CN-116506723-B - Image acquisition method and device, scanning electron microscope and storage medium

CN116506723BCN 116506723 BCN116506723 BCN 116506723BCN-116506723-B

Abstract

The embodiment of the application provides an image acquisition method, which comprises the steps of acquiring an objective current value corresponding to an image at a first reference position in an interested region and Z-axis parameters of a sample platform, determining Z-axis parameters of the sample platform corresponding to the image at a plurality of second reference positions based on the Z-axis parameters of the sample platform under the condition that the objective current value is unchanged, determining a height difference of a sample in a preset direction based on the Z-axis parameters of the sample platform corresponding to the image at different reference positions, determining pile point information of Z-axis interpolation in the image acquisition process based on the height difference and the depth of field of a scanning electron microscope, and carrying out image acquisition of the interested region based on the pile point information and the objective current value. The embodiment of the application also provides a device for realizing the method, a scanning electron microscope and a storage medium.

Inventors

ZHANG HAN
LI YANG
ZHANG CHEN
TAN YUQI
FEI YAQIAN

Assignees

聚束科技（北京）有限公司

Dates

Publication Date: 20260505
Application Date: 20230428

Claims (9)

1. An image acquisition method, the method comprising: Acquiring a corresponding objective current value and a Z-axis parameter of a sample stage when an image at a first reference position in the region of interest is clear; Under the condition that the objective current value is unchanged, determining Z-axis parameters of the sample stage corresponding to the clear images at a plurality of second reference positions based on the Z-axis parameters of the sample stage; Determining the height difference of the sample in a preset direction based on Z-axis parameters of a corresponding sample table when images at different reference positions are clear; determining pile point information of Z-axis interpolation in the image acquisition process based on the height difference and the depth of field of the scanning electron microscope; image acquisition of the region of interest is carried out based on the pile point information and the objective current value; the determining pile point information of Z-axis interpolation in the image acquisition process based on the height difference and the depth of field of the scanning electron microscope comprises the following steps: Determining the number of pile points interpolated on the Z axis in a preset direction based on the height difference of the sample in the preset direction and the depth of field of the scanning electron microscope; And determining the total pile point number of the Z-axis interpolation and the Z-axis parameter corresponding to each pile point in the process of acquiring the image of the region of interest based on the pile point numbers of the Z-axis interpolation in different preset directions.
2. The method of claim 1, wherein acquiring the Z-axis parameters of the sample stage and the corresponding objective current values at which the image at the first reference location in the region of interest is sharp comprises: Controlling the electron beam to move to the first reference position; Adjusting the current value of an objective lens of a scanning electron microscope until a clear image is obtained; And recording Z-axis parameters of the sample stage under the condition of clear images.
3. The method of claim 1, wherein determining Z-axis parameters of the sample stage corresponding to the sharp image at the plurality of second reference locations based on the Z-axis parameters of the sample stage comprises: Configuring a total travel of movement of the sample stage and a step length of each movement during auto-focusing based on the sample surface features for each second reference position; image acquisition is carried out after each step length of movement of the sample stage until the total travel movement is finished; And selecting the image with the best quality from all the acquired images, and recording the Z-axis parameters of the sample stage when the image with the best quality is acquired.
4. The method according to claim 1, wherein determining the height difference of the sample in the preset direction based on the Z-axis parameters of the sample stage corresponding to the sharp images at the different reference positions comprises: Acquiring Z-axis parameters of a corresponding sample table when images at reference positions of edges at two sides of a sample in a preset direction are clear on a two-dimensional plane where the sample is positioned; calculating the difference value of the two Z-axis parameters; and determining the difference value as the height difference of the sample in the preset direction.
5. The method of claim 1, wherein the image acquisition of the region of interest based on the stake point information and the objective current values comprises: dividing the region of interest into a plurality of image blocks with equal size based on image acquisition requirements, wherein the subareas formed by the adjacent preset number of image blocks correspondingly comprise one pile point, and the number of the image blocks is larger than the total pile point number; and acquiring an image of the region of interest based on the objective current value and the Z-axis parameter of the pile point contained in each sub-region.
6. An image acquisition device, characterized in that it is applied to a scanning electron microscope, comprising: the system comprises a processing unit, a Z-axis parameter determining unit, a height difference determining unit, a Z-axis interpolation pile point information determining unit and a Z-axis interpolation pile point information determining unit, wherein the Z-axis parameter determining unit is used for determining the Z-axis parameter of a sample table corresponding to the image at a first reference position in an interested region when the image is clear, and the Z-axis parameter of the sample table corresponding to the image at a plurality of second reference positions when the image is clear under the condition that the objective current value is unchanged; the processing unit is also used for determining the number of pile points of the Z-axis interpolation in the preset direction based on the height difference of the sample in the preset direction and the depth of field of the scanning electron microscope, and determining the total number of pile points of the Z-axis interpolation and Z-axis parameters corresponding to each pile point in the image acquisition process of the region of interest based on the number of pile points of the Z-axis interpolation in different preset directions; And the image acquisition unit is used for acquiring the image of the region of interest based on the pile point information and the objective current value.
7. A scanning electron microscope, comprising: the first processor is used for acquiring the corresponding objective current value and the Z-axis parameter of the sample stage when the image at the first reference position in the region of interest is clear; under the condition that the objective current value is unchanged, determining Z-axis parameters of a plurality of sample tables corresponding to the images at the second reference positions when the images are clear based on the Z-axis parameters of the sample tables, determining the height difference of the sample in a preset direction based on the Z-axis parameters of the sample tables corresponding to the images at the different reference positions when the images are clear, and determining pile point information of Z-axis interpolation in the image acquisition process based on the height difference and the depth of field of a scanning electron microscope; The first processor is further used for determining the number of pile points of the Z-axis interpolation in the preset direction based on the height difference of the sample in the preset direction and the depth of field of the scanning electron microscope; and the image processor is used for acquiring the image of the region of interest based on the pile point information and the objective current value.
8. A scanning electron microscope comprising a first processor and a first memory for storing a computer program capable of running on the processor, Wherein the first processor is adapted to perform the steps of the method of any of claims 1 to 5 when the computer program is run.
9. A storage medium having stored thereon a computer program, which when executed by a processor performs the steps of the method according to any of claims 1 to 5.

Description

Image acquisition method and device, scanning electron microscope and storage medium Technical Field The present application relates to the field of scanning electron microscope technologies, and in particular, to an image acquisition method and apparatus, a scanning electron microscope, and a storage medium. Background With rapid development of science and technology, the application of the scanning electron microscope is becoming wider and wider. In order to more fully understand the information of the sample, a scanning electron microscope is gradually applied to image acquisition of a large area. When scanning an array of a sample by a scanning electron microscope, refocusing of a partial region is required due to sample flatness, coil hysteresis and the like, and currently, focusing is usually performed by adjusting an electromagnetic lens of a scanning particle beam microscope to determine a proper focusing current value. However, the method needs to be repeatedly adjusted to determine a proper focusing current value, and can only judge whether the working distance of the scanning electron microscope is accurate or not according to the definition degree of image focusing, the consumed focusing time is long, and in addition, for the sample with poor conductivity, the sample is easily damaged due to the overlong focusing time, and particularly, the sample with poor conductivity is easily accumulated with charges, so that the image quality is affected. Disclosure of Invention Accordingly, the embodiments of the present application are expected to provide an image acquisition method, an image acquisition device, a scanning electron microscope, and a storage medium, which can improve the image acquisition flux in the array scanning process, thereby reducing the damage to the sample. The technical scheme of the embodiment of the application is realized as follows: the embodiment of the application provides an image acquisition method, which comprises the following steps: Acquiring a corresponding objective current value and a Z-axis parameter of a sample stage when an image at a first reference position in the region of interest is clear; Under the condition that the objective current value is unchanged, determining Z-axis parameters of the sample stage corresponding to the clear images at a plurality of second reference positions based on the Z-axis parameters of the sample stage; Determining the height difference of the sample in a preset direction based on Z-axis parameters of a corresponding sample table when images at different reference positions are clear; determining pile point information of Z-axis interpolation in the image acquisition process based on the height difference and the depth of field of the scanning electron microscope; and acquiring an image of the region of interest based on the pile point information and the objective current value. The obtaining the objective current value and the Z-axis parameter of the sample stage corresponding to the clear image at the first reference position in the region of interest includes: Controlling the electron beam to move to the first reference position; Adjusting the current value of an objective lens of a scanning electron microscope until a clear image is obtained; And recording Z-axis parameters of the sample stage under the condition of clear images. The determining the Z-axis parameters of the sample stage corresponding to the clear images at the plurality of second reference positions based on the Z-axis parameters of the sample stage includes: Configuring a total travel of movement of the sample stage and a step length of each movement during auto-focusing based on the sample surface features for each second reference position; image acquisition is carried out after each step length of movement of the sample stage until the total travel movement is finished; And selecting the image with the best quality from all the acquired images, and recording the Z-axis parameters of the sample stage when the image with the best quality is acquired. The determining the height difference of the sample in the preset direction based on the Z-axis parameters of the sample table corresponding to the clear images at different reference positions comprises the following steps: Acquiring Z-axis parameters of a corresponding sample table when images at reference positions of edges at two sides of a sample in a preset direction are clear on a two-dimensional plane where the sample is positioned; calculating the difference value of the two Z-axis parameters; and determining the difference value as the height difference of the sample in the preset direction. The determining pile point information of Z-axis interpolation in the image acquisition process based on the height difference and the depth of field of the scanning electron microscope comprises the following steps: Determining the number of pile points interpolated on the Z axis in a preset direction based on