Method for accurately positioning and processing sample piece in ion beam processing process

Abstract

The invention relates to a method for accurately positioning and processing a sample piece in an ion beam processing process, which comprises the following steps of: measuring beam current distribution of an ion beam through a Faraday cup, and measuring beam current density distribution and corresponding coordinates of the ion beam; the offset of the ion beam is determined by fitting the beam distribution to obtain the offset of the beam distribution center of the ion beam and the center of the Faraday cup, and the offset of the sample piece center and the center of the sample table is obtained by measuring the clamping and positioning center through a spectrum confocal displacement sensor; the processing coordinates of the sample piece are compensated by the offset of the ion beam and the offset of clamping and positioning of the sample piece, so that high-precision ion beam processing is realized; the method is scientific and reasonable in process and easy to operate, the spectrum confocal displacement sensor is combined with the Faraday cup to accurately position ion beam processing, and the processing precision of products is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of ion beam processing and manufacturing technology for optical components, and in particular to a method for precisely positioning and processing samples during ion beam processing. Background Technology

[0002] With the development of space optics, astronomical optics, and space exploration and identification technologies, optical imaging systems are demanding increasingly higher surface accuracy from optical components, leading to a surge in the need for high-precision optical elements. Ion beam polishing, with its nanometer-level processing precision, is a crucial method for achieving high-precision surface-shape optical components. Ion beam processing of optical components is a deterministic process; the dwell time at different processing positions is determined based on the elevation of various points on the sample surface to achieve surface shaping. Therefore, improving the accuracy of the ion source's center position and the sample's clamping and positioning is particularly important for enhancing the ion beam processing effect.

[0003] Existing technologies do not provide ideal positioning accuracy for ion beam processing. Therefore, it is necessary to develop a method for precise positioning of samples during ion beam processing to achieve accurate positioning during ion beam processing. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for precise positioning and processing of samples in the ion beam processing process, so as to solve the influence of the shaping deviation caused by the clamping error of the sample in the existing ion beam processing process and improve the accuracy of the ion beam shaping of the optical element surface.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a method for precise positioning and processing of samples in an ion beam processing process, characterized by comprising the following steps:

[0006] 1) Use Faraday cup scanning to obtain beam distribution information of the ion source;

[0007] 2) Fit the beam information obtained from the Faraday cup scanning to obtain the position of the beam distribution center of the ion source, and then calculate the offset of the beam distribution center of the ion source relative to the center of the Faraday cup, and correct the offset in the numerical control system.

[0008] 3) Use a spectral confocal displacement sensor to measure the clamping and positioning of the sample, determine the clamping center position of the sample, calculate the offset between the clamping center of the sample and the origin of the sample coordinate system, and thus correct the clamping and positioning error of the sample.

[0009] 4) Correct the processing coordinates of the sample based on the offset of the ion beam and the offset of the sample clamping and positioning, and accurately position the ion beam processing.

[0010] As an improvement, in step 1), the distance the ion source moves relative to the Faraday cup should be greater than the aperture of the ion source. During the Faraday cup measurement, the ion source moves intermittently, and each time it moves a certain distance and stays for a certain period of time to ensure the accuracy of the collected data.

[0011] Furthermore, step 2) specifically involves: using the least squares method to fit a Gaussian function to determine the center position of the ion beam distribution. Specifically, the distance between the position of the Faraday cup (Fx, Fy) and the origin position (Sx, Sy) of the sample platform is fixed. The fitted ion beam center position is (Fx', Fy'), and the offset is (Fx-Fx', Fy-Fy'). Then, the processing origin position of the rectified sample is (Sx-Fx+Fx', Sy-Fy+Fy').

[0012] Furthermore, in step 2), the maximum beam current density xI-max is the center of the ion beam in the X direction, and the offset of the ion beam center in the X direction is xI-max-Fx. The maximum beam current density (yI-max) is the center of the ion beam in the Y direction, and the offset of the ion beam center in the Y direction is (yI-max-Fy).

[0013] Furthermore, step 3) specifically involves the following steps: After the sample is clamped, the spectral confocal displacement sensor is kept at a certain working distance from the sample surface. The spectral confocal displacement sensor is moved to scan the sample surface, and the signal reception during the scanning process is recorded to obtain the clamping center position of the sample. The deviation between the clamping center of the sample and the origin of the sample coordinate system is calculated, thereby correcting the clamping positioning error of the sample.

[0014] Furthermore, the spectral confocal displacement sensor receives signals from the surface of the sample during planar scanning, including signal triggering and loss. By recording the triggering and loss of signals, the edge position of the sample during the planar scanning process is obtained.

[0015] Furthermore, the flat scan of the sample includes scanning the sample surface in two perpendicular directions, X and Y. The origin position of the sample platform is (Sx, Sy). When the sample is scanned in the X direction, the position of the first trigger signal of the spectral confocal displacement sensor in the flat scan direction is X0, and the position of the first lost signal in the flat scan direction is X1. Then the center position of the sample in the flat scan direction is (x1+x0) / 2. When the sample is scanned in the Y direction, the position of the first trigger signal of the spectral confocal displacement sensor in the flat scan direction is y0, and the position of the first lost signal in the flat scan direction is y1. Then the center position of the sample in the flat scan direction is (y0+y1) / 2. The clamping center coordinates of the installed sample are ((x0+x1) / 2, (y0+y1) / 2). The positioning error of the sample is (Sx-(x0+x1) / 2, Sy-(y0+y1) / 2).

[0016] Finally, the machining coordinates of the sample in step 4) are (x+Sx-(x0+x1) / 2+xI-max-Fx, y+Sy-(y0+y1) / 2+yI-max-Fy).

[0017] Compared with existing technologies, the advantages of this invention are as follows: The beam current distribution of the ion beam is measured using a Faraday cup. By measuring the beam current density distribution and corresponding coordinates, the beam current distribution is fitted to obtain the offset between the beam current distribution center and the center of the Faraday cup, thus determining the ion beam offset. A spectral confocal displacement sensor is used to measure the clamping and positioning center, obtaining the offset between the sample center and the sample stage center. The processing coordinates of the sample are compensated by the ion beam offset and the sample clamping and positioning offset, achieving high-precision ion beam processing. This invention's process is scientifically sound, easy to operate, and achieves precise positioning for ion beam processing through a combination of a spectral confocal displacement sensor and a Faraday cup, significantly improving the processing accuracy of the product. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structural arrangement of the various parts of the ion beam processing provided by the present invention;

[0019] Figure 2 This is a schematic diagram of a spectral confocal displacement sensor scanning a sample.

[0020] Figure 3 This is a schematic diagram of signal transmission from a spectral confocal displacement sensor.

[0021] Figure 4 This is a schematic diagram of an ion beam Faraday scan.

[0022] Figure 5 A schematic diagram of fitting data from an ion beam Faraday scan. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] like Figures 1-5 As shown, a method for precise positioning and processing of a sample during ion beam processing includes the following steps:

[0025] 1) Use Faraday cup scanning to obtain beam distribution information of the ion source; the distance the ion source moves relative to the Faraday cup should be greater than the aperture of the ion source. During the Faraday cup measurement, the ion source moves intermittently, and each time it moves a certain distance and stays for a certain period of time to ensure the accuracy of the collected data.

[0026] 2) Fit the beam information obtained from the Faraday cup scanning to obtain the beam distribution center position of the ion source, and then calculate the offset of the beam distribution center of the ion source relative to the center of the Faraday cup. Correct the offset in the CNC system. Use the least squares method to fit the Gaussian function to determine the beam distribution center position of the ion beam. Specifically, the distance between the position of the Faraday cup (Fx, Fy) and the origin position (Sx, Sy) of the sample platform is fixed. The fitted ion beam center position is (Fx', Fy'), and the offset is (Fx-Fx', Fy-Fy'). Then the processing origin position of the sample after correction is (Sx-Fx+Fx', Sy-Fy+Fy').

[0027] 3) The clamping and positioning of the sample is measured using a spectral confocal displacement sensor to determine the clamping center position of the sample, and the offset between the clamping center and the origin of the sample coordinate system is calculated to correct the clamping and positioning error of the sample. The specific process is as follows: After the sample is clamped, the spectral confocal displacement sensor is kept at a certain working distance from the sample surface. The spectral confocal displacement sensor is moved to scan the sample surface, and the signal reception during the scanning process is recorded to obtain the clamping center position of the sample. The deviation between the clamping center and the origin of the sample coordinate system is calculated to correct the clamping and positioning error of the sample.

[0028] The reception of signals on the sample surface by the spectral confocal displacement sensor during planar scanning, including signal triggering and loss, is recorded to obtain the edge position of the sample during the planar scanning process.

[0029] The sample scanning process involves scanning the sample surface in two perpendicular directions, X and Y. The origin of the sample platform is (Sx, Sy). When scanning the sample in the X direction, the position of the first trigger signal of the spectral confocal displacement sensor in the scanning direction is x0, and the position of the first lost signal in the scanning direction is x1. Therefore, the center position of the sample in the scanning direction is (x1+x0) / 2. When scanning the sample in the Y direction, the position of the first trigger signal of the spectral confocal displacement sensor in the scanning direction is y0, and the position of the first lost signal in the scanning direction is y1. Therefore, the center position of the sample in the scanning direction is (yo+y1) / 2. The clamping center coordinates of the installed sample are ((x0+x1) / 2, (y0+y1) / 2). The positioning error of the sample is (Sx-(x0+x1) / 2, Sy-(y0+y1) / 2).

[0030] 4) Correct the processing coordinates of the sample based on the offset of the ion beam and the offset of the sample clamping and positioning, and accurately position the ion beam processing.

[0031] The invention will now be described in more detail with reference to the drawings:

[0032] Figure 1The arrangement of the Faraday cup, ion source, sample, and spectral confocal displacement sensor is shown. The Faraday cup is used to measure the offset of the ion beam, and the spectral confocal displacement sensor is used to measure the offset of the sample. The position of the Faraday cup in the sample coordinate system is (Fx, Fy), and the coordinates of the center of the sample stage are (Sx, Sy).

[0033] Figure 2 This involves using a spectral confocal displacement sensor to perform positioning measurements on the sample before sample processing. First, the spectral confocal displacement sensor is moved to the bottom of the sample and gradually brought closer to determine its working distance. Then, it is moved off the component surface. During component positioning, the spectral confocal displacement sensor scans the sample surface along a fixed direction, recording the initial signal reception position as x0 and the signal loss position as x1. (See [link to documentation]). Figure 3 Then the coordinates of the midpoint of the sample in the X direction are x' = (x0 + x1) / 2.

[0034] After determining the X-axis coordinates of the sample, the spectral confocal displacement sensor scans along the Y-axis of the sample from outside the sample with x' as the abscissa value. The position where the initial signal is received is recorded as y0, and the position where the signal is lost is recorded as y1. Then the coordinates of the midpoint of the sample in the Y-axis are y' = (y0 + y1) / 2.

[0035] The center coordinates of the installed sample were measured by a spectral confocal displacement sensor as ((x0+x1) / 2, (y0+y1) / 2), and the positioning error of the sample was (Sx-(x0+x1) / 2, Sy-(y0+y1) / 2).

[0036] Figure 4 This method uses a Faraday cup to detect the beam current distribution of an ion beam. The ion source is turned on and the ion beam is made electrically neutral. The ion beam passes through the bottom of the Faraday cup along the X-axis and pauses intermittently for a certain period. The Faraday cup receives the charge of the ion beam, and the beam current density at that point during the pause is measured. The magnitude of the beam current density and the x-coordinate position are recorded. See also... Figure 5 After the scan is completed, the recorded beam current density value is fitted. Since the ion beam is symmetrically distributed, the maximum beam current density (xI-max) is the center of the ion beam in the X direction. The offset of the ion beam center in the X direction is (xI-max-Fx).

[0037] The X-coordinate of the ion beam is set as (xI-max). A Faraday scan is performed along the Y direction. The ion beam passes through the bottom of the Faraday cup along the Y direction and stays intermittently for a certain period of time. The Faraday cup receives the charge of the ion beam. The beam current density at that point of the ion beam is measured at the time of the stay. The magnitude of the beam current density and the Y-coordinate position are recorded. After the scan is completed, the recorded beam current density value is fitted. The maximum beam current density (yI-max) is the center of the ion beam in the Y direction. The offset of the ion beam center in the Y direction is (yI-max-Fy).

[0038] Based on the measured sample installation positioning error and ion beam center offset error, the deviation between the ion beam center and the sample center is determined to be (Sx-(x0+x1) / 2+xI-max-Fx, Sy-(y0+y1) / 2+yI-max-Fy). Therefore, when processing the sample, the coordinates of each processing point of the sample are (x+Sx-(x0+x1) / 2+xI-max-Fx, y+Sy-(y0+y1) / 2+yI-max-Fy).

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for precisely positioning and processing a sample during ion beam processing, characterized in that... Includes the following steps: 1) Use Faraday cup scanning to obtain beam distribution information of the ion source; 2) Fit the beam information obtained from the Faraday cup scanning to obtain the position of the beam distribution center of the ion source, and then calculate the offset of the beam distribution center of the ion source relative to the center of the Faraday cup, and correct the offset in the numerical control system. 3) Use a spectral confocal displacement sensor to measure the clamping and positioning of the sample, determine the clamping center position of the sample, calculate the offset between the clamping center of the sample and the origin of the sample coordinate system, and thus correct the clamping and positioning error of the sample. 4) Correct the processing coordinates of the sample based on the offset of the ion beam and the offset of the sample clamping and positioning, and accurately position the ion beam processing.

2. The method according to claim 1, characterized in that: In step 1), the distance the ion source moves relative to the Faraday cup should be greater than the aperture of the ion source. During the Faraday cup measurement, the ion source moves intermittently, moving a certain distance each time and staying for a certain period of time to ensure the accuracy of the collected data.

3. The method according to claim 2, characterized in that: The specific process of step 2) is as follows: the least squares method is used to fit the Gaussian function to determine the center position of the ion beam distribution. Specifically, the distance between the position of the Faraday cup (Fx, Fy) and the origin position (Sx, Sy) of the sample platform is fixed. The fitted ion beam center position is (Fx', Fy') and the offset is (Fx-Fx', Fy-Fy'). Then the processing origin position of the sample after correction is (Sx-Fx+Fx', Sy-Fy+Fy').

4. The method according to claim 3, characterized in that: In step 2), the maximum beam current density xI-max is the center of the ion beam in the X direction, and the offset of the ion beam center in the X direction is xI-max-Fx. The maximum beam current density (yI-max) is the center of the ion beam in the Y direction, and the offset of the ion beam center in the Y direction is (yI-max-Fy).

5. The method according to any one of claims 1 to 4, characterized in that: The specific process of step 3) is as follows: After the sample is clamped, the spectral confocal displacement sensor is kept at a certain working distance from the sample surface. The spectral confocal displacement sensor is moved to scan the sample surface and the signal reception during the scanning process is recorded to obtain the clamping center position of the sample. The deviation between the clamping center of the sample and the origin of the sample coordinate system is calculated to correct the clamping positioning error of the sample.

6. The method according to claim 5, characterized in that: The spectral confocal displacement sensor receives signals from the surface of the sample during planar scanning, including signal triggering and loss. The edge position of the sample during the planar scanning process is obtained by recording the signal triggering and loss.

7. The method according to claim 6, characterized in that: The sample scanning involves scanning the sample surface in two perpendicular directions, X and Y. The origin of the sample platform is (Sx, Sy). When scanning the sample in the X direction, the position of the first trigger signal of the spectral confocal displacement sensor is x0, and the position of the first lost signal is x1. Therefore, the center position of the sample in the scanning direction is (x1+x0) / 2. When scanning the sample in the Y direction, the position of the first trigger signal of the spectral confocal displacement sensor is y0, and the position of the first lost signal is y1. Therefore, the center position of the sample in the scanning direction is (y0+y1) / 2. The clamping center coordinates of the installed sample are ((x0+x1) / 2, (y0+y1) / 2). The positioning error of the sample is (Sx-(x0+x1) / 2, Sy-(y0+y1) / 2).

8. The method according to claim 7, characterized in that: In step 4), the machining coordinates of the sample are (x+Sx-(x0+x1) / 2+xI-max-Fx, y+Sy-(y0+y1) / 2+yI-max-Fy).

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