Signal calibration system and method applied to plasma etching machine

Abstract

This application discloses a signal calibration system for a plasma etching machine. The signal calibration system includes a constant current source device, an electronic load instrument, and a host computer. The target constant current output unit in the constant current source device is communicatively connected to both the host computer and the electronic load instrument. The host computer is also communicatively connected to the electronic load instrument. The host computer sequentially sends M1 calibration currents to the target constant current output unit. The target constant current output unit outputs a drive current based on each calibration current and generates corresponding ADC sampling codes and DAC setting codes. The electronic load instrument detects the drive current and outputs the measured current. The host computer generates a calibration table based on the measured current and the corresponding ADC sampling codes and DAC setting codes, and sends the calibration table to the target constant current output unit. This signal calibration system uses the electronic load instrument as the calibration benchmark, ensuring that the authenticity of all calibration data is traceable to national metrological standards, thus improving calibration accuracy.

Description

Technical Field

[0001] This application relates to the field of semiconductor equipment technology, specifically to a signal calibration system and method for use in a plasma etching machine. Background Technology

[0002] In the semiconductor manufacturing field, plasma etching machines guide plasma to etch substrates using a magnetic field generated by coils. The driving current required for the coils is provided by a constant current source device, the accuracy of which directly affects the stability and uniformity of the etching process. The constant current source device integrates an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC) for current sampling and output setting, respectively. However, due to factors such as component errors and temperature drift, the ADC / DAC signals may deviate from the actual physical quantities, thus requiring calibration.

[0003] In related technologies, the calibration of constant current source devices mainly adopts software calibration methods. Although software calibration achieves automatic calibration, the calibration results are not traceable and have low accuracy. Summary of the Invention

[0004] To address the aforementioned technical problems, embodiments of this application provide a signal calibration system and method, thereby improving the inaccuracy of signal calibration in related technologies.

[0005] In a first aspect, embodiments of this application provide a signal calibration system for a plasma etching machine, the signal calibration system comprising: a constant current source device, an electronic load instrument, and a host computer; The constant current source device includes N constant current output units. The target constant current output unit among the N constant current output units is communicatively connected to the host computer and the electronic load instrument. The target constant current output unit is configured to receive M1 calibration currents sequentially sent by the host computer, and output a corresponding first drive current based on each calibration current, and generate an ADC sampling code and a DAC setting code corresponding to the first drive current. The target constant current output unit is any one of the N constant current output units, and M1 and N are both integers greater than 1. The electronic load instrument is configured to detect the first drive current and output the corresponding measured current. The host computer is also connected to the electronic load instrument and is configured to generate a calibration table based on the measured current and the ADC sampling code and DAC setting code corresponding to the measured current, and send the calibration table to the target constant current output unit. The calibration table includes an ADC calibration table and a DAC calibration table.

[0006] In a second aspect, embodiments of this application provide a signal calibration method applied to the signal calibration system described above, the method comprising: The target constant current output unit receives M1 calibration currents sequentially sent by the host computer, and outputs a corresponding first drive current based on each calibration current, and generates an ADC sampling code and a DAC setting code corresponding to the first drive current. The target constant current output unit is any one of the N constant current output units, and M1 and N are both integers greater than 1. The electronic load instrument detects the first driving current and outputs the corresponding measured current. The host computer generates a calibration table based on the measured current, the ADC sampling code and the DAC setting code corresponding to the measured current, and sends the calibration table to the target constant current output unit. The calibration table includes an ADC calibration table and a DAC calibration table.

[0007] The beneficial effects of this application's embodiments: The signal calibration system in this application embodiment includes a constant current source device, an electronic load, and a host computer. The constant current source device includes N constant current output units. A target constant current output unit among the N constant current output units is communicatively connected to both the host computer and the electronic load. The host computer is also communicatively connected to the electronic load. The host computer sequentially sends M1 calibration currents to the target constant current output unit. The target constant current output unit outputs a corresponding first driving current based on each calibration current and generates an ADC sampling code and a DAC setting code corresponding to the first driving current. The electronic load detects the first driving current and outputs the corresponding measured current. The host computer generates a calibration table based on the measured current and the corresponding ADC sampling code and DAC setting code, and sends the calibration table to the target constant current output unit. The calibration table includes an ADC calibration table and a DAC calibration table.

[0008] This signal calibration system introduces an external high-precision electronic load instrument as the calibration benchmark, ensuring that the authenticity of all calibration data is traceable to national metrological standards. This fundamentally solves the problem that relying solely on internal closed-loop self-testing cannot guarantee absolute accuracy. Simultaneously, the host computer centrally controls the equipment and instruments, automating the calibration process, improving calibration efficiency, and eliminating the need for unpacking the device for calibration, thus enhancing convenience. Attached Figure Description

[0009] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0010] Figure 1 This is a schematic diagram of the structure of a signal calibration system provided in an embodiment of this application; Figure 2A schematic diagram of a plasma etching machine provided for related technologies; Figure 3 This is a schematic diagram of the structure of one of the signal calibration systems provided in the embodiments of this application; Figure 4 This is a schematic diagram of the structure of one of the signal calibration systems provided in the embodiments of this application; Figure 5 This is a schematic diagram of the circuit structure of one of the signal calibration systems provided in the embodiments of this application; Figure 6 This is a schematic diagram of one type of host computer operation interface provided in an embodiment of this application; Figure 7 This is a schematic diagram of one type of host computer operation interface provided in an embodiment of this application; Figure 8 This is a schematic diagram of one type of host computer operation interface provided in an embodiment of this application; Figure 9 This is a schematic diagram of one type of curve drawing interface provided in an embodiment of this application; Figure 10 A schematic flowchart illustrating one signal calibration method provided in an embodiment of this application; Figure 11 This is a schematic flowchart of one of the signal calibration methods provided in the embodiments of this application. Detailed Implementation

[0011] To facilitate understanding of this application, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "electrically connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "upper," "lower," "inner," "outer," "bottom," etc., used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0012] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items. Furthermore, technical features involved in the different embodiments of this application described below may be combined with each other as long as they do not conflict with each other.

[0013] The following embodiments of this application provide a signal calibration system applied to a plasma etching machine. Please refer to... Figure 1 The plasma etching machine 200 is used to etch the substrate, and the signal calibration system 100 is used to calibrate the constant current source device in the plasma etching machine 200 to ensure the current accuracy of the drive coil, thereby ensuring the accuracy and stability of the magnetic field within the etching cavity. It is understood that the plasma etching machine described in this embodiment can be any existing plasma etching machine. However, the working principle of the signal calibration system 100 provided in this embodiment is closely related to the product structure and principle of the plasma etching machine, and can work in conjunction with the plasma etching machine to accurately calibrate the constant current source device, ensuring the repeatability and reliability of the plasma etching process.

[0014] To facilitate understanding of the embodiments of this application, the plasma etching machine 200 is described in detail below. Please refer to... Figure 2 The plasma etching machine 200 includes a gas output module 21, an etching chamber 22, and an electrostatic chuck 23.

[0015] The gas output module 21 is configured to input gas into the gas inlet of the etching chamber 22. The gas output module 21 is located outside the plasma etching machine 200 and is connected to the gas inlet of the etching chamber 22 via a pipeline. The gas inlet of the etching chamber 22 is typically designed at the top of the etching chamber 22 to ensure that the gas can diffuse evenly throughout the entire etching chamber 22, cover the substrate surface, and then exit from the gas output port at the bottom. The gas output module 21 can output specific types of gas as needed, including CF4 gas, SF6 gas, CHF3 gas, etc.

[0016] An electrostatic chuck 23 is disposed at the bottom of the etching cavity 22 and is configured to hold the substrate 23a. The substrate can be a wafer, a display panel substrate, etc. After the substrate 23a is placed on the surface of the electrostatic chuck 23, the electrostatic chuck 23 firmly fixes the substrate 23a in place through electrostatic adsorption, preventing the substrate 23a from shifting or vibrating during the etching process.

[0017] Please see Figure 3The signal calibration system 100 includes a constant current source device 11, an electronic load instrument 12, and a host computer 13. The constant current source device 11 is the constant current source used to drive the coil 24 in the plasma etching machine 200. It is configured to output a drive current according to preset etching process parameters to drive the coil 24 to generate a magnetic field within the etching cavity 22, guiding the plasma to etch the substrate. The constant current source device 11 integrates an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC): the DAC generates a corresponding setting code based on the etching process parameters to produce the drive current, and the ADC collects the output current in real time for closed-loop control of the device. However, due to component errors, temperature drift, and other factors, there will be a deviation between the accuracy of the ADC / DAC signal and the actual physical quantity of the current. Therefore, the ADC and DAC need to be calibrated to ensure the accuracy of the drive current.

[0018] Furthermore, the accuracy of the driving current output by the constant current source device 11 directly determines the accuracy of the magnetic field generated by the coil 24, which in turn affects the directionality and uniformity of plasma etching. Therefore, it is crucial to periodically or as needed to calibrate the constant current source device 11 to ensure that its output current always meets the requirements of the etching process parameters, which is essential for ensuring the etching quality and process stability of the plasma etching machine 200.

[0019] In related technologies, the calibration of constant current source devices mainly employs software calibration methods. Software calibration schemes can achieve automatic calibration upon power-on. However, the calibration accuracy of this method is difficult to guarantee.

[0020] To address the aforementioned issues, this application provides a signal calibration system, which further includes an electronic load instrument 12. This application provides a calibration reference through the electronic load instrument 12, ensuring the accuracy of calibration data and improving calibration precision.

[0021] Specifically, such as Figure 3As shown, the electronic load 12 is configured to be electrically connected to the output terminal of the constant current source device 11, serving as an external high-precision reference source. It measures the first drive current actually output by the constant current source device 11 in real time and transmits the measured current value to the host computer 13. The host computer 13 is communicatively connected to both the constant current source device 11 and the electronic load 12. It is configured to control the constant current source device 11 to output the corresponding first drive current sequentially based on a preset calibration current sequence. Simultaneously, it acquires the ADC sampling code and DAC setting code generated internally by the constant current source device 11 when outputting each first drive current, and receives the measured current value fed back by the electronic load 12. The host computer 13 establishes a one-to-one mapping relationship between the ADC sampling code, DAC setting code, and the measured current value of the electronic load 12, generating an ADC calibration table and a DAC calibration table. These calibration tables are then sent to the constant current source device 11 for storage, specifically to the target constant current output unit within the constant current source device 11.

[0022] When the constant current source device 11 is running normally, the current sampling reading can be corrected according to the ADC calibration table, and the first drive current of the output can be accurately set according to the DAC calibration table, thereby ensuring that the first drive current output to the coil 24 is precisely consistent with the requirements of the etching process parameters, ensuring the accuracy and stability of the magnetic field in the etching cavity 22, and ultimately improving the process quality of plasma etching.

[0023] It should be noted that the constant current source device 11 includes N constant current output units, where N is an integer greater than 1, such as 3, 5, or more. Each constant current output unit is independently connected to a coil 24 in the plasma etching machine 200 to provide a first driving current to the corresponding coil. Since the coils are located at different positions within the etching cavity 22 and have different magnetic field strength requirements, each constant current output unit needs to be calibrated independently to ensure that the first driving current output by each line meets the process requirements.

[0024] During the calibration process, the host computer 13 calibrates the N constant current output units one by one. Specifically, the host computer 13 first selects the current constant current output unit to be calibrated from the N constant current output units according to the channel number specified by the user or the preset calibration order, and designates it as the target constant current output unit. For example, when the third constant current output unit needs to be calibrated, the host computer 13 marks it as the target constant current output unit, and all subsequent calibration commands and data are sent to this unit. The other unselected constant current output units maintain their original working state or are in standby mode, unaffected by the calibration process.

[0025] For each target constant current output unit, the host computer 13 executes a complete calibration process. The host computer 13 sequentially sends the M1 calibration currents to the target constant current output units in the form of current commands or signals. Each time a target constant current output unit receives a calibration current, it drives its internal circuitry according to the calibration current value, outputting a corresponding first drive current to the coil 24 connected to it. Furthermore, the target constant current output unit internally generates an ADC sampling code and a DAC setting code corresponding to the first drive current and feeds these codes back to the host computer 13. Simultaneously, the electronic load instrument 12 also detects the first drive current, measures its actual value in real time, generates the corresponding measured current, and transmits the measured current to the host computer 13.

[0026] The host computer 13 correlates and matches the received ADC sampling code and DAC setting code with the measured current fed back by the electronic load instrument 12 at the same moment to form a complete calibration record. This process is repeated until all M1 calibration currents have been sent out, at which point the host computer 13 obtains M1 sets of calibration data containing "ADC sampling code - DAC setting code - measured current". Based on the M1 sets of calibration data, the host computer 13 generates an ADC calibration table and a DAC calibration table, and sends them to the target constant current output unit. At this point, the host computer 13 completes the calibration of the current target constant current output unit.

[0027] After the current target constant current output unit is calibrated, the host computer 13 automatically switches to the next constant current output unit to be calibrated, and uses it as the new target constant current output unit. The process of sending M1 calibration currents, collecting ADC sampling codes and DAC setting codes, and synchronously receiving the measured current sent by the electronic load instrument 12 is repeated until all N constant current output units are calibrated.

[0028] By using this method of calibration one by one, the host computer 13 can independently generate corresponding ADC calibration tables and DAC calibration tables for each constant current output unit, ensuring that each output can meet the required accuracy requirements, thereby ensuring the uniformity and stability of the magnetic field in the etching cavity 22.

[0029] In some embodiments, the target constant current output unit, the electronic load instrument 12, and the host computer 13 are all connected via serial communication. For example, the target constant current output unit and the host computer 13 are connected via a 485 debugging port, and the electronic load instrument 12 and the host computer 13 are connected via UART. Through serial port pass-through, the host computer 13 can simultaneously operate the electronic load instrument 12 and the constant current source device 11 for calibration, eliminating the need for unpacking and calibration, improving the convenience and flexibility of calibration, increasing calibration efficiency, and expanding calibration scenarios.

[0030] In summary, this signal calibration system, by introducing an external high-precision electronic load instrument as the calibration benchmark, ensures that the authenticity of all calibration data is traceable to national metrological standards, fundamentally solving the deficiency that relying solely on internal closed-loop self-testing cannot guarantee absolute accuracy. Simultaneously, the centralized control of equipment and instruments by the host computer automates the calibration process, improving calibration efficiency and eliminating the need for unpacking for calibration, thus enhancing convenience.

[0031] In some embodiments, before starting calibration, the host computer 13 needs to pre-generate M1 calibration currents. In some embodiments, the host computer 13 first loads preset calibration parameters, which include a calibration current range (e.g., 0–20A) and a number of calibration points M1 (e.g., 20 points). Based on the preset calibration current range and the number of calibration points M1, the host computer 13 generates M1 sequentially increasing calibration currents using an equally spaced interpolation method. These calibration currents uniformly cover the entire calibration range and are used to control the output of the target constant current output unit during subsequent calibration.

[0032] The preset calibration range and number of points can be set by the user through the host computer interface, or the system default value can be used to ensure that the calibration points can fully reflect the linearity of the constant current output unit across the entire range.

[0033] In some embodiments, after loading preset calibration parameters, the calibration current range is divided into K calibration current intervals, where K is an integer greater than or equal to 3, and then M1 calibration currents are generated based on the K calibration current intervals and the number of calibration points M1.

[0034] For example, if the calibration current range is 0–20A, it can be divided into three intervals: a low interval (0–5A), a medium interval (5–15A), and a high interval (15–20A). The purpose of dividing the range is to flexibly allocate the number of calibration points based on the differences in the nonlinear characteristics of the constant current output unit within each current interval, thereby improving the overall calibration accuracy. After the interval division is completed, the host computer 13 can allocate M1 points to each interval using either a uniform or non-uniform allocation method, depending on the degree of nonlinearity of the constant current output unit within each interval. For example, more calibration points can be allocated to the lower and higher intervals where nonlinearity is stronger, while fewer calibration points can be allocated to the medium interval where linearity is better, thus improving the calibration effect without changing the total number of points. The calibration points allocated within each interval are then interpolated at equal or unequal intervals to generate specific current values, ultimately forming M1 calibration current sequences covering the entire calibration range for subsequent point-by-point calibration.

[0035] It should be noted that the embodiments of this application do not limit the specific division of the calibration current range, and the calibration current range can be set as needed. For example, if the calibration current range is 0 to 20A, the calibration current range can be (0 to 5A), (5 to 15A), and (15 to 20A), or it can be (0 to 1A), (1 to 19A), and (19 to 20A), etc.

[0036] In some embodiments, before starting calibration, the host computer 13 needs to configure the operating mode of the electronic load instrument to adapt it to the current calibration requirements and ensure measurement accuracy. Specifically, the preset calibration parameters also include the target operating mode and target resistance value of the electronic load instrument, wherein the target operating mode is a constant resistance RC mode. The host computer 13 generates a mode switching command based on the target operating mode and sends the mode switching command to the electronic load instrument 12 through the communication interface, setting the operating mode of the electronic load instrument 12 to constant resistance RC mode to ensure that the load impedance remains constant during the calibration process, simulating the stable load characteristics under actual working conditions. At the same time, the host computer 13 generates a resistance configuration command based on the target resistance value and then sends the resistance configuration command to the electronic load instrument 12 to set the internal working resistance of the electronic load instrument 12 to the target resistance value (e.g., 1Ω), so that it matches the output characteristics of the constant current source device 11, thereby enabling accurate measurement of the first drive current value at each calibration point. After configuration, the electronic load instrument 12 enters a standby state, ready to collect and feed back measured current data in real time during the calibration process.

[0037] Therefore, before calibration begins, the host computer 13 pre-generates calibration current, flexibly allocates calibration points by dividing K segments, and automatically configures the electronic load instrument 12 to constant resistance RC mode. This not only achieves a high degree of automation in the calibration process and reduces manual intervention and misoperation, but also improves the calibration accuracy across the entire range. At the same time, it ensures that the working state of the external reference source is consistent with the actual working conditions, providing a reliable guarantee for the authenticity, traceability, and measurement consistency of subsequent calibration data.

[0038] Please see Figure 4 Each constant current output unit 111 consists of two parts: a control unit 1111 and a power unit 1112. The two parts are connected through a communication interface, such as the control unit 1111 and the power unit 1112 communicating via SPI.

[0039] The control unit 1111, as the digital control core, is responsible for processing instructions issued by the host computer 13, generating DAC setting codes, and generating ADC sampling codes. The power unit 1112, as the analog power output core, is responsible for converting the first control signal into the first drive current output. The control unit 1111 is communicatively connected to the host computer 13, and the output terminal of the power unit 1112 is connected to the coil 24 and, in calibration mode, to the electronic load instrument 12.

[0040] During the calibration process, the host computer 13 selects the target constant current output unit to be calibrated and sequentially sends M1 calibration currents to the control unit 1111 of that unit. The control unit 1111 generates a corresponding DAC setting code based on each calibration current, and generates a corresponding first control signal based on the DAC setting code, and then sends the corresponding first control signal to the power unit 1112.

[0041] After receiving the first control signal, the power unit 1112 outputs the corresponding first drive current, which is measured in real time by the electronic load instrument 12. At the same time, the control unit 1111 collects the first drive current, generates the corresponding ADC sampling code, and reports the sampling code to the host computer 13 for association processing with the measured current fed back by the electronic load instrument 12.

[0042] In this embodiment, by separating the control unit 1111 and the power unit 1112, physical isolation between the digital and analog circuits is achieved, effectively reducing the interference of digital noise on the analog signal and improving the purity and stability of the first drive current. The communication interface between the control unit 1111 and the power unit 1112 ensures high-speed and reliable data exchange, providing support for high-precision closed-loop control and efficient calibration.

[0043] In this embodiment, the control unit 1111 is specifically embodied as a core board, and the power unit 1112 is specifically embodied as a power board. The two are connected via SPI bus communication.

[0044] When calibrating each constant current output unit 111, the control unit 1111 receives each calibration current from the host computer 13 and needs to convert it into a DAC setting code for driving the power unit 1112. Since the device has not been precisely calibrated before calibration, the control unit 1111 relies on the internally stored default first mapping table to initially determine the DAC setting code, thereby outputting the corresponding first drive current for measurement by the electronic load instrument 12.

[0045] Specifically, the control unit 1111 acquires a pre-stored first mapping table, which represents a one-to-one mapping relationship between the set current and the preset DAC codes. This first mapping table is a default table established at the factory based on an ideal model or rough testing, representing the initial parameters before calibration. The first mapping table stores several discrete set current points and their corresponding preset DAC codes. For example, it stores the corresponding code values ​​at points such as 0A, 5A, 10A, 15A, and 20A. These points are usually sparsely distributed but cover the entire calibration range and are stored in the Flash memory of the control unit 1111 as the initial basis before calibration. The purpose of this default first mapping table is to provide an operable starting point for the calibration process, so that even before calibration is completed, the device can still output a preliminarily controllable current based on a limited number of discrete points, thereby creating conditions for the measurement of the electronic load instrument 12 and the generation of subsequent calibration tables.

[0046] The control unit 1111 then queries the first mapping table to obtain the first set current and the second set current that match the calibration current, wherein the calibration current is greater than or equal to the first set current and less than or equal to the second set current. Specifically, for any issued calibration current Icnt, the control unit 1111 traverses the set current points in the first mapping table, finds the maximum set current not greater than Icnt as the first set current Iarr, and finds the minimum set current not less than Icnt as the second set current Iarr_next. These two points define the current range of the calibration current Icnt, satisfying Iarr ≤ Icnt ≤ Iarr_next. During the query process, if the calibration current Icnt is exactly equal to a certain set current point, then the first set current and the second set current can be the same point; if the calibration current is less than the minimum value in the first mapping table, then the minimum value is used as the second set current, and zero or the starting point of the first mapping table is used as the first set current; if the calibration current is greater than the maximum value in the first mapping table, then the maximum value is used as the first set current, and the maximum value is also used as the second set current. In this way, it is ensured that any calibration current can find a corresponding adjacent interval or boundary point in the first mapping table, laying the foundation for subsequent interpolation calculations.

[0047] Subsequently, the control unit 1111 retrieves the first DAC preset code corresponding to the first set current and the second DAC preset code corresponding to the second set current from the first mapping table. Specifically, the control unit 1111 reads the corresponding first DAC preset code DAarr from the first mapping table based on the retrieved first set current Iarr, and similarly, reads the corresponding second DAC preset code DAarr_next based on the second set current Iarr_next. These two codes represent the theoretical code values ​​that need to be written into the DAC register to make the power unit 1112 output an approximate current at the corresponding set current points. These preset codes are obtained through preliminary calibration at the factory. Although their accuracy is limited, the trend of change between adjacent points can reflect the basic law of DAC conversion characteristics, and therefore can be used as the basis for interpolation.

[0048] Finally, the control unit 1111 generates a DAC setting code based on the calibration current, the first set current and the corresponding first DAC preset code, and the second set current and the corresponding second DAC preset code, using a linear interpolation method. Since the actual required DAC setting code and the output current can be approximately linearly related within a small interval, the control unit 1111 uses a linear interpolation formula to calculate the precise DAC setting code DAval corresponding to the calibration current Icnt.

[0049] In some embodiments, the DAC setting code is calculated using the following formula: DAval=DAarr+(Icnt-Iarr) / (Iarr_next-Iarr)×(DAarr_next-DAarr) (1) Wherein, DAval is the DAC setting code, Icnt is the calibration current, Iarr is the first setting current, Iarr_next is the second setting current, DAarr is the first DAC preset code, and DAarr_next is the second DAC preset code.

[0050] Using formula (1), the control unit 1111 can generate a preliminary DAC setting code for any calibration current, and based on this, send a first control signal to the power unit 1112 to drive it to output the corresponding first drive current. This first drive current is measured in real time by the electronic load instrument 12, providing basic data for the subsequent generation of a high-precision calibration table.

[0051] After receiving the measured current, ADC sampling code, and DAC setting code, the host computer 13 establishes a one-to-one mapping relationship between the measured current and the corresponding ADC sampling code to generate an ADC calibration table, and establishes a one-to-one mapping relationship between the measured current and the corresponding DAC setting code to generate a DAC calibration table. Thus, the host computer 13 completes the calibration of the constant current output unit.

[0052] It should be noted that the DAC setting code generated based on the default first mapping table is only used for the initial output during the calibration process. Its purpose is to enable the device to generate a measurable current for the electronic load instrument to collect. After the host computer 13 completes data processing and generates a calibration table, the default first mapping table will be replaced by the newly generated DAC calibration table. The device will then perform precise output based on the calibration table during subsequent operation, thereby achieving higher precision current control.

[0053] In some embodiments, please refer to Figure 5 The constant current source device 11 also includes a communication unit 14, which is communicatively connected to the host computer 13 and each constant current output unit 111. The communication unit 14 receives the target constant current output unit number information and M1 calibration currents sent by the host computer 13, and forwards the M1 calibration currents sequentially to the corresponding target constant current output units based on the number information.

[0054] Specifically, the communication unit 14 acts as a data relay hub between the host computer 13 and each constant current output unit 111, undertaking the functions of instruction parsing and data distribution. When the host computer 13 needs to calibrate a specific channel, it first sends a data packet containing the target channel number (e.g., channel 3) and calibration instructions to the communication unit 14. After receiving the data packet, the communication unit 14 parses out the target channel number and accurately forwards the subsequent M1 calibration currents to the constant current output unit corresponding to that number. The constant current output units 111 of other channels will not receive these calibration currents, thus ensuring that the calibration process is only performed on the specified channel and does not affect the normal operation or standby state of other channels.

[0055] For example, suppose the constant current source device 11 has eight constant current output units 111, which are connected to eight coils 24 around the etching cavity 22. When the constant current output unit 111 corresponding to the fifth coil needs to be calibrated, the host computer 13 sends the "channel 5" number information and 20 calibration currents to the communication unit 14. The communication unit 14 forwards these 20 calibration currents to the fifth constant current output unit 111 one by one according to the number information, while the first to fourth and sixth to eighth constant current output units 111 maintain their original working state or are in standby mode during this period, without any interference.

[0056] By adding communication unit 14, online calibration of multi-channel devices is achieved, solving the problem of needing to open the device for later maintenance. Maintenance personnel only need to connect the host computer 13 to the device's external debugging serial port to calibrate any specified channel in the device's overall state, without any physical plugging or unplugging, greatly simplifying the maintenance process. At the same time, communication unit 14 can accurately identify and forward calibration commands, ensuring that calibration data is sent only to the target channel, avoiding bus conflicts or data confusion that may be caused by multiple channels receiving commands simultaneously, thus improving the efficiency and accuracy of multi-channel calibration.

[0057] Furthermore, the introduction of communication unit 14 enhances the system's scalability. When the number of channels needs to be increased, it is only necessary to connect the newly added constant current output unit 111 to the bus of communication unit 14 and update the first channel mapping table. No major modifications to the software and hardware interfaces of the host computer 13 are required, reducing the difficulty and cost of system upgrades.

[0058] In this embodiment, the communication unit 14 is specifically embodied as a central control board. The central control board has a built-in microcontroller and multiple communication interfaces. One end is connected to the host computer 13 through a debugging serial port (such as through a 485 serial port / ECAT serial port), and the other end is connected to the control unit 1111 of each constant current output unit 111 through an internal bus (such as through a 232 serial port communication connection) to realize centralized data forwarding and channel management.

[0059] Therefore, by introducing an external high-precision electronic load instrument as the calibration benchmark, this signal calibration system ensures that the authenticity of all calibration data is traceable to national metrological standards, fundamentally solving the problem that relying solely on internal closed-loop self-testing cannot guarantee absolute accuracy. Simultaneously, the centralized control of equipment and instruments by the host computer automates the calibration process, improving calibration efficiency and eliminating the need for unpacking for calibration, thus enhancing convenience.

[0060] In some embodiments, the host computer 13 calibrates each constant current output unit in an open-loop manner. After calibration is completed, the calibration table needs to be re-verified in a closed loop.

[0061] Specifically, after generating and distributing the calibration tables, the host computer 13 initiates a re-verification process to verify the accuracy and reliability of the newly generated ADC and DAC calibration tables. The host computer 13 again sends M1 calibration currents, identical to those in the calibration process, to the target constant current output unit 111 via the communication unit 14. The values ​​and order of these calibration currents are consistent with the previous process, ensuring the comparability of the re-verification process with the calibration process. The communication unit 14 accurately forwards each calibration current to the corresponding control unit 1111 based on the target channel's numbering information, providing a data basis for subsequent re-verification operations.

[0062] The target constant current output unit receives M1 calibration currents sequentially from the host computer. For each calibration current, the target constant current output unit calculates the corresponding target DAC setting code based on the DAC calibration table, and outputs the corresponding target first drive current based on the target DAC setting code. Specifically, after receiving the calibration current Icnt, the control unit 1111 no longer uses the default first mapping table, but instead calls the DAC calibration table stored in Flash. This DAC calibration table establishes a precise mapping relationship between the measured current value and the DAC setting code. The control unit 1111 first searches for the two measured current points Ireal_k and Ireal_k+1 that are closest to Icnt in the DAC calibration table, and reads their corresponding DAC setting codes DA_k and DA_k+1.

[0063] The target DAC setting code DA_val corresponding to Icnt is calculated using the following formula: DA_val = DA_k + (Icnt - Ireal_k) / (Ireal_k+1 - Ireal_k) × (DA_k+1 -DA_k) (2) Where DA_val is the target DAC setting code, Icnt is the calibration current, Ireal_k and Ireal_k+1 are the two measured current points closest to Icnt, and DA_k and DA_k+1 are the DAC setting codes corresponding to the two measured current points.

[0064] The control unit 1111 sends the DAC setting code to the power unit 1112 via the SPI bus, and the power unit 1112 outputs the target first drive current accordingly.

[0065] The control unit 1111 samples the output target first drive current in real time, generates the corresponding measured ADC sampling code, and retrieves the target measured current corresponding to the sampling code from the ADC calibration table. Specifically, the first drive current output by the power unit 1112 is converted into a voltage signal through a sampling resistor. This voltage signal is transmitted to the control unit 1111 via a feedback loop. The ADC module inside the control unit 1111 performs analog-to-digital conversion to generate the measured ADC sampling code ADCsample, which is then fed back to the control unit 1111 via the SPI bus. The control unit 1111 then accesses the ADC calibration table in Flash, which establishes a precise mapping relationship between the ADC sampling code and the measured current value.

[0066] The current sampling circuit inside the control unit 1111 samples the output target first drive current in real time, generates the corresponding measured ADC sampling code, and retrieves the target measured current corresponding to the measured ADC sampling code from the ADC calibration table. Specifically, the first drive current output by the power unit 1112 is converted into a voltage signal through a sampling resistor. This voltage signal is transmitted to the control unit 1111 via a feedback loop, where the ADC module inside the control unit 1111 performs analog-to-digital conversion to generate the measured ADC sampling code ADCsample. The control unit 1111 then accesses the ADC calibration table in Flash memory. This table, indexed by the ADC sampling code, directly records the measured current value corresponding to each ADC sampling code. The control unit 1111 uses the current measured ADC sampling code ADCsample as a key to search for a matching entry in the ADC calibration table, thereby reading the corresponding target measured current Ireal_target.

[0067] Finally, the control unit 1111 uploads the obtained target measured current Ireal_target to the host computer 13 via the communication unit 14. The host computer 13 compares the received target measured current with the originally issued calibration current Icnt point by point, calculates the absolute error and relative error at each point, and calculates the maximum error across the entire range.

[0068] If the error at all points is within the preset allowable range (e.g., ±0.1%), the host computer 13 determines that the re-verification has passed, and the newly generated calibration table officially takes effect and can be used for subsequent normal operation. If there are out-of-tolerance points, the host computer 13 determines that the re-verification has failed and immediately sends a command to the target constant current output unit to erase the newly written calibration table in Flash, restore the default first mapping table, and at the same time pop up an alarm prompt on the host computer interface, suggesting recalibration or checking the device status.

[0069] In this embodiment of the application, the signal calibration system ensures the validity and reliability of the calibration table through the above-mentioned verification mechanism, avoids abnormal equipment output due to calibration errors, and ensures the stability of the plasma etching process.

[0070] In some embodiments, the constant current output unit outputs a drive current, which flows through a corresponding coil to generate a corresponding voltage. The constant current output unit detects this voltage, and the signal calibration system can perform overvoltage protection or voltage closed-loop control functions based on the detected voltage. However, inaccurate detection may lead to false protection (protection triggered under normal conditions) or failure to protect (no action taken during overvoltage), endangering equipment safety. Therefore, the signal calibration system also needs to perform voltage calibration to ensure that the constant current output unit can accurately detect the voltage.

[0071] Specifically, the host computer 13 generates M2 current output commands based on M2 calibration voltages and sequentially sends these commands to the target constant current output unit. The target constant current output unit outputs a corresponding second driving current based on each current output command. This second driving current flows through the electronic load instrument 12 to generate an output voltage. The target constant current output unit detects this output voltage, generates a corresponding voltage register value, and uploads this voltage register value to the host computer 13. The electronic load instrument 12 detects the output voltage and outputs the corresponding measured voltage, which is then uploaded to the host computer 13. When the measured voltage reaches the calibration voltage, the host computer 13 generates a second mapping table based on the measured voltage and the corresponding voltage register value. This second mapping table represents a one-to-one mapping relationship between the voltage register value and the measured voltage.

[0072] The voltage calibration process is similar to the current calibration process. The host computer 13 calibrates the N constant current output units one by one, and for each target constant current output unit, the host computer 13 performs a complete calibration process.

[0073] Before calibration, the host computer 13 needs to reset the target resistance value of the electronic load instrument 12. First, the host computer 13 acquires M2 preset calibration voltage values, which uniformly cover the entire voltage detection range, for example, from 0V to the maximum detection voltage. According to Ohm's law and in conjunction with the target resistance value of the electronic load instrument 12, the host computer 13 converts each calibration voltage into a corresponding current output command, thereby obtaining M2 current output commands.

[0074] In some embodiments, the host computer 13 sequentially sends M2 current output commands to the target constant current output unit via the communication unit 14. The control unit 1111 in the target constant current output unit receives the current output command and generates a corresponding second control signal based on each current output command, so that the power unit in the target constant current output unit outputs a corresponding second drive current based on the second control signal.

[0075] Simultaneously, the control unit 1111 acquires the output voltage of the electronic load instrument 12 in real time and generates the corresponding voltage register value after analog-to-digital conversion. The voltage register value is the digital value generated after analog-to-digital conversion of the acquired analog voltage. This digital value is stored in a specific register inside the control unit 1111 for software to read.

[0076] The second driving current flows through the electronic load instrument 12 to generate a voltage, called the output voltage. The electronic load instrument 12 detects this output voltage in real time and generates a measured voltage. The measured voltage gradually stabilizes to the calibration voltage. When the measured voltage reaches the calibration voltage, the host computer 13 records the measured voltage at the current moment and the voltage register value reported by the target constant current output unit. The host computer 13 establishes a one-to-one mapping relationship between the two and generates a second mapping table. This second mapping table is the voltage calibration table. This second mapping table is used to convert the voltage register value inside the target constant current output unit during subsequent normal operation into the calibrated detection voltage, thereby eliminating the inherent nonlinear deviation of the voltage detection circuit in the target constant current output unit.

[0077] Therefore, through the above methods, this signal calibration system can perform voltage calibration. Furthermore, by introducing an external high-precision electronic load as a calibration benchmark, the system ensures that the authenticity of all calibration data is traceable to national metrological standards, fundamentally solving the problem that relying solely on internal closed-loop self-testing cannot guarantee absolute accuracy. Simultaneously, centralized control of the equipment and instruments by the host computer automates the calibration process, improving calibration efficiency and eliminating the need for unpacking the device, thus enhancing the convenience of calibration.

[0078] In some embodiments, during voltage calibration, the initial measured voltage often deviates from the calibration voltage due to the accuracy of the second drive current output by the target constant current output unit and the slight error in the resistance of the electronic load 12. Therefore, the host computer 13 employs a closed-loop adjustment strategy to ensure that the final measured voltage reaches the calibration voltage.

[0079] Specifically, the host computer 13 receives the measured voltage sent by the electronic load instrument 12, subtracts the measured voltage from the calibration voltage to obtain the voltage deviation, performs PID calculation on the voltage deviation, and adjusts the current output command according to the result of the PID calculation until the measured voltage reaches the calibration voltage.

[0080] The host computer 13 compares the measured voltage with the calibration voltage. If the voltage deviation exceeds the allowable range, it dynamically adjusts the current output command based on the voltage deviation and resends it to the target constant current output unit until the measured voltage measured by the electronic load instrument 12 stably reaches the calibration voltage. This closed-loop adjustment process can be executed repeatedly to ensure that the measured voltage accurately converges to the calibration voltage.

[0081] In some embodiments, the host computer 13 may also use a successive approximation method to dynamically adjust the current output command, so that the measured voltage gradually approaches the calibration voltage.

[0082] Therefore, the closed-loop regulation operation described above can eliminate the deviation caused by the gradual mapping error between the current output command and the output voltage under open-loop control (such as load resistance drift, module output nonlinearity, etc.), ensuring the accuracy and reliability of the voltage detection calibration benchmark. Furthermore, the closed-loop regulation automatically compensates for the effects of changes in external conditions, such as slight fluctuations in the resistance of the electronic load instrument 12 and drift in the module output characteristics caused by changes in ambient temperature, ensuring that the calibration voltage can be stably reached under different operating conditions, thus improving the reliability and consistency of the calibration process. Simultaneously, only when the measured voltage accurately reaches the calibration voltage does the voltage register value recorded by the host computer 13 have a true and valid correspondence, thereby ensuring that the generated second mapping table can truly reflect the mapping relationship between the internal detection value of the constant current output unit and the actual voltage, ultimately improving the overall accuracy of the voltage detection of the constant current source device.

[0083] In some embodiments, if the maximum value among the M2 calibration voltages is greater than the overvoltage protection threshold of the target constant current output unit, the host computer 13 will disable the overvoltage protection function of the target constant current output unit before issuing the M2 current output commands in sequence.

[0084] To ensure the calibration accuracy of voltage detection across the entire range (including the critical region near and above the overvoltage protection threshold), the maximum calibration voltage must be set higher than the protection threshold to obtain complete mapping data. Simultaneously, if the output voltage reaches or exceeds the protection threshold during calibration, the module's protection logic will trigger an interruption process, preventing subsequent high-voltage points from being calibrated. Therefore, the overvoltage protection function must be temporarily disabled before calibration begins to ensure continuous calibration.

[0085] The above method enables accurate calibration across the entire voltage detection range, avoiding calibration blind spots near the protection threshold. It also ensures the continuity and reliability of the calibration process, preventing interruptions or repeated restarts due to false protection triggers. Reactivating the protection function after calibration does not affect the safety of the equipment during actual operation.

[0086] In some embodiments, after calibration is completed, a re-verification is required to check whether the second mapping table is correct. Specifically, during the verification phase after calibration, the target constant current output unit receives M2 current output commands sequentially issued by the host computer 13. For each current output command, the target constant current output unit reads the corresponding target voltage register value. Then, the target constant current output unit queries the second mapping table to obtain the target measured voltage that matches the target voltage register value. Finally, the target measured voltage is uploaded to the host computer 13 so that the host computer 13 can re-verify the second mapping table based on the calibration voltage corresponding to the current output command and the corresponding target measured voltage.

[0087] For example, suppose five calibration voltage points are set during the voltage calibration phase: 5V, 10V, 15V, 20V, and 25V. The 25V voltage exceeds the overvoltage protection threshold of 20V. After calibration, the host computer 13 enters the verification phase, sending the same five current output commands (corresponding to 5V, 10V, 15V, 20V, and 25V) sequentially to the target constant current output unit. For the 15V calibration point, the target constant current output unit outputs a second drive current based on the received current output command. This current flows through the electronic load instrument 12 to generate an output voltage, and its internal voltage detection circuit reads a voltage register value of 712 (this value is the uncalibrated raw digital value).

[0088] Subsequently, the target constant current output unit uses 712 as the key value to look up the value in the generated second mapping table (voltage calibration table). If the second mapping table already establishes a mapping relationship between register value 701 and 14.98V, and 720 and 15.02V, then the target measured voltage corresponding to 712 is obtained as 15.01V through linear interpolation. The target constant current output unit uploads this target measured voltage to the host computer 13. The host computer 13 compares the target measured voltage of 15.01V with the calibration voltage of 15V, calculates the absolute error as 0.01V and the relative error as 0.067%, which is within the preset allowable range of ±0.1V or ±1%, and determines that the retest at this point has passed.

[0089] After verifying all five points sequentially, if the errors at each point meet the requirements, the host computer 13 confirms that the second mapping table is correct and valid, and it can be officially put into use. If the error at any point exceeds the limit, the host computer 13 determines that the verification has failed and prompts for recalibration or hardware inspection. This verification mechanism ensures the reliability and accuracy of voltage calibration.

[0090] Therefore, by conducting a retest after calibration, the correctness and reliability of the second mapping table can be effectively verified, avoiding voltage detection deviations caused by abnormal data acquisition or incorrect mapping calculations during calibration. The retest process compares each calibrated voltage individually, accurately locating voltage ranges that fail calibration, providing a basis for recalibration or hardware repair. Furthermore, the equipment can only be put into use after passing the retest, ensuring that the voltage detection accuracy of the constant current source meets process requirements in actual operation. This reduces the risk of overvoltage protection malfunctions or failures due to calibration errors, improving the overall safety and production stability of the equipment.

[0091] To provide a more detailed description of the signal calibration system of this application embodiment, the complete calibration and testing process of the signal calibration system is described below in conjunction with the host computer operation interface.

[0092] Suppose a plasma etching machine is equipped with an 8-channel programmable constant current source. The fifth constant current output unit needs to be calibrated. First, the user connects an electronic load to the output of the fifth channel via a power cable and connects the electronic load's communication interface to a host computer. Simultaneously, the host computer is connected to the debugging serial port on the back of the device chassis via a serial cable. After the hardware connection is complete, the user opens the calibration software on the host computer.

[0093] The software displays the following after startup: Figure 6 The "Parameter Setting" interface is shown. The user selects the channel number to be calibrated in the multi-board calibration channel selection box, for example, "Channel 5". Then, in the calibration parameter interface, the user sets the calibration current range to 0–21A, the number of calibration points to 22, the electronic load instrument's operating mode to constant resistance RC mode, and the resistance value to 0.3Ω. Calibration current 1 is 1A, calibration current 2 is 19A, and calibration current 3 is 21A, indicating the calibration current ranges are (0–1A), (1–19A), and (19–21A). The host computer automatically sends mode switching and resistance configuration commands to the electronic load instrument via the communication interface, configuring the electronic load instrument to the specified constant resistance RC mode and setting the resistance value to 0.3Ω. Simultaneously, the host computer generates 22 calibration currents based on the set range and number of points, for example, calibration currents of 0A, 1.0526A, 2.1053A, ..., 21A.

[0094] Figure 7 The interface shows channel settings and open-loop enable settings. Users can configure each module before calibration to ensure proper calibration.

[0095] After setting the calibration parameters, click the "Start Test" button, and the software will start the automatic calibration process. The host computer first sends an erase Flash command to the 5th constant current output unit via the communication unit, initializing its internally stored default parameters. Then, the host computer begins sending calibration currents point by point. For the first calibration point 0A, the host computer sends the calibration current value to the control unit of the 5th constant current output unit via the communication unit. The control unit, based on its internally pre-stored default first mapping table, generates the corresponding DAC setting code through linear interpolation and sends the first control signal to the power unit. The power unit outputs the corresponding first drive current. This first drive current is measured in real time by the electronic load instrument, obtaining the measured current. The electronic load instrument reports the measured current (e.g., 0.003A) to the host computer via the communication interface. Simultaneously, the control unit acquires this first drive current, generates the corresponding ADC sampling code (e.g., 12), and reports it to the host computer via the communication unit. The host computer associates and stores the received ADC sampling code, DAC setting code, and the measured current value fed back by the electronic load instrument.

[0096] After the first calibration point is completed, the host computer automatically sends the second calibration current of 1.0526A. The above process is repeated until all 22 calibration points are completed.

[0097] After all 22 points are calibrated, the host computer automatically generates two calibration tables based on the 22 sets of collected data: one is the ADC calibration table, which establishes the mapping relationship between the ADC sampling code and the measured current, and the other is the DAC calibration table, which establishes the mapping relationship between the measured current and the DAC setting code.

[0098] Subsequently, the host computer sends these two calibration tables to the control unit of the 5th constant current output unit through the communication unit. The control unit writes them into the Flash memory, replacing the original default first mapping table.

[0099] Users Figure 8 The full table query interface shown allows you to view detailed data tables for 22 calibration points, including calibration current, ADC sampling code, DAC setting code, and measured current value, to confirm the reasonableness of the calibration results. You can also query the ADC calibration table and DAC calibration table, and perform operations such as reading, writing, deleting, importing, and exporting the two calibration tables.

[0100] In some embodiments, during the current calibration process, the system continuously acquires each calibration current at a high frequency (e.g., 100 to 1000 times per second), records the measured current value fed back by the electronic load instrument in real time, dynamically generates a current oscillation curve, and simultaneously plots the curves before and after calibration for comparison. The plotting page is shown below. Figure 9 As shown, by analyzing steady-state fluctuation amplitude, dynamic response characteristics (such as overshoot and oscillation time), and abnormal features in the curves (such as glitches and drift), the system can effectively screen out constant current source devices or current output units within constant current source devices that have unstable current output, poor dynamic response, or hardware defects. Modules with excessive fluctuations, abnormal responses, or obvious abnormalities are judged as hardware unqualified and eliminated. This allows for simultaneous hardware quality screening during the calibration process, ensuring product output accuracy and stability while improving production efficiency and yield.

[0101] In some embodiments, to ensure calibration accuracy, the host computer again sends the same 22 calibration current values ​​to the 5th constant current output unit. However, this time, the control unit no longer uses the default first mapping table, but directly uses the newly generated DAC calibration table to obtain the DAC setting code and drive the power unit output current. Simultaneously, the control unit acquires the ADC sampling code and uses the newly generated ADC calibration table to find the corresponding measured current, reporting this value to the host computer. The host computer compares the reported value with the originally sent calibration current point by point and displays the verification result on the operation interface. Finally, if the operation interface displays "Verification passed, maximum error 0.05%", it indicates that the output accuracy of the calibrated 5th constant current output unit meets the process requirements across the entire range.

[0102] The entire process can be completed without opening the device chassis, simply by connecting the debugging serial port, which is quick and greatly simplifies maintenance operations.

[0103] The host computer automatically sends a resistance configuration command to the electronic load instrument via the communication interface, setting the resistance of the electronic load instrument to a preset value (e.g., 1Ω). At the same time, the host computer generates a corresponding calibration voltage sequence based on the set voltage calibration range and the number of calibration points, such as calibration voltages of 0V, 6.25V, 12.5V, 18.75V, and 25V, where 25V exceeds the overvoltage protection threshold.

[0104] Subsequently, the host computer enters the voltage calibration process. First, the overvoltage protection function of the 5th constant current output unit is disabled; it is then re-enabled during actual use of the constant current device. For each calibration voltage, the host computer generates a corresponding current output command based on Ohm's law and sends it sequentially to the 5th constant current output unit via the communication unit. Upon receiving the command, the 5th constant current output unit outputs the corresponding second drive current, which flows through the constant resistance load of the electronic load instrument to generate an output voltage. The electronic load instrument monitors this output voltage in real time and reports the measured voltage value to the host computer. Simultaneously, the voltage detection circuit inside the 5th constant current output unit acquires the output voltage, generates the corresponding voltage register value, and uploads it to the host computer. The host computer compares the measured voltage with the current calibration voltage. If the deviation exceeds the allowable range, the current output command is dynamically adjusted based on the deviation, re-issued, and the above process is repeated until the measured voltage stabilizes at the calibration voltage. Once the measured voltage meets the requirements, the host computer establishes a one-to-one mapping relationship between the current measured voltage and the voltage register value, storing it as a second mapping table. After completing all calibration voltages in sequence, the host computer sends the second mapping table to the fifth constant current output unit and writes it into Flash, which is used to convert the voltage register value into the calibrated detection voltage during subsequent operation.

[0105] The host computer initiates the re-verification process, again sending M2 current output commands (e.g., corresponding to the five calibration voltage points of 0V, 6.25V, 12.5V, 18.75V, and 25V) sequentially to the 5th constant current output unit via the communication unit, identical to those in the voltage calibration phase. For each sent current output command, the 5th constant current output unit outputs the corresponding second drive current, which flows through the constant resistance load of the electronic load instrument to generate an output voltage. The voltage detection circuit inside the 5th constant current output unit acquires the output voltage, generates the corresponding voltage register value R_val, and then uses the voltage register value R_val as the key to look up (or calculate through interpolation) the corresponding target measured voltage U_target_measured in the stored second mapping table. Subsequently, the 5th constant current output unit uploads the target measured voltage U_target_measured to the host computer.

[0106] The host computer compares the target measured voltage U_target_measured with the calibration voltage U_cal (i.e., the set value, such as 6.25V) corresponding to the current output command, calculates the absolute error ΔU = |U_target_measured - U_cal| and the relative error δ = (ΔU / U_cal) × 100%, and determines whether it meets the preset accuracy requirements (e.g., relative error ≤ 1% or absolute error ≤ 0.1V). After performing the above comparison for all calibration voltage points, if the error at each point is within the allowable range, the host computer determines that the re-verification is successful, the second mapping table officially takes effect, and the voltage detection accuracy of the 5th constant current output unit meets the process requirements. If the error at any point exceeds the limit, the re-verification is deemed a failure, and the host computer prompts that recalibration or hardware inspection is required. Through this re-verification process, the accuracy of the voltage calibration table in mapping the voltage register value to the target measured voltage is directly verified, ensuring that the calibrated voltage detection value is consistent with the set target.

[0107] In summary, this signal calibration system, by introducing an external high-precision electronic load instrument as the calibration benchmark, ensures that the authenticity of all calibration data is traceable to national metrological standards, fundamentally solving the deficiency that relying solely on internal closed-loop self-testing cannot guarantee absolute accuracy. Simultaneously, the centralized control of equipment and instruments by the host computer automates the calibration process, improving calibration efficiency and eliminating the need for unpacking for calibration, thus enhancing convenience.

[0108] As another aspect of the embodiments of this application, the following embodiments of this application provide a signal calibration method applied to the signal calibration system 100 described in the above embodiments. Figure 10 As shown, the signal calibration method S100 includes: S10: The target constant current output unit receives M1 calibration currents sequentially sent by the host computer, and outputs the corresponding first drive current based on each calibration current, and generates the ADC sampling code and DAC setting code corresponding to the first drive current. The target constant current output unit is any one of the N constant current output units, and M1 and N are both integers greater than 1. S20: The electronic load instrument detects the first drive current and outputs the corresponding measured current; S30: The host computer generates a calibration table based on the measured current and the corresponding ADC sampling code and DAC setting code, and sends the calibration table to the target constant current output unit. The calibration table includes an ADC calibration table and a DAC calibration table.

[0109] In this embodiment, the signal calibration method introduces an external high-precision electronic load instrument as a calibration benchmark, ensuring that the authenticity of all calibration data is traceable to national metrological standards. This fundamentally solves the problem that relying solely on internal closed-loop self-testing cannot guarantee absolute accuracy. Simultaneously, the centralized control of the equipment and instruments by the host computer automates the calibration process, improving calibration efficiency and eliminating the need for unpacking the equipment, thus enhancing the convenience of calibration.

[0110] In some embodiments, each constant current output unit includes a control unit and a power unit connected in communication. The signal calibration method further includes: the control unit in the target constant current output unit receives M1 calibration currents sent by the host computer, generates a corresponding DAC setting code based on each calibration current, and generates a corresponding first control signal based on the DAC setting code; the power unit in the target constant current output unit receives the first control signal and outputs a corresponding first drive current based on the first control signal, so that the control unit collects the first drive current and generates the ADC sampling code corresponding to the first drive current.

[0111] The process of generating the corresponding DAC setting code based on each calibration current specifically includes: obtaining a pre-stored first mapping table, wherein the first mapping table represents a one-to-one mapping relationship between setting currents and DAC preset codes; querying the first setting current and the second setting current that match the calibration current from the first mapping table, wherein the calibration current is greater than or equal to the first setting current and the calibration current is less than or equal to the second setting current; querying the first DAC preset code corresponding to the first setting current and the second DAC preset code corresponding to the second setting current from the first mapping table; and generating the DAC setting code based on the calibration current, the first setting current and the corresponding first DAC preset code, the second setting current and the corresponding second DAC preset code, using a linear interpolation method.

[0112] Specifically, the DAC setting code is generated using a linear interpolation method based on the calibration current, the first set current and the corresponding first DAC preset code, and the second set current and the corresponding second DAC preset code. This includes: The DAC setting code is calculated using the following formula: DAval=DAarr+(Icnt-Iarr) / (Iarr_next-Iarr)×(DAarr_next-DAarr); Wherein, DAval is the DAC setting code, Icnt is the calibration current, Iarr is the first setting current, Iarr_next is the second setting current, DAarr is the first DAC preset digital code, and DAarr_next is the second DAC preset digital code.

[0113] In some embodiments, the signal calibration method further includes: The host computer loads preset calibration parameters, which include a calibration current range and a calibration point number M1. The host computer divides the calibration current range into K calibration current intervals, where K is an integer greater than or equal to 3. Based on the K calibration current intervals and the calibration point number M1, the host computer generates M1 calibration currents.

[0114] In some embodiments, the preset calibration parameters further include the target operating mode and target resistance value of the electronic load, wherein the target operating mode is a constant resistance RC mode, and the signal calibration method further includes: The host computer generates a mode switching instruction based on the target operating mode and sends the mode switching instruction to the electronic load device, so that the electronic load device switches its own operating mode to the target operating mode according to the mode switching instruction; the host computer generates a resistance configuration instruction based on the target resistance value and sends the resistance configuration instruction to the electronic load device, so that the electronic load device sets its own operating resistance to the target resistance value according to the resistance configuration instruction.

[0115] Specifically, generating a calibration table based on the measured current, the ADC sampling code corresponding to the measured current, and the DAC setting code includes: establishing a one-to-one mapping relationship between the measured current and the corresponding ADC sampling code to generate the ADC calibration table; and establishing a one-to-one mapping relationship between the measured current and the corresponding DAC setting code to generate the DAC calibration table.

[0116] In some embodiments, the signal calibration method further includes: The target constant current output unit receives M1 calibration currents sequentially sent by the host computer. For each calibration current, the target constant current output unit calculates the corresponding target DAC setting code based on the DAC calibration table, and outputs the corresponding target first drive current based on the target DAC setting code. The target constant current output unit samples the target first drive current, generates the corresponding measured ADC sampling code, and retrieves the target measured current corresponding to the measured ADC sampling code from the ADC calibration table. The target constant current output unit uploads the target measured current to the host computer, so that the host computer can re-verify the calibration table based on the calibration current and the corresponding target measured current.

[0117] In some embodiments, the constant current source device further includes a communication unit, and the signal calibration method further includes: the communication unit receiving the number information of the target constant current output unit and M1 calibration currents sent by the host computer, and forwarding the M1 calibration currents sequentially to the corresponding target constant current output unit based on the number information.

[0118] In some embodiments, such as Figure 11 As shown, the signal calibration method S100 further includes: S40: The target constant current output unit receives M2 current output commands sequentially issued by the host computer, and outputs the corresponding second drive current based on each current output command, and detects the output voltage to generate the corresponding voltage register value. The output voltage is the voltage generated by the second drive current flowing through the electronic load instrument, the current output command is the command generated by the host computer based on the calibration voltage, and the target constant current output unit is any one of the N constant current output units. M2 and N are both integers greater than 1. S50: The electronic load tester detects the output voltage and outputs the corresponding measured voltage. S60: When the measured voltage reaches the calibration voltage, the host computer generates a second mapping table based on the measured voltage and the voltage register value corresponding to the measured voltage, and sends the second mapping table to the target constant current output unit. The second mapping table represents the one-to-one mapping relationship between the voltage register value and the measured voltage.

[0119] Therefore, this signal calibration method, by introducing an external high-precision electronic load instrument as the calibration benchmark, ensures that the authenticity of all calibration data is traceable to national metrological standards, fundamentally solving the deficiency that relying solely on internal closed-loop self-testing cannot guarantee absolute accuracy. Simultaneously, centralized control of the equipment and instruments by the host computer automates the calibration process, improving calibration efficiency, and eliminating the need for unpacking the equipment, thus enhancing the convenience of calibration.

[0120] In some embodiments, the control unit in the target constant current output unit receives M2 current output commands issued by the host computer and generates a corresponding second control signal based on each current output command; The power unit in the target constant current output unit receives the second control signal and outputs the corresponding second drive current based on the second control signal.

[0121] In some embodiments, the control unit in the target constant current output unit acquires the output voltage on the electronic load instrument in real time, and generates the corresponding voltage register value after analog-to-digital conversion.

[0122] In some embodiments, the host computer receives the measured voltage sent by the electronic load instrument; The host computer subtracts the measured voltage from the calibration voltage to obtain the voltage deviation, performs PID calculation on the voltage deviation, and adjusts the current output command according to the result of the PID calculation until the measured voltage reaches the calibration voltage.

[0123] In some embodiments, if the maximum value among the M2 calibration voltages is greater than the overvoltage protection threshold of the target constant current output unit, the host computer disables the overvoltage protection function of the target constant current output unit before sequentially issuing the M2 current output commands.

[0124] In some embodiments, during the verification phase after calibration, the target constant current output unit receives M2 current output commands sequentially issued by the host computer again, and reads the corresponding target voltage register value for each current output command. The target constant current output unit retrieves the target measured voltage that matches the target voltage register value from the second mapping table; The target constant current output unit uploads the target measured voltage to the host computer, so that the host computer can verify the second mapping table based on the calibration voltage corresponding to the current output command and the corresponding target measured voltage.

[0125] It should be noted that in the above embodiments, there is no necessarily a certain order between the steps. Those skilled in the art can understand from the description of the embodiments of this application that the above steps may have different execution orders in different embodiments, that is, they may be executed in parallel or in turn, etc.

[0126] Since the signal calibration method described above is based on the same inventive concept as the signal calibration system 100 in the above embodiments, the corresponding content in the above system embodiments is also applicable to the method embodiments, and will not be described in detail here.

[0127] In summary, this signal calibration method, by introducing an external high-precision electronic load instrument as the calibration benchmark, ensures that the authenticity of all calibration data is traceable to national metrological standards, fundamentally solving the deficiency that relying solely on internal closed-loop self-testing cannot guarantee absolute accuracy. Simultaneously, centralized control of the equipment and instruments by the host computer automates the calibration process, improving calibration efficiency and eliminating the need for unpacking the equipment, thus enhancing the convenience of calibration.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above, which are not provided in detail for the sake of brevity; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A signal calibration system for use in a plasma etching machine, characterized in that, The signal calibration system includes: a constant current source device, an electronic load instrument, and a host computer; The constant current source device includes N constant current output units. The target constant current output unit among the N constant current output units is communicatively connected to the host computer and the electronic load instrument. The target constant current output unit is configured to receive M1 calibration currents sequentially sent by the host computer, and output a corresponding first drive current based on each calibration current, and generate an ADC sampling code and a DAC setting code corresponding to the first drive current. The target constant current output unit is any one of the N constant current output units, and M1 and N are both integers greater than 1. The electronic load instrument is configured to detect the first drive current and output the corresponding measured current. The host computer is also connected to the electronic load instrument and is configured to generate a calibration table based on the measured current and the ADC sampling code and DAC setting code corresponding to the measured current, and send the calibration table to the target constant current output unit. The calibration table includes an ADC calibration table and a DAC calibration table.

2. The signal calibration system according to claim 1, characterized in that, Each of the constant current output units includes a control unit and a power unit that are connected in communication. The control unit in the target constant current output unit is also connected to the host computer and is configured to receive M1 calibration currents sent by the host computer, generate a corresponding DAC setting code based on each calibration current, and generate a corresponding control signal based on the DAC setting code. The power unit in the target constant current output unit is also communicatively connected to the electronic load instrument and is configured to receive the control signal and output the corresponding first drive current based on the control signal, so that the control unit can collect the first drive current and generate the ADC sampling code corresponding to the first drive current.

3. The signal calibration system according to claim 2, characterized in that, Based on each calibration current, a corresponding DAC setting code is generated, specifically including: Obtain a pre-stored mapping table, wherein the mapping table represents a one-to-one mapping relationship between the set current and the preset digital code of the DAC; The first set current and the second set current that match the calibration current are obtained by querying the mapping table, wherein the calibration current is greater than or equal to the first set current and the calibration current is less than or equal to the second set current; The first DAC preset digital code corresponding to the first set current and the second DAC preset digital code corresponding to the second set current are obtained by querying the mapping table. Based on the calibration current, the first set current and the corresponding first DAC preset code, the second set current and the corresponding second DAC preset code, the DAC setting code is generated by linear interpolation.

4. The signal calibration system according to claim 3, characterized in that, Based on the calibration current, the first set current and the corresponding first DAC preset code, the second set current and the corresponding second DAC preset code, the DAC setting code is generated through linear interpolation, specifically including: The DAC setting code is calculated using the following formula: DAval=DAarr+(Icnt-Iarr) / (Iarr_next-Iarr)×(DAarr_next-DAarr); Wherein, DAval is the DAC setting code, Icnt is the calibration current, Iarr is the first setting current, Iarr_next is the second setting current, DAarr is the first DAC preset digital code, and DAarr_next is the second DAC preset digital code.

5. The signal calibration system according to claim 1, characterized in that, The host computer is also configured to: Load preset calibration parameters, wherein the preset calibration parameters include calibration current range and number of calibration points M1; The calibration current range is divided into K calibration current intervals, where K is an integer greater than or equal to 3; Based on the K-segment calibration current range and the number of calibration points M1, M1 calibration currents are generated.

6. The signal calibration system according to claim 5, characterized in that, The preset calibration parameters also include the target operating mode and target resistance value of the electronic load instrument, wherein the target operating mode is a constant resistance RC mode; The host computer is also configured to: A mode switching instruction is generated based on the target operating mode, and the mode switching instruction is sent to the electronic load instrument so that the electronic load instrument switches its own operating mode to the target operating mode according to the mode switching instruction; A resistance configuration instruction is generated based on the target resistance value, and the resistance configuration instruction is sent to the electronic load instrument so that the electronic load instrument sets its own operating resistance to the target resistance value according to the resistance configuration instruction.

7. The signal calibration system according to claim 1, characterized in that, A calibration table is generated based on the measured current, the ADC sampling code corresponding to the measured current, and the DAC setting code, specifically including: Establish a one-to-one mapping relationship between the measured current and the corresponding ADC sampling code to generate the ADC calibration table; A one-to-one mapping relationship is established between the measured current and the corresponding DAC setting code to generate the DAC calibration table.

8. The signal calibration system according to claim 1, characterized in that, The target constant current output unit is further configured as follows: The system then receives M1 calibration currents sequentially sent by the host computer. For each calibration current, the corresponding target DAC setting code is calculated based on the DAC calibration table, and the corresponding target drive current is output based on the target DAC setting code; The target driving current is sampled to generate a corresponding measured ADC sampling code, and the target measured current corresponding to the measured ADC sampling code is obtained from the ADC calibration table. The target measured current is uploaded to the host computer so that the host computer can re-verify the calibration table based on the calibration current and the corresponding target measured current.

9. The signal calibration system according to any one of claims 1-8, characterized in that, The constant current source device also includes a communication unit, which is communicatively connected to the host computer and each of the constant current output units. The communication unit is configured to receive the number information of the target constant current output unit and M1 calibration currents sent by the host computer, and based on the number information, forward the M1 calibration currents sequentially to the corresponding target constant current output unit.

10. A signal calibration method, characterized in that, Applied to the signal calibration system as described in any one of claims 1-9, the method comprises: The target constant current output unit receives M1 calibration currents sequentially sent by the host computer, and outputs a corresponding first drive current based on each calibration current, and generates an ADC sampling code and a DAC setting code corresponding to the first drive current. The target constant current output unit is any one of the N constant current output units, and M1 and N are both integers greater than 1. The electronic load instrument detects the first driving current and outputs the corresponding measured current. The host computer generates a calibration table based on the measured current, the ADC sampling code and the DAC setting code corresponding to the measured current, and sends the calibration table to the target constant current output unit. The calibration table includes an ADC calibration table and a DAC calibration table.

Images