independently outputs high-voltage interlock level signals; Ethernet module: Connected to the parallel main control module, used to enable bidirectional data interaction between the parallel main control module and the host computer; Host computer: Used to send vacuuming commands, voltage stabilization commands, or pressure relief commands to the parallel main control module, and to display real-time data on the full operating status of the vacuum system; General-purpose IO expansion module: This module provides an expansion interface for connecting to the acquisition and drive channels of newly added cavities or valves. New hardware can be adapted by updating the firmware.

[0011] Furthermore, both the multi-channel voltage divider analog conditioning circuit and the multi-channel voltage divider DI protection circuit adopt a 1:8 resistor voltage divider protection circuit to suppress input surges and prevent overvoltage from damaging the acquisition chip and the FPGA main control IO port.

[0012] Furthermore, the multi-channel synchronous analog-to-digital acquisition module adopts the AD7606 synchronous ADC chip to realize synchronous analog-to-digital conversion of multiple analog signals at the same time, eliminating timing deviations in multi-channel acquisition.

[0013] Furthermore, the pump valve isolation relay drive array adopts G5Q-1A4-EU-DC12V isolation relays. The control level output by the parallel main control module drives the relay coil after photoelectric isolation. The relay contacts drive the mechanical pump, molecular pump, ion pump, pre-pumping connecting valve, main cavity isolation valve, and various process valves.

[0014] Furthermore, the Ethernet module adopts the W5500 hardware Ethernet chip, which has a built-in TCP / IP protocol stack. Ethernet data transmission and reception operate independently and do not occupy the computing resources of the parallel main control module. The FPGA main control chip is the XC7S50-2FTGB196C chip.

[0015] Furthermore, the analog signals synchronously acquired by the multi-channel synchronous analog-to-digital acquisition module include the pre-evacuation chamber vacuum gauge signal, the main chamber vacuum gauge signal, the electron gun upper chamber ion pump vacuum value signal, the electron gun lower chamber ion pump vacuum value signal, the nitrogen pressure signal, the total gas source pressure signal, and the molecular pump analog signal. The digital signals acquired by the multi-channel voltage divider DI protection circuit include the pre-extraction connecting valve limit signal, the V5 main cavity isolation valve limit signal, the limit signals of each process valve, the molecular pump operating status signal, the molecular pump speed status signal, and the ion pump operating status signal.

[0016] This invention also provides a precision instrument vacuum measurement and control method based on an FPGA reconfigurable parallel architecture, applied to the aforementioned precision instrument vacuum measurement and control system based on an FPGA reconfigurable parallel architecture, comprising the following steps: S1. After the system is powered on, the parallel main control module performs hardware self-tests on the acquisition channel, drive channel, and limit channel, loads vacuum threshold, gas source pressure safety lower limit, pump rated power, and isolation valve lock-up judgment parameters, and establishes bidirectional communication with the host computer via Ethernet; the firmware selects to enable or disable the pre-evacuation chamber control branch according to the configuration. S2. The host computer issues vacuuming, pressure stabilization, and pressure relief process commands. The FPGA main control chip identifies the current gas path topology in parallel and automatically matches the corresponding multi-stage vacuuming and pressure relief timing sequence. S3. After performing voltage division protection on multiple vacuum signals, gas source pressure signals, and pump analog electrical parameters, synchronous analog-to-digital conversion is implemented and the data is sent to the parallel main control module; parallel acquisition of digital signals such as valve limit and pump group working status is also performed. S4. Perform nonlinear fitting conversion on different cavity vacuum ranges, calculate the real-time pump power based on the collected electrical parameters and identify abnormal load conditions. S5. Parallel acquisition of the limit status of the pre-extraction connecting valve, main cavity isolation valve, process valve and pump group feedback switch, as the input basis for hardware lock logic and interlock determination; S6. When the vacuum of the corresponding cavity is not up to standard, the hardware will block the corresponding isolation valve drive; when the cavity vacuum drops, the corresponding isolation valve will be shut off, and the host computer command cannot force the isolation valve with substandard vacuum to open. S7. When the pre-extraction chamber control branch is activated, the complete process flow including pre-extraction, valve unlocking, air extraction, pressure stabilization and pressure relief is executed. Before pressure relief, the two isolation valves are locked first. When the pre-extraction chamber control branch is closed, the pre-extraction sequence is skipped. The pump group status and load are monitored throughout the process. If the load is abnormal, the process is suspended and the fault is reported. S8: Parallel acquisition and summarization of various operating parameters such as cavity vacuum, gas source pressure, pump power, and valve limit; high-pressure unlocking is only output when all parameters meet safety conditions; if any parameter does not meet safety conditions, the high-pressure interlock output is cut off.

[0017] Furthermore, it also includes: S9. Store the vacuum threshold, gas source lower limit, pump power judgment range, and pre-evacuation timing in the firmware; update the firmware to switch topologies to adapt to different precision instruments.

[0018] Furthermore, in steps S3-S8, vacuum acquisition, vacuum calculation, pump power calculation, valve hardware lock logic, and high-pressure interlock determination are all executed in parallel by the FPGA main control chip, without relying on the software serial scanning cycle, and the valve control action and high-pressure interlock cutoff achieve microsecond-level response.

[0019] Furthermore, the high-pressure interlock determination synchronously incorporates nitrogen pressure and total gas source pressure as determination conditions; abnormal gas source pressure directly triggers the high-pressure cutoff interlock.

[0020] According to specific embodiments provided by the present invention, the precision instrument vacuum measurement and control system and method based on FPGA reconfigurable parallel architecture disclosed in the present invention specifically discloses the following technical effects: First, the hardware is highly universal, reducing the cost of hardware iteration and modification. The acquisition and driving I / O ports of this invention are standardized and universal. The same set of hardware circuits does not require PCB modification. The pre-evacuation chamber staged evacuation and depressurization process can be enabled or disabled simply by updating the firmware. It is compatible with both vacuum topologies with and without pre-evacuation chambers and can be used with various precision vacuum equipment such as scanning electron microscopes, transmission electron microscopes, vacuum probe stations, and vacuum coating equipment. This avoids redesigning hardware due to differences in equipment gas paths, significantly reducing material, assembly, and hardware iteration and modification costs. At the same time, the overall size of the machine is significantly smaller than that of traditional PLC solutions.

[0021] Second, the system enables synchronous acquisition of multi-source signals, ensuring consistency in measurement and control judgment benchmarks. It synchronously acquires analog and digital signals from multiple vacuum signals, nitrogen / total gas source pressure, and pump analog electrical parameters. All analog signal sampling is free of timing deviations. Combined with parallel reading of valve and pump limit status digital signals, this eliminates data timing differences caused by traditional time-division sampling, preventing false triggering of valve control and high-pressure interlocks due to asynchronous acquisition, and improving the accuracy of vacuum process control.

[0022] Third, hardware parallelization enables pump unit condition monitoring and early fault prediction. Through FPGA hardware parallel logic, the pump speed, operating status of the molecular pump, the operating status of the ion pump, and the real-time load power of the pump are monitored and calculated online. This allows for the identification of abnormal operating conditions such as pump idling and overload, and faults can be reported in the early stages of pump stall or pumping speed decline, thus avoiding the risks of vacuum process failure and unexpected equipment downtime.

[0023] Fourth, the underlying hardware lock provides protection against gas backflow safety accidents at the hardware level. An underlying hardware lock mechanism is implemented for the V5 main chamber isolation valve and pre-evacuation connecting valve, preventing the host computer software from unauthorizedly opening isolation valves with substandard vacuum. When the chamber vacuum drops, the isolation valve can be quickly shut off, effectively preventing low-vacuum gas from backflowing into the electron gun's ultra-high vacuum chamber, avoiding irreversible equipment damage such as electron gun cathode burnout, and strengthening the protection capabilities of core components of precision instruments.

[0024] Fifth, multi-dimensional parallel high-pressure interlocking addresses safety loopholes in gas source operation. The high-pressure interlocking judgment integrates multiple operating parameters, including chamber vacuum, nitrogen / total gas source pressure, pump load, and valve limits, rather than relying solely on a single vacuum value for interlocking judgment. When any of the vacuum, gas source pressure, or pump load conditions are abnormal, high-pressure cutoff is triggered, filling the safety logic loophole in existing technologies that lack interlocking protection for gas source failures and improving the overall operational safety of the equipment.

[0025] Sixth, the entire chain of hardware parallel computing ensures fast protection response speed. Vacuum acquisition, vacuum nonlinear calculation, pump power calculation, valve interlocking logic, and high-pressure interlocking determination are all executed in parallel by FPGA hardware, eliminating the millisecond-level delay caused by the serial scanning cycle of traditional PLC and MCU software, achieving microsecond-level response for valve control and high-pressure interlocking, and providing instantaneous safety protection in emergency fault scenarios such as vacuum drop.

[0026] Seventh, the firmware is flexible and reduces later maintenance costs. All vacuum thresholds, gas source safety parameters, pump judgment conditions, and pumping / releasing pressure sequences are configured within the firmware. Modifying process logic and adapting to new equipment only requires updating the firmware, without modifying the hardware circuitry. This facilitates later function iterations, on-site maintenance and upgrades, and improves equipment reusability.

[0027] In summary, compared with traditional PLC-based vacuum control solutions, this invention has a smaller overall size and lower material and maintenance costs. At the same time, it achieves dual-topology compatibility, synchronous data acquisition, pump fault prediction, hardware-level backflow prevention, multi-dimensional high-pressure interlocking, and microsecond-level hardware response capabilities. The reliability of multi-level vacuum processes and the safety of core components such as electron guns are greatly improved. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of a precision instrument vacuum measurement and control system based on an FPGA reconfigurable parallel architecture according to an embodiment of the present invention; Figure 2 This is a structural diagram of a multi-stage differential vacuum circuit of a scanning electron microscope with an independent pre-evacuation chamber, according to an embodiment of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention relates to the technical fields of multi-level differential vacuum measurement and control for scanning electron microscopes, hardware parallel programmable control, multi-channel synchronous analog-to-digital acquisition, online monitoring of vacuum pump power, dual-topology adaptive control of the pre-evacuation chamber, high-voltage interlocking of vacuum-gas source linkage hardware, isolation relay drive, and independent hardware Ethernet communication.

[0032] The purpose of this invention is to provide a precision instrument vacuum measurement and control system and method based on a FPGA-based reconfigurable parallel architecture. Employing an FPGA hardware parallel architecture, the same hardware requires no modification; only firmware updates are needed to switch between two stages of evacuation and depressurization processes with and without a pre-evacuation chamber. It achieves simultaneous acquisition of multiple vacuum and gas source pressures, with all analog signals sampled synchronously without timing deviations. Hardware parallel monitoring of molecular pump speed, molecular pump operating status, and ion pump operating status allows for early prediction of pump failures. A hardware lock is implemented at the bottom layer for the main chamber isolation valve and the pre-evacuation connecting valve, preventing software from opening valves without authorization and preventing gas backflow. High-pressure interlocking is synchronously incorporated into multi-dimensional judgments of vacuum, nitrogen, total gas source, and pump load, addressing gas source interlocking vulnerabilities. Vacuum acquisition, valve control, high-pressure, and pump calculations are all performed in hardware parallelism with microsecond-level response, eliminating software scanning delays. All acquisition and driver I / O are standardized and universal; process modifications only require firmware updates, without hardware modifications. The solution described in this invention is compatible with various precision vacuum equipment such as scanning electron microscopes, transmission electron microscopes, vacuum probe stations, and vacuum coating equipment, improving equipment safety and reducing hardware iteration and maintenance costs.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1 The object of embodiment 1 of this invention is a multi-stage differential vacuum circuit structure for a scanning electron microscope with an independent pre-evacuation chamber, such as... Figure 2As shown, the vacuum circuit structure mainly includes four chambers: the upper electron gun chamber, the lower electron gun chamber, the main chamber, and the pre-evacuation chamber; four sets of vacuum acquisition devices: a mechanical pump, a molecular pump, ion pump 1, and ion pump 2; six vacuum valves (V1 to V6); and a vacuum gauge G1 for the main chamber and a vacuum gauge G2 for the pre-evacuation chamber. V1, V3, V4, and V5 are controlled valves equipped with limit switches, while V2 and V6 are venting valves. Ion pump 1 is connected externally to the upper electron gun chamber, and ion pump 2 is connected externally to the lower electron gun chamber. The lower electron gun chamber is connected to the main chamber via the V5 main chamber isolation valve with a limit switch. The V5 main chamber isolation valve is used to cut off or connect the electron gun and the main chamber. The gas path between the main chamber and the pre-evacuation chamber is designed to prevent low-vacuum gas backflow from damaging the electron gun components. Limit switches provide feedback on the actual opening and closing status of the valves. The main chamber is equipped with a main chamber vacuum gauge G1 and a main chamber vent valve V2. The main chamber is connected to the pre-evacuation chamber via a V4 pre-evacuation connecting valve with a limit switch, and is also directly connected to the molecular pump. The molecular pump pre-stage is connected to the mechanical pump via a V1 molecular pump-mechanical pump connecting valve with a limit switch. G1 is used to detect the vacuum level of the main chamber, the V2 main chamber vent valve is used to depressurize the main chamber, the V4 pre-evacuation connecting valve controls the gas path between the main chamber and the pre-evacuation chamber, and V1 is used to enable the mechanical pump to evacuate the pre-stage gas of the molecular pump. The pre-evacuation chamber is equipped with a pre-evacuation valve. The vacuum gauge G2 and the V6 pre-evacuation chamber vent valve are connected to the mechanical pump via the V3 mechanical pump pre-evacuation valve with a limit switch. The pre-evacuation chamber serves as a sample exchange transition chamber. G2 is used to detect the vacuum level of the pre-evacuation chamber. The V6 pre-evacuation chamber vent valve enables independent pressure relief of the pre-evacuation chamber. V3 controls the mechanical pump to evacuate the pre-evacuation chamber independently. The mechanical pump, as the primary low-vacuum pump, provides pre-evacuation power to the pre-evacuation chamber and provides a forestage vacuum to the molecular pump. The molecular pump provides high-vacuum evacuation capability to the main chamber. Ion pumps 1 and 2 maintain the ultra-high vacuum in the upper and lower chambers of the electron gun, respectively. G1 and G2 output the collected chamber vacuum values. In the measurement and control system described in this invention, the limit switches of V1, V3, V4, and V5 serve as the basis for determining the unlocking and interlocking protection of the isolation valve. They provide feedback on the actual valve position status to the measurement and control system for hardware lock logic and high-pressure interlocking determination. During operation, the mechanical pump first independently pre-pumps the pre-pumping chamber. V4 can only be opened after the vacuum in the pre-pumping chamber reaches the standard. After the mechanical pump completes the pre-pumping of the molecular pump, it starts the molecular pump to pump gas into the main chamber. V5 is opened after the vacuum in the main chamber reaches the standard. Then, the ion pump maintains the ultra-high vacuum of the electron gun. When depressurizing, V4 and V5 are closed first to isolate each chamber. Then, the main chamber and the pre-pumping chamber are independently vented through V2 and V6 respectively.

[0035] This embodiment 1 uses Figure 2 The multi-stage differential vacuum circuit structure of the scanning electron microscope with an independent pre-evacuation chamber shown is used as the controlled object. The precision instrument vacuum measurement and control system based on a FPGA reconfigurable parallel architecture, provided by this invention, is used to achieve overall vacuum process control and safety protection. For example... Figure 1As shown, the system hardware mainly includes: a parallel main control module, a multi-channel synchronous analog-to-digital acquisition module, a multi-channel voltage divider analog conditioning circuit, a multi-channel voltage divider DI protection circuit, a pump and valve isolation relay drive array, an Ethernet module, a host computer, and a general-purpose IO expansion module.

[0036] The parallel main control module uses an XC7S50-2FTGB196C FPGA main control chip, which integrates a multi-channel vacuum parallel fitting unit, a molecular pump real-time power calculation unit, a dual hardware lock unit for the pre-evacuation connecting valve and the V5 main cavity isolation valve, a vacuum air source multi-dimensional high-pressure instantaneous interlock unit, and a firmware dynamic reconstruction logic unit. The parallel main control module is used to perform vacuum acquisition control, vacuum value calculation, pump power calculation, valve hardware lock management, high-pressure interlock determination, and firmware reconstruction control in parallel.

[0037] The multi-channel voltage divider analog conditioning circuit is used to uniformly divide and condition multiple vacuum gauge signals, gas source pressure signals, and molecular pump analog signals, outputting analog signals that meet the input range of the multi-channel synchronous analog-to-digital acquisition module. The multi-channel synchronous analog-to-digital acquisition module performs synchronous analog-to-digital conversion on all input analog signals simultaneously and transmits the conversion results to the parallel main control module via the SPI bus. The multi-channel synchronous analog-to-digital acquisition module uses an AD7606 synchronous ADC chip to achieve synchronous analog-to-digital conversion of multiple analog signals at the same time, eliminating timing deviations in multi-channel acquisition. The analog signals synchronously acquired by the multi-channel synchronous analog-to-digital acquisition module include the pre-evacuation chamber vacuum gauge signal, the main chamber vacuum gauge signal, the vacuum value signal of the electron gun upper chamber ion pump, the vacuum value signal of the electron gun lower chamber ion pump, the nitrogen pressure signal, the total gas source pressure signal, and the molecular pump analog signal, etc.

[0038] The multi-channel voltage divider DI protection circuit is used to uniformly divide and protect all valve limit signals and pump limit signals, and inputs the divided digital signals into the parallel main control module. The digital signals collected by the multi-channel voltage divider DI protection circuit include the pre-extraction connecting valve limit signal, the V5 main chamber isolation valve limit signal, the limit signals of each process valve, the molecular pump operating status signal, the molecular pump speed status signal, and the ion pump operating status signal, etc.

[0039] The multi-channel voltage divider analog conditioning circuit and the multi-channel voltage divider DI protection circuit both adopt a 1:8 resistor voltage divider protection circuit to suppress input surges and prevent overvoltage from damaging the acquisition chip and the FPGA main control IO port.

[0040] The pump and valve isolation relay drive array is connected to the output of the parallel main control module, receives the control signal from the parallel main control module, and drives the opening and closing of the vacuum pump and various vacuum valves. The parallel main control module also independently outputs a high-voltage interlock level signal. The pump and valve isolation relay drive array uses G5Q-1A4-EU-DC12V isolation relays. The control level output by the parallel main control module drives the relay coil after photoelectric isolation. The relay contacts drive the mechanical pump, molecular pump, ion pump, pre-evacuation connecting valve, V5 main cavity isolation valve, and various process valves.

[0041] The Ethernet module is connected to the parallel main control module to enable bidirectional data interaction between the parallel main control module and the host computer. The Ethernet module uses a W5500 hardware Ethernet chip with a built-in TCP / IP protocol stack. Ethernet data transmission and reception operate independently and do not occupy the computing resources of the parallel main control module.

[0042] The host computer is used to send vacuuming commands, voltage stabilization commands, or pressure relief commands to the parallel main control module, and to display the full operating data of the vacuum system in real time. The general-purpose IO expansion module is a reserved expansion interface for connecting to the acquisition and drive channels of newly added cavities or valves. It can be adapted to the new hardware by updating the firmware.

[0043] The hardware signal wiring relationships are as follows: For vacuum detection signals, the vacuum simulation signals from the main cavity vacuum gauge G1, the pre-evacuation chamber vacuum gauge G2, the electron gun upper chamber ion pump 1, and the electron gun lower chamber ion pump 2, as well as the molecular pump simulation electrical parameter signals, are connected to a multi-channel unified voltage divider AI conditioning circuit for surge protection before being sent to the AD7606 synchronous analog-to-digital acquisition module. For valve and pump group status digital signals, the valve limit switch signals of V1, V3, V4, and V5, the nitrogen pressure switch, the main gas source pressure switch, the molecular pump operating status, the molecular pump speed status, and the operating status signals of ion pump 1 and ion pump 2 are input to the FPGA after voltage division by a multi-channel unified voltage divider DI protection circuit. Digital I / O ports; in terms of drive output, the FPGA outputs control signals via a pump and valve isolation relay drive array to drive the mechanical pump, molecular pump, ion pump 1, ion pump 2, and all valves V1 to V6 respectively. At the same time, the FPGA independently outputs 6 high-voltage interlock level signals, corresponding to the electron gun high voltage, 3 detector high voltages, acceleration high voltage, and bias high voltage respectively. The 6 high voltages share the same set of interlock trigger judgment conditions. When a vacuum abnormality or equipment operating state abnormality occurs, the 6 high voltages will synchronously execute interlock cut-off protection. Each interlock level signal is connected to the corresponding high-voltage power supply circuit of the scanning electron microscope to realize hardware cut-off protection of multiple high voltages.

[0044] Example 2 The hardware platform of the precision instrument vacuum measurement and control system based on FPGA reconfigurable parallel architecture provided by this invention requires no modification to any hardware components. It can be adapted to multi-stage differential vacuum chamber topologies without independent pre-evacuation chambers simply by updating the FPGA firmware to close the pre-evacuation chamber control branch. Unlike Embodiment 1, in this working mode, the V3 mechanical pump pre-evacuation valve and the V4 pre-evacuation connecting valve remain permanently closed at the hardware level. The control logic corresponding to the pre-evacuation chamber vacuum gauge G2 and the pre-evacuation chamber venting valve V6 is disabled and no longer participates in the system process timing and interlocking determination, thereby realizing the control of the vacuum circuit topology of the scanning electron microscope without a pre-evacuation chamber.

[0045] The vacuum control process is as follows: the system starts the vacuum process, controls the mechanical pump and the V1 molecular pump-mechanical pump connecting valve to start; the mechanical pump establishes the pre-stage vacuum conditions for the molecular pump, and after the pre-stage meets the requirements, the molecular pump starts to evacuate the main chamber; when the vacuum degree of the main chamber reaches the set threshold, the hardware lock of the V5 main chamber isolation valve is released, allowing the V5 main chamber isolation valve to open, connecting the lower chamber of the electron gun to the main chamber; at this time, the scanning electron microscope meets the conditions for the electron gun to start working.

[0046] The corresponding vacuum breaking procedure is as follows: When performing pressure relief, the V5 main chamber isolation valve is first forcibly closed by hardware to isolate the electron gun ultra-high vacuum chamber from the main chamber; the mechanical pump, the V1 molecular pump-mechanical pump connecting valve, and the molecular pump are closed in sequence; then the V2 main chamber venting valve is opened to vent the main chamber until the vacuum in the main chamber reaches atmospheric pressure, thus completing the vacuum breaking operation.

[0047] Under this operating condition, the system still retains all safety measurement and control functions, such as multi-channel signal synchronous acquisition, parallel monitoring of pump power, underlying hardware lock of V5 main chamber isolation valve, and multi-dimensional high-pressure interlock between vacuum and gas source. Only the process branches related to the pre-evacuation chamber are removed, while the rest of the hardware parallel operation and microsecond-level fault protection mechanism remain unchanged.

[0048] The hardware platform of the measurement and control system described in this invention is uniformly compatible with both scanning electron microscope vacuum circuit topologies with and without a pre-evacuation chamber; the upper and lower electron gun chambers are physically completely isolated and each is equipped with an independent ion pump. The lower electron gun chamber is connected to the main chamber via a V5 isolation valve. -8The main sample chamber is Torr; the pre-evacuation chamber is an independent low-vacuum chamber, isolated from the main chamber by a pre-evacuation connecting valve; the system synchronously acquires two vacuum gauges, two ion pump vacuum values, nitrogen / total gas source pressure, molecular pump speed, molecular pump operating status, ion pump operating status, and all valve limit signals; it reads the vacuum values ​​of each chamber in real time, and the hardware determines the opening and closing permissions of the V5 main chamber isolation valve, pre-evacuation connecting valve, and each process valve in parallel; it uses the pre-evacuation chamber, main chamber, electron gun vacuum, gas source pressure, pump operating power, and valve limits as the comprehensive judgment basis for high-pressure interlocking, and instantly cuts off the high pressure if any parameter is abnormal; the hardware ports are standardized and universal, requiring no hardware modification, and only an update to the FPGA firmware is needed to switch between two complete staged evacuation and depressurization processes, adapting to various precision vacuum equipment such as scanning electron microscopes, transmission electron microscopes, vacuum probe stations, and vacuum coating.

[0049] Example 3 This embodiment provides a precision instrument vacuum measurement and control method based on an FPGA reconfigurable parallel architecture, applied to the aforementioned precision instrument vacuum measurement and control system based on an FPGA reconfigurable parallel architecture, and includes the following steps: S1. System Power-On Parallel Initialization: Upon system power-on initialization, the parallel main control module performs hardware self-tests of the acquisition channel, drive channel, and limit channel in parallel; loads the chamber vacuum threshold, gas source pressure safety lower limit, molecular pump rated power, and lockout judgment parameters of the main chamber isolation valve and pre-evacuation connecting valve; and establishes a two-way communication link with the host computer through the Ethernet module; the firmware automatically enables or disables the pre-evacuation chamber control branch according to the configuration. S2. Parallel parsing of host computer process instructions: The host computer issues vacuuming, pressure stabilization and pressure relief process instructions, and the FPGA main control chip identifies the current gas path topology in parallel and automatically matches the corresponding multi-stage vacuuming and pressure relief timing sequence. S3. Synchronous acquisition of multiple vacuum-gas-pump electrical parameters: After unified voltage division protection of the pre-evacuation chamber vacuum signal, main chamber vacuum signal, electron gun upper and lower chamber vacuum signals, nitrogen pressure signal, total gas source pressure signal, and molecular pump analog electrical parameter signal, the synchronous analog-to-digital acquisition module completes the ADC conversion at the same time and inputs it to the main control module; at the same time, the valve limit, molecular pump working status, molecular pump speed status, and the working status digital signals of the two ion pumps are acquired in parallel. S4. Parallel nonlinear solution of vacuum intervals and parallel calculation of pump power: Perform corresponding nonlinear fitting and conversion for different vacuum intervals of electron gun, main sample chamber and pre-evacuation chamber; calculate the real-time power of molecular pump based on the collected electrical parameters, and identify no-load and overload faults. S5 and DI limit signal parallel recognition: Parallel reading of the limit status of the pre-extraction connecting valve, main cavity isolation valve, all process valves, and pump group feedback switch, as the input basis for hardware lock logic and interlock judgment; S6. Hardware-based hierarchical locking control of dual isolation valves: When the vacuum in the pre-evacuation chamber does not meet the standard, the hardware blocks the drive signal of the pre-evacuation connecting valve. When the vacuum in the main chamber does not meet the standard, the hardware blocks the drive signal of the main chamber isolation valve. When the vacuum in the corresponding chamber of any isolation valve drops, the drive of that isolation valve is shut off in microseconds. The host computer cannot force the opening of the non-compliant isolation valve by command. S7. Dual-topology fully automatic graded closed-loop vacuum process: When the firmware enables the pre-evacuation chamber control branch, it sequentially executes the pre-evacuation chamber pre-evacuation, unlocking the pre-evacuation connecting valve, main chamber evacuation, unlocking the main chamber isolation valve, and ion pump pressure stabilization process; for pressure relief, it prioritizes locking the two isolation valves before performing nitrogen pressure relief; when the firmware closes the pre-evacuation chamber control branch, it directly skips the pre-evacuation sequence; the pump group status and load are monitored throughout the process, and the process is suspended and the fault is reported if the load is abnormal. S8, Vacuum-Gas Source Multi-Dimensional Parallel Instantaneous High-Pressure Interlock: Parallel summarization of cavity vacuum, gas source pressure, molecular pump power, and valve limit parameters; output high-pressure unlock when all parameters meet safety conditions; cut off high-pressure interlock output when any parameter is below the safety threshold; S9, firmware without hardware reconstruction adaptation: vacuum, gas source, pump judgment parameters, and pre-evacuation timing are all stored in the firmware; the acquisition and driver IO are universal, no hardware modification is required, only firmware updates are needed to switch topologies and adapt to various vacuum devices. The measurement and control method is applied to the multi-stage differential vacuum circuit structure of the scanning electron microscope with an independent pre-evacuation chamber described in Example 1, specifically including: After the system is powered on, step S1 of the measurement and control method of this invention is executed. The parallel main control module FPGA automatically completes the full-domain parallel hardware self-test of AD7606, voltage divider conditioning circuit, relay drive array, and W5500 Ethernet module; loads the pre-configured vacuum threshold of each cavity, the safety lower limit of nitrogen and total gas source pressure, the rated power parameters of molecular pump, the locking judgment parameters of V5 main cavity isolation valve and V4 pre-evacuation connecting valve; establishes a bidirectional communication link with the host computer through an independent hardware Ethernet module; and configures the firmware to enable the pre-evacuation chamber control branch to adapt to the gas path topology of the scanning electron microscope with pre-evacuation chamber in this embodiment.

[0050] When executing step S2, the operator issues a vacuuming process command through the host computer. The FPGA hardware parallel link directly identifies the gas path topology with the pre-evacuation chamber in use and automatically calls the multi-stage evacuation and depressurization sequence corresponding to the pre-evacuation chamber, eliminating software queuing delays.

[0051] In step S3, the multi-channel analog and digital signal synchronous acquisition stage, the vacuum analog quantity, nitrogen pressure, total gas source pressure, and molecular pump electrical parameters output by the main cavity vacuum gauge G1, the pre-evacuation chamber vacuum gauge G2, and the upper and lower chamber ion pumps of the electron gun are converted by the AD7606 at the same time after 1:8 voltage division protection. The acquired data is then sent to the FPGA. At the same time, the FPGA acquires the digital signals of the valve limit switch status of V1, V3, V4, and V5, the working and speed status of the molecular pump, and the working status of the two ion pumps in parallel. All signals are acquired synchronously to eliminate the timing deviation caused by time-division sampling and avoid interlocking false triggering.

[0052] Step S4 involves performing interval-based vacuum nonlinear parallel calculations and pump power parallel computations: The FPGA's internal multi-channel vacuum parallel fitting unit calls the corresponding conversion formula based on the selected vacuum detection device model to complete the vacuum degree calculation. For example, the ion pump vacuum value uses the conversion formula P=10. 1.2U-11 The vacuum gauge uses the conversion formula P=10. (u-6.304) / 1.286 In the formula, P is the calculated vacuum value output, and U and u are the sampled values ​​of the acquired analog signals; the multi-channel parallel vacuum fitting unit inside the FPGA is respectively designed for the upper cavity of the electron gun 10 -10 Torr ultra-high vacuum zone, electron gun lower chamber, main chamber 10 -8 The high vacuum zone of the Torr chamber and the low vacuum zone of the pre-evacuation chamber perform their own exclusive nonlinear fitting conversion to obtain the true vacuum degree of each chamber; the real-time power calculation unit of the molecular pump calculates the output power of the molecular pump in real time based on the collected electrical parameters of the molecular pump voltage and current, and identifies abnormal load conditions such as no-load and overload of the molecular pump.

[0053] In step S5, for parallel identification of DI limit signals, the FPGA reads the limit status of V4 pre-extraction connecting valve, V5 main cavity isolation valve, V1 / V3 process valve, and pump group feedback switch in parallel. The actual valve position information is directly used as the hardware input basis for subsequent dual isolation valve hardware lock logic and high-pressure interlock determination, without relying on software status registers, to prevent safety risks caused by inconsistency between instructions and actual valve positions.

[0054] Proceed to step S6, executing the hardware-level locking control of the dual isolation valves: the FPGA hardware layer implements the hardware locking logic for the V4 pre-evacuation connecting valve and the V5 main chamber isolation valve, and software commands have no right to override this control. The measurement and control system reads the measured vacuum of the pre-evacuation chamber vacuum gauge G2. If the pre-evacuation chamber vacuum does not reach the unlocking threshold, the hardware directly blocks the drive signal of the V4 pre-evacuation connecting valve, and V4 cannot be opened regardless of any opening command issued by the host computer. If the pre-evacuation chamber vacuum drops during operation, the V4 drive is directly cut off within microseconds. Only when G2 detects that the pre-evacuation chamber vacuum meets the standard can the hardware lock of V4 be released; similarly, the main chamber vacuum is monitored by G1, and if the main chamber vacuum does not reach 10... -8During Torr, the hardware blocks the drive signal of the V5 main cavity isolation valve, and the host computer cannot start V5. Once the vacuum in the main cavity drops during operation, the hardware shuts off V5 in microseconds, preventing the backflow of low vacuum gas from the pre-evacuation chamber and main cavity into the electron gun cavity from the hardware level, thus avoiding the electron gun cathode being burned out.

[0055] In step S7, the dual-topology fully automatic staged closed-loop vacuum process is executed. In this embodiment, the firmware enables the pre-evacuation chamber branch, and the system control relay array opens the V3 mechanical pump pre-evacuation valve, starting the mechanical pump to independently pre-evacuate the pre-evacuation chamber 4. After G2 feedback indicates that the pre-evacuation chamber vacuum has reached the standard, the hardware releases the V4 pre-evacuation connecting valve lock, and the system starts V4. Subsequently, the V1 molecular pump-mechanical pump connecting valve is opened, and the mechanical pump provides the forestage vacuum to the molecular pump. After the forestage conditions are met, the molecular pump starts to evacuate the main chamber 3. When G1 detects that the main chamber vacuum reaches 10... -8 Torr, the hardware unlocks the V5 main chamber isolation valve, opens V5, connects the main chamber to the lower chamber of the electron gun, and starts ion pump 1 and ion pump 2 to maintain the ultra-high vacuum in the upper and lower chambers of the electron gun. Throughout the process cycle, the operating status and power load of the molecular pump and ion pump are continuously monitored. Once a pump no-load or overload fault is detected, the system immediately suspends the vacuuming process and reports a fault code to the host computer. When a pressure relief command is received from the host computer, the system will first use hardware logic to forcibly lock the V4 pre-evacuation connecting valve and the V5 main chamber isolation valve to isolate the gas paths of the electron gun, main chamber, and pre-evacuation chamber from each other. Then, the V2 main chamber vent valve and the V6 pre-evacuation chamber vent valve are opened respectively to complete the independent nitrogen pressure relief of the main chamber and the pre-evacuation chamber.

[0056] In step S8, a multi-dimensional parallel instantaneous high-pressure interlock between the vacuum and gas source is executed. The FPGA summarizes all operating parameters in parallel, including vacuum parameters of the electron gun chamber, main chamber, and pre-evacuation chamber, nitrogen pressure, total gas source pressure, real-time power of the molecular pump, and limit status of each valve. Only when all parameters meet the safety threshold conditions will the high-pressure unlock level be output, and the high voltage of the scanning electron microscope be allowed to be powered on. During operation, if the vacuum of any chamber is insufficient, the nitrogen / total gas source pressure is lower than the lower limit, the molecular pump load is abnormal, or the valve limit is abnormal, the FPGA will cut off the high-pressure interlock output in microseconds, directly cutting off the high-pressure power supply of the scanning electron microscope, realizing instantaneous safety protection against faults and filling the logical loophole that the protection cannot be triggered when the gas source pressure is abnormal.

[0057] In this embodiment, all vacuum acquisition, vacuum calculation, pump power calculation, valve hardware locking, and high-pressure interlock determination are executed by FPGA hardware parallel logic, without software serial scanning cycles. Valve control and high-pressure interlock responses reach the microsecond level. If this hardware platform needs to be adapted to vacuum equipment without a pre-evacuation chamber, no hardware circuit modifications are required. Simply update the FPGA firmware and disable the pre-evacuation chamber control branch to directly skip the pre-evacuation chamber-related timing and execute the evacuation and depressurization process without a pre-evacuation chamber. The I / O ports remain universal, enabling a single hardware setup to adapt to various precision vacuum equipment.

[0058] The measurement and control method is applied to the vacuum circuit topology of the scanning electron microscope without a pre-evacuation chamber as described in Example 2, specifically including: During the full-domain parallel initialization step of the S1 system power-on, the firmware is configured to close the pre-evacuation chamber control branch. Although the system will still collect the hardware signals of the pre-evacuation chamber vacuum gauges G2, V3, V4, and V6, it will no longer load the relevant threshold parameters of the pre-evacuation chamber. The pre-evacuation connecting valve lock-up logic and the pre-evacuation chamber process timing will not participate in the process control. After receiving the vacuuming or depressurization process command from the host computer in step S2, the FPGA identifies that the current topology is without a pre-evacuation chamber and automatically matches the vacuuming and depressurization timing sequence corresponding to the absence of a pre-evacuation chamber. Step S3 still performs full-channel synchronous acquisition, retaining all AI and DI hardware channel acquisitions, but the acquisition data related to the pre-sampling chamber is not used in process judgment. Step S4 performs nonlinear fitting calculations only on the upper and lower chambers of the electron gun and the vacuum zone of the main sample chamber, while simultaneously calculating the power of the molecular pump and identifying pump idling and overload faults. In step S5, all valve limit statuses are read in parallel. The control effect of V3 and V4 limit signals on the process flow is ignored. Only the limit statuses of V5 main cavity isolation valve and V1 valve are used as valid inputs for hardware lock and interlock determination. Although the hardware circuit is retained in the pre-vacuum connecting valve hardware lock logic in step S6, the firmware logic shields the output of the locking unit and only retains the hardware hierarchical locking control of the V5 main chamber isolation valve. When the main chamber vacuum does not reach the set threshold, the hardware shields the V5 main chamber isolation valve drive signal. When the main chamber vacuum drops, V5 is shut down in microseconds. No instruction from the host computer can force V5 to open. In the S7 dual-topology fully automatic staged closed-loop vacuum process, the firmware closes the pre-evacuation chamber branch, directly skipping the pre-evacuation sequence. When performing the vacuum evacuation process, the system controls the opening of the mechanical pump and the V1 molecular pump-mechanical pump connecting valve to establish a pre-vacuum for the molecular pump. Once the pre-vacuum conditions are met, the molecular pump is started to evacuate the main chamber. After the main chamber vacuum reaches the standard, the V5 hardware lock is released and V5 is opened, connecting the lower chamber of the electron gun to the main chamber. The ion pump is started to maintain the ultra-high vacuum of the electron gun, and the scanning electron microscope meets the conditions for opening the gun. Throughout the process, the working status and load of the molecular pump and ion pump are continuously monitored. If an abnormal load occurs, the process is immediately paused and the fault is reported to the host computer. When performing the depressurization process, the V5 main chamber isolation valve is forcibly closed by hardware first to isolate the electron gun chamber. Then, the mechanical pump, V1 valve, and molecular pump are closed in sequence. Subsequently, the V2 main chamber vent valve is opened until the main chamber returns to atmospheric pressure, completing the vacuum breaking operation. In the S8 vacuum-gas source multi-dimensional parallel instantaneous high-pressure interlocking process, the pre-evacuation chamber vacuum parameters are no longer introduced as a judgment condition. Only the electron gun cavity, main chamber vacuum, gas source pressure, molecular pump power, and effective valve limit parameters are summarized. Only when all parameters meet the safety conditions will 6 high-pressure interlock unlocking signals be output. If any parameter is abnormal, the FPGA will cut off the high-pressure interlocking output in microseconds, directly cutting off the high-pressure power supply to the scanning electron microscope, realizing instantaneous safety protection against faults and filling the logical loophole that the protection cannot be triggered when the gas source pressure is abnormal.

[0059] In this invention, the firmware does not require any hardware reconfiguration adaptation steps. The topology adaptation without pre-extraction chambers can be completed simply by closing the relevant branch logic of the pre-extraction chamber in the firmware.

[0060] Under this operating condition, all core safety mechanisms, including multi-channel signal synchronous acquisition, parallel pump power calculation, V5 hardware lock protection, multi-dimensional high-voltage interlocking, and microsecond-level fault response, are fully retained.

[0061] It should be noted that the two multi-stage differential vacuum chamber structures described in the embodiments of this invention, one with an independent pre-evacuation chamber and the other without, are standardized layouts for commercial scanning electron microscopes from Zeiss, Hitachi, Thermo Fisher Scientific, and domestic manufacturers. These are conventional structures commonly known to those skilled in the art and are not unique topologies customized for this application. The core structural features of this type of chamber layout are: the upper and lower chambers of the electron gun are physically isolated and each is equipped with an ion pump; the lower chamber of the electron gun is connected to the main sample chamber through a main chamber isolation valve; an independent pre-evacuation chamber can be optionally configured with a pre-evacuation connecting valve; the mechanical pump simultaneously performs the functions of evacuating gas from the pre-evacuation chamber and evacuating gas before the molecular pump. The only difference between the two topologies is whether or not a pre-evacuation chamber pipeline is added; the core ultra-high vacuum isolation architecture remains completely consistent. The basic function of this layout is to prevent low-vacuum gas backflow from damaging the electron gun cathode, which is a common safety design in the industry. This invention addresses the existing general-purpose cavity architecture by proposing a measurement and control system and method based on an FPGA-reconfigurable parallel architecture. Through hardware parallel acquisition and computation, dual isolation valve underlying hardware lock, multi-dimensional high-pressure interlock between vacuum and gas source, and firmware without hardware reconfiguration, it achieves universal safety measurement and control for the two types of existing standard vacuum cavities.

[0062] The beneficial effects of this invention are as follows: A single hardware system is compatible with both topologies with and without a pre-evacuation chamber, eliminating the need for PCB modifications and significantly reducing iterative costs. Dual-layer hardware locks on the main chamber isolation valve and pre-evacuation connecting valve prevent low-vacuum backflow contamination of the electron gun, offering significantly superior safety compared to existing software-only control solutions. Simultaneous acquisition of multiple vacuum air sources, with interval-based nonlinear fitting, results in significantly higher vacuum measurement accuracy over a wide range than PLC linear conversion. Real-time online power monitoring of the molecular pump allows for early prediction of no-load and stall conditions, preventing vacuum process failures. Dual-dimensional parallel microsecond-level high-pressure interlocking of the vacuum air source fills the safety gaps in existing gas source detection systems. Full hardware parallel computation eliminates the tens of milliseconds of scanning delay in PLCs, providing instantaneous fault protection. High hardware integration reduces the overall size of the machine, significantly lowering the comprehensive costs of materials, assembly, and maintenance. Standardized and universal I / O ports mean that modifications to processes and equipment replacements only require firmware upgrades, eliminating hardware modification costs. Real-time monitoring of the ion pump's operating status allows for early prediction of anomalies, preventing vacuum process failures.

[0063] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A precision instrument vacuum measurement and control system based on an FPGA-reconfigurable parallel architecture, adaptable to two types of scanning electron microscope vacuum topologies: one without a pre-evacuation chamber and the other with an independent pre-evacuation chamber. The upper and lower electron gun chambers are physically isolated and each is equipped with an ion pump. The lower electron gun chamber is connected to the main sample chamber via a main chamber isolation valve. The pre-evacuation chamber is connected to the main sample chamber via a pre-evacuation connection valve. The system is characterized in that... include: Parallel main control module: It is an FPGA main control chip, which integrates a multi-channel vacuum parallel fitting unit, a molecular pump real-time power calculation unit, a dual hardware lock unit for the pre-evacuation connecting valve and the main cavity isolation valve, a vacuum air source multi-dimensional high-pressure instantaneous interlock unit, and a firmware dynamic reconstruction logic unit. The parallel main control module is used to perform vacuum acquisition control, vacuum value calculation, pump power calculation, valve hardware lock management, high-pressure interlock determination, and firmware reconstruction control in parallel. Multi-channel voltage divider analog conditioning circuit: used to uniformly divide and condition multiple vacuum gauge signals, gas source pressure signals and molecular pump analog signals, and output analog signals that meet the input range of the multi-channel synchronous analog-to-digital acquisition module; Multi-channel synchronous analog-to-digital acquisition module: used to perform synchronous analog-to-digital conversion on all input analog signals at the same time, and transmit the conversion results to the parallel main control module via SPI bus; Multi-channel voltage divider DI protection circuit: used to perform unified voltage divider protection on all valve limit signals and pump limit signals, and input the voltage-divided digital signals into the parallel main control module; Pump and valve isolation relay drive array: connected to the output of the parallel main control module, receiving control signals from the parallel main control module, and driving the opening and closing actions of vacuum pumps and various vacuum valves; the parallel main control module also independently outputs high-voltage interlock level signals; Ethernet module: Connected to the parallel main control module, used to enable bidirectional data interaction between the parallel main control module and the host computer; Host computer: Used to send vacuuming commands, voltage stabilization commands, or pressure relief commands to the parallel main control module, and to display real-time data on the full operating status of the vacuum system; General-purpose IO expansion module: This module provides an expansion interface for connecting to the acquisition and drive channels of newly added cavities or valves. New hardware can be adapted by updating the firmware.

2. The precision instrument vacuum measurement and control system based on FPGA reconfigurable parallel architecture according to claim 1, characterized in that, The multi-channel voltage divider analog conditioning circuit and the multi-channel voltage divider DI protection circuit both adopt a 1:8 resistor voltage divider protection circuit to suppress input surges and prevent overvoltage from damaging the acquisition chip and the FPGA main control IO port.

3. The precision instrument vacuum measurement and control system based on FPGA reconfigurable parallel architecture according to claim 1, characterized in that, The multi-channel synchronous analog-to-digital acquisition module uses the AD7606 synchronous ADC chip to achieve synchronous analog-to-digital conversion of multiple analog signals at the same time, eliminating timing deviations in multi-channel acquisition.

4. The precision instrument vacuum measurement and control system based on FPGA reconfigurable parallel architecture according to claim 1, characterized in that, The pump and valve isolation relay drive array uses G5Q-1A4-EU-DC12V isolation relays. The control level output by the parallel main control module drives the relay coil after opto-isolation. The relay contacts drive the mechanical pump, molecular pump, ion pump, pre-pumping connecting valve, main cavity isolation valve, and various process valves.

5. The precision instrument vacuum measurement and control system based on FPGA reconfigurable parallel architecture according to claim 1, characterized in that, The Ethernet module uses the W5500 hardware Ethernet chip, which has a built-in TCP / IP protocol stack. Ethernet data transmission and reception operate independently and do not occupy the computing resources of the parallel main control module. The FPGA main control chip is the XC7S50-2FTGB196C chip.

6. The precision instrument vacuum measurement and control system based on FPGA reconfigurable parallel architecture according to claim 1, characterized in that, The analog signals synchronously acquired by the multi-channel synchronous analog-to-digital acquisition module include the pre-evacuation chamber vacuum gauge signal, the main chamber vacuum gauge signal, the electron gun upper chamber ion pump vacuum value signal, the electron gun lower chamber ion pump vacuum value signal, the nitrogen pressure signal, the total gas source pressure signal, and the molecular pump analog signal. The digital signals acquired by the multi-channel voltage divider DI protection circuit include the pre-extraction connecting valve limit signal, the V5 main cavity isolation valve limit signal, the limit signals of each process valve, the molecular pump operating status signal, the molecular pump speed status signal, and the ion pump operating status signal.

7. A method for vacuum measurement and control of precision instruments based on a FPGA-reconfigurable parallel architecture, characterized in that, The precision instrument vacuum measurement and control system based on FPGA reconfigurable parallel architecture as described in any one of claims 1-6 includes the following steps: S1. After the system is powered on, the parallel main control module performs hardware self-tests on the acquisition channel, drive channel, and limit channel, loads vacuum threshold, gas source pressure safety lower limit, pump rated power, and isolation valve lock-up judgment parameters, and establishes bidirectional communication with the host computer via Ethernet; the firmware selects to enable or disable the pre-evacuation chamber control branch according to the configuration. S2. The host computer issues vacuuming, pressure stabilization, and pressure relief process commands. The FPGA main control chip identifies the current gas path topology in parallel and automatically matches the corresponding multi-stage vacuuming and pressure relief timing sequence. S3. After performing voltage division protection on multiple vacuum signals, gas source pressure signals, and pump analog electrical parameters, synchronous analog-to-digital conversion is implemented and the data is sent to the parallel main control module; parallel acquisition of digital signals such as valve limit and pump group working status is also performed. S4. Perform nonlinear fitting conversion on different cavity vacuum ranges, calculate the real-time pump power based on the collected electrical parameters and identify abnormal load conditions. S5. Parallel acquisition of the limit status of the pre-extraction connecting valve, main cavity isolation valve, process valve and pump group feedback switch, as the input basis for hardware lock logic and interlock determination; S6. When the vacuum of the corresponding cavity is not up to standard, the hardware will block the corresponding isolation valve drive; when the cavity vacuum drops, the corresponding isolation valve will be shut off, and the host computer command cannot force the isolation valve with substandard vacuum to open. S7. When the pre-extraction chamber control branch is activated, the complete process flow including pre-extraction, valve unlocking, air extraction, pressure stabilization and pressure relief is executed. Before pressure relief, the two isolation valves are locked first. When the pre-extraction chamber control branch is closed, the pre-extraction sequence is skipped. The pump group status and load are monitored throughout the process. If the load is abnormal, the process is suspended and the fault is reported. S8: Parallel acquisition and summarization of various operating parameters such as cavity vacuum, gas source pressure, pump power, and valve limit; high-pressure unlocking is only output when all parameters meet safety conditions; if any parameter does not meet safety conditions, the high-pressure interlock output is cut off.

8. The precision instrument vacuum measurement and control method based on FPGA reconfigurable parallel architecture according to claim 7, characterized in that, Also includes: S9. Store the vacuum threshold, gas source lower limit, pump power judgment range, and pre-evacuation timing in the firmware. You can switch topologies to adapt to different precision instruments by updating the firmware.

9. The precision instrument vacuum measurement and control method based on FPGA reconfigurable parallel architecture according to claim 7, characterized in that, In steps S3-S8, vacuum acquisition, vacuum calculation, pump power calculation, valve hardware lock logic, and high-pressure interlock determination are all executed in parallel by the FPGA main control chip, without relying on the software serial scan cycle. Valve control actions and high-pressure interlock cutoff achieve microsecond-level response.

10. The precision instrument vacuum measurement and control method based on FPGA reconfigurable parallel architecture according to claim 7, characterized in that, The high-pressure interlock determination process incorporates nitrogen pressure and total gas source pressure as determination conditions. Abnormal gas source pressure directly triggers the high-pressure cutoff interlock.

Images