Charged particle microscope and measurement image correction method thereof
View Patent ↗A charged particle microscope corrects distortion in an image caused by effects of drift in the sampling stage by measuring the correction reference image in a shorter time than the observation image, making corrections by comparing the shape of the observation image with the shape of the correction reference image, and reducing distortion in the observation images. The reference image for distortion correction is measured at the same position and magnification as when acquiring images for observation. In order to reduce effects from drift, the reference image is at this time measured within a shorter time than the essential observation image. The shape of the observation image is corrected by comparing the shapes of the reference image and observation image, and correcting the shape of the observation image to match the reference image.
1. A scanning electron microscope system comprising:
a scanning electron microscope including a sampling stage capable of mounting the specimen for observation and moving to change the observation position of the specimen;
an image input device to obtain the signals measured by the scanning electron microscope as images;
a storage device to store the images that were input;
an arithmetic logic unit (ALU) to process the image and make various types of corrections;
an input device to enter the conditions for making corrections; and
an output device to output the corrected image,
wherein the scanning electron microscope system measures a correction reference image in a shorter time than the observation image: and
detects distortion in the observation image caused by drift of the sampling stage that occurred during specimen observation in line units on the applicable observation image by comparing the observation image with the correction reference image, and corrects the detected distortion in line units, and outputs an image with lower distortion.
2. The scanning electron microscope system according to claim 1 ,
wherein one correction reference image is acquired in order to correct distortion in one observation image.
3. The scanning electron microscope system according to claim 1 ,
wherein distortion in the observation image is corrected by detecting the distortion in the lateral direction in the observation image as the drift amount on the line in the lateral direction the observation image by comparing the observation image with the correction reference image.
4. The scanning electron microscope system according to claim 1 ,
wherein distortion in the observation image is corrected by detecting the distortion in the vertical direction in the observation image as the drift amount on the line in the vertical direction in the observation image by comparing the observation image with the correction reference image.
5. The scanning microscope system according to claim 1 ,
wherein in the lateral and vertical drift amount in the observation image, an approximate curve is found from the applicable drift amount, and the distortion in the observation image is corrected by utilizing the drift amount found from the applicable approximate curve as the correction amount.
6. The scanning electron microscope system according to claim 1 ,
wherein the presence or absence of drift in the observation image is displayed on the operating screen.