Imaging compensation method of electron beam equipment, medium and computer program product

Abstract

The invention discloses an imaging compensation method of electron beam equipment, a medium and a computer program product, and relates to the technical field of semiconductor measurement. The imaging compensation method of the electron beam equipment comprises the following steps: applying and adjusting a deceleration voltage to an uncharged wafer to simulate an additional electric field formed under different charged conditions; after the deceleration voltage is adjusted each time, adjusting the excitation current of an objective lens coil in the electron beam equipment to enable the first definition of the collected first image to reach a preset threshold value, and recording the deceleration voltage and the excitation current at the moment; and the response relationship of the electron beam equipment can be obtained by fitting based on multiple groups of deceleration voltages and excitation currents. The response relationship can be accurately matched with hardware characteristics of the electron beam equipment, so that the electron beam equipment can perform imaging compensation on a plurality of wafers with consistent electrification conditions based on the response relationship of the electron beam equipment, and the imaging compensation consistency is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor manufacturing, and particularly relates to an imaging compensation method of an electron beam device, a medium and a computer program product. BACKGROUND

[0002] In the field of semiconductor manufacturing, a wafer needs to go through multiple processes such as plasma etching, photoresist coating, mechanical hand transmission, etc. During the process, non-uniformly charged areas are easily formed on the wafer surface due to factors such as plasma charge injection and friction static electricity accumulation. This charging phenomenon will have a negative impact on the imaging and metrology of subsequent electron beam devices (such as image defocus, electron beam deviation, wafer yield reduction, etc.). Therefore, the charged wafer needs to be compensated for imaging to reduce the negative impact of the charging phenomenon on the semiconductor process.

[0003] Currently, parameter adjustment is generally used for imaging compensation, that is, the additional electric field of the charged wafer is offset by manually or automatically adjusting the objective lens coil current and other parameters of the device, until the image is restored to be clear. Due to the differences in the hardware characteristics (such as the number of turns of the objective lens coil, the distance between the wafer support table and the objective lens, etc.) of different electron beam devices, the compensation parameter values obtained by adjusting the parameters of a certain electron beam device for the same charged wafer cannot be reused in other electron beam devices. Even for the same charged wafers (such as wafers in the same batch), multiple electron beam devices cannot achieve imaging compensation for the charged wafers by reusing the compensation parameter values. SUMMARY

[0004] The embodiments of the present application provide an imaging compensation method of an electron beam device, a medium and a computer program product, which can uniformly compensate for the imaging of charged wafers with consistent charging conditions, and has high consistency.

[0005] In a first aspect, the embodiments of the present application provide an imaging compensation method of an electron beam device, comprising: acquiring, by an electron beam device, a first image of an uncharged wafer; applying a deceleration voltage to the uncharged wafer, and adjusting the deceleration voltage to simulate an additional electric field formed by the uncharged wafer under different charging conditions; adjusting an excitation current of an objective lens coil in the electron beam device after each adjustment of the deceleration voltage, and detecting a first definition of the first image; when the first definition is greater than a preset threshold, recording the adjusted deceleration voltage and the excitation current; fitting a response relationship of the electron beam device based on multiple sets of the deceleration voltage and the excitation current, and the response relationship is used for imaging compensation of multiple wafers with consistent charging conditions.

[0006] In a second aspect, the embodiment of the present application provides an imaging compensation device of an electron beam device, comprising: The imaging module is configured to acquire a first image of an uncharged wafer by the electron beam device. The simulation module is configured to apply a deceleration voltage to the uncharged wafer, and adjust the deceleration voltage to simulate an additional electric field formed by the uncharged wafer under different charged conditions. The definition determination module is configured to adjust an excitation current of an objective lens coil in the electron beam device after each adjustment of the deceleration voltage, and detect a first definition of the first image. The data recording module is configured to record the adjusted deceleration voltage and the excitation current when the first definition is greater than a preset threshold. The response relationship module is configured to obtain a response relationship of the electron beam device based on a plurality of sets of the deceleration voltage and the excitation current, and the response relationship is used for imaging compensation of a plurality of wafers with the same charged condition.

[0007] In a third aspect, the embodiment of the present application provides an electronic device, which comprises a memory and a program or instruction stored in the memory and executable on a processor, and the program or instruction is executed by the processor to implement the imaging compensation method of the electron beam device provided in any one of the above aspects of the embodiment of the present application.

[0008] In a fourth aspect, the embodiment of the present application provides a readable storage medium, and a program or instruction is stored in the readable storage medium, and the program or instruction is executed by the processor to implement the imaging compensation method of the electron beam device provided in any one of the above aspects of the embodiment of the present application.

[0009] In a fifth aspect, the embodiment of the present application provides a computer program product, and instructions in the computer program product are executed by a processor of an electronic device to enable the electronic device to perform the imaging compensation method of the electron beam device provided in any one of the above aspects of the embodiment of the present application.

[0010] The technical solution provided by the embodiment of the present application at least brings the following beneficial effects: In the imaging compensation method of the electron beam device provided by the embodiment of the present application, the additional electric field formed by the wafer under different charged conditions can be simulated by applying and adjusting the deceleration voltage to the uncharged wafer; after adjusting the deceleration voltage each time, the first clarity of the first image collected is adjusted to reach the preset threshold value by adjusting the excitation current of the objective lens coil in the electron beam device, and the deceleration voltage and the excitation current at this time are recorded; and the response relationship of the electron beam device can be fitted based on the multiple sets of deceleration voltage and excitation current. The response relationship can accurately match the hardware characteristics of the electron beam device, so that the electron beam device can perform imaging compensation on multiple wafers with consistent charged conditions based on the response relationship thereof, and the consistency of the imaging compensation between multiple electron beam devices is realized. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced. Those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0012] Figure 1 FIG. 1 is a flowchart of an imaging compensation method of an electron beam device provided by an embodiment of the present application; Figure 2 FIG. 2 is a schematic diagram of imaging by an electron beam device provided by an embodiment of the present application; Figure 3 FIG. 3 is a schematic diagram of a response relationship provided by an embodiment of the present application; Figure 4 FIG. 4 is a flowchart of imaging compensation on a target wafer provided by an embodiment of the present application; Figure 5 FIG. 5 is a schematic diagram of an additional electric field of a target wafer provided by an embodiment of the present application; Figure 6 FIG. 6 is a structural schematic diagram of an imaging compensation device of an electron beam device provided by an embodiment of the present application; Figure 7 FIG. 7 is a schematic diagram of an imaging compensation device of an electron beam device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0013] The features and exemplary embodiments of the various aspects of the present application will be described in detail below with reference to the drawings. For the purpose of clarity, not all of the individual features of the application are described in detail herein. The following detailed description is merely exemplary of the application and is not intended to limit the application unless otherwise specified.

[0014] It should be noted that the relational terms herein, such as first and second, and the like, are used solely to distinguish one from another entity or action without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0015] It should be noted that the acquisition, storage, use, processing, etc. of data in the technical solutions of the present application comply with the relevant provisions of national laws and regulations. In the embodiments of the present application, some industry existing solutions, components, models, etc. may be mentioned, which should be considered as exemplary, and the purpose is only to illustrate the feasibility of the implementation of the technical solutions of the present application, but it does not mean that the applicant has or will necessarily use the solution.

[0016] First, the terms related to one or more embodiments of the present application are explained.

[0017] Plasma charge implantation refers to the phenomenon that the charged particles in high-energy plasma hit and embed into the wafer surface or photoresist layer due to the action of the electric field in the plasma etching process, resulting in the accumulation of excess charge on the wafer.

[0018] Frictional electrostatic accumulation refers to the phenomenon that the wafer surface generates and retains electric charge due to the transfer of electrons between different materials during wafer transmission or contact / separation with other equipment components.

[0019] Electron beam equipment refers to semiconductor equipment used for imaging or metrology in the semiconductor manufacturing field, which generates images by detecting reflected or secondary electron signals through electron beam bombardment of the wafer surface.

[0020] Compensation parameter refers to the parameter of the electron beam device (such as the excitation current of the objective lens coil) adjusted to offset the additional electric field interference formed by the attachment of electric charges on the wafer surface.

[0021] Uncharged wafer refers to a wafer with no excess charge accumulation on the surface or no impact on the electron beam.

[0022] Retarding voltage (RV) refers to a reverse bias voltage applied in the wafer or electron beam path, used to form a retarding electric field opposite to the direction of electron beam motion, to slow down the electron beam after acceleration of the electron gun.

[0023] Additional electric field refers to the additional electric field formed on the wafer surface due to charge accumulation, which interferes with the electron beam trajectory.

[0024] Objective lens (OL) refers to the component in the electron beam device that controls the electron beam trajectory, generates a magnetic field by passing a specific size of excitation current, and uses the Lorentz force of the magnetic field on the electron beam to achieve focusing, deflection or pixel correction of the electron beam. The size of the excitation current directly affects the quality of the electron beam imaging.

[0025] Excitation current refers to the current passed through the objective lens coil, the size of which directly determines the strength of the magnetic field generated by the objective lens coil.

[0026] In the field of semiconductor manufacturing, wafers need to go through multiple processes such as plasma etching, photoresist coating, mechanical hand transmission, etc. During the process, non-uniformly charged areas may be formed on the wafer surface due to factors such as plasma charge injection and friction static charge accumulation. This charging phenomenon can have a negative impact on subsequent imaging and measurement of electron beam equipment (such as image defocus, electron beam deviation, wafer yield reduction, etc.). Therefore, compensation for charged wafers is needed to reduce the negative impact of charging on semiconductor manufacturing.

[0027] Currently, parameter adjustment is generally used for imaging compensation, that is, the objective lens coil current and other parameters are manually or automatically adjusted by the device to offset the interference of the additional electric field of the charged wafer on the electron beam trajectory until the image is restored to be clear. Due to differences in hardware characteristics (such as the number of turns of the objective lens coil, the distance between the wafer support table and the objective lens, sensor sensitivity, etc.) of different electron beam devices, the compensation parameter value obtained by adjusting the parameters of a certain electron beam device for the same charged wafer cannot be reused in other electron beam devices. Even for charged wafers with the same charging condition (such as wafers in the same batch), multiple electron beam devices cannot achieve imaging compensation for charged wafers by reusing the compensation parameter value.

[0028] To solve the above technical problems, the present application provides an imaging compensation method of an electron beam device and a computer program product. In the imaging compensation method of the electron beam device provided in the embodiment of the present application, first, an uncharged wafer with no excess charge accumulation is obtained as a carrier for subsequent parameter calibration and additional electric field simulation. Second, a first image of the uncharged wafer is collected by an electron beam device, and a deceleration voltage is applied to the uncharged wafer. The deceleration voltage is adjusted to simulate an additional electric field formed by the uncharged wafer under different charged conditions. Then, for each electron beam device, after adjusting the deceleration voltage each time, the excitation current of the objective lens coil in the electron beam device is adjusted, and when the first clarity of the first image reaches a preset threshold, the adjusted deceleration voltage and excitation current at this time are recorded. Finally, based on multiple sets of deceleration voltage and excitation current, the response relationship of the electron beam device is fitted. Multiple electron beam devices can perform unified imaging compensation on multiple wafers with consistent charged conditions based on their own response relationships, thereby improving the consistency and efficiency of imaging compensation.

[0029] For example, the imaging compensation method of the electron beam device provided in the embodiment of the present application can be applied to the production line of a semiconductor manufacturing enterprise to solve the compensation consistency problem when multiple electron beam devices image wafers with consistent charged conditions. In actual application, through the process of "deceleration voltage simulating additional electric field and excitation current adjusting clarity", the response relationship conforming to the hardware characteristics of each electron beam device is fitted, and the response relationship of each electron beam device is stored in a data storage device. When a charged wafer with consistent charged conditions enters the imaging or detection link, an electron beam device can be selected to image the charged wafer, and the imaging clarity can be improved by adjusting the excitation current. The response relationship of the electron beam device can be used to determine the additional electric field of a single charged wafer. Then, the operator or the automatic system can determine the corresponding compensation excitation current of each electron beam device based on the response relationship of each electron beam device and the additional electric field of the single charged wafer, so as to perform imaging compensation on other charged wafers with consistent charged conditions.

[0030] It should be noted that the application scenarios described in the above embodiments of the present application are used to more clearly illustrate 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. It is known to those skilled in the art that, with the emergence of new application scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems. The imaging compensation method of the electron beam device provided in the embodiments of the present application can be applied to various application scenarios that need to detect the additional electric field of a charged wafer or perform imaging compensation on a charged wafer.

[0031] The imaging compensation method of the electron beam device provided by the embodiments of the present application is introduced below. In actual application, the execution subject of the imaging compensation method of the electron beam device of the embodiments of the present application can be a terminal device such as a desktop computer, a notebook computer, etc., or a remote device similar to a server. Of course, the embodiments of the present application can also adopt an execution subject in the form of presentation software, for example, a client, a software program, etc. installed in a terminal device, and the specific type of the execution subject corresponding to the technical solution provided by the embodiments of the present application is not strictly limited here, and can be flexibly selected according to actual application scenarios and actual needs.

[0032] The specific embodiments of the imaging compensation method, the device, the electronic device, the storage medium and the computer program product of the electron beam device provided by the embodiments of the present application are introduced below. First, an imaging compensation method of an electron beam device is introduced.

[0033] Figure 1 The flowchart of the imaging compensation method of an electron beam device provided by the embodiments of the present application is shown in FIG. 1. As shown in FIG. 1, the method includes steps S100 to S104. Figure 1

[0034] S100: collecting a first image of an uncharged wafer by an electron beam device; S101: applying a deceleration voltage to the uncharged wafer, and adjusting the deceleration voltage to simulate an additional electric field formed by the uncharged wafer under different charging conditions.

[0035] In one or more embodiments of the present application, in order to provide data support for fitting the response relationship of the electron beam device in the subsequent steps. In this step, the present application needs to apply and adjust the deceleration voltage to the uncharged wafer to simulate the additional electric field formed by the uncharged wafer under different charging conditions.

[0036] Specifically, taking an electron beam device (such as a scanning electron microscope) in a semiconductor production line as an example, an uncharged wafer is selected, the uncharged wafer is transmitted into the electron beam device, and the electron beam device is started. The first image of the uncharged wafer is collected by the electron beam device, and the electrode system of the electron beam device is used to apply a deceleration voltage (an adjustable voltage output by the power supply in the electrode system can form a controllable electric field on the wafer surface or the electron beam transmission path) to the uncharged wafer. By adjusting the deceleration voltage, the additional electric field formed by the uncharged wafer under different charging conditions is simulated.

[0037] ​It should be noted that the uncharged wafer refers to a wafer without excess charge accumulation or no impact on the electron beam, that is, the uncharged wafer refers to a wafer with a charge density less than a preset charge density threshold, which may affect the electron beam trajectory of the electron beam device when the charge density exceeds the charge density threshold. In this application, the acquisition method of the uncharged wafer is not limited, which can be set according to actual needs, such as the uncharged wafer can be a wafer after charge neutralization treatment, or a wafer without plasma etching and other charged processes. In this application, the wafer range for collecting the first image is not limited, which can be set according to actual needs, such as the first image can be an image collected on a local area (such as a single die size area) of the uncharged wafer. Since the first image collected on the local area has better visibility of the clarity of the microstructure of the wafer, the clarity has high sensitivity to the excitation current, and the first image of the whole wafer has wide coverage, when the excitation current has small amplitude change, the clarity change is not obvious, and the sensitivity to the excitation current is poor. Then in order to capture the subtle changes of the clarity and improve the detection accuracy of the clarity in the subsequent steps, in one or more embodiments of the present application, the present application can image a local area of a preset size on the uncharged wafer through the electron beam device to obtain the first image.

[0038] Meanwhile, in this application, the way of adjusting the deceleration voltage is not limited, which can be set according to actual needs, such as adjusting the deceleration voltage in a preset coverage voltage interval (the coverage voltage interval needs to cover the charging condition of the wafer, such as determining according to the damage / breakdown voltage of the wafer, which is not limited in this application) according to a preset step; dividing the coverage voltage interval to obtain a plurality of voltage subintervals, adjusting the deceleration voltage in different voltage subintervals with different preset steps (such as using a first step in a common wafer charging interval, and using a second step in a non-common wafer charging interval, the first step is smaller than the second step), to balance the sampling density of different charging conditions, reduce redundant sampling, and improve the accuracy of the simulated additional electric field; or set an initial deceleration voltage (such as Vd=0v), determine the coverage voltage interval (Vd-45~Vd+45) with the initial deceleration voltage as the center, and then adjust the deceleration voltage according to the preset step.

[0039] Figure 2 The schematic diagram of imaging by the electron beam device provided by the embodiments of the present application is shown in FIG. 1. Figure 2 As shown in FIG. 1, the light source 201 is used to emit an electron beam; the objective lens coil 202 is used to focus and control the electron beam, so that the electron beam can accurately act on the wafer 203; the power supply 204 provides power for the electron beam device, such as applying a deceleration voltage on the wafer.

[0040] S102: After adjusting the deceleration voltage each time, adjusting the excitation current of the objective lens coil in the electron beam device, and detecting the first clarity of the first image.

[0041] S103: record the deceleration voltage and the excitation current after the adjustment when the first definition is greater than the preset threshold.

[0042] In one or more embodiments of the present application, in order to provide data support for fitting the response relationship of the electron beam device in subsequent steps. In steps S102 and S103, the present application needs to adjust the excitation current of the objective lens coil in the electron beam device after each adjustment of the deceleration voltage, so that the first definition of the first image in step S100 is greater than the preset threshold.

[0043] Specifically, in step S101, after each adjustment of the deceleration voltage, the present application needs to adjust the excitation current of the objective lens coil in the electron beam device to adjust the focusing state of the electron beam by changing the magnetic field strength generated by the objective lens coil. At the same time, the first definition of the first image is detected, and when the first definition reaches the preset threshold (clear imaging standard), the deceleration voltage after the adjustment and the corresponding excitation current are recorded to form a set of data.

[0044] It should be noted that in the present application, the specific way of detecting the definition is not limited, and can be set according to actual needs, such as definition quantization based on pixel gray gradient, manual observation of labeled definition (by observing the edges and lines of the structure in the local area of the first image), etc. Different definition quantization methods will make the distinction between clear and blurred different, and the present application does not limit the size of the preset threshold, which can be adaptively set according to the actual definition detection method, which is not limited in the present application. In one or more embodiments of the present application, the present application can quantize the first definition of the first image in multiple dimensions to improve the detection accuracy of the definition, as follows: First, the present application matches the feature points of the first image with the design layout of the uncharged wafer to determine the matching degree of the first image, so as to evaluate the definition from the image consistency of the image and the design layout. Secondly, the present application can calculate the edge gradient value of the first image to determine the edge definition of the first image, so as to evaluate the definition from the sharpness of the small structure (such as circuit lines). Then, the present application calculates the image information entropy of the first image to determine the feature completeness of the first image, so as to evaluate the definition from the richness of the image details. Finally, the first definition is determined according to the matching degree, the edge definition and the feature completeness.

[0045] In this embodiment, the present application does not limit the specific way of determining the first definition based on the three-dimensional definition evaluation results, which can be set according to actual needs, such as weighted summation after normalization processing, etc. The definition is detected by multi-dimensional definition evaluation, which is more comprehensive and accurate.

[0046] S104: fitting a response relationship of the electron beam device based on the multiple sets of deceleration voltage and excitation current, the response relationship being used for imaging compensation of multiple wafers with consistent charging conditions.

[0047] In one or more embodiments of the present application, in this step, the present application needs to convert the multiple sets of discrete data (deceleration voltage and excitation current) obtained in step S103 into a continuous response relationship that can be directly applied, so that the electron device can realize imaging compensation of the wafer based on the response relationship and the charging condition of the wafer.

[0048] Specifically, the multiple sets of "deceleration voltage-excitation current" data pairs recorded in step S103 are sorted and preprocessed (such as removing outliers, interpolation processing, etc.), and then the multiple sets of preprocessed deceleration voltage and excitation current are fitted to establish the response relationship between the deceleration voltage and the excitation current, and the response relationship of the electron beam device is used for imaging compensation of multiple wafers with consistent charging conditions.

[0049] It should be noted that in the present application, the specific way of fitting the deceleration voltage and the excitation current is not limited, and can be set according to actual needs, such as using fitting algorithms, linear regression, polynomial fitting or least squares method, table fitting, etc. For example, if the data shows a linear distribution, the multiple sets of deceleration voltage and excitation current can be fitted by a linear equation; if it shows a nonlinear distribution, the multiple sets of deceleration voltage and excitation current can be fitted by a quadratic equation or an exponential equation. After the corresponding relationship is fitted, the deviation (such as mean square error) between the response relationship and the actual "deceleration voltage-excitation current" data pair can be calculated to ensure that the deviation is less than a preset deviation threshold. If the deviation is not less than the deviation threshold, new data pairs or updated fitting equations / algorithms are needed until the deviation is less than the deviation threshold, and the response relationship that meets the application requirements is obtained. In the case of multiple electron beam devices, due to the differences in hardware characteristics of each electron beam device, the hardware characteristics can be characterized by parameters such as the number of turns of the objective lens coil, the magnetic field strength, the distance between the wafer and the objective lens, the material, etc. This difference makes it difficult to infer the response relationship of other electron beam devices based on the response relationship of a single electron beam device. Therefore, in the present application, the multiple electron beam devices used for imaging compensation need to be subjected to the processes of deceleration voltage simulation, excitation current matching and data fitting (steps S100 to S104) respectively, so as to establish the response relationship of each electron beam device itself, thereby ensuring the consistency of imaging compensation of multiple electron beam devices.

[0050] Meanwhile, the consistent charging condition refers to that the charge distribution characteristics (such as the charge density, the charging area, and the charge polarity) of the plurality of wafer surfaces are completely the same or within a preset error range. The additional electric field formed by the wafers with the consistent charging condition is consistent in affecting / interfering with the electron beam imaging. In the present application, the source of the wafers with the consistent charging condition is not limited, and can be set according to the requirements. For example, the wafers of the same batch produced in the same process are subjected to the same manufacturing processes, including plasma etching, thin film deposition, and transmission speed, which can accumulate charges on the wafers, so that the difference in charge accumulation of the wafers of the same batch is within the preset error range, that is, the charging conditions of the wafers of the same batch are consistent.

[0051] Figure 3 A schematic diagram of a response relationship provided by an embodiment of the present application is shown in FIG. 3. Figure 3 As shown in FIG. 3, the horizontal coordinate represents the excitation current (I) of the objective lens coil (OL), and the vertical coordinate represents the deceleration voltage Vd.

[0052] In the imaging compensation method of the electron beam device, the response relationship of the electron beam device is obtained by the processes of deceleration voltage simulation, excitation current matching, and data fitting of the electron beam device. In actual application, since the additional electric field formed by the wafers with the consistent charging condition is consistent, the response relationship of each electron beam device can be called to automatically calculate the compensation excitation current based on the additional electric field of the charged wafer, so as to realize the consistency of the imaging compensation, which is low in cost and high in efficiency.

[0053] In one or more embodiments of the present application, the additional electric field (voltage distribution) of a target wafer (such as any wafer in the plurality of wafers with the consistent charging condition) can be determined based on the electron beam device for which the response relationship fitting has been completed.

[0054] Figure 4 A flowchart of the process of imaging compensation for a target wafer provided by an embodiment of the present application is shown in FIG. 4. Figure 4 As shown in FIG. 4, the method includes steps S400 to S402, which are specifically as follows. S400: In the case of a plurality of electron beam devices, at least one electron beam device for which the response relationship fitting has been completed is selected as a target device.

[0055] S401: The second image of the target wafer is acquired by the target device, and the additional electric field of the target wafer is determined according to the target excitation current when the resolution of the second image is greater than a preset threshold value and the response relationship of the target device.

[0056] S402: determining, based on the additional electric field of the target wafer and the response relationship of the at least one other electron beam device, an excitation current of the at least one other electron beam device for compensating for imaging of a charged wafer consistent with the charging condition of the target wafer.

[0057] Specifically, for other electron beam devices for which the response relationship fitting has been completed, the additional electric field of the target wafer is substituted into the response relationship of each electron beam device itself, and the corresponding compensation excitation current of each electron beam device is obtained, so that the objective lens coil is adjusted according to the compensation excitation current obtained by each electron beam device, and the imaging of a charged wafer consistent with the charging condition (additional electric field) of the target wafer is compensated.

[0058] It should be noted that the target device is started to image the target wafer, and the excitation current of the objective lens coil in the target device is adjusted until the clarity of the second image collected reaches a preset threshold, and the target excitation current of the objective lens coil at this time is recorded, and then the additional electric field of the target wafer is determined based on the target excitation current and the response relationship of the target device. However, in actual application, the electric charge on the wafer can present a non-uniform distribution (such as high local etching area charge density, edge area charge distance, or point charge), and at this time, the excitation current adjustment of a single point / region / overall region cannot accurately reflect the additional electric field of the wafer. Therefore, in order to fully characterize the charge distribution of the wafer, in one or more embodiments of the present application, multiple regions / points on the target wafer can be selected for imaging to calculate the additional electric field of the wafer, as follows: First, the present application can determine multiple target sampling regions of the target wafer, and for each target sampling region, the target device collects a second image at the target sampling region. The present application does not limit the area of a single target sampling region, which can be set according to actual needs, such as the area of a target sampling region being the size of a single die. The present application does not limit the consistency of the size of each target sampling region (which can be consistent or inconsistent), which can be set according to actual needs.

[0059] Secondly, for each second image, the excitation current of the target device is adjusted, and the second clarity of the second image is detected; when the second clarity of the second image is greater than a preset threshold, the adjusted target excitation current is recorded. Finally, according to the target excitation current corresponding to each target sampling region, the response relationship of the target device is used to determine the additional voltage of each target sampling region; and according to the additional voltage, the additional electric field of the target wafer is determined.

[0060] It should be noted that the distribution of the target sampling area is not limited in the present application, and can be set according to actual needs, such as uniform distribution sampling. The area on the wafer containing the preset device structure (such as a gate, a capacitor, etc.) directly affecting the performance of the chip is more sensitive to the imaging clarity of the additional electric field. When disturbed by the additional electric field, edge blur and size measurement deviation problems will occur, affecting the accuracy of the measurement data. In order to ensure the imaging compensation accuracy of the more sensitive area to the additional electric field, in one or more embodiments of the present application, the present application can combine the design layout of the target wafer and the characteristics of the device structure involved, and specifically divide the sampling range and set the sampling density according to the characteristics of the device structure involved, as follows: First, the present application can determine the area containing the preset device structure on the target wafer as the first sampling range according to the design layout of the target wafer, and the other range on the target wafer except the first sampling range as the second sampling range. In the present application, the specific content of the preset device structure is not limited, and can be set according to actual needs, such as the preset device structure can include a gate, a capacitor, a nanowire structure, and other important or more sensitive device / structure to the additional electric field.

[0061] Secondly, the present application can determine the target sampling area in the first sampling range according to the preset first density.

[0062] Finally, the present application can determine the target sampling area in the second sampling range according to the preset second density. Wherein, the second density is less than the first density.

[0063] It should be noted that the range sampling according to the first density and the second density realizes the design of "high-density sampling in sensitive / important area and low-density sampling in non-sensitive / non-important area", which ensures the detection accuracy of the key structure additional electric field, and reduces unnecessary sampling work, and balances the detection accuracy and detection efficiency. Of course, the specific size of the first density and the second density is not limited in the present application, and can be set according to actual needs.

[0064] Figure 5 The schematic diagram of the additional electric field of the target wafer provided by the present application embodiment.

[0065] Similarly, when compensating for the imaging of the other charged wafer based on the additional electric field of the target wafer, in addition to considering the response relationship under the hardware characteristics of different electron beam devices, the additional voltage at the imaging position also needs to be considered, especially when the additional electric field of the charged wafer is non-uniformly distributed. If the uniform imaging compensation is performed based on the global additional electric field, the clarity at the local imaging position may deviate due to the charge video and cannot reach the preset threshold. Therefore, in one or more embodiments of the present application, the present application can compensate for the imaging of the charged wafer in combination with the response relationship reflecting the hardware characteristics of the imaging device, the imaging position, and the additional electric field of the target wafer, as follows: Firstly, the present application can determine the second device for imaging the charged wafer, and the imaging position of the charged wafer. Secondly, according to the additional electric field of the target wafer and the imaging position of the charged wafer, the additional voltage at the imaging position is determined, and then according to the additional voltage at the imaging position and the response relationship of the second device, the compensation excitation current is determined. Finally, the imaging compensation is performed according to the compensation excitation current.

[0066] In addition, in actual application, there may be a case that the imaging clarity does not reach the preset threshold after the imaging compensation based on the compensation excitation current, which may be caused by the deviation of the hardware parameters of the electron beam device after long-term use, the insufficient sampling area to cover the entire range, and other factors. Therefore, in one or more embodiments of the present application, after the imaging compensation based on the compensation excitation current, the present application can acquire a third image at the imaging position by the second device, and detect a third clarity of the third image. If the third clarity is not greater than the preset threshold, the compensation excitation current of the second device is adjusted, and the compensation excitation current after the adjustment is recorded when the third clarity reaches the preset threshold. Thus, the response relationship of the second device can be corrected based on the additional voltage at the imaging position and the adjusted compensation excitation current.

[0067] For example, the additional voltage at the imaging position is +8v, and the compensation excitation current determined according to the current response relationship is 0.9A, but the third clarity of the third image does not reach the preset threshold (not clear enough). Therefore, the excitation current (compensation excitation current) of the objective lens coil in the electron beam device needs to be fine-tuned until the third clarity reaches the preset threshold. The adjusted compensation excitation current 0.8A is recorded at this time, and the response relationship of the second device is corrected based on the data of "+8v, 0.8A" to make the corrected response relationship more accurate.

[0068] Similarly, in the case of hardware parameter drift of the electron beam device, in one or more embodiments of the present application, the present application can also re-collect multiple groups of deceleration voltage and excitation current (when the image definition reaches the preset threshold) according to the preset period, fit to obtain the first relationship of the electron beam device, and update the response relationship of the electron beam device according to the preset weight based on the parameter value in the first relationship. In the present application, the size of the preset weight is not limited, and can be set according to actual needs, for example, the parameter weight of the first relationship is set to 0.6, and the parameter weight of the response relationship at this time is 0.4.

[0069] In this embodiment, the present application does not directly use the first relationship re-fitted to replace the original response relationship, but introduces a preset weight to integrate the parameters of the first relationship into the original response relationship, so as to ensure the accuracy of the response relationship through smooth updating.

[0070] The imaging compensation method based on the electron beam device. Correspondingly, the present application also provides specific embodiments of the imaging compensation device of the electron beam device.

[0071] As shown in Figure 6 The imaging compensation device 600 of the electron beam device provided by the embodiment of the present application includes an imaging module 601, an analog module 602, a definition determination module 603, a data recording module 604, and a response relationship module 605.

[0072] The imaging module 601 is configured to collect a first image of an uncharged wafer by an electron beam device; The analog module 602 is configured to apply a deceleration voltage to the uncharged wafer, and adjust the deceleration voltage to simulate an additional electric field formed by the uncharged wafer under different charged conditions; The definition determination module 603 is configured to adjust an excitation current of an objective lens coil in the electron beam device after each adjustment of the deceleration voltage, and detect a first definition of the first image; The data recording module 604 is configured to record the adjusted deceleration voltage and the excitation current after the first definition is greater than a preset threshold; The response relationship module 605 is configured to fit to obtain a response relationship of the electron beam device based on multiple groups of the deceleration voltage and the excitation current, and the response relationship is used for imaging compensation of multiple wafers with the same charged condition.

[0073] In some embodiments, the apparatus further includes an imaging compensation module, configured to: in the case of multiple electron beam devices, select at least one electron beam device that has completed the response relationship fitting as a target device; collect a second image of a target wafer by the target device, and determine the additional electric field of the target wafer according to the target excitation current when the definition of the second image is greater than the preset threshold, and the response relationship of the target device; and determine the excitation current of each of the electron beam devices for imaging compensation of a charged wafer consistent with the charging condition of the target wafer based on the additional electric field of the target wafer and the response relationship of each of the electron beam devices.

[0074] In some embodiments, the apparatus further includes an imaging compensation module, which can be further configured to: determine a plurality of target sampling regions of a target wafer, and for each of the target sampling regions, collect a second image at the target sampling region by the target device; for each of the second images, adjust the excitation current of the target device, and detect a second definition of the second image; for each of the second images, record the adjusted target excitation current when the second definition of the second image is greater than the preset threshold; determine additional voltages of the target sampling regions according to the target excitation current corresponding to each of the target sampling regions, and the response relationship of the target device; and determine the additional electric field of the target wafer according to the additional voltages.

[0075] In some embodiments, the apparatus further includes an imaging compensation module, which can be further configured to: determine a second device for imaging the charged wafer, and an imaging position of the charged wafer; determine the additional voltage of the imaging position according to the additional electric field of the target wafer and the imaging position of the charged wafer; determine a compensation excitation current according to the additional voltage of the imaging position and the response relationship of the second device; and perform imaging compensation according to the compensation excitation current.

[0076] In some embodiments, the apparatus further includes an imaging compensation module, which can be further configured to: determine a range containing a preset device structure on the target wafer as a first sampling range according to a design layout of the target wafer, the preset device structure including at least one of a gate and a capacitor; determine a second sampling range on the target wafer other than the first sampling range; determine the target sampling regions in the first sampling range according to a preset first density; and determine the target sampling regions in the second sampling range according to a preset second density, the second density being less than the first density.

[0077] In some embodiments, the apparatus further includes an imaging compensation module, and the apparatus is further configured to: acquire, by the second device, a third image at the imaging position; detect a third definition of the third image, and in a case where the third definition is not greater than the preset threshold, adjust the compensation excitation current of the second device, and record the compensation excitation current after the adjustment when the third definition reaches the preset threshold; and correct the response relationship of the second device based on the additional voltage of the imaging position and the compensation excitation current after the adjustment.

[0078] In some embodiments, the apparatus further includes an imaging compensation module, and the apparatus is further configured to: acquire a plurality of groups of the deceleration voltage and the excitation current according to a preset period, and fit to obtain a first relationship of the electron beam device; and update the response relationship of the electron beam device according to each parameter value in the first relationship and a preset weight.

[0079] In some embodiments, the data acquisition module is specifically configured to: perform feature point matching on the first image and a design layout of the wafer without charge to obtain a matching degree of the first image; perform edge gradient value calculation on the first image to determine an edge definition of the first image; perform image information entropy calculation on the first image to determine a feature completeness of the first image; and determine the first definition according to the matching degree, the edge definition, and the feature completeness.

[0080] An imaging compensation method of an electron beam device is provided. Accordingly, a specific embodiment of an imaging compensation device of an electron beam device is also provided.

[0081] Figure 7 A hardware structure schematic diagram of an imaging compensation device of an electron beam device provided by an embodiment of the present application is shown.

[0082] The imaging compensation device of the electron beam device can include a processor 701 and a memory 702 having computer program instructions stored therein.

[0083] Specifically, the processor 701 can include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present application.

[0084] The memory 702 can include mass storage for data or instructions. As an example and not by way of limitation, the memory 702 can include a hard disk drive (HDD), a floppy disk drive, flash memory, an optical disc (e.g., a compact disc (CD) or a Blu-ray Disc®), a tape drive, a USB drive, or a combination of two or more of these. The memory 702 can include removable or non-removable (or fixed) media, where appropriate. The memory 702 can be internal or external to the integrated gateway disaster recovery appliance, where appropriate. In particular embodiments, the memory 702 is non-volatile, solid-state memory.

[0085] The processor 701 implements the imaging compensation method of any of the above-described embodiments of the electron beam device by reading and executing computer program instructions stored in the memory 702.

[0086] In one example, the electronic device can also include a communication interface 703 and a bus 710. As shown, the processor 701, the memory 702, and the communication interface 703 are connected by the bus 710 and complete communication with each other. Figure 7

[0087] The communication interface 703 is mainly used to realize the communication between the modules, devices, units and / or equipment in the embodiments of the present application.

[0088] The bus 710 includes hardware, software, or both, that couples components of the electronic device to each other. As an example and not by way of limitation, the bus can include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an InfiniBand (IB) interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or another suitable bus or interconnect, or a combination of two or more of these. Where appropriate, the bus 710 can include one or more buses. Although the present application describes and illustrates a particular bus, this application contemplates any suitable bus or interconnect.

[0089] In addition, in combination with the processing method of the wafer topography scanning signal in the above-described embodiments, the present application can provide a computer storage medium to realize. The computer storage medium has computer program instructions stored thereon; the computer program instructions are executed by the processor to realize the imaging compensation method of any of the above-described embodiments of the electron beam device.

[0090] ​In addition, in combination with the imaging compensation method of the electron beam device in the above-mentioned embodiments, the embodiments of the present application can provide a computer program product to implement, and the instructions in the computer program product are executed by the processor of the electronic device, so that the electronic device executes the imaging compensation method of the electron beam device provided by any one of the above-mentioned embodiments of the present application.

[0091] It should be noted that the present application is not limited to the specific configurations and processes described above and shown in the drawings. For the sake of brevity, detailed descriptions of well-known methods are omitted herein. In the above-mentioned embodiments, several specific steps are described and shown as examples. However, the method processes of the present application are not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order of the steps, after understanding the spirit of the present application.

[0092] The functional blocks shown in the structural block diagrams described above can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a functional card, etc. When implemented in software, the elements of the present application are program or code segments used to perform the required tasks. The program or code segments can be stored in a machine-readable medium or transmitted through a data signal carried in a carrier wave over a transmission medium or communication link. The "machine-readable medium" can include any medium capable of storing or transmitting information. Examples of the machine-readable medium include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segments can be downloaded via a computer network such as the Internet, an intranet, etc.

[0093] It should also be noted that the exemplary embodiments mentioned in the present application describe some methods or systems based on a series of steps or devices. However, the present application is not limited to the order of the above-mentioned steps, that is, the steps can be executed in the order mentioned in the embodiments, or in an order different from that in the embodiments, or several steps can be executed simultaneously.

[0094] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other processing device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other processing device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0095] The above only is a specific implementation of the present application, and those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described system, module and unit can refer to the corresponding process in the foregoing method embodiments, which will not be described herein. It should be understood that the protection scope of the present application is not limited to this, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed in the present application, and these modifications or replacements shall be covered within the protection scope of the present application.

Claims

1. An imaging compensation method for an electron beam device, characterized in that, include: The first image of the uncharged wafer is acquired using an electron beam device; A deceleration voltage is applied to the uncharged wafer, and the deceleration voltage is adjusted to simulate the additional electric field formed by the uncharged wafer under different charging conditions; After each adjustment of the deceleration voltage, the excitation current of the objective lens coil in the electron beam device is adjusted, and the first sharpness of the first image is detected. When the first resolution is greater than a preset threshold, record the deceleration voltage and the excitation current after the adjustment; Based on multiple sets of the deceleration voltage and the excitation current, the response relationship of the electron beam device is fitted, and the response relationship is used to perform imaging compensation on multiple wafers with the same charging condition.

2. The method as described in claim 1, characterized in that, After fitting the response relationship of the electron beam device based on multiple sets of the deceleration voltages and the excitation currents, the method further includes: When there are multiple electron beam devices, at least one electron beam device that has completed the fitting of the response relationship is selected as the target device; The target device acquires a second image of the target wafer, and the additional electric field of the target wafer is determined based on the target excitation current when the clarity of the second image is greater than the preset threshold and the response relationship of the target device. Based on the additional electric field of the target wafer and the response relationship of at least one of the electron beam devices, the excitation current for imaging compensation of the charged wafer with the same charging condition as the target wafer is determined by at least one of the electron beam devices.

3. The method as described in claim 2, characterized in that, The target device acquires a second image of the target wafer, and based on the target excitation current when the clarity of the second image is greater than a preset threshold, and the response relationship of the target device, determines the additional electric field of the target wafer, including: Multiple target sampling regions of the target wafer are determined, and for each target sampling region, a second image at that target sampling region is acquired by the target device; For each of the second images, the excitation current of the target device is adjusted, and the second sharpness of the second image is detected; For each of the second images, when the second sharpness of the second image is greater than the preset threshold, the adjusted target excitation current is recorded; Based on the target excitation current corresponding to each target sampling region, the additional voltage of each target sampling region is determined through the response relationship of the target device; The additional electric field of the target wafer is determined based on each of the additional voltages.

4. The method as described in claim 3, characterized in that, Based on the additional electric field of the target wafer and the response relationship of each electron beam device, the excitation current for imaging compensation of the charged wafer with the same charging condition as the target wafer by each electron beam device is determined, including: Determine the second device for imaging the charged wafer, and the imaging position of the charged wafer; The additional voltage at the imaging position is determined based on the additional electric field of the target wafer and the imaging position of the charged wafer; The compensation excitation current is determined based on the additional voltage at the imaging position and the response relationship of the second device; Imaging compensation is performed based on the compensation excitation current.

5. The method as described in claim 2, characterized in that, Determine multiple target sampling regions for the target wafer, including: Based on the design layout of the target wafer, the range on the target wafer containing a preset device structure is determined as the first sampling range, wherein the preset device structure includes at least one of a gate and a capacitor. The other areas on the target wafer besides the first sampling range are taken as the second sampling range; The target sampling area within the first sampling range is determined according to a preset first density; The target sampling region within the second sampling range is determined based on a preset second density, wherein the second density is less than the first density.

6. The method as described in claim 4, characterized in that, After performing imaging compensation based on the compensated excitation current, the method further includes: The third image at the imaging location is acquired using the second device; The third sharpness of the third image is detected, and if the third sharpness is not greater than the preset threshold, the compensation excitation current of the second device is adjusted, and the adjusted compensation excitation current is recorded when the third sharpness reaches the preset threshold. The response relationship of the second device is corrected based on the additional voltage at the imaging position and the adjusted compensation excitation current.

7. The method as described in claim 1, characterized in that, After fitting the response relationship of the electron beam device based on multiple sets of the deceleration voltages and the excitation currents, the method further includes: According to a preset cycle, multiple sets of the deceleration voltage and the excitation current are collected, and the first relationship of the electron beam device is obtained by fitting. The response relationship of the electron beam device is updated based on the parameter values ​​in the first relationship and the preset weights.

8. The method as described in claim 1, characterized in that, Detecting the first sharpness of the first image includes: The first image is matched with the design layout of the uncharged wafer by feature point matching to obtain the matching degree of the first image; The edge gradient value of the first image is calculated to determine the edge sharpness of the first image; The image information entropy of the first image is calculated to determine the feature completeness of the first image; The first sharpness is determined based on the matching degree, the edge sharpness, and the feature completeness.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a program or instructions that, when executed by a processor, implement an imaging compensation method for an electron beam device as described in any one of claims 1-7.

10. A computer program product, characterized in that, When the instructions in the computer program product are executed by the processor of the electronic device, the electronic device performs an imaging compensation method for an electron beam device as described in any one of claims 1-7.

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