Detection system performance detection method and device, detection system and storage medium

Abstract

The invention discloses a detection system performance detection method and device, a detection system and a storage medium, and belongs to the technical field of detection. The method comprises the following steps: under the condition of blocking an electron beam, controlling the voltage of a photomultiplier in a detection system to change according to a plurality of voltage values in a voltage value sequence, and determining first gray data of a measurement image corresponding to each voltage value in the voltage value sequence; under the condition that the reference sample is irradiated by the electron beam, controlling the voltage of the photomultiplier to change according to a plurality of voltage values in the voltage value sequence, and determining second gray data of the measurement image corresponding to each voltage value; determining the corresponding detection quantum efficiency based on the first gray data and the second gray data under the same voltage value and the related information of the electron beam; and determining the performance of the detection system based on each voltage value in the voltage value sequence and the corresponding detection quantum efficiency. According to the invention, performance evaluation can be carried out on the detection system through a simple and rapid method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection, in particular to a detection system performance detection method and device, a detection system and a storage medium. BACKGROUND

[0002] As an important micro-morphology analysis instrument, the imaging quality of a SEM (Scanning Electron Microscope) depends largely on the performance of a detection system. The detection system in a SEM generally includes an electron beam modulation device in a lens barrel, an electron detector, and a circuit acquisition and imaging system after the detector, and other components. Since the detection system involves multiple interrelated components, its overall performance is difficult to be quantitatively evaluated by a simple single parameter, and only through a complex test system and test method can the performance of the detection system be evaluated. Therefore, there is an urgent need for a simple and fast method to evaluate the performance of the detection system. SUMMARY

[0003] In view of the problems in the prior art, the present application provides a detection system performance detection method and device, a detection system and a storage medium, which can evaluate the performance of the detection system by a simple and fast method. The technical solution is as follows:

[0004] In one aspect, a detection system performance detection method is provided, which includes:

[0005] In the case of blocking the electron beam, the voltage of a photomultiplier tube in the detection system is controlled to change according to a plurality of voltage values in a voltage value sequence, and the first gray scale data of a measurement image corresponding to each voltage value in the voltage value sequence is determined;

[0006] In the case of irradiating a reference sample with an electron beam, the voltage of the photomultiplier tube is controlled to change according to a plurality of voltage values in the voltage value sequence, and the second gray scale data of a measurement image corresponding to each voltage value in the voltage value sequence is determined, the second gray scale data corresponding to the same voltage value as the first gray scale data;

[0007] Based on the first gray scale data and the second gray scale data under the same voltage value and the related information of the electron beam, the corresponding detection quantum efficiency is determined.

[0008] Based on each voltage value in the voltage value sequence and the corresponding detection quantum efficiency, the performance of the detection system is determined.

[0009] Optionally, the determination of the corresponding detection quantum efficiency based on the first gray scale data and the second gray scale data under the same voltage value and the related information of the electron beam includes:

[0010] determine a first signal-to-noise ratio based on the first gray data and the second gray data under the same voltage value;

[0011] determine a second signal-to-noise ratio based on the related information of the electron beam;

[0012] determine a corresponding detection quantum efficiency according to the first signal-to-noise ratio and the second signal-to-noise ratio.

[0013] Optionally, the related information of the electron beam includes an electron beam current of the electron beam and a dwell time of the electron beam; the second signal-to-noise ratio is positively correlated with the electron beam current of the electron beam, and the second signal-to-noise ratio is also positively correlated with the dwell time of the electron beam.

[0014] Optionally, the first gray data includes a first gray mean value, and the second gray data includes a second gray mean value and a gray standard deviation; the determining of the first signal-to-noise ratio based on the first gray data and the second gray data includes:

[0015] determining a gray parameter based on the second gray mean value and the first gray mean value;

[0016] determining the first signal-to-noise ratio according to the gray parameter and the gray standard deviation.

[0017] Optionally, the determining of the first signal-to-noise ratio according to the gray parameter and the gray standard deviation includes:

[0018] determining a ratio of the gray parameter to the gray standard deviation as the first signal-to-noise ratio.

[0019] Optionally, the determining of the corresponding detection quantum efficiency according to the first signal-to-noise ratio and the second signal-to-noise ratio includes:

[0020] determining a ratio of a square of the first signal-to-noise ratio to a square of the second signal-to-noise ratio as the corresponding detection quantum efficiency.

[0021] Optionally, the determining of the performance of the detection system based on each voltage value in the sequence of voltage values and the corresponding detection quantum efficiency thereof includes:

[0022] determining a detection efficiency curve according to each voltage value in the sequence of voltage values and the corresponding detection quantum efficiency thereof;

[0023] determining the performance of the detection system according to the detection efficiency curve.

[0024] Optionally, the determining of the performance of the detection system according to the detection efficiency curve includes:

[0025] determining a target curve segment in the detection efficiency curve, an absolute value of a slope of a line connecting a starting point and an ending point of the target curve segment being less than or equal to a slope threshold value;

[0026] determining the performance of the detection system according to a voltage value interval corresponding to the target curve segment and the detection quantum efficiency.

[0027] Optionally, a difference between two adjacent voltage values in the voltage value sequence is equal.

[0028] In another aspect, a detection system performance detection device is provided, the device comprising:

[0029] a first control module configured to control a voltage of a photomultiplier tube in the detection system to change according to a plurality of voltage values in a voltage value sequence in a case where an electron beam is blocked, and determine first grayscale data of a measurement image corresponding to each voltage value in the voltage value sequence;

[0030] a second control module configured to control the voltage of the photomultiplier tube to change according to the plurality of voltage values in the voltage value sequence in a case where the electron beam irradiates a reference sample, and determine second grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence, the second grayscale data being the same as the first grayscale data corresponding to the voltage value;

[0031] a first determination module configured to determine a corresponding detection quantum efficiency based on the first grayscale data and the second grayscale data under the same voltage value and related information of the electron beam;

[0032] a second determination module configured to determine the performance of the detection system based on each voltage value in the voltage value sequence and the corresponding detection quantum efficiency.

[0033] In another aspect, a detection system is provided, the detection system comprising:

[0034] a detector comprising a photomultiplier tube, the detector converting and amplifying an optical signal into an electrical signal through the photomultiplier tube to enable the detection system to collect a signal generated by interaction between an electron beam and a reference sample;

[0035] a memory configured to store a computer program and / or instructions;

[0036] a processor configured to implement steps of the above-mentioned detection system performance detection method when executing the computer program and / or instructions stored in the memory.

[0037] In another aspect, a computer readable storage medium is provided, the storage medium storing a computer program, the computer program being executed by a processor to implement steps of the above-mentioned detection system performance detection method.

[0038] In another aspect, a computer program product containing instructions which, when executed on a computer, cause the computer to perform the steps of the above-mentioned method of detecting performance of a detection system is provided.

[0039] The technical solutions provided in the present application can bring at least the following beneficial effects:

[0040] The present application can control the voltage of the photomultiplier tube in the detection system to change according to a plurality of voltage values in the case of blocking the electron beam, and obtain corresponding first gray scale data, control the voltage of the photomultiplier tube to change according to a plurality of voltage values in the voltage value sequence in the case of electron beam irradiation of the reference sample, and obtain corresponding second gray scale data, then determine the corresponding detection quantum efficiency based on the first gray scale data and the second gray scale data under the same voltage value and the related information of the electron beam, and then determine the performance of the detection system based on the voltage value and the detection quantum efficiency, thereby the performance of the detection system can be evaluated by a simple and fast method, the detection complexity is simplified, the detection accuracy is improved, and the response capability of the detection system to different signal inputs can be measured quickly; and compared with the step-by-step inspection test of the efficiency of the detector parts such as the scintillator, the light guide, and the photomultiplier tube in the detection system, or the test using a separate controllable electron beam flow to directly bombard the detector, the method provided in the present application can perform fast standardized detection on the actual SEM product, which is more fast and simple, and low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A structural schematic diagram of an implementation environment provided for an embodiment of the present application;

[0042] Figure 2 A structural schematic diagram of another implementation environment provided for an embodiment of the present application;

[0043] Figure 3 A flowchart of a detection system performance detection method provided for an embodiment of the present application;

[0044] Figure 4 A schematic diagram of a detection efficiency curve provided for an embodiment of the present application;

[0045] Figure 5 A structural schematic diagram of a detection system performance detection device provided for an embodiment of the present application. DETAILED DESCRIPTION

[0046] The application will be described in further detail below with specific reference being made to the drawings. Like elements are referred to with like reference numerals throughout the specification. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the application. However, it will be apparent to one skilled in the art that the application can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the application. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the application. However, it will be apparent to one skilled in the art that the application can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the application.

[0047] In addition, features, operations or characteristics described in the specification can be combined in any appropriate manner to form various embodiments. Meanwhile, the steps or actions in the method description can also be sequentially adjusted or changed in a manner that is apparent to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment, and do not mean that the sequence is necessary, unless otherwise stated that a certain sequence must be followed.

[0048] The serial numbers of components in this paper, such as "first", "second", etc., are only used to distinguish the described objects, and do not have any sequence or technical meaning. The "connection" and "coupling" in this paper include direct and indirect connection (coupling) unless otherwise specified.

[0049] Before the performance detection method of the detection system provided by the embodiments of the application is explained in detail, the implementation environment involved in the embodiments of the application is introduced.

[0050] Please refer to Figure 1 , Figure 1 is a schematic diagram of an implementation environment including a detection system 1 according to an exemplary embodiment, the detection system 1 including a detector 11, a memory 12 and a processor 13.

[0051] The detector 11 includes a photomultiplier tube 111, and the detector 11 can convert a light signal into an electrical signal and amplify it through the photomultiplier tube 111, so that the detection system collects the signal generated by the interaction of the electron beam with the reference sample; the memory 12 is used to store computer programs and / or instructions; the processor 13 is used to implement the performance detection method of the detection system in the embodiments of the application when executing the computer programs and / or instructions stored in the memory 12, that is, the detection system 1 can perform performance evaluation by itself through its own processor.

[0052] In some embodiments, please refer toFigure 2 The implementation environment can also include the detection system 1 and the host computer 2, and the host computer 2 is connected with the detection system 1, which can be a wired connection or a wireless connection. The embodiments of the present application do not limit this.

[0053] The host computer 2 can control the voltage of the photomultiplier tube 11 in the detection system 1 to change according to a plurality of voltage values in a voltage value sequence in the case of blocking the electron beam, and determine the first gray scale data of the measurement image corresponding to each voltage value in the voltage value sequence, and then control the voltage of the photomultiplier tube 11 to change according to a plurality of voltage values in the voltage value sequence in the case of irradiating the reference sample with the electron beam, and determine the second gray scale data of the measurement image corresponding to each voltage value in the voltage value sequence. The second gray scale data corresponds to the same voltage value as the first gray scale data. Then, based on the first gray scale data and the second gray scale data under the same voltage value and the related information of the electron beam, the detection quantum efficiency corresponding to the voltage value is determined, and based on each voltage value in the voltage value sequence and the detection quantum efficiency corresponding to the voltage value, the performance of the detection system 1 is determined.

[0054] The host computer 2 can be any electronic product that can interact with a user through one or more of a keyboard, a touchpad, a touch screen, a remote control, voice interaction, or a handwriting device, such as a PC (Personal Computer), a mobile phone, a smart phone, a PDA (Personal Digital Assistant), a wearable device, a Pocket PC, a tablet computer, a smart car, a smart television, a smart speaker, and the like.

[0055] Those skilled in the art should understand that the above-mentioned detection system 1 and host computer 2 are only examples, and other existing or future detection systems or host computers, such as those that can be applicable to the embodiments of the present application, should also be included within the scope of protection of the embodiments of the present application, and are hereby incorporated by reference.

[0056] It should be noted that the application scenarios and implementation environments described in the embodiments of the present application are for more clearly illustrating the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Those skilled in the art can know that the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems as new application scenarios appear and implementation environments evolve.

[0057] Next, a detection system performance detection method provided by the embodiments of the present application will be explained in detail.

[0058] Figure 3 is a diagram of a detection system performance detection method provided by the embodiments of the present application. Please refer toFigure 3 The method includes the following steps:

[0059] Step 301: With the electron beam blocked, the voltage of the photomultiplier tube in the detection system is controlled to change according to multiple voltage values ​​in the voltage value sequence, and the first grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence is determined.

[0060] In some embodiments, the electron beam can be blocked by a blanking device or an internal gas valve to allow for subsequent dark noise measurements. The blanking device, also known as an electron beam blanking device or beam blanking device, is an electro-optical component inside the SEM tube that can quickly and controllably "cut off" or "deflect" the electron beam, preventing it from reaching the sample surface.

[0061] It should be noted that the above description refers to blocking the electron beam using a blanking device or an internal gas valve in the lens barrel. Alternatively, other methods can be used to block the electron beam in practice. This application does not limit this approach.

[0062] Since the performance of a detection system is not measured by a single signal level, but rather by changing the signal quantity, the signal input can be altered by changing the voltage of the photomultiplier tube in the detection system. This allows the detection system to assess its response to different signal inputs.

[0063] In some embodiments, the voltage value sequence includes multiple different voltage values. Thus, the voltage of the photomultiplier tube in the detection system can be changed according to the multiple voltage values ​​in the voltage value sequence, and the measurement images corresponding to each voltage value in the voltage value sequence can be obtained at different voltages. Then, the first grayscale data of the measurement images corresponding to each voltage value in the voltage value sequence can be determined.

[0064] As an example, assuming the voltage values ​​in the voltage value sequence include X1, X2, X3, and X4, then, with the electron beam blocked, the voltage of the photomultiplier tube in the detection system can be controlled to change to X1, and the measurement image corresponding to X1 can be acquired. Based on this measurement image, the first grayscale data corresponding to the voltage value X1 can be determined. Then, the voltage of the photomultiplier tube in the detection system can be controlled to change to X2, and the measurement image corresponding to X2 can be acquired. Based on this measurement image, the first grayscale data corresponding to the voltage value X2 can be determined. And so on, the first grayscale data corresponding to voltage values ​​X3 and X4 can be obtained respectively. Thus, the first grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence can be obtained.

[0065] In some embodiments, the difference between any two adjacent voltage values ​​in the voltage value sequence is equal. That is, the voltage value sequence is an arithmetic progression sequence. For example, the voltage values ​​in the voltage value sequence can be taken at equal intervals within the range of 250V to 900V. For instance, the voltage values ​​in the voltage value sequence can be 320V, 370V, 420V, 470V, 520V, 570V, 620V, 670V, 720V, and 770V in sequence.

[0066] It should be noted that the voltage value sequence described above is merely an example. In practical applications, the voltage value sequence can be set according to actual needs. This application does not limit this.

[0067] In some embodiments, only one frame of the measurement image needs to be acquired for each voltage value. This avoids the need for additional processing of multiple frames, ensuring that subsequent results, such as the signal-to-noise ratio, accurately reflect the performance of the detection system itself.

[0068] In some embodiments, the electron beam current needs to be stabilized before blocking the electron beam. For example, the electron beam current can be monitored using a Faraday cup inside the SEM tube. If the electron beam current (i.e., the falling beam current that eventually reaches the sample surface) does not exceed 10 pA, there is no need to change the measurement position during detection. If the falling beam current exceeds 10 pA, the measurement position needs to be adjusted according to the actual situation to avoid damage to the reference sample, thereby ensuring the validity of the subsequent data.

[0069] In some embodiments, before the detection system begins detection, the SEM's field of view needs to be moved to the surface of a reference sample (such as a featureless wafer) to set the SEM magnification. This is to avoid situations where excessive magnification leads to excessively high beam current density on the sample surface, causing carbon blackening and affecting subsequent accuracy; or to avoid situations where insufficient magnification results in differences in electron collection efficiency at different locations. For example, the SEM magnification can be controlled between 10k and 50k.

[0070] Step 302: When the reference sample is irradiated by an electron beam, the voltage of the photomultiplier tube is controlled to change according to multiple voltage values ​​in the voltage value sequence, and the second grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence is determined. The second grayscale data is the same as the voltage value corresponding to the first grayscale data.

[0071] In some embodiments, the electron beam can be allowed to irradiate the reference sample by closing the blanking device or opening the gas valve inside the microscope tube. That is, if the electron beam is blocked by the blanking device in step 301, then the electron beam can be allowed to irradiate the reference sample by closing the blanking device; if the electron beam is blocked by the gas valve inside the microscope tube in step 301, then the electron beam can be allowed to irradiate the reference sample by opening the gas valve inside the microscope tube.

[0072] In addition, in some embodiments, in order to ensure the accuracy of the performance evaluation of the detection system, when the electron beam irradiates the reference sample, other parameters, such as the SEM magnification and the size of the falling beam, need to be the same as those when the electron beam is blocked, except for the difference between whether the electron beam irradiates the reference sample or not.

[0073] In some embodiments, when the reference sample is irradiated by an electron beam, it is also necessary to control the voltage of the photomultiplier tube to change according to multiple voltage values ​​in the voltage value sequence, and to obtain the measurement image corresponding to each voltage value in the voltage value sequence at different voltages. Then, the second grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence can be determined.

[0074] As an example, assuming the voltage values ​​in the voltage value sequence include X1, X2, X3, and X4, when the electron beam irradiates the reference sample, the voltage of the photomultiplier tube in the detection system can be controlled to change to X1, and the measurement image corresponding to X1 can be acquired. Based on the measurement image, the second grayscale data corresponding to the voltage value X1 can be determined. Then, the voltage of the photomultiplier tube in the detection system can be controlled to change to X2, and the measurement image corresponding to X2 can be acquired. Based on the measurement image, the second grayscale data corresponding to the voltage value X2 can be determined. This process can be repeated to obtain the second grayscale data corresponding to voltage values ​​X3 and X4. Thus, the second grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence can be obtained.

[0075] As described above, in the case of electron beam obstruction and when the reference sample is irradiated by an electron beam, it is necessary to control the voltage of the photomultiplier tube to change according to multiple voltage values ​​in the voltage value sequence, and to determine the first grayscale data or the second voltage data corresponding to each voltage value. Therefore, the second grayscale data corresponds to the same voltage value as the first grayscale data; that is, under the same voltage value, the corresponding first grayscale data and the corresponding second grayscale data can be obtained.

[0076] As an example, assuming the voltage values ​​in the voltage value sequence include X1, X2, X3, and X4, then, for voltage value X1, the corresponding first grayscale data and the corresponding second grayscale data can be obtained; for voltage value X2, the corresponding first grayscale data and the corresponding second grayscale data can be obtained; and so on, for voltage values ​​X3 and voltage value X4, the corresponding first grayscale data and the corresponding second grayscale data can also be obtained.

[0077] Step 303: Determine the corresponding detection quantum efficiency based on the first grayscale data and the second grayscale data under the same voltage value, as well as the relevant information of the electron beam.

[0078] As described above, the voltage value corresponding to the second grayscale data is the same as that corresponding to the first grayscale data. Therefore, the detection quantum efficiency corresponding to this voltage value can be determined based on the first and second grayscale data at the same voltage value, as well as the relevant information of the electron beam.

[0079] As an example, if the first grayscale data corresponding to voltage value X1 is A1 and the second grayscale data is A2, that is, A1 and A2 are data obtained based on the same voltage value X1, then the detection quantum efficiency corresponding to voltage value X1 can be determined based on A1, A2, and relevant information of the electron beam.

[0080] In some embodiments, the corresponding detection quantum efficiency can be determined by following steps (1)-(3);

[0081] (1) Determine the first signal-to-noise ratio based on the first grayscale data and the second grayscale data under the same voltage value.

[0082] In some embodiments, the first grayscale data includes a first grayscale average value, and the second grayscale data includes a second grayscale average value and a grayscale standard deviation. Grayscale parameters can be determined first based on the second grayscale data and the first grayscale data, and then the first signal-to-noise ratio can be determined based on the grayscale parameters and the grayscale standard deviation.

[0083] Wherein, the first gray-scale average value is the average gray-scale value of the measurement image under electron beam blocking conditions, the second gray-scale average value is the average gray-scale value of the measurement image under electron beam irradiation of the reference sample, and the gray-scale standard deviation is the gray-scale standard deviation of the measurement image under electron beam irradiation of the reference sample. Since the first gray-scale average value, the second gray-scale average value, and the gray-scale standard deviation may change under different voltage values, the first signal-to-noise ratio obtained under different voltage values ​​will also change.

[0084] It should be noted that the first grayscale average, the second grayscale average, and the grayscale standard deviation mentioned above can be determined using existing calculation methods. This application does not limit these methods.

[0085] In some embodiments, the reference sample is a featureless silicon wafer. Therefore, the measurement images obtained, whether with the electron beam blocked or with the reference sample irradiated by electrons, are images of the featureless silicon wafer. A featureless silicon wafer refers to a specially prepared silicon wafer with an extremely flat, smooth, and clean surface, lacking any natural or artificial microstructure. Under ideal observation conditions, it should appear as a perfectly uniform gray area. Because of its "featurelessness," any inhomogeneities (such as variations in brightness, texture, or graininess) obtained when probed by a SEM system are theoretically not from the reference sample itself, but from the probe system. Therefore, the performance of the probe system can be evaluated using the first grayscale data, second grayscale data, and grayscale standard deviation of the measurement image of the featureless silicon wafer.

[0086] As described above, the first gray-scale average value is obtained under electron beam obstruction, while the second gray-scale average value is obtained under electron beam illumination of the reference sample. Since there is no electron beam, the first gray-scale average value can be considered the average value of the background or dark signal, representing the inherent offset of the detection system itself. Because the electron beam can illuminate the surface of the reference sample, the second gray-scale average value can represent the average signal intensity measured from the reference sample, such as a featureless silicon wafer, in the presence of noise.

[0087] In some embodiments, grayscale parameters can be determined based on a second grayscale average value and a first grayscale average value. As an example, grayscale parameters can be determined by subtracting the first grayscale average value from the second grayscale average value. That is, the grayscale parameter is a parameter after deducting the system background, which is a net signal. Therefore, the grayscale parameter can be used to characterize the signal electron emission rate of silicon materials.

[0088] It should be noted that the above explanation describes determining the grayscale parameter by subtracting the first grayscale average from the second grayscale average. Alternatively, in application, the grayscale parameter can be determined in other ways. This application does not limit this method.

[0089] In some embodiments, for a measurement image of a featureless silicon wafer, any pixel brightness fluctuation is considered noise. Therefore, the grayscale standard deviation can be used to indicate the total noise level, such as shot noise and electrical noise, in the measurement image. The ratio of the grayscale parameter to the grayscale standard deviation directly reflects how many times the effective signal strength is relative to the noise level. Therefore, by determining the ratio of the grayscale parameter to the grayscale standard deviation as the first signal-to-noise ratio, the ability of the detection system to acquire reliable images can be evaluated.

[0090] (2) Determine the second signal-to-noise ratio based on the relevant information of the electron beam.

[0091] Because different SEMs use different types of electron beams, and the number of scattering events within the microscope tube varies, using absolute signal-to-noise ratio (SNR) to assess the performance of the detection system can introduce significant errors. Since the number of electrons falling onto the reference sample surface typically follows an ideal Poisson distribution, a theoretical SNR (containing only shot noise) can be determined based on the number of electrons falling onto the reference sample surface per unit time and used as a benchmark for comparison. The ideal Poisson distribution describes the probability distribution of the number of random events occurring within a fixed time or space; its core principle is that the events occur completely randomly and independently.

[0092] Continuing from the previous description, the theoretical signal-to-noise ratio (SNR) of the shot noise of the electron beam falling onto the surface of the reference sample, namely the second SNR, is related to the relevant information of the electron beam. Therefore, the second SNR can be determined based on the relevant information of the electron beam.

[0093] In some embodiments, the relevant information of the electron beam includes the electron beam current and the residence time of the electron beam; the second signal-to-noise ratio is positively correlated with the electron beam current and also positively correlated with the residence time of the electron beam.

[0094] In some embodiments, the dwell time of the electron beam is set within a reasonable range according to the actual situation. If the dwell time is too short, the signal-to-noise ratio will be too poor. If the dwell time is too long, the charging effect will occur. In this embodiment, the dwell time of the electron beam is preferably a value between 500 ns and 1000 ns.

[0095] As an example, suppose there are detection systems A and B. If the electron beam current of the electron beam in detection system A is greater than that of the electron beam in detection system B, and the residence time of the electron beam in detection system A is equal to that of the electron beam in detection system B, then the second signal-to-noise ratio (SNR) of detection system A is greater than that of detection system B. As another example, if the residence time of the electron beam in detection system A is shorter than that of the electron beam in detection system B, and the electron beam current of the electron beam in detection system A is equal to that of the electron beam in detection system B, then the second SNR of detection system A is greater than that of detection system B.

[0096] In some embodiments, when a detection system is being tested for performance, only the voltage of the photomultiplier tube changes according to a series of voltage values ​​when the reference sample is irradiated by an electron beam, while the electron beam current and residence time remain unchanged. In other words, the second signal-to-noise ratio obtained when a detection system is being tested for performance is constant.

[0097] (3) Determine the corresponding detection quantum efficiency based on the first signal-to-noise ratio and the second signal-to-noise ratio.

[0098] In some embodiments, the ratio of the square of the first signal-to-noise ratio to the square of the second signal-to-noise ratio can be determined as the corresponding detection quantum efficiency.

[0099] It should be noted that the above explanation uses the ratio of the square of the first signal-to-noise ratio to the square of the second signal-to-noise ratio as the corresponding detection quantum efficiency. Alternatively, in applications, other methods can be used to determine the detection quantum efficiency. This application does not limit this approach.

[0100] Step 304: Determine the performance of the detection system based on each voltage value in the voltage value sequence and its corresponding detection quantum efficiency.

[0101] For each voltage value in the voltage value sequence, its corresponding detection quantum efficiency can be obtained. Therefore, the performance of the detection system can be determined based on the voltage value and its corresponding detection quantum efficiency.

[0102] In some embodiments, in order to intuitively determine the performance of the detection system, a detection efficiency curve can be determined based on each voltage value in the voltage value sequence and its corresponding detection quantum efficiency, and then the performance of the detection system can be determined based on the detection efficiency curve.

[0103] As an example, the detection efficiency curve can be as follows: Figure 4 As shown, the horizontal axis of the detection efficiency curve represents the voltage value, and the vertical axis represents the detection quantum efficiency. From... Figure 4 As can be seen, the detection quantum efficiency changes with the voltage of the photomultiplier tube. In the first stage, from 320V to 520V, the voltage increases. Due to inherent noise in the detection system, such as dark noise from the photomultiplier tube, circuit noise, and stray light noise, the proportion of this noise decreases as the voltage increases. Therefore, the first signal-to-noise ratio (SNR) increases, while the second SNR remains unchanged, resulting in a continuous increase in detection quantum efficiency. In the second stage, from 520V to 620V, the detection efficiency curve flattens out. In this stage, noise is caused by changes in the signal itself. Both the signal and noise are amplified together with the voltage change of the photomultiplier tube, so the first SNR remains essentially unchanged, and the second SNR does not change, thus the detection quantum efficiency also remains constant. In the third stage, from 620V to 770V, signal saturation in the circuit causes sampling distortion, leading to an abnormally reduced grayscale standard difference. This causes an abnormally high first SNR, resulting in an abnormally high detection quantum efficiency in this stage.

[0104] In some embodiments, in order to determine the linear interval of the detection system so as to determine the performance of the detection system in subsequent processes based on the linear interval of the detection system and the detection quantum efficiency corresponding to the linear interval, a target curve segment in the detection efficiency curve can be first determined. The absolute value of the slope of the line connecting the start and end points of the target curve segment is less than or equal to a slope threshold. Then, the performance of the detection system is determined based on the voltage value interval corresponding to the target curve segment and the detection quantum efficiency. In other words, the voltage value interval corresponding to the target curve segment can be determined as the linear interval of the detection system.

[0105] Determining the linear range of the detection system ensures that the photomultiplier tube operates within this range during actual use, minimizing signal distortion and preventing a decline in the detection performance. Determining the detection quantum efficiency corresponding to the linear range allows for the evaluation of the detection system's performance; higher quantum efficiency indicates better performance, and vice versa. Furthermore, detecting quantum efficiency enables the assessment of whether the detectors within the system are functioning correctly and allows for rapid troubleshooting of issues such as abnormal noise and unstable efficiency.

[0106] As an example, assuming the slope threshold is 0.1, meaning the line connecting the start and end points of the target curve segment should be roughly parallel to the horizontal axis, then in the case of... Figure 4 In the detection efficiency curve shown, the second stage, i.e., the stage with a voltage value of 520V to 620V, can be defined as the target curve segment. Furthermore, the voltage range corresponding to this target curve segment is 520V to 620V, meaning the linear range of the detection system is 520V to 620V. Figure 4 As can be seen, the detection quantum efficiency corresponding to the target curve segment is approximately 0.125. Therefore, the performance of the detection system can be evaluated by using the range of the linear interval and the value of the detection quantum efficiency corresponding to the linear interval.

[0107] This application embodiment controls the voltage of the photomultiplier tube in the detection system to change according to multiple voltage values ​​when the electron beam is blocked, and obtains the corresponding first grayscale data. When the electron beam irradiates the reference sample, the voltage of the photomultiplier tube is controlled to change according to multiple voltage values ​​in the voltage value sequence, and obtains the corresponding second grayscale data. Then, based on the first grayscale data and the second grayscale data under the same voltage value and the relevant information of the electron beam, the corresponding detection quantum efficiency is determined. Subsequently, the performance of the detection system is determined based on the voltage value and the detection quantum efficiency. Thus, the performance of the detection system can be evaluated in a simple and fast way, simplifying the detection complexity, improving the detection accuracy, and quickly measuring the response capability of the detection system to different signal inputs. Moreover, compared with the step-by-step testing of the detector components such as scintillators, light guides, and photomultiplier tube efficiencies in the detection system, or the testing using a separate device that directly bombards the detector with a controllable electron beam, the method provided by this application embodiment can perform rapid and standardized testing on actual SEM products, which is faster, simpler, and lower in cost.

[0108] Figure 5 This is a schematic diagram of the structure of a detection system performance testing device provided in an embodiment of this application. See also... Figure 5 The device includes a first control module 501, a second control module 502, a first determination module 503, and a second determination module 504.

[0109] The first control module 501 is used to control the voltage of the photomultiplier tube in the detection system to change according to multiple voltage values ​​in a voltage value sequence when the electron beam is blocked, and to determine the first grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence.

[0110] The second control module 502 is used to control the voltage of the photomultiplier tube to change according to multiple voltage values ​​in the voltage value sequence when the reference sample is irradiated by an electron beam, and to determine the second grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence, wherein the second grayscale data is the same as the voltage value corresponding to the first grayscale data.

[0111] The first determining module 503 is used to determine the corresponding detection quantum efficiency based on the first grayscale data and the second grayscale data under the same voltage value and the relevant information of the electron beam.

[0112] The second determining module 504 is used to determine the performance of the detection system based on each voltage value in the voltage value sequence and its corresponding detection quantum efficiency.

[0113] The embodiments of this application enable performance evaluation of the detection system using a simple and rapid method.

[0114] It should be noted that the detection system performance testing device provided in the above embodiments is only illustrated by the division of the above functional modules when performing performance testing on the detection system. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the detection system performance testing device provided in the above embodiments and the detection system performance testing method embodiments belong to the same concept, and their specific implementation process is described above and will not be repeated here.

[0115] Those skilled in the art will understand that all or part of the functions of the various methods in the above embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, which may include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to achieve the above functions. For example, the program can be stored in the memory of a device, and when the program in the memory is executed by the processor, all or part of the above functions can be achieved. In addition, when all or part of the functions in the above embodiments are implemented by computer programs, the program can also be stored in a server, another computer, disk, optical disk, flash drive, or external hard drive, etc., and can be downloaded or copied to the memory of a local device, or the system of the local device can be updated. When the program in the memory is executed by the processor, all or part of the functions in the above embodiments can be achieved.

[0116] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A method for testing the performance of a detection system, characterized in that, The method includes: In the case of blocking the electron beam, the voltage of the photomultiplier tube in the detection system is controlled to change according to multiple voltage values ​​in the voltage value sequence, and the first grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence is determined. When the reference sample is irradiated by an electron beam, the voltage of the photomultiplier tube is controlled to change according to multiple voltage values ​​in the voltage value sequence, and the second grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence is determined. The second grayscale data is the same as the voltage value corresponding to the first grayscale data. Based on the first and second grayscale data at the same voltage value and the relevant information of the electron beam, the corresponding detection quantum efficiency is determined; The performance of the detection system is determined based on each voltage value in the voltage value sequence and its corresponding detection quantum efficiency.

2. The method as described in claim 1, characterized in that, The determination of the corresponding detection quantum efficiency based on the first and second grayscale data at the same voltage value and the relevant information of the electron beam includes: The first signal-to-noise ratio is determined based on the first grayscale data and the second grayscale data under the same voltage value; Based on the relevant information of the electron beam, a second signal-to-noise ratio is determined; The corresponding detection quantum efficiency is determined based on the first signal-to-noise ratio and the second signal-to-noise ratio.

3. The method as described in claim 2, characterized in that, The relevant information of the electron beam includes the electron beam current and the residence time of the electron beam; the second signal-to-noise ratio is positively correlated with the electron beam current and also positively correlated with the residence time of the electron beam.

4. The method as described in claim 2, characterized in that, The first grayscale data includes a first grayscale average value, and the second grayscale data includes a second grayscale average value and a grayscale standard deviation; determining the first signal-to-noise ratio based on the first grayscale data and the second grayscale data includes: The grayscale parameters are determined based on the second grayscale average value and the first grayscale average value; The first signal-to-noise ratio is determined based on the grayscale parameters and the grayscale standard deviation.

5. The method as described in claim 4, characterized in that, Determining the first signal-to-noise ratio based on the grayscale parameters and the grayscale standard deviation includes: The ratio of the grayscale parameter to the grayscale standard deviation is determined as the first signal-to-noise ratio.

6. The method as described in claim 2, characterized in that, The step of determining the corresponding detection quantum efficiency based on the first signal-to-noise ratio and the second signal-to-noise ratio includes: The ratio of the square of the first signal-to-noise ratio to the square of the second signal-to-noise ratio is determined as the corresponding detection quantum efficiency.

7. The method as described in claim 1, characterized in that, Determining the performance of the detection system based on each voltage value in the voltage value sequence and its corresponding detection quantum efficiency includes: Based on each voltage value in the voltage value sequence and its corresponding detection quantum efficiency, a detection efficiency curve is determined; The performance of the detection system is determined based on the detection efficiency curve.

8. The method as described in claim 7, characterized in that, Determining the performance of the detection system based on the detection efficiency curve includes: Determine the target curve segment in the detection efficiency curve, wherein the absolute value of the slope of the line connecting the start and end points of the target curve segment is less than or equal to a slope threshold. The performance of the detection system is determined based on the voltage range corresponding to the target curve segment and the detection quantum efficiency.

9. The method as described in claim 1, characterized in that, The difference between any two adjacent voltage values ​​in the voltage value sequence is equal.

10. A detection system performance testing device, characterized in that, The device includes: The first control module is used to control the voltage of the photomultiplier tube in the detection system to change according to multiple voltage values ​​in a voltage value sequence when the electron beam is blocked, and to determine the first grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence. The second control module is used to control the voltage of the photomultiplier tube to change according to multiple voltage values ​​in the voltage value sequence when the reference sample is irradiated by an electron beam, and to determine the second grayscale data of the measurement image corresponding to each voltage value in the voltage value sequence, wherein the second grayscale data is the same as the voltage value corresponding to the first grayscale data. The first determining module is used to determine the corresponding detection quantum efficiency based on the first grayscale data and the second grayscale data under the same voltage value and the relevant information of the electron beam; The second determining module is used to determine the performance of the detection system based on each voltage value in the voltage value sequence and its corresponding detection quantum efficiency.

11. A detection system, characterized in that, include: The detector includes a photomultiplier tube, which converts optical signals into electrical signals and amplifies them so that the detection system can collect signals generated by the interaction between the electron beam and the reference sample. Memory, used to store computer programs and / or instructions; A processor for implementing the method of any one of claims 1 to 9 when executing a computer program and / or instructions stored in the memory.

12. A computer-readable storage medium, characterized in that, The medium stores a computer program that can be executed by a processor to implement the method as described in any one of claims 1 to 9.

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