CN-122023205-A - Scanning electron microscope image distortion correction method and device based on scanning magnetic field compensation

CN122023205ACN 122023205 ACN122023205 ACN 122023205ACN-122023205-A

Abstract

The invention provides a scanning electron microscope image distortion correction method and device based on scanning magnetic field compensation, belonging to the technical field of electron microscopes, the scanning electron microscope image distortion correction method based on scanning magnetic field compensation of the invention corrects analog signals at the source of scanning signal generation, the image is undistorted when being collected, the CPU is not required to be occupied for image processing, the image resolution is not reduced or artifacts are not generated because of interpolation algorithm, by adopting the multipath multiplication type digital-to-analog conversion circuit, the scanning vector in any direction can be accurately synthesized, so that the non-orthogonal distortion of the magnetic field coil caused by processing errors is perfectly counteracted, the physical error parameter and the user operation parameter are completely decoupled in algorithm, the scanning direction is rotated anyway, the image always keeps in a distortion-free state, and the user experience and instrument usability are greatly improved.

Inventors

MAO RUIRUI
LU DABAO
FANG XIAOWEI

Assignees

合肥国镜仪器科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (10)

1. A scanning electron microscope image distortion correction method based on scanning magnetic field compensation is characterized by comprising the following steps: generating an X-direction original scanning signal and a Y-direction original scanning signal for driving a scanning coil of a scanning electron microscope; based on the set amplitude correction parameter, phase correction parameter and electron beam rotation angle, calculating a corresponding digital control coefficient by using a scanning signal correction model; Taking the X-direction original scanning signal and the Y-direction original scanning signal as reference inputs, taking the digital control coefficient as modulation input, carrying out orthogonalization coupling modulation on the original scanning signals through a multiplication type digital-to-analog conversion circuit, and outputting corrected analog scanning signals; and driving the scanning coil to generate a magnetic field through the corrected analog scanning signal, collecting an image, and adjusting the amplitude correction parameter and the phase correction parameter according to the image distortion condition until the image distortion is eliminated.
2. The scanning electron microscope image distortion correction method based on the scanning magnetic field compensation according to claim 1, wherein the orthogonalizing coupling modulation is performed on the original scanning signal by the multiplication type digital-to-analog conversion circuit, and the corrected analog scanning signal is output, comprising: the X-direction original scanning signal is connected to the reference voltage input ends of the first and third paths of multiplication digital-to-analog converters through the multipath multiplication digital-to-analog converters, and the Y-direction original scanning signal is connected to the reference voltage input ends of the second and fourth paths of multiplication digital-to-analog converters; respectively issuing the calculated digital control coefficients to the digital input ends of the corresponding multiplication digital-to-analog converters through upper computer software; And superposing the third path output and the fourth path output of the multiplication digital-to-analog conversion circuit to form a Y-direction correction signal.
3. The scanning electron microscope image distortion correction method based on the scanning magnetic field compensation according to claim 2, wherein the digital control coefficient is: ; ; ; ; Wherein RcA, rcB, rcC, rcD is the digital control coefficient corresponding to each path of the multiplication type digital-to-analog converter, M 1 、M 2 is the amplitude correction parameter, t 1 、t 2 is the phase correction parameter, and θ is the electron beam rotation angle.
4. The scanning electron microscope image distortion correction method based on the scanning magnetic field compensation according to claim 1, wherein the adjusting the amplitude correction parameter and the phase correction parameter according to the image distortion condition comprises: adjusting the amplitude correction parameters by using a circular standard sample to enable the image to show a positive ellipse or a circle; and adjusting the phase correction parameters to eliminate the rotation angle, so that the image gradually approaches to a perfect circle.
5. The scanning electron microscope image distortion correction method based on the scanning magnetic field compensation according to claim 4, wherein after the adjustment of the phase correction parameter eliminates the rotation angle so that the image gradually approaches to a perfect circle, the method further comprises: And measuring geometrical parameters of the image by an image measuring tool, and iteratively and finely adjusting the amplitude correction parameters and the phase correction parameters according to the deviation between the measured value and the standard value until the distortion of the image is eliminated.
6. The scanning electron microscope image distortion correction method based on the scanning magnetic field compensation according to claim 5, wherein after the adjusting of the amplitude correction parameter and the phase correction parameter according to the image distortion condition, the method further comprises: after finishing parameter adjustment, changing the rotation angle and the magnification of the electron beam, determining whether the standard sample image is distorted, if so, recalculating and updating the digital control coefficient until the same group of correction parameters are applicable to all rotation angles.
7. A scanning electron microscope image distortion correction device based on scanning magnetic field compensation, characterized by comprising: the generating module is used for generating an X-direction original scanning signal and a Y-direction original scanning signal for driving a scanning coil of the scanning electron microscope; The first output module is used for calculating a corresponding digital control coefficient by using the scanning signal correction model based on the set amplitude correction parameter, the set phase correction parameter and the set electron beam rotation angle; The second output module is used for taking the X-direction original scanning signal and the Y-direction original scanning signal as reference inputs, taking the digital control coefficient as modulation input, carrying out orthogonalization coupling modulation on the original scanning signal through the multiplication type digital-to-analog conversion circuit, and outputting a corrected analog scanning signal; and the correction module is used for driving the scanning coil to generate a magnetic field through the corrected analog scanning signal, collecting an image and adjusting the amplitude correction parameter and the phase correction parameter according to the image distortion condition until the image distortion is eliminated.
8. A scanning electron microscope image distortion correction system based on scanning magnetic field compensation, which performs image correction by using the scanning electron microscope image distortion correction method based on scanning magnetic field compensation as claimed in any one of claims 1 to 6, characterized in that the system comprises: The upper computer control module is used for providing a man-machine interaction interface, receiving input amplitude correction parameters and phase correction parameters, and calculating a digital control coefficient according to a preset correction model based on the electron beam rotation angle; a scan signal generator for generating original analog scan waveforms in an X-direction and a Y-direction; The signal modulation correction module is respectively connected with the upper computer control module and the scanning signal generator and is used for receiving the original analog scanning waveform as a reference signal, receiving the digital control coefficient as a modulation signal and outputting a corrected analog scanning signal through hardware multiplication operation; and the driving module is connected with the signal modulation correction module and is used for amplifying the power of the corrected analog scanning signal and driving the scanning coil.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the scanning electron microscope image distortion correction method based on scanning magnetic field compensation as claimed in any one of claims 1 to 6 when executing the program.
10. A non-transitory computer readable storage medium having stored thereon a computer program, wherein the computer program when executed by a processor implements the scanning electron microscope image distortion correction method based on the scanning magnetic field compensation as claimed in any one of claims 1 to 6.

Description

Scanning electron microscope image distortion correction method and device based on scanning magnetic field compensation Technical Field The invention relates to the technical field of electron microscopes, in particular to a scanning electron microscope image distortion correction method and device based on scanning magnetic field compensation. Background Scanning Electron Microscopy (SEM) uses a focused electron beam to raster scan over the sample surface and image by collecting an electron signal. The scan coils are core components for controlling deflection of the electron beam, ideally, the scan magnetic fields in the X-direction and the Y-direction should be strictly orthogonal, and the magnetic field strength generated under the same driving signal should conform to a preset ratio, typically 1:1 or a specific aspect ratio, to ensure that the image is not geometrically distorted. However, in practical manufacturing and assembly processes, limited by machining precision and coil winding process, the X-axis coil and the Y-axis coil tend to be difficult to achieve physically strict orthogonality, and the magnetic field efficiency (gauss/amp) of the two is also inevitable. In addition, when an operator uses the electron beam rotation function for observing different angles of the sample, the above physical errors are coupled with the rotation angle, resulting in parallelogram distortion, keystone distortion, or nonlinear stretching of the image. Existing correction methods typically employ either software interpolation correction or simple analog potentiometer adjustment. The analog potentiometer has low adjustment precision and large temperature drift, and cannot adapt to the dynamic change after the electron beam rotates, so that a user needs to recalibrate after changing the scanning angle, the operation is complicated, and the working efficiency and the imaging quality are seriously affected. Therefore, a correction scheme capable of compensating hardware errors in real time and having correction parameters independent of scan angle is needed. Disclosure of Invention The invention provides a scanning electron microscope image distortion correction method and device based on scanning magnetic field compensation, which are used for solving the defect that a correction mode is not ideal enough in the prior art and realizing the effect of improving correction effect and operation independence. The invention provides a scanning electron microscope image distortion correction method based on scanning magnetic field compensation, which comprises the following steps: generating an X-direction original scanning signal and a Y-direction original scanning signal for driving a scanning coil of a scanning electron microscope; based on the set amplitude correction parameter, phase correction parameter and electron beam rotation angle, calculating a corresponding digital control coefficient by using a scanning signal correction model; Taking the X-direction original scanning signal and the Y-direction original scanning signal as reference inputs, taking the digital control coefficient as modulation input, carrying out orthogonalization coupling modulation on the original scanning signals through a multiplication type digital-to-analog conversion circuit, and outputting corrected analog scanning signals; and driving the scanning coil to generate a magnetic field through the corrected analog scanning signal, collecting an image, and adjusting the amplitude correction parameter and the phase correction parameter according to the image distortion condition until the image distortion is eliminated. According to the scanning electron microscope image distortion correction method based on the scanning magnetic field compensation provided by the invention, the original scanning signal is subjected to orthogonalization coupling modulation by utilizing the multiplication type digital-to-analog conversion circuit, and the corrected analog scanning signal is output, and the method comprises the following steps: the X-direction original scanning signal is connected to the reference voltage input ends of the first and third paths of multiplication digital-to-analog converters through the multipath multiplication digital-to-analog converters, and the Y-direction original scanning signal is connected to the reference voltage input ends of the second and fourth paths of multiplication digital-to-analog converters; respectively issuing the calculated digital control coefficients to the digital input ends of the corresponding multiplication digital-to-analog converters through upper computer software; And superposing the third path output and the fourth path output of the multiplication digital-to-analog conversion circuit to form a Y-direction correction signal. According to the scanning electron microscope image distortion correction method based on the scanning magnetic field compensation, the digital control coefficients are as fo