Method and system for correcting multi-path signal conversion channel of semiconductor scanning electron microscope

Abstract

The invention provides a method and a system for correcting multiple signal conversion channels of a semiconductor scanning electron microscope, and relates to component correction of the semiconductor scanning electron microscope. The correction method comprises the following steps: controlling a standard signal source to provide a standard signal sequence; signal conversion is carried out through a reference conversion channel, and a reference measurement value sequence is obtained; fitting a benchmark reference curve according to the benchmark measurement value sequence, and generating a compensation parameter of a benchmark conversion channel by using the benchmark reference curve based on the benchmark measurement value sequence; performing signal conversion on the standard signal sequence path by path through multiple paths of conversion channels to be calibrated, and obtaining multiple paths of measured value sequences to be calibrated; and based on each path of calibrated measurement value sequence, using the benchmark reference curve to respectively generate compensation parameters of each path of calibrated conversion channel. According to the scheme, a unified correction reference is provided, the problem of reference difference caused by independent correction of each channel is avoided, and distortion of a detection image of the semiconductor scanning electron microscope caused by signal conversion is avoided.

Description

Technical Field

[0001] This invention relates to component calibration of a semiconductor scanning electron microscope (SEM), and particularly to a calibration method and system for a multi-channel signal conversion channel of a semiconductor SEM. Background Technology

[0002] The semiconductor scanning electron microscope (SEM) is an indispensable core precision instrument in the field of semiconductor manufacturing and inspection. It generates high-resolution microscopic images of samples based on the interaction between the electron beam and the sample surface (such as secondary electron emission and backscattered electrons). It can control key aspects such as nanoscale defect detection, circuit structure characterization, and dimensional accuracy measurement of semiconductor devices such as wafers and chips, and directly affects the yield and performance reliability of semiconductor products.

[0003] The imaging and measurement accuracy of SEM (Sequencing Electron Microscopy) hinges on the precise control of the scanning electron beam. Specifically, the SEM scanning system outputs multiple scanning signals to drive electrodes in the electron optics system, generating a controllable electromagnetic field that guides the electron beam to scan the sample along a preset trajectory. To ensure the uniformity, positional accuracy, and stability of the scanning range, the multiple scanning signals must be processed through a series of signal conversion channels (such as digital-to-analog converters) before being transmitted to the execution components. Therefore, the signal processing accuracy of the scanning signal conversion channels is a crucial factor affecting the quality of SEM imaging.

[0004] In practical applications, SEM scanning systems typically employ multiple parallel signal conversion channels to achieve two-dimensional or multi-dimensional electron beam scanning control. However, due to inherent hardware differences in these multiple conversion channels and drift during use, the processing characteristics of different channels for the same scanning signal deviate. Specifically, the amplitude of the output signal differs after the same input signal is processed by different conversion channels, leading to image distortion. Therefore, SEM requires calibration of these multiple conversion channels. Existing calibration methods generally involve calibrating the input-output characteristics of the conversion channels to a standard signal curve using signal measurements. However, the standard signal curve may differ significantly from the inherent signal characteristics of the conversion channels, making calibration during signal conversion difficult. Furthermore, manual calibration is time-consuming and inefficient. Summary of the Invention

[0005] One objective of this invention is to improve the correction efficiency of the multiplexed signal conversion channels in a semiconductor scanning electron microscope.

[0006] A further objective of this invention is to ensure the consistency of the multiple signal conversion channels in a semiconductor scanning electron microscope.

[0007] Specifically, the present invention provides a method for correcting multiple signal conversion channels of a semiconductor scanning electron microscope, comprising: Start the standard signal source and control the standard signal source to provide a standard signal sequence; The standard signal sequence is converted using a reference conversion channel, and the measured values ​​of the converted signal are obtained to obtain a reference measurement value sequence. A reference curve is fitted based on the reference measurement value sequence, and the compensation parameters of the reference conversion channel are generated based on the reference measurement value sequence and the reference reference curve. The compensation parameters of the reference conversion channel are used to correct the output signal of the reference conversion channel when processing the scan signal to ensure that the error of the corresponding value of the reference reference curve is less than the set error threshold. The standard signal sequence is converted one by one through multiple calibration conversion channels, and the measured value of the converted signal is obtained to obtain a multi-channel calibration measurement value sequence. Based on the measurement value sequence of each channel being calibrated, compensation parameters for each calibrated conversion channel are generated using a reference curve. The compensation parameters for each calibrated conversion channel are used to correct the output signal of each calibrated conversion channel when processing the scanning signal to ensure that the error between the output signal and the corresponding value of the reference curve is less than the error threshold.

[0008] Furthermore, the steps for controlling the standard signal source to output a standard signal sequence include: Obtain the full-scale range of the input signal value of the reference conversion channel; Select the calibration interval within the full-scale range; The standard signal source is controlled to output signals sequentially within the correction range with a set step size, forming a standard signal sequence.

[0009] Furthermore, the steps for selecting the calibration interval within the full-scale range include: The entire full-scale range is used as the correction interval, and the standard signal sequence uses the minimum and maximum values ​​of the input signal value range as the starting and ending signal values, respectively.

[0010] Further, the step of selecting the correction interval within the full-scale range includes: The default setting for obtaining the scanning signal from a semiconductor scanning electron microscope; The range of input signal values ​​corresponding to the default gear is used as the correction range.

[0011] Furthermore, after selecting the correction interval, the following is also included: Obtain the number of measurement points required for calibration; The step size is set according to the ratio of the length of the calibration interval to the number of measurement points.

[0012] Furthermore, the reference curve is a linear curve passing through the origin of the coordinate system, and the step of fitting the reference curve based on the reference measurement value sequence includes: A linear fit is performed on the benchmark measurement sequence through the origin to obtain the benchmark reference curve.

[0013] Furthermore, the steps for signal conversion of the standard signal sequence through the reference conversion channel include: Connect the interface between the standard signal source and the input terminal of the reference conversion channel, and use a switching switch to connect the output terminal of the reference conversion channel to the signal measurement device, whereby the reference conversion channel completes the signal conversion.

[0014] Furthermore, the steps of performing signal conversion on the standard signal sequence one by one through multiple calibration conversion channels include: Connect the standard signal source to the interface of each calibrated conversion channel one by one, and use a switching switch to connect the output of each calibrated conversion channel to the signal measurement device, and then each calibrated conversion channel completes the signal conversion one by one.

[0015] According to another aspect of the present invention, a calibration system for a multiplexed signal conversion channel of a semiconductor scanning electron microscope is also provided, comprising: A standard signal source, configured to provide a standard signal sequence to the reference conversion channel and the conversion channel being calibrated; A signal measuring device configured to measure the output signals of the reference conversion channel and the calibration conversion channel; The calibration host is signal connected to a standard signal source and a signal measuring device respectively, and includes a memory, a processor and a computer program stored in the memory and running on the processor, and the processor executes the computer program to implement the steps of the calibration method for the multiple signal conversion channel according to any of the above.

[0016] Furthermore, the correction system for the multiple signal conversion channels of the aforementioned semiconductor scanning electron microscope also includes: A switch is connected to the calibration host signal and configured to controllably connect the outputs of the reference conversion channel and the conversion channel being calibrated to the signal measurement device.

[0017] The present invention provides a calibration method for multiple signal conversion channels of a semiconductor scanning electron microscope (SEM). This method utilizes a reference conversion channel to provide a unified calibration benchmark for the multiple signal conversion channels, avoiding benchmark differences caused by independent calibration of each channel. Specifically, compensation parameters are generated using a reference curve to achieve precise calibration of the output signals of both the reference channel and the channel being calibrated. This ensures that the output deviation of all channels processing scanning signals is controlled within a set threshold, improving the consistency and accuracy of multi-channel signal conversion and preventing distortion of the SEM's detection images due to signal conversion issues. The calibration process is highly automated, significantly improving efficiency and reducing the complexity of equipment debugging and maintenance.

[0018] Furthermore, the calibration method for the multi-channel signal conversion of the semiconductor scanning electron microscope of the present invention can flexibly select the calibration interval within the full-scale range of the input signal value of the reference conversion channel according to the calibration requirements, thereby improving the precision of data calibration and meeting the application scenario requirements of multi-channel signal conversion of semiconductor scanning electron microscopes.

[0019] Furthermore, the calibration method for the multi-channel signal conversion of the semiconductor scanning electron microscope of the present invention fits a reference curve based on the reference measurement value reflecting the inherent properties of the reference conversion channel, resulting in small calibration deviation, low computational resources required, and a compact calibration system structure.

[0020] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0021] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a schematic diagram of a calibration system for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a calibration method for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention; Figure 3 This is a schematic flowchart of controlling a standard signal source in a calibration method for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention. Figure 4 This is a schematic flowchart illustrating an application example of a calibration method for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention. Figure 5This is a comparison diagram of the input-output characteristic curves before and after coarse calibration of a calibration method for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention. Figure 6 This is a comparison diagram of the input-output characteristic curves before and after fine calibration of a calibration method for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention. Figure 7 This is a schematic diagram of a calibration host in a calibration system for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention. Detailed Implementation

[0022] Figure 1 This is a schematic diagram of a calibration system for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention. The calibration system generally includes: a standard signal source 100, a signal measuring device 300, and a calibration host 400; in some embodiments, a switching switch 210 may also be configured.

[0023] The standard signal source 100 is configured to provide a standard signal sequence to the reference conversion channel and the calibration conversion channel. The standard signal sequence includes a set of standard signals arranged in sequence. For example, when the reference conversion channel and the calibration conversion channel are used for digital-to-analog signal conversion, the standard signals can be a set of digital quantities arranged in order of magnitude. The standard signal source 100 can be a waveform generator (WG), and the standard signals are the source signals for the reference conversion channel and the calibration conversion channel.

[0024] The signal measuring device 300 is configured to measure the output signals of the reference conversion channel and the calibration conversion channel, and the output signal is the conversion result of the reference conversion channel and the calibration conversion channel. During digital-to-analog signal conversion, the output signal is the analog signal obtained by converting the digital quantity. The measurement resolution of the signal measuring device 300 is required to accurately measure the error between the output signal and the reference value; for example, the signal measuring device 300 can use a voltage measuring device with a minimum resolution of 0.1 μV.

[0025] The calibration host 400 is connected to both the standard signal source 100 and the signal measuring device 300. On one hand, the calibration host 400 sends start commands and signal generation commands to the standard signal source 100, controlling it to generate the standard signal required for calibration. On the other hand, the calibration host 400 also acquires the measurement results from the signal measuring device 300 and completes the calibration of the reference conversion channel and the conversion channel being calibrated by executing the multi-channel signal conversion calibration method of this embodiment.

[0026] The switching switch 210 can be connected to the calibration host 400 and configured to controllably connect the outputs of the reference conversion channel and the calibrated conversion channel to the signal measurement device 300. The switching switches 210 can form a calibration module 200. The calibration module 200 has multiple switching switches 210, each corresponding to a reference conversion channel and a calibrated conversion channel; that is, each switching switch 210 corresponds to one conversion channel. The switching switch 210 can be a single-pole double-throw (SPDT) relay, with its common signal input connected to the standard signal source 100, and two sets of switching outputs connected to the calibration and conversion output terminals of the conversion channel, respectively. During the calibration of the conversion channel, the interface connected to the input terminal of the standard signal source 100 is activated, and the output terminal of the conversion channel is connected to the signal measurement device 300 via the switching switch 210. During subsequent scanning by this semiconductor scanning electron microscope, the switching switch 210 connects the output terminal of the conversion channel to the conversion output terminal, thereby providing a scanning signal to the scanning interface 500. The calibration system has a compact structure, requires few computing resources, and can greatly improve the efficiency of conversion channel calibration.

[0027] In some embodiments, when calibrating the conversion channels one by one, the calibration terminals of the conversion channels can be interconnected and ultimately connected to the signal measurement device 300. The switching switch 210 calibrates one channel at a time, first the reference conversion channel, and then calibrates each of the conversion channels to be calibrated, so that the reference conversion channel and the multiple conversion channels to be calibrated have the same conversion characteristics (reference curve), that is, the reference conversion channel and the multiple conversion channels to be calibrated output signals after conversion for the same input are approximately the same.

[0028] This embodiment also provides a method for calibrating the multiple signal conversion channels of a semiconductor scanning electron microscope. Figure 2 This is a schematic diagram of a calibration method for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention. The calibration method for the multiplexed signal conversion channel of the semiconductor scanning electron microscope includes: Step S201: Start the standard signal source and control the standard signal source to provide a standard signal sequence. During digital-to-analog conversion correction, the standard signal sequence is a set of standard digital quantities.

[0029] Step S202: The standard signal sequence is converted using a reference conversion channel, and the measured values ​​of the converted signal are obtained to obtain a reference measurement value sequence. The control process for the reference conversion channel to convert the standard signal sequence can be as follows: the interface connecting the standard signal source to the input terminal of the reference conversion channel is turned on; the output terminal of the reference conversion channel is connected to the signal measurement device via a switching switch; and the reference conversion channel completes the signal conversion.

[0030] Step S203: Fit a reference curve based on the reference measurement value sequence, and generate compensation parameters for the reference conversion channel based on the reference measurement value sequence and the reference reference curve. The compensation parameters for the reference conversion channel are used to correct the output signal of the reference conversion channel when processing the scanning signal to ensure that the error between the output signal and the corresponding value of the reference reference curve is less than a set error threshold. During analog-to-digital conversion correction, the reference reference curve can be a straight line passing through the origin of the coordinate system.

[0031] Step S204: The standard signal sequence is converted one by one through multiple calibration conversion channels, and the measured values ​​of the converted signals are obtained to obtain a multi-channel calibration measurement value sequence. The process of converting the standard signal sequence one by one through multiple calibration conversion channels can be as follows: the interface of each calibration conversion channel is connected to the standard signal source one by one, the output terminal of each calibration conversion channel is connected to the signal measurement device through a switching switch, and the signal conversion is completed one by one by each calibration conversion channel.

[0032] Step S205: Based on the measured value sequences of each channel being calibrated, compensation parameters are generated for each calibrated conversion channel using a reference curve. These compensation parameters are used to correct the output signal of each calibrated conversion channel when processing the scan signal, ensuring the error between the output signal and the corresponding value on the reference curve is less than an error threshold. That is, after correction, all calibrated conversion channels output signals approximately the same as the output signal of the reference conversion channel for the same input signal, and all conversion channels have the same conversion characteristics.

[0033] The calibration method for the multi-channel signal conversion of a semiconductor scanning electron microscope (SEM) in this embodiment utilizes a reference conversion channel to provide a unified calibration benchmark for the multiple signal conversion channels, avoiding benchmark differences caused by independent calibration of each channel. Specifically, compensation parameters are generated using a reference curve to achieve precise calibration of the output signals of the reference channel and the channel being calibrated. This ensures that the output deviation of all channels processing scanning signals is controlled within a set threshold, improving the consistency and accuracy of multi-channel signal conversion and preventing distortion of the SEM's detection images due to signal conversion issues. The calibration process is highly automated, significantly improving efficiency and reducing the complexity of equipment debugging and maintenance.

[0034] Figure 3 This is a schematic flowchart illustrating the control of a standard signal source in a calibration method for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention. The step of controlling the standard signal source to output a standard signal sequence may include: Step S301: Obtain the full-scale range of the input signal value of the reference conversion channel. For example, in the case of a 16-bit digital-to-analog converter, the full-scale range can be -32768 to +32767.

[0035] Step S302: Select the calibration interval within the full-scale range.

[0036] Step S303: Control the standard signal source to output signals sequentially within the correction range with a set step size to form a standard signal sequence.

[0037] The calibration method for the multiple signal conversion channels of the semiconductor scanning electron microscope in this embodiment can have two optional calibration modes: full-scale calibration (or coarse calibration) and interval calibration (or fine calibration).

[0038] In the case of full-scale calibration, the full-scale range of the reference conversion channel is used as the calibration interval. The steps for selecting the calibration interval within the full-scale range can include: using the entire full-scale range as the calibration interval, and using the minimum and maximum values ​​of the input signal value range as the starting and ending signal values, respectively, for the standard signal sequence. In the case of 16-bit digital-to-analog conversion, the standard signal source can output signals incrementally from -32768 to +32767 in a set step size, where the starting signal value is -32768 and the ending signal value is +32767. With a step size of X, the number of standard signals (i.e., calibration points) N is: N = 65536 / X.

[0039] In the case of interval correction, a portion of the full-scale range is used as the correction interval. The step of selecting the correction interval within the full-scale range includes: obtaining the default range of the scanning signal from the semiconductor scanning electron microscope; and using the range of input signal values ​​corresponding to the default range as the correction interval. The default range of the scanning signal is generally the most commonly used range for semiconductor scanning electron microscopes. The range of input signal values ​​corresponding to the default range is used as the correction interval, and the overall conversion characteristics of the full-scale range are corrected to be approximately consistent with the correction interval. When using the same number N of standard signals, interval correction uses a shorter step size for the standard signals, resulting in higher correction accuracy.

[0040] The process of setting the step size of the above output signal can be as follows: after selecting the correction interval, obtain the number of measurement points required for correction; set the step size according to the ratio of the length of the correction interval to the number of measurement points.

[0041] In the embodiment of digital-to-analog signal conversion in the reference conversion channel and the calibration conversion channel, the reference curve is a linear curve passing through the origin of the coordinate system, and the above-mentioned step of fitting the reference curve based on the reference measurement value sequence may include: performing linear fitting on the reference measurement value sequence passing through the origin of the coordinate system to obtain the reference curve.

[0042] The calibration method for the multi-channel signal conversion of the semiconductor scanning electron microscope described in the above embodiments can flexibly select the calibration interval within the full-scale range of the input signal value of the reference conversion channel according to the calibration requirements, thereby improving the precision of data calibration and meeting the application scenario requirements of multi-channel signal conversion of semiconductor scanning electron microscopes.

[0043] Taking the calibration process of 8 digital-to-analog conversion channels as an example, the calibration method of the multi-channel signal conversion channel of the semiconductor scanning electron microscope in the above embodiment is introduced. Based on this, those skilled in the art can realize the calibration of any number and type of conversion channels. Figure 4 This is a schematic flowchart illustrating an application example of a calibration method for multiple signal conversion channels in a semiconductor scanning electron microscope according to an embodiment of the present invention. The process of calibrating eight digital-to-analog conversion channels may include: Step S401: Start calibration and set the output of the standard signal source to zero; Step S402: Open the first conversion channel (as the reference conversion channel). Step S403: Control the standard signal source to output standard signals one by one according to the correction points within the correction interval; Step S404: Obtain the measurement results from the signal measuring device; Step S405: Fit a reference curve based on the measurement results of the first conversion channel; Step S406: Set the output of the standard signal source to zero; Step S407: Open the next conversion channel and repeat the output of the standard signal and the acquisition of the measurement results; Step S408: Determine whether the measurement of the 8-channel conversion is complete; if yes, proceed to step S409; if not, proceed to step S407 to perform the measurement of the next channel. Step S409: Correct the measurement results of the 8 conversion channels using the reference curve. Step S410: Reconvert the standard signal using the calibrated conversion channel and obtain the calibrated measurement result; Step S411: Perform a consistency check based on the corrected measurement results. One way to perform the consistency check is as follows: if the range (difference between the maximum and minimum values) of the conversion results of the 8 conversion channels for the same standard signal is less than a set range threshold (e.g., 1mV), the check passes; otherwise, it fails.

[0044] Step S412: If the consistency check fails, perform a round of correction based on the previously corrected results.

[0045] In practical use, coarse calibration and fine calibration can be selected according to the usage scenario. During the coarse calibration process, the entire full-scale range of the digital-to-analog conversion channel is calibrated. The first conversion channel is used as the reference conversion channel, and the 2nd to 8th conversion channels are used as the conversion channels to be calibrated. The deviation coefficients K and B are obtained by measurement compared to the linear curve at the zero-crossing point (the first conversion channel), where K is the slope and B is the intercept. Figure 5 This is a comparison graph of the input-output characteristic curves before and after coarse calibration of a calibration method for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention.

[0046] During the fine calibration process, the scanning signal is further finely corrected in segments. For the same conversion channel, a certain segment (corresponding to the numerical range of the default setting) is used as a reference, and all components of all conversion channels are calibrated based on this reference to ensure that the scanning signal has a uniform input and output characteristic curve. Figure 6 This is a comparison graph of the input-output characteristic curves before and after fine calibration of a calibration method for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention.

[0047] The above Figure 5 and Figure 6 As can be shown, the correction method for the multiple signal conversion channels applied in this embodiment can improve the consistency of the multiple conversion channels and solve the image distortion caused by the scanning signal.

[0048] Figure 7 This is a schematic diagram of a calibration host 400 in a calibration system for a multiplexed signal conversion channel of a semiconductor scanning electron microscope according to an embodiment of the present invention. The calibration host 400 may include a memory 410, a processor 420, and a computer program 411 stored in the memory 410 and running on the processor 420. When the processor 420 executes the computer program 411, it implements the steps of the calibration method for the multiplexed signal conversion channel according to any of the above embodiments.

[0049] The computer program 411 used to perform the operations of this invention can be assembly instructions, Instruction Set Architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, integrated circuit configuration data, or source code or object code written in any combination of one or more programming languages ​​and procedural programming languages. The computer program 411 can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer can connect to the user's computer via any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or it can connect to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, to perform aspects of the invention, electronic circuits, including, for example, programmable logic circuits, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), can execute computer-readable program instructions to personalize the electronic circuits by utilizing state information of computer-readable program instructions.

[0050] More specific examples (a non-exhaustive list) of memory 410 include the following: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable optical disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory stick, floppy disk, mechanical encoding device, and any suitable combination of the foregoing.

[0051] The calibration host 400 can be, for example, a server, desktop computer, laptop computer, tablet computer, or smartphone. The calibration host 400 can be described in the general context of computer system executable instructions (such as program modules) executed by a computer system. Typically, program modules can include routines, programs, object programs, components, logic, data structures, etc., that perform specific tasks or implement specific abstract data types.

[0052] The calibration host 400 may include a processor 420 adapted to execute stored instructions and a memory 410 that provides temporary storage space for the operation of said instructions during operation. The processor 420 may be a single-core processor, a multi-core processor, a computing cluster, or any other configuration.

[0053] The calibration host 400 may also include a network adapter / interface and an input / output (I / O) interface. The I / O interface allows data input and output using external devices that can be connected to the computer equipment. The network adapter / interface provides communication between the computer equipment and a network, typically represented as a communication network.

[0054] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A method for calibrating a multiplexed signal conversion channel of a semiconductor scanning electron microscope, comprising: Start the standard signal source and control the standard signal source to provide a standard signal sequence; The standard signal sequence is converted using a reference conversion channel, and the measured values ​​of the converted signal are obtained to obtain a reference measurement value sequence. A reference curve is fitted based on the reference measurement value sequence, and compensation parameters for the reference conversion channel are generated based on the reference measurement value sequence and the reference reference curve. The compensation parameters for the reference conversion channel are used to correct the output signal of the reference conversion channel when processing the scan signal to a value less than a set error threshold. The standard signal sequence is converted one by one through multiple calibration conversion channels, and the measured value of the converted signal is obtained to obtain a multi-channel calibration measurement value sequence. Based on the measured value sequence of each channel, compensation parameters for each channel of the calibration conversion channel are generated using the reference curve. The compensation parameters for each channel of the calibration conversion channel are used to correct the output signal of each channel of the calibration conversion channel when processing the scanning signal to ensure that the error between the output signal and the value corresponding to the reference curve is less than the error threshold.

2. The calibration method for the multiple signal conversion channels of a semiconductor scanning electron microscope according to claim 1, wherein, The steps of controlling the standard signal source to output a standard signal sequence include: Obtain the full-scale range of the input signal value of the reference conversion channel; Select a calibration interval within the full-scale range; The standard signal source is controlled to output signals sequentially within the correction interval with a set step size, forming the standard signal sequence.

3. The calibration method for the multiple signal conversion channels of a semiconductor scanning electron microscope according to claim 2, wherein, The steps for selecting the calibration interval within the full-scale range include: The entire full-scale range is used as the correction interval, and the standard signal sequence uses the minimum and maximum values ​​of the input signal value range as the starting and ending signal values, respectively.

4. The calibration method for the multiple signal conversion channels of a semiconductor scanning electron microscope according to claim 2, wherein, The steps for selecting the calibration interval within the full-scale range include: Obtain the default setting of the scanning signal from the semiconductor scanning electron microscope; The range of input signal values ​​corresponding to the default gear is used as the correction range.

5. The calibration method for the multiplexed signal conversion channels of a semiconductor scanning electron microscope according to any one of claims 2 to 4, wherein, After selecting the correction interval, the following is also included: Obtain the number of measurement points required for calibration; The step size is set according to the ratio of the length of the correction interval to the number of measurement points.

6. The calibration method for the multiple signal conversion channels of a semiconductor scanning electron microscope according to claim 1, wherein, The reference curve is a linear curve passing through the origin, and the step of fitting the reference curve based on the reference measurement value sequence includes: The reference curve is obtained by performing a linear fit through the origin on the reference measurement value sequence.

7. The calibration method for the multiple signal conversion channels of a semiconductor scanning electron microscope according to claim 1, wherein, The steps for performing signal conversion on the standard signal sequence through a reference conversion channel include: Connect the interface between the standard signal source and the input terminal of the reference conversion channel, and use a switching switch to connect the output terminal of the reference conversion channel to the signal measurement device, whereby the reference conversion channel completes the signal conversion.

8. The calibration method for the multiple signal conversion channels of a semiconductor scanning electron microscope according to claim 1, wherein, The steps of performing signal conversion on the standard signal sequence one by one through multiple calibration conversion channels include: The standard signal source is connected to the interface of each of the calibration conversion channels one by one. The output of each calibration conversion channel is connected to the signal measurement device by a switching switch, and the signal conversion is completed by each calibration conversion channel one by one.

9. A calibration system for a multiplexed signal conversion channel of a semiconductor scanning electron microscope, comprising: A standard signal source, configured to provide a standard signal sequence to the reference conversion channel and the conversion channel being calibrated; A signal measuring device configured to measure the output signals of the reference conversion channel and the conversion channel being calibrated; The calibration host is signal-connected to the standard signal source and the signal measuring device respectively, and includes a memory, a processor and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of the calibration method for the multiple signal conversion channel according to any one of claims 1 to 8.

10. The calibration system for the multiple signal conversion channels of the semiconductor scanning electron microscope according to claim 9, further comprising: A switching switch is connected to the calibration host signal and configured to controllably connect the output terminals of the reference conversion channel and the calibration conversion channel to the signal measurement device.

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