Image-based electron beam magnetic effect correction method and system
By dividing the wafer into an array of regions and scanning rectangular marker images, calculating and correcting the marker values, and constructing a magnetic effect map, the problem of magnetic effect deviation in electron beam exposure equipment is solved, and the overlay and stitching accuracy is improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 48TH RES INST OF CHINA ELECTRONICS TECH GROUP CORP
- Filing Date
- 2023-10-19
- Publication Date
- 2026-06-23
Smart Images
Figure CN117631471B_ABST
Abstract
Description
Technical Field
[0001] This invention relates primarily to the field of semiconductor equipment technology, and more specifically to an image-based method and system for correcting the magnetic effect of an electron beam. Background Technology
[0002] The booming development of the information industry has greatly driven the development of the integrated circuit industry. Electron beam exposure equipment can be used for direct-write exposure of wafers and masks in the integrated circuit manufacturing process, and it is one of the most important process equipment on the integrated circuit production line. The overlay accuracy and splicing accuracy of the exposed pattern are the most critical indicators of electron beam exposure equipment. However, the magnetic effect between the wafer and the electron beam objective lens coil can cause deviations in the electron beam when exposing the pattern. Therefore, the magnetic effect must be corrected during the electron beam exposure process to ensure the pattern exposure accuracy of the electron beam exposure equipment. Summary of the Invention
[0003] The technical problem to be solved by the present invention is to provide an image-based electron beam magnetic effect correction method and system that is simple to implement, easy to operate, and has high correction accuracy, in response to the technical problems existing in the prior art.
[0004] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:
[0005] An image-based method for correcting the magnetic effect of an electron beam includes the following steps:
[0006] 1) Divide the wafer into regions with fixed intervals along the X-axis and Y-axis to form a region array;
[0007] 2) The electron beam device moves to each region location and scans the rectangular marker array on the surface of the wafer at that region location to obtain an image of the rectangular marker array of the scan field at that region location;
[0008] 3) Calculate the centroid position, width, height, and rotation angle of all markers in the region's position scanning field using the rectangular marker array image;
[0009] 4) Calculate the distortion coefficient of the region position scanning field through the centroid position of the marker, and correct the width, height and rotation angle values of the marker according to the distortion coefficient to obtain the corrected width, height and rotation angle values of the marker.
[0010] 5) Obtain the electron beam magnetic effect correction value of the region position scanning field based on the corrected width, height, and rotation angle of the marker;
[0011] 6) During the electron beam exposure patterning process, based on the position of the exposed pattern on the wafer, the electron beam magnetic effect correction value of the scanning field of the adjacent region is queried in order to obtain the electron beam magnetic effect compensation value of that region.
[0012] Preferably, in step 1), the spacing between adjacent regions in the array region along the X-axis or Y-axis of the wafer is equal, and the size of the region is the size of the electron beam scanning field.
[0013] Preferably, in step 3), the electron beam device enters the electron microscope scanning mode to obtain images of all the marks in the scanning field, and uses a target detection algorithm to locate the position of each mark in the image. Then, the marks are fitted with a minimum bounding rectangle, and the centroid position, height, width and rotation angle of the obtained minimum bounding rectangle are calculated.
[0014] Preferably, in step 4), a system of polynomial equations is established based on the centroid coordinates of the markers calculated in the image and the actual centroid coordinates to calculate the distortion coefficients of the scan field.
[0015] Preferably, in step 4), the width, height, and rotation angle values of the mark are multiplied by the distortion coefficient to obtain the corrected width, height, and rotation angle values of the mark.
[0016] Preferably, in step 5), the average values of the width, height and rotation angle of the corrected mark are calculated, and the differences between these values and the actual width, height and rotation angle of the mark are calculated to obtain the electron beam magnetic effect correction value of the scanning field.
[0017] Preferably, in step 5), the center coordinates of all regions are matched with the corresponding electron beam magnetic effect correction values to form an electron beam magnetic effect map.
[0018] Preferably, in step 6), the adjacent region positions are the positions of four adjacent regions.
[0019] Preferably, in step 6), the electron beam magnetic effect correction values of the scanning fields of four adjacent regions are linearly fitted to obtain the magnetic effect compensation value of that region.
[0020] The present invention also discloses an image-based electron beam magnetic effect correction system, comprising an interconnected memory and a processor, wherein the memory stores a computer program, which, when run by the processor, executes the steps of the method described above.
[0021] Compared with the prior art, the advantages of the present invention are as follows:
[0022] The image-based electron beam magnetic effect correction method of this invention can accurately calculate the error caused by the objective lens magnetic effect when the electron beam equipment exposes patterns at each position on the wafer using a simple rectangular marker array. By eliminating the electron beam magnetic effect error, the overlay accuracy and stitching accuracy during electron beam exposure can be greatly improved. The above correction method is simple to implement, easy to operate, and has high correction accuracy, which well meets the requirements of electron beam magnetic effect error correction and significantly improves the production accuracy of electron beam exposure equipment. Attached Figure Description
[0023] Figure 1 This is a schematic diagram illustrating the principle of region array division in the wafer in this invention.
[0024] Figure 2 The flowchart shows the modified method of the present invention in an embodiment. Detailed Implementation
[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0026] like Figure 2 As shown, the image-based electron beam magnetic effect correction method of this invention includes the following steps:
[0027] 1) Divide the wafer into multiple regions with fixed intervals along the X-axis and Y-axis to form a region array, such as... Figure 1 As shown, this includes three rows and three columns of regions, with equal spacing in both the horizontal and vertical directions, and each region is the same size, corresponding to the electron beam scanning field.
[0028] 2) The electron beam device moves to each region position via the workpiece stage and scans the rectangular mark array on the surface of the wafer at the region position to obtain an image of the rectangular mark array of the scan field at the region position;
[0029] like Figure 1 As shown, the marker array on the wafer surface has a spacing of 100µm, the marker shape is rectangular, and the marker size is 10µm x 10µm.
[0030] 3) Calculate the centroid position, width, height, and rotation angle of all markers in the above-mentioned area using the rectangular marker array image;
[0031] Specifically, the electron beam device enters the electron microscope scanning mode to obtain an image of the array markers in the scanning field, and uses a target detection algorithm to locate the position of each marker in the image. Then, the markers are fitted with a minimum bounding rectangle approximation, and the centroid position, width, height and rotation angle of the obtained minimum bounding rectangle are calculated.
[0032] 4) Based on the calculated centroid coordinates of the marker and the actual centroid coordinates, establish a system of polynomial equations to calculate the distortion coefficients of each scan field and obtain the distortion coefficient matrix of all scan fields; then multiply the calculated width, height and rotation angle values of the marker by the distortion coefficient matrix to obtain the corrected width, height and rotation angle values of the marker image.
[0033] 5) The electron beam magnetic effect correction value of the region position scanning field is obtained by calculating the mean of the width, height and rotation angle of the corrected marker image within the region position scanning field and subtracting it from the actual width, height and rotation angle of the marker.
[0034] Match the center coordinates of all regions with the corresponding electron beam magnetic effect correction values, save them as an electron beam magnetic effect map, and form a map list;
[0035] 6) During the electron beam exposure mapping process, since the exposed pattern is located at any position on the wafer, and the electron beam magnetic effect map only contains the magnetic effect correction value of the marked position, the correction compensation value of the four adjacent regions in the map list is queried according to the position of the exposed pattern on the wafer, and linear fitting is performed to obtain the magnetic effect compensation value of the region. Then, the electron beam magnetic effect error is eliminated according to the magnetic effect compensation value.
[0036] The image-based electron beam magnetic effect correction method of this invention calculates the magnetic effect correction value at the marked positions on the wafer by acquiring an image of a rectangular marker array to construct an electron beam magnetic effect map. The magnetic effect map is then used to approximately fit and calculate the magnetic effect correction value at any position on the wafer. Therefore, based on the electron beam magnetic effect map, errors caused by the objective lens magnetic effect during pattern exposure at each position on the wafer can be accurately eliminated. Eliminating electron beam magnetic effect errors significantly improves the overlay and stitching accuracy during electron beam pattern exposure. This correction method is simple to implement, easy to operate, and has high correction accuracy, effectively meeting the requirements for magnetic effect error correction in electron beam exposure and significantly improving the production accuracy of electron beam exposure equipment.
[0037] This invention also provides an image-based electron beam magnetic effect correction system, including an interconnected memory and a processor. The memory stores a computer program, which, when run by the processor, executes the steps of the method described above. The correction system of this invention corresponds to the correction method described above and also possesses the advantages described above.
[0038] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.
Claims
1. An image-based method for correcting the magnetic effect of an electron beam, characterized in that, Including the following steps: 1) Divide the wafer into regions with fixed intervals along the X-axis and Y-axis to form a region array; 2) The electron beam device moves to each region location and scans the rectangular marker array on the surface of the wafer at that region location to obtain an image of the rectangular marker array of the scan field at that region location; 3) Calculate the centroid position, width, height, and rotation angle of all markers in the region's position scanning field using the rectangular marker array image; 4) Calculate the distortion coefficient of the region position scanning field through the centroid position of the marker, and correct the width, height and rotation angle values of the marker according to the distortion coefficient to obtain the corrected width, height and rotation angle values of the marker. 5) Obtain the electron beam magnetic effect correction value of the region position scanning field based on the corrected width, height, and rotation angle of the marker; 6) During the electron beam exposure patterning process, based on the position of the exposed pattern on the wafer, the electron beam magnetic effect correction value of the scanning field of the adjacent region is queried in order to obtain the electron beam magnetic effect compensation value of that region.
2. The image-based electron beam magnetic effect correction method according to claim 1, characterized in that, In step 1), the spacing between adjacent regions in the array region along the X-axis or Y-axis of the wafer is equal, and the size of the region is the size of the electron beam scanning field.
3. The image-based electron beam magnetic effect correction method according to claim 1, characterized in that, In step 3), the electron beam device enters the electron microscope scanning mode to obtain images of all the marks in the scanning field, and uses the target detection algorithm to locate the position of each mark in the image. Then, the minimum bounding rectangle is used to approximate the marks, and the centroid position, height, width and rotation angle of the obtained minimum bounding rectangle are calculated.
4. The image-based electron beam magnetic effect correction method according to claim 1, 2, or 3, characterized in that, In step 4), a system of polynomial equations is established based on the centroid coordinates of the markers calculated in the image and the actual centroid coordinates to calculate the distortion coefficients of the scan field.
5. The image-based electron beam magnetic effect correction method according to claim 4, characterized in that, In step 4), the width, height, and rotation angle values of the mark are multiplied by the distortion coefficient to obtain the corrected width, height, and rotation angle values of the mark.
6. The image-based electron beam magnetic effect correction method according to claim 1, 2, or 3, characterized in that, In step 5), the average values of the width, height, and rotation angle of the corrected mark are calculated, and the differences between these values and the actual width, height, and rotation angle of the mark are calculated to obtain the electron beam magnetic effect correction value of the scanning field.
7. The image-based electron beam magnetic effect correction method according to claim 6, characterized in that, In step 5), the center coordinates of all regions are matched with the corresponding electron beam magnetic effect correction values to form an electron beam magnetic effect map.
8. The image-based electron beam magnetic effect correction method according to claim 7, characterized in that, In step 6), the adjacent region positions are the positions of four adjacent regions.
9. The image-based electron beam magnetic effect correction method according to claim 8, characterized in that, In step 6), the electron beam magnetic effect correction values of the scanning fields of four adjacent regions are linearly fitted to obtain the magnetic effect compensation value of that region.
10. An image-based electron beam magnetic effect correction system, comprising an interconnected memory and a processor, wherein the memory stores a computer program, characterized in that, The computer program, when run by a processor, performs the steps of the method as described in any one of claims 1-9.