Inspection method and system

摘要

A sample, which has a mesa portion having a pattern thereon, is placed on a Z table. Light is irradiated to the mesa portion through an optical system and light reflected by the mesa portion is received to measure a height of the mesa portion. A height map of the mesa portion is created based on a height of a corner position. A height using the height map is corrected based on a deviation of a measured value from a target value, and a temporal variation of a focal position of light irradiated to the mesa portion. An optical image of the pattern is obtained based on the corrected height of the mesa portion. The optical image is compared with a reference image and a defect is determined when a difference value between the optical image and the reference image is more than a predetermined threshold value.

主权项

1. An inspection method comprising:
placing a sample, which has a mesa portion having a pattern thereon, on a table; irradiating light to the mesa portion through an optical system, and receiving light reflected by the mesa portion for measuring a height of the mesa portion; creating a height map of the mesa portion based on a height of corner positions of the mesa portion; correcting a height of the mesa portion using the height map based on an amount of difference between a height data of the height map of the mesa portion and a target value, and a temporal variation of a focal position of light irradiated to the mesa portion; obtaining an optical image of the pattern while controlling a height of a position of the table based on the corrected height of the mesa portion; and comparing the optical image with a reference image and determining a defect when a difference value between the optical image and the reference image is more than a predetermined threshold value.