Calibration method, electron beam exposure machine, electron beam exposure system, medium and product

Abstract

The invention discloses a calibration method, an electron beam exposure machine, an electron beam exposure system, a medium and a product, which are applied to the technical field of electron beam lithography. The calibration method is applied to the electron beam exposure machine, the electron beam exposure machine comprises a displacement table and a deflection coil, and the calibration method comprises the following steps: scanning a preset mark pattern to generate a first calibration image; the displacement table is controlled to move, so that the preset mark pattern is located in the writing field range of the deflection coil; scanning the preset mark pattern again to generate a second calibration image; controlling the deflection coil to deflect so as to enable the first calibration image to be matched with the second calibration image, and reading a first actual deflection voltage value of the deflection coil during matching; and calibrating the deflection coil based on a mapping relation between the first actual deflection voltage value and an ideal deflection voltage value corresponding to the preset mark pattern. The calibration precision of the deflection coil can be improved, and then the accuracy of the electron beam exposure process is improved.

Description

Technical Field

[0001] This application belongs to the field of electron beam lithography technology, and particularly relates to a calibration method, an electron beam exposure machine, an electron beam exposure system, a computer-readable storage medium, and a computer program product. Background Technology

[0002] In electron beam lithography, calibration using markers is a crucial prerequisite for ensuring exposure accuracy. During electron beam scanning, the electron beam is susceptible to drift due to long-term equipment operation and fluctuations in ambient temperature, leading to deviations between the actual exposure position and the designed position. By pre-fabricating markers and performing calibration, the scanning parameters of the electron beam and the movement trajectory of the stage can be corrected in reverse, ensuring the exposure accuracy of the subsequent pattern to be exposed.

[0003] Traditional calibration methods rely on fixed markers for calibration. However, due to process fluctuations in the marker preparation stage, the actual markers after processing can easily deviate from the designed markers. When the deviation exceeds the recognition threshold, it can lead to marker recognition failure, resulting in misalignment at the splicing points of the area to be exposed, distortion of the graphic edges, and other problems. Ultimately, this seriously affects the accuracy of the electronic exposure process and reduces the performance stability and yield of the finished product. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a calibration method, an electron beam exposure machine, an electron beam exposure system, a computer-readable storage medium, and a computer program product, which can improve the calibration accuracy of the deflection coil, thereby improving the accuracy of the electron beam exposure process.

[0005] In a first aspect, this application provides a calibration method applied to an electron beam exposure machine, the electron beam exposure machine including a displacement stage and a deflection coil, the calibration method comprising: Scan the preset marker pattern to generate the first calibration image; The displacement stage is controlled to move so that the preset marking pattern is located within the writing field range of the deflection coil; The preset marker pattern is scanned again to generate a second calibration image; The deflection coil is controlled to deflect so that the first calibration image and the second calibration image are matched, and the first actual deflection voltage value of the deflection coil is read when the match is achieved. The deflection coil is calibrated based on the mapping relationship between the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset mark pattern.

[0006] Secondly, this application provides an electron beam exposure machine, including a displacement stage, a deflection coil, a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-mentioned calibration method.

[0007] Thirdly, this application provides an electron beam exposure system, including a host computer and the aforementioned electron beam exposure machine.

[0008] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described calibration method.

[0009] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the above-described calibration method.

[0010] The calibration method, electron beam exposure machine, electron beam exposure system, computer-readable storage medium, and computer program product provided in this application embodiment scan a preset mark pattern and use the obtained first calibration image as a comparison reference; the first calibration image reflects the actual preset mark pattern and has virtually no deviation from the preset mark pattern; by moving the displacement stage, the preset mark pattern is placed within the writing field range of the deflection coil, so that the electron beam can scan the preset mark pattern under the action of the deflection coil, and the scanned preset mark pattern is used as the second mark pattern.

[0011] By controlling the deflection coil, the second calibration image obtained from the rescanning is compared and matched with the first calibration image, and the first actual deflection voltage value when the second calibration image matches the first calibration image is read. Based on the mapping relationship between the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset mark pattern, the deflection coil is calibrated. This improves the calibration accuracy of the deflection coil, enhances the accuracy of the electron beam exposure process, and ultimately improves the performance stability and yield of the finished product.

[0012] Additional aspects and advantages of embodiments of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of this application. Attached Figure Description

[0013] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is an application scenario diagram of the calibration method provided in the embodiments of this application; Figure 2 This is a first flowchart illustrating the calibration method provided in this application embodiment; Figure 3 This is a schematic diagram of the surface of the device to be exposed provided in the embodiments of this application; Figure 4 This is a schematic diagram of the second process of the calibration method provided in the embodiments of this application; Figure 5 This is a schematic diagram of the third process of the calibration method provided in the embodiments of this application; Figure 6 This is a schematic diagram of the fourth process of the calibration method provided in the embodiments of this application; Figure 7 This is a schematic diagram of the fifth step of the calibration method provided in the embodiments of this application; Figure 8 This is a schematic diagram of the sixth process of the calibration method provided in the embodiments of this application; Figure 9 This is a schematic diagram of the calibration device provided in the embodiments of this application; Figure 10 This is a schematic diagram of the electron beam exposure machine provided in the embodiments of this application; and Figure 11 This is a schematic diagram of the electron beam exposure system provided in the embodiments of this application. Detailed Implementation

[0014] The embodiments of this application are described in detail below. Examples of the embodiments of this application are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0015] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0016] To facilitate understanding, the application scenarios of this application will be introduced below: Please see Figure 1 , Figure 1 This is an application scenario diagram of a calibration method provided in an embodiment of this application. The application scenario provided in this application includes an electron beam exposure machine 100 and a host computer 110. The electron beam exposure machine 100 includes an electron gun 10, a displacement stage 20, a deflection coil 30, and a main controller 40. The calibration method provided in this application can be executed by at least one of the host computer 110 and the main controller 40.

[0017] Among them, the electron gun 10 is a component used for the electron beam; the electron gun 10 can generate a high-brightness, high-stability electron beam.

[0018] Optionally, the electron gun 10 can be a thermionic electron gun (such as a tungsten filament electron gun or a lanthanum hexaboride electron gun), a field emission electron gun (such as a cold field emission electron gun or a hot field emission electron gun), etc., and the embodiments of this application do not limit this.

[0019] The displacement stage 20 is a platform that supports the device 120 to be exposed (such as a wafer or calibration template) and has high-precision displacement. During the exposure period, it is fixed on the displacement stage 20 and moves with the movement of the displacement stage 20. The displacement stage 20, through stepping or continuous movement, ensures that the reachable area of ​​the electron beam can cover the device 120 to be exposed.

[0020] Optionally, the displacement stage 20 can be a piezoelectric driven displacement stage, an electromagnetic driven displacement stage, a linear motor driven displacement stage, an air-bearing guide rail displacement stage, or a flexible hinge displacement stage, etc., and this application embodiment does not limit this.

[0021] Among them, the deflection coil 30 is a device used to control the deflection of the electron beam; when a set electrical signal is passed to the deflection coil 30, the deflection coil 30 generates a magnetic field or electric field, and the electron beam is deflected under the action of the magnetic field force or electric field force.

[0022] Optionally, the deflection coil 30 includes a lateral deflection coil and a longitudinal deflection coil, the lateral deflection coil being used to control the electron beam in the lateral direction (i.e., Figure 3 The longitudinal deflection coil is used to control the deflection of the electron beam in the longitudinal direction (i.e., the x-direction). Figure 3 The deflection in the y-direction.

[0023] Optionally, the deflection coil 30 can be a magnetic deflection coil, an electrostatic deflection coil, a composite deflection coil, etc., and this application embodiment does not limit this.

[0024] In an alternative embodiment, the electron beam exposure machine 100 further includes a focusing lens 50, a vacuum assembly 60, and a pattern generator 70.

[0025] The focusing lens 50 is a component used to control the transmission, shaping, and focusing of the electron beam generated by the electron gun 10. The focusing lens 50 compresses the beam spot of the diverging electron beam generated by the electron gun 10 to the nanometer or sub-nanometer scale and adjusts the beam cross-section of the electron beam (such as circular or rectangular) to adapt to different pattern requirements.

[0026] Optionally, the focusing lens 50 can be an electrostatic lens, a magnetic lens, a compound electronic lens, etc., and this application embodiment does not limit this.

[0027] The vacuum component 60 is used to create a vacuum environment. The displacement stage 20 and the device to be exposed 120 are located in the vacuum environment. The vacuum environment can prevent water vapor, oxygen and other substances in the air from contaminating the device to be exposed 120 and avoid defects in the exposed pattern (such as broken lines or blurring). After being focused and deflected, the electron beam hits the device to be exposed 120 in the vacuum environment. The vacuum environment can prevent beam scattering and energy attenuation caused by collisions between the electron beam and air molecules, thus ensuring the accuracy of the electron beam.

[0028] The vacuum assembly 60 may consist of a vacuum pump (such as a mechanical pump, diffusion pump, turbomolecular pump, etc.), a vacuum gauge (such as a cold cathode vacuum gauge, capacitive vacuum gauge, etc.), and a filter.

[0029] The pattern generator 70 is a component used to convert exposure pattern data into control signals required for electron beam exposure. The pattern generator 70 receives exposure pattern data transmitted from the host computer 110 or the main controller 40, breaks down the unit pattern in the exposure pattern data into lines and dots, and then converts the digital quantities (lines and dots) into high-precision control signals to achieve electron beam scanning.

[0030] Optionally, the pattern generator 70 may be a Gaussian beam pattern generator, a variable rectangular beam pattern generator, a raster scan pattern generator, etc., and the embodiments of this application do not limit this.

[0031] The main controller 40 is a component used to control the operating conditions of various components of the electron beam exposure machine 100. The main controller 40 can control the displacement stage 20 to achieve displacement at the micrometer, submicrometer, and nanometer scales, control the electron gun 10 to generate an electron beam, control the focusing lens 50 to focus the electron beam and stabilize the transmission path of the electron beam, and control the magnitude of the magnetic field generated by the deflection coil 30 so that the electron beam is deflected according to the set parameters.

[0032] Optionally, the main controller 40 can also collect data such as the vacuum level of the vacuum environment generated by the vacuum component 60, the beam current intensity of the electron beam, and the positioning accuracy in real time, and trigger an alarm in case of abnormal data to ensure the stability of the electron beam exposure process.

[0033] Optionally, the main controller 40 may be a combination of a programmable logic controller (PLC), a field-programmable gate array (FPGA), and a digital signal processor (DSP), etc., and this application embodiment does not limit this.

[0034] The host computer 110 is a component used for human-computer interaction and data management. The host computer 110 is connected to the main controller 40. The host computer 110 can receive user input operations and generate the image data to be exposed. The host computer 110 can also control the main controller 40 to perform electron beam exposure, and can also receive feedback data from the main controller 40 for storage and / or display.

[0035] Optionally, the host computer 110 can be a terminal (such as an industrial terminal), a server, a general-purpose computer-type host computer, an embedded host computer, a dedicated industrial control computer, etc., and this application embodiment does not limit this.

[0036] Based on the above description of the relevant scenarios, this application provides a calibration method, which will be described in detail below: Please see Figure 2 The calibration method provided in this application embodiment is implemented by steps 011, 012, 013, 014 and 015, which are described in detail below.

[0037] Step 011: Scan the preset marker pattern to generate the first calibration image; Step 012: Control the movement of the displacement stage so that the preset marking pattern is located within the writing field range of the deflection coil; The preset marking pattern is a specific graphic located on the device to be exposed, based on experience or user-defined criteria; for example, a cross, a square, a T-shape, an L-shape, etc. Figure 3 As shown, the four preset marking patterns (S1, S2, S3 and S4) in the device to be exposed are all cross-shaped.

[0038] The first calibration image is the image obtained by scanning a preset marker pattern before calibration.

[0039] The writing field range refers to the size of the area that the electron beam can effectively expose without moving the displacement stage.

[0040] Optionally, the writing field is generally square (e.g., Figure 3 (As shown in the dashed box), it can also be a rectangle, etc.

[0041] Specifically, the preset marking pattern is formed by pre-processing the device to be exposed using a corresponding method (such as electron beam lithography or stripping). Before calibration, the preset marking pattern is scanned by an electron beam. The electron beam interacts with the preset marking pattern to generate backscattered electrons and other signals. These signals are collected and converted into electrical signals. The signal intensity is different at different locations. By digitally processing the signal intensity, the first calibration image can be accurately determined and stored.

[0042] During the calibration process, if the preset marking pattern is not within the writing field range, the electron beam cannot scan the preset marking pattern. Therefore, it is necessary to control the movement of the displacement stage to move the device to be exposed in order to ensure that the preset marking pattern is within the writing field range.

[0043] Optionally, if the preset mark is within the writing field range, it is not necessary to control the movement of the displacement stage.

[0044] Step 013: Scan the preset marker pattern again to generate a second calibration image; Step 014: Control the deflection coil to deflect so that the first calibration image and the second calibration image match, and read the first actual deflection voltage value of the deflection coil when they match; Step 015: Based on the mapping relationship between the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset marking pattern, calibrate the deflection coil.

[0045] The second calibration image is the image obtained by scanning a preset marker pattern during the calibration process.

[0046] The ideal deflection voltage value refers to the voltage value that enables the electron beam to accurately scan the preset marking pattern with the expected precision and range.

[0047] The mapping relationship is a pre-defined equation that includes the coefficients to be solved, and the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset mark pattern.

[0048] For example, the mapping relationship is X = A + Bx + Cy + Dxy; where X is the first actual deflection voltage value, x is the ideal deflection voltage value of the transverse deflection coil, y is the ideal deflection voltage value of the longitudinal deflection coil, and A, B, C, and D are coefficients to be solved. Optionally, the mapping relationship can also be a second-order equation, a higher-order equation, etc.

[0049] Specifically, the process of deflecting the electron beam to the position of the preset marker pattern in the writing field range, scanning the preset marker pattern again, and generating the second calibration image is basically similar to the process of generating the first calibration image (step 011). To avoid repetition, it will not be described again here.

[0050] By applying a voltage, a current flows through the deflection coil, generating a magnetic field around it. The magnitude of this magnetic field changes accordingly by controlling the applied voltage. When an electron beam passes through the magnetic field generated by the deflection coil, it is deflected to different degrees in different directions by the Lorentz force, allowing the electron beam to scan the entire writing field.

[0051] In one optional embodiment, the first calibration image and the second calibration image are matched, including the first calibration image and the second calibration image having a similarity greater than a preset similarity.

[0052] The preset similarity is based on experience or user-defined values, such as 0.9, 0.95, etc.

[0053] Similarity is characterized by calculating the degree of grayscale difference between corresponding pixels in the first and second calibration images. The average of the normalized grayscale differences of each pixel is used as the similarity score; the greater the grayscale difference, the lower the similarity. Thus, by comparing with a preset similarity score, the accuracy and efficiency of determining whether a match exists can be improved.

[0054] If the similarity between the first calibration image and the second calibration image is less than or equal to a preset similarity, the first calibration image and the second calibration image do not match.

[0055] By using the first actual deflection voltage value, the ideal deflection voltage value corresponding to the preset marking pattern, and the mapping relationship between the two, the coefficients to be solved in the mapping relationship can be calculated, thus obtaining a definite mapping relationship. Through this definite mapping relationship, the ideal deflection voltage value can be converted into the corresponding first actual deflection voltage value, completing the calibration of the deflection coil.

[0056] This improves the calibration accuracy of the deflection coil, enhances the accuracy of the electron beam exposure process, and consequently improves the performance stability and yield of the finished product.

[0057] In one alternative embodiment, please refer to Figure 4 Optionally, step 012 includes: Step 0121: Control the displacement stage to move to the upper left, lower left, upper right and lower right directions respectively, so that the four preset mark patterns are located within the writing field range of the deflection coil.

[0058] Specifically, please refer to Figure 3 Four preset marker patterns are located at the four corners of the device to be exposed: the upper left, upper right, lower left, and lower right. There are at least four preset marker patterns, each located in a different position. By scanning the four preset marker patterns, corresponding second calibration images are obtained. Calibration is performed based on these four second calibration images to correct orthogonality errors and improve the calibration accuracy of the deflection coil.

[0059] Optionally, the four preset marker patterns can be the same (e.g., Figure 3 All are cross-shaped, some are the same, or all are different (e.g., they are cross-shaped, T-shaped, triangle-shaped, and square-shaped respectively).

[0060] In one optional embodiment, four preset marker patterns are located directly to the right, above, to the left, and below the center of the device to be exposed. The control displacement stage moves to the right, above, to the left, and below, respectively, so that the four preset marker patterns are respectively located within the writing field range of the deflection coil.

[0061] In one optional embodiment, the preset marking patterns include eight patterns, which are arranged in a star-shaped pattern to the right, upper right, upper left, upper left, lower left, lower right, and lower right of the center of the device to be exposed. The control displacement stage moves to the right, upper right, upper left, upper left, lower left, lower right, and lower right directions respectively, so that the eight preset marking patterns are respectively located within the writing field range of the deflection coil.

[0062] This allows for more comprehensive coverage of the area to be exposed, improving calibration accuracy.

[0063] In one alternative embodiment, please continue to refer to Figure 4 Optionally, step 014 includes: Step 0141: Control the deflection coil to deflect so that the first calibration image and the second calibration image match, and read the first actual deflection voltage value when scanning the preset position of the preset mark pattern during the matching. The preset position is either based on experience or user-defined. For example, if the preset marker pattern is a cross, the preset position is the center of the cross; if the preset marker pattern is a T, the preset position is the bottom of the T.

[0064] Specifically, the pixel corresponding to the preset position is determined by the second calibration image, and the corresponding first actual deflection voltage value is determined based on the position of the pixel. Reading the first actual deflection voltage value corresponding to the preset position can avoid reading confusion caused by random point selection, ensure that each calibration is based on the same reference, and reduce operational errors.

[0065] In one alternative embodiment, please refer to Figure 4 Optionally, step 015 includes: Step 0151: Calculate calibration parameters based on the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset mark pattern; Step 0152: Generate a mapping relationship based on calibration parameters; Step 0153: Based on the mapping relationship, calibrate the deflection coil.

[0066] Among them, the calibration parameters are used to correct the accuracy of the deflection coil.

[0067] Specifically, the correspondence between the first actual deflection voltage value when scanning the preset position during matching and the ideal deflection voltage value corresponding to the preset position of the preset mark pattern is clear. An equation can be precisely constructed based on the mapping relationship of the coefficients to be solved (i.e., calibration parameters). By solving the equation, the accurate value of the corresponding calibration parameter can be calculated. Based on the accurate value of the corresponding calibration parameter, a precise mapping relationship can be obtained. Based on the ideal deflection voltage value at any exposure position, the corresponding first actual deflection voltage value can be obtained, thus achieving the calibration of the deflection coil.

[0068] In this way, the deflection coil can be precisely calibrated to ensure accurate deflection of the electron beam and guarantee the positioning accuracy of the writing field.

[0069] In one alternative embodiment, please refer to Figure 5 Optionally, step 0151 includes: Step 01511: Based on the first actual deflection voltage value and the ideal deflection voltage value corresponding to the four preset mark patterns, establish four first equations corresponding to the first calibration parameter and four second equations corresponding to the second calibration parameter; Step 01512: Solve the four first equations to obtain the first calibration parameters; Step 01513: Solve the four second equations to obtain the second calibration parameters.

[0070] The first calibration parameter is used to calibrate the deviation in the first direction; the second calibration parameter is used to calibrate the deviation in the second direction. The first direction is perpendicular to the second direction, as shown below. Figure 3 As shown, the first direction is the x-direction (i.e., the horizontal direction), and the second direction is the y-direction (i.e., the vertical direction); or, the first direction is the y-direction (i.e., the vertical direction), and the second direction is the x-direction (i.e., the horizontal direction).

[0071] In one optional embodiment, the first calibration parameters include a first translation calibration parameter A1, a first scaling calibration parameter B1, a first rotation calibration parameter C1, and a first trapezoidal distortion calibration parameter D1; the second calibration parameters include a second translation calibration parameter A2, a second scaling calibration parameter B2, a second rotation calibration parameter C2, and a second trapezoidal distortion calibration parameter D2.

[0072] Specifically, the translation calibration parameters, scaling calibration parameters, rotation calibration parameters, and trapezoidal distortion calibration parameters of the deflection coil are the main parameters affecting electron beam deflection. Any abnormality in any of these four calibration parameters can easily lead to geometric distortion problems.

[0073] The first equation is used to solve for the first calibration parameter; the second equation is used to solve for the second calibration parameter. Specifically, the first direction is horizontal (i.e.) Figure 3The x-direction in the middle), the second direction is the longitudinal direction (i.e., the x-direction). Figure 3 In the case of the y-direction, the lateral deflection coil is used to control the deflection of the electron beam in the first direction, and the longitudinal deflection coil is used to control the deflection of the electron beam in the second direction. Four preset marker patterns are included. By acquiring the first actual deflection voltage value and the ideal deflection voltage value at the corresponding preset position when the first calibration image and the second calibration image corresponding to each preset marker pattern are matched, and combining this with the mapping relationship of the calibration parameters to be solved, four first equations and four second equations are obtained respectively.

[0074] Solving the four first equations yields the specific values ​​of the four unknown parameters in the first calibration parameters; solving the four second equations yields the specific values ​​of the four unknown parameters in the second calibration parameters.

[0075] For example, please see Figure 3 Four preset marker patterns are designated S1, S2, S3, and S4. The displacement stage is moved, and the deflection coil is used to deflect the electron beam. The first actual deflection voltage value (V) corresponding to the preset position of the preset marker pattern S1 is obtained. x1 V y1 Ideal deflection voltage (V) x2 V y2 The first actual deflection voltage value (V) corresponding to the preset position of the preset mark pattern S2. x3 V y3 Ideal deflection voltage (V) x4 V y4 The first actual deflection voltage value (V) corresponding to the preset position of the preset mark pattern S3. x5 V y5 Ideal deflection voltage (V) x6 V y6 The first actual deflection voltage value (V) corresponding to the preset position of the preset mark pattern S4. x7 V y7 Ideal deflection voltage (V) x8 V y8 ); The mapping relationship of the lateral deflection coil is X=A1+B1x+C1y+D1xy; where X is the first actual deflection voltage value, x is the ideal deflection voltage value of the lateral deflection coil, y is the ideal deflection voltage value of the longitudinal deflection coil, and A1, B1, C1 and D1 are all the first calibration parameters to be solved. The mapping relationship between the longitudinal deflection coil and the longitudinal deflection coil is Y = A2 + B2x + C2y + D2xy; where Y is the first actual deflection voltage value, x is the ideal deflection voltage value of the transverse deflection coil, y is the ideal deflection voltage value of the longitudinal deflection coil, and A2, B2, C2 and D2 are all second calibration parameters to be solved. The four first equations are as follows: V x1 =A1+B1·V x2 +C1·V y2 +D1·V x2 ·V y2 ; (1) V x3 =A1+B1·V x4 +C1·V y4 +D1·V x4 ·V y4 ; (2) V x5 =A1+B1·V x6 +C1·V y6 +D1·V x6 ·V y6 ; (3) V x7 =A1+B1·V x8 +C1·V y8 +D1·V x8 ·V y8 ; (4) The four second equations are as follows: V y1 =A² + B²·V x2 +C2·V y2 +D2·V x2 ·V y2 ; (5) V y3 =A² + B²·V x4 +C2·V y4 +D2·V x4 ·V y4 ; (6) V y5 =A² + B²·V x6 +C2·V y6 +D2·V x6 ·V y6 ; (7) V y7 =A² + B²·V x8 +C2·V y8 +D2·V x8 ·V y8 ; (8) Solving the four first equations yields the specific values ​​of the four first calibration parameters A1, B1, C1, and D1; solving the four second equations yields the specific values ​​of the four second calibration parameters A2, B2, C2, and D2; thus, the mapping relationship between the lateral deflection coil and the longitudinal deflection coil is obtained, completing the precise calibration of the lateral deflection coil and the longitudinal deflection coil.

[0076] In one alternative embodiment, please continue to refer to Figure 5 Optionally, step 0153 includes: Step 01531: Process the image to be exposed and generate the first deflection voltage value; Step 01532: Calibrate the first deflection voltage value based on the mapping relationship to generate the second deflection voltage value; Step 01533: Based on the second deflection voltage value, control the deflection coil to deflect the electron beam.

[0077] Among them, the image to be exposed is an image that records the graphic information of the finished product; the image to be exposed is composed of individual pixels, and each pixel corresponds to a specific physical area on the finished device (such as circuit lines, electrodes, etc.).

[0078] The first deflection voltage value is the ideal deflection voltage value corresponding to the pixel in the image to be exposed; the second deflection voltage value is the calibrated first deflection voltage value.

[0079] Specifically, the pixel information of the image to be exposed is converted into coordinate data, and the coordinates of each pixel to be exposed within the field of view are determined (e.g., ...). Figure 3 The x and y coordinates of the target are used to determine the target coordinates that the electron beam needs to reach. Based on the characteristics of the deflection coil, the displacement of each target coordinate is converted into the voltage value required to drive the deflection coil (horizontally and longitudinally), which is the first deflection voltage value corresponding to the pixel.

[0080] By accurately mapping the transverse and longitudinal deflection coils, the first deflection voltage value is input, and the corresponding second deflection voltage value is calculated. The second deflection voltage value is used to control the transverse and longitudinal deflection coils to deflect the electron beam, so that the deflected electron beam can accurately hit the exact position in the writing field range.

[0081] This ensures accurate deflection of the electron beam, avoids exposure deviation, and guarantees positioning accuracy and the quality of the finished device.

[0082] In one alternative embodiment, please refer to Figure 6 The calibration method also includes steps 016, 017, 018, 019, 020 and 021, which are explained in detail below.

[0083] Step 016: Scan each preset mark pattern to generate a corresponding third calibration image. The preset mark patterns include a first preset mark pattern, a second preset mark pattern, and a third preset mark pattern. The first and second preset mark patterns are distributed sequentially along a first direction, and the first and third preset mark patterns are distributed sequentially along a second direction. The first and second directions are perpendicular to each other. Step 017: Control the displacement stage to move so that any target mark pattern is within the writing field range of the deflection coil. The target mark pattern is any preset mark pattern. The third calibration image is a reference image used to calibrate positional deviations; Specifically, the process of scanning each preset mark pattern and generating the corresponding third calibration image is basically similar in principle to the process of generating the first calibration image (step 011); the process of controlling the displacement stage to move so that any target mark pattern is within the writing field range of the deflection coil is basically similar in principle to the process of step 012, and will not be repeated here to avoid repetition.

[0084] For example, please see Figure 3 The first direction is the x-direction, and the second direction is the y-direction; the preset mark pattern S1 is scanned to obtain the first preset mark pattern, the preset mark pattern S2 is scanned to obtain the second preset mark pattern, and the preset mark pattern S3 is scanned to obtain the third preset mark pattern.

[0085] Step 018: Scan the preset marker pattern again to generate the fourth calibration image; Step 019: Control the deflection coil to deflect so that the third calibration image and the fourth calibration image match, and read the second actual deflection voltage value of the deflection coil when they match; Step 020: Determine the actual coordinates of the target mark pattern based on the deviation between the second actual deflection voltage value and the ideal deflection voltage value corresponding to the target mark pattern; The fourth calibration image is a comparison image used to calibrate positional deviations.

[0086] Specifically, the process of scanning the preset mark pattern again and generating the fourth calibration image is basically similar in principle to the process of generating the first calibration image (step 011); the process of step 019 is basically similar in principle to the process of step 014, and will not be repeated here to avoid repetition.

[0087] Since the deflection coil has been accurately calibrated, the second actual deflection voltage value corresponding to the preset position is taken as the actual deflection voltage value. By substituting the mapping relationship between the accurate actual deflection voltage value and the ideal deflection voltage value, the corresponding ideal deflection voltage value can be obtained, and thus the actual position of the target mark pattern in the writing field range, i.e., the actual coordinates, can be obtained.

[0088] When the target marking patterns are the first preset marking pattern, the second preset marking pattern, and the third preset marking pattern, respectively, the actual positions (i.e., actual coordinates) of the first preset marking pattern, the second preset marking pattern, and the third preset marking pattern in the device to be exposed can be obtained by combining the displacement of the displacement stage (or the displacement of the writing field range).

[0089] Step 021: Generate a first deviation based on the actual coordinates of the first and second preset mark patterns and the preset distance in the first direction, and calculate a second deviation based on the actual coordinates of the first and third preset mark patterns and the preset distance in the second direction.

[0090] The preset distance is a distance value set based on experience or user-defined.

[0091] For example, please see Figure 3 The actual coordinates of the first preset mark pattern S1 and the second preset mark pattern S2 are the same in the second direction. Based on their actual coordinates, the distance in the first direction is determined to be 99 micrometers. The distance between the first preset mark pattern S1 and the second preset mark pattern S2 in the first direction is set to be 100 micrometers. Therefore, the first deviation is 99 micrometers minus 100 micrometers, which is -1 micrometer. Similarly, the actual coordinates of the first preset mark pattern S1 and the third preset mark pattern S3 are the same in the first direction. Based on their actual coordinates, the distance in the second direction is determined to be 101 micrometers. The distance between the first preset mark pattern S1 and the third preset mark pattern S3 in the second direction is set to be 100 micrometers. Therefore, the second deviation is 101 micrometers minus 100 micrometers, which is 1 micrometer.

[0092] In one optional embodiment, each time a device to be exposed is replaced, steps 016 to 021 are executed sequentially to calibrate the distance between preset marking patterns. This can avoid pattern overlap or gaps between adjacent writing fields, eliminate splicing errors caused by individual differences of individual devices to be exposed, and ensure the exposure accuracy of each finished product.

[0093] In one alternative embodiment, please refer to Figure 7 The calibration method also includes steps 022, 023, 024 and 025, which are explained in detail below.

[0094] Step 022: Based on the preset distance in the first direction, the preset distance in the second direction, the first deviation, and the second deviation of the fourth preset mark pattern and the first mark pattern, control the displacement stage to move so that the fourth mark pattern is located within the writing field range of the deflection coil; Step 023: Control the deflection coil to deflect based on the ideal deflection voltage value corresponding to the fourth preset mark pattern, so as to scan the fourth preset mark pattern and generate the fifth calibration image; The fourth preset mark pattern is used to verify the accuracy of the calibration of the positional deviation between preset mark patterns. The fourth preset mark pattern and the second preset mark pattern are distributed sequentially along the second direction, and the fourth preset mark pattern and the third preset mark pattern are distributed sequentially along the first direction.

[0095] The fifth calibration image is used to verify the accuracy of the calibration of the positional deviation between the preset marker patterns.

[0096] Specifically, taking the first mark pattern as being located within the writing field range of the deflection coil as a reference, due to the existence of the first error, the distance the control displacement stage moves in the first direction is: the preset distance between the fourth preset mark pattern and the first mark pattern in the first direction plus the first deviation; due to the existence of the second error, the distance the control displacement stage moves in the second direction is: the preset distance between the fourth preset mark pattern and the first mark pattern in the second direction plus the second deviation.

[0097] For example, if the first deviation is -1 micrometer, the second deviation is 1 micrometer, and the fourth preset mark pattern and the first mark pattern have a preset distance of 100 micrometers in the first direction and a preset distance of 100 micrometers in the second direction, then the control displacement stage moves 99 micrometers in the first direction and 100 micrometers in the second direction.

[0098] The ideal deflection voltage value corresponding to the fourth preset mark pattern is converted into the first actual deflection voltage by combining the accurate mapping relationship, thereby controlling the deflection coil to deflect the electron beam, scan the fourth preset mark pattern, and generate the fifth calibration image. The basic principle of generating the fifth calibration image is basically similar to the principle of generating the first calibration image (step 011), and will not be repeated here to avoid repetition.

[0099] Step 024: Determine whether the third calibration image and the fifth calibration image match; Step 025: If a match is found, then the first and second deviations are confirmed to be accurate.

[0100] Specifically, whether the third calibration image and the fifth calibration image match can be determined based on the similarity between the third calibration image and the fifth calibration image. The basic principle is similar to that of determining whether the first calibration image and the second calibration image match based on similarity. To avoid repetition, it will not be elaborated here.

[0101] If the third and fifth calibration images do not match, then the first and second deviations are determined to be inaccurate; the first and second deviations need to be recalibrated.

[0102] In this way, erroneous calibration can be avoided due to misjudgment of the first and second deviations in a single determination, thus ensuring exposure accuracy and alignment accuracy between different layers in overlay exposure scenarios.

[0103] In one alternative embodiment, please refer to Figure 8 The calibration method also includes steps 026, 027 and 028, which are explained in detail below.

[0104] Step 026: Process the image to be exposed and generate the third deflection voltage value; Step 027: Calibrate the third deflection voltage value based on the first and second deviations to generate the fourth deflection voltage value; Step 028: Based on the fourth deflection voltage value, control the deflection coil to deflect the electron beam.

[0105] The third deflection voltage value is the ideal deflection voltage value corresponding to the pixel in the image to be exposed after the deflection coil and the preset mark pattern position are calibrated; the fourth deflection voltage value is the calibrated third deflection voltage value.

[0106] Specifically, after the deflection coils and preset marker patterns have been calibrated, a third deflection voltage value is generated based on the coordinate data converted from the pixel information of the image to be exposed. A first deviation is added to the voltage value of the deflection coil controlling the first direction in the third deflection voltage value, and a second deviation is added to the voltage value of the deflection coil controlling the second direction in the third deflection voltage value to obtain a fourth deflection voltage value. Based on the fourth deflection voltage value, the transverse deflection coil and the longitudinal deflection coil are controlled to deflect the electron beam, ensuring that the deflected electron beam accurately hits the precise position within the writing field.

[0107] This ensures accurate deflection of the electron beam, avoids exposure deviation, and guarantees positioning accuracy and the quality of the finished device.

[0108] Based on the method described in the above embodiments, this application also provides a calibration apparatus for performing the steps in the above calibration method. Please refer to... Figure 9 , Figure 9 This is a schematic diagram of the modules of the calibration device 200 provided in this application embodiment. The calibration device 200 includes: The first scanning module 201 is used to scan a preset marking pattern to generate a first calibration image; The moving module 202 is used to control the movement of the displacement stage so that the preset marking pattern is located within the writing field range of the deflection coil; The second scanning module 203 is used to scan the preset mark pattern again to generate a second calibration image; The control module 204 is used to control the deflection of the deflection coil so that the first calibration image and the second calibration image are matched, and to read the first actual deflection voltage value of the deflection coil when they are matched. The calibration module 205 is used to calibrate the deflection coil based on the mapping relationship between the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset marking pattern.

[0109] It should be noted that the specific details of each module unit in the above calibration device have been described in detail in the embodiments of the above calibration method, and will not be repeated here.

[0110] In this application embodiment, the term "module" or "hopefully" refers to a computer program or part of a computer program with a predetermined function, which works together with other related parts to achieve a predetermined goal, and can be implemented wholly or partially using software, hardware (such as processing circuitry or memory), or a combination thereof. Similarly, a processor (or multiple processors or memory) can be used to implement one or more modules or units. Furthermore, each module or unit can be part of an overall module or unit that includes the functionality of that module or unit.

[0111] In one optional embodiment, the calibration device in this application embodiment can be implemented in hardware, such as an electron beam exposure machine or a host computer, or a component in the electron beam exposure machine or host computer, such as an integrated circuit or a chip; the calibration device can also be implemented in software, such as as an application installed in an electron beam exposure machine or host computer.

[0112] This application also provides an electron beam exposure machine, including a displacement stage, a deflection coil, a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the calibration method as described in any of the above embodiments.

[0113] In one alternative embodiment, please refer to Figure 10 , Figure 10 This is a schematic diagram of the electron beam exposure machine provided in an embodiment of this application. The electron beam exposure machine 300 includes a displacement stage 301, a deflection coil 302, a processor 303, and a memory 304. The memory 304 stores a computer program 305 that can run on the processor 303. When the computer program 305 is executed by the processor 303, it implements the various processes of the above-described calibration method embodiments and achieves the same technical effects. To avoid repetition, it will not be described again here.

[0114] This application also provides an electron beam exposure system, including a host computer and the electron beam exposure machine described above.

[0115] The host computer uses dedicated software (such as graphic editing and path planning software) to convert the user-defined instructions for exposure patterns and field division into machine-recognizable signals and send them to the electron beam exposure machine, thereby controlling the electron beam emission and stop, deflection trajectory, and movement of the displacement stage.

[0116] The electron beam exposure machine can collect key status data (such as electron beam current, preset marker image, position of the displacement stage, and vacuum degree) in real time and feed them back to the host computer. The host computer analyzes the data in real time, and if a deviation is found (such as calibration abnormality), it will automatically adjust the instructions or trigger an alarm to ensure that the electron beam exposure process can proceed with the preset accuracy.

[0117] Optionally, the host computer may include a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the calibration method as described in any of the above embodiments.

[0118] Optionally, the host computer can be a terminal (such as an industrial terminal), a server, an industrial control computer, a high-performance desktop computer, etc., and this application embodiment does not limit this.

[0119] In one alternative embodiment, please refer to Figure 11 , Figure 11 This is a schematic diagram of the electron beam exposure system provided in this application embodiment. The electron beam exposure system 400 includes a host computer 410 and an electron beam exposure machine 300. The host computer 410 and the electron beam exposure machine 300 work together to complete the various processes of the above-described calibration method embodiment and complete the exposure process of the device to be exposed to obtain the finished product.

[0120] This application also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the various processes of the above-described calibration method embodiments and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0121] The processor can be the processor in the electron beam lithography machine or the host computer in the above embodiments. The computer-readable storage medium can be a computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, etc.

[0122] Computer-readable media can include computer storage media and communication media. Computer storage media includes volatile and non-volatile, removable and non-removable media implemented by any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media include RAM, ROM, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other solid-state storage technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape cassettes, magnetic tape, disk storage, or other magnetic storage devices. Of course, those skilled in the art will recognize that computer storage media are not limited to the above-mentioned types.

[0123] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described calibration method. The processor can be the electron beam exposure machine or the processor in a host computer as described in the above embodiments. When executed by the processor, the computer program implements the various processes of the embodiments of the above-described calibration method and achieves the same technical effects; therefore, to avoid repetition, further details are omitted here.

[0124] It is understood that in the specific implementation of this application, data related to user identity or characteristics is involved. When the above embodiments of this application are applied to specific products or technologies, user permission or consent is required, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0125] In the description of this specification, the references to terms such as "some embodiments," "in one example," "exemplarily," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0126] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0127] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A calibration method, characterized in that, The calibration method is applied to an electron beam exposure machine, which includes a displacement stage and a deflection coil, and includes: Scan the preset marker pattern to generate the first calibration image; The displacement stage is controlled to move so that the preset marking pattern is located within the writing field range of the deflection coil; The preset marker pattern is scanned again to generate a second calibration image; The deflection coil is controlled to deflect so that the first calibration image and the second calibration image are matched, and the first actual deflection voltage value of the deflection coil is read when the match is achieved. The deflection coil is calibrated based on the mapping relationship between the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset mark pattern.

2. The calibration method according to claim 1, characterized in that, The preset marker pattern includes at least four patterns. Controlling the displacement stage to move the preset marker pattern so that it is within the writing field range of the deflection coil includes: The displacement stage is controlled to move in the upper left, lower left, upper right, and lower right directions respectively, so that the four preset mark patterns are respectively located within the writing field range of the deflection coil.

3. The calibration method according to claim 1, characterized in that, Matching the first calibration image and the second calibration image includes: The similarity between the first calibration image and the second calibration image is greater than a preset similarity.

4. The calibration method according to claim 1 or 3, characterized in that, The reading of the first actual deflection voltage value of the deflection coil during matching includes: The first actual deflection voltage value when scanning the preset position of the preset mark pattern during matching.

5. The calibration method according to claim 1, characterized in that, The calibration of the deflection coil based on the mapping relationship between the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset marking pattern includes: The calibration parameters are calculated based on the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset mark pattern; The mapping relationship is generated based on the calibration parameters; The deflection coil is calibrated based on the mapping relationship.

6. The calibration method according to claim 5, characterized in that, The calibration parameters include a first calibration parameter for calibrating the deviation in a first direction and a second calibration parameter for calibrating the deviation in a second direction, wherein the first direction is perpendicular to the second direction. The preset mark pattern includes four patterns. The calculation of calibration parameters based on the first actual deflection voltage value and the ideal deflection voltage value corresponding to the preset mark pattern includes: Based on the first actual deflection voltage value and the ideal deflection voltage value corresponding to the four preset mark patterns, four first equations corresponding to the first calibration parameter and four second equations corresponding to the second calibration parameter are established. Solve the four first equations to obtain the first calibration parameters; Solve the four second equations to obtain the second calibration parameters.

7. The calibration method according to claim 6, characterized in that, The first calibration parameters include a first translation calibration parameter, a first scaling calibration parameter, a first rotation calibration parameter, and a first trapezoidal distortion calibration parameter; the second calibration parameters include a second translation calibration parameter, a second scaling calibration parameter, a second rotation calibration parameter, and a second trapezoidal distortion calibration parameter.

8. The calibration method according to claim 5, characterized in that, The calibration of the deflection coil based on the mapping relationship includes: Process the image to be exposed and generate the first deflection voltage value; The first deflection voltage value is calibrated based on the mapping relationship to generate the second deflection voltage value; Based on the second deflection voltage value, the deflection coil is controlled to deflect the electron beam.

9. The calibration method according to any one of claims 1-8, characterized in that, Also includes: Scan each of the preset marker patterns to generate a corresponding third calibration image. The preset marker patterns include a first preset marker pattern, a second preset marker pattern, and a third preset marker pattern. The first preset marker pattern and the second preset marker pattern are distributed sequentially along a first direction, and the first preset marker pattern and the third preset marker pattern are distributed sequentially along a second direction. The first direction and the second direction are perpendicular to each other. The displacement stage is controlled to move so that any target marking pattern is located within the writing field range of the deflection coil, and the target marking pattern is any of the preset marking patterns; The preset marker pattern is scanned again to generate a fourth calibration image; The deflection coil is controlled to deflect so that the third calibration image and the fourth calibration image are matched, and the second actual deflection voltage value of the deflection coil is read when they are matched. The actual coordinates of the target mark pattern are determined based on the deviation between the second actual deflection voltage value and the ideal deflection voltage value corresponding to the target mark pattern. A first deviation is generated based on the actual coordinates corresponding to the first preset mark pattern and the second preset mark pattern, and a preset distance in the first direction. A second deviation is calculated based on the actual coordinates corresponding to the first preset mark pattern and the third preset mark pattern, and a preset distance in the second direction.

10. The calibration method according to claim 9, characterized in that, The preset mark pattern further includes a fourth preset mark pattern, the fourth preset mark pattern and the second preset mark pattern are sequentially distributed along the second direction, and the fourth preset mark pattern and the third preset mark pattern are sequentially distributed along the first direction. The calibration method further includes: Based on the preset distance between the fourth preset mark pattern and the first mark pattern in the first direction, the preset distance in the second direction, the first deviation, and the second deviation, the displacement stage is controlled to move so that the fourth mark pattern is located within the writing field range of the deflection coil; The deflection coil is controlled to deflect based on the ideal deflection voltage value corresponding to the fourth preset mark pattern in order to scan the fourth preset mark pattern and generate a fifth calibration image. Determine whether the third calibration image and the fifth calibration image match; If they match, then the first deviation and the second deviation are determined to be accurate.

11. The calibration method according to claim 10, characterized in that, Also includes: Process the image to be exposed and generate a third deflection voltage value; The third deflection voltage value is calibrated based on the first deviation and the second deviation to generate a fourth deflection voltage value; Based on the fourth deflection voltage value, the deflection coil is controlled to deflect the electron beam.

12. An electron beam exposure machine, characterized in that, It includes a displacement stage, a deflection coil, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the calibration method as described in any one of claims 1-11.

13. An electron beam exposure system, characterized in that, It includes a host computer and the electron beam exposure machine as described in claim 12.

14. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the calibration method as described in any one of claims 1-11.

15. A computer program product, characterized in that, It includes a computer program that, when executed by a processor, implements the calibration method as described in any one of claims 1-11.

Images