Autofocus assistance method, autofocus assistance device, and autofocus assistance program

An autofocus support device, comprising:

• a stage on which a semiconductor device having a substrate and a device pattern formed on one main surface side of the substrate is placed;
• an imaging device having a light source for emitting light to the semiconductor device and a photodetector for detecting light from the semiconductor device;
• and
• a control device for controlling a relative position between the stage and the imaging device,
• wherein the control device is configured to:
• acquires a first image focused on the substrate;
• acquires a spatial frequency image from the first image by Fourier transform and generates mask data for masking linear patterns in the same direction on the substrate based on the spatial frequency image;
• acquire a plurality of second images captured by using the imaging device while changing a focal position of the imaging device on the other main surface side of the substrate and performs filtering on the second images by using the mask data;
• and
• focus the imaging device on the device pattern based on the second image after filtering.

A non-transitory computer-readable storage medium storing an autofocus support program for supporting autofocus for a semiconductor device having a substrate and a device pattern formed on one main surface side of the substrate, the program causing a computer to function as:

• an image acquisition unit that acquires a first image focused on the substrate;
• a generation unit that acquires a spatial frequency image from the first image by Fourier transform and generates mask data for masking linear patterns in the same direction on the substrate based on the spatial frequency image;
• a processing unit that acquires a plurality of second images captured by using an imaging device while changing a focal position of the imaging device on the other main surface side of the substrate and performs filtering on the second images by using the mask data;
• and
• a focus adjustment unit that focuses the imaging device on the device pattern based on the second image after filtering.