Inspection apparatus and inspection method

摘要

An inspection apparatus comprising, a focal position detector that detects a reference focal position of an image plane of a sample from a variation of an output value in optical image data of the sample, the output value being acquired by changing a distance between a first lens and the sample, and detects an optimum focal position of an inspection from the reference focal position, an image processor that obtains at least one of either an average gradation value in each predetermined unit region or a variation of a gradation value in the unit region with respect to the optical image data obtained at the optimum focal position, and a defect detector that detects a defect of the sample based on at least one of either the average gradation value or the variation of the gradation value.

主权项

1. An inspection apparatus comprising:
a light source that emits light having a predetermined wavelength; a first lens that transmits the light having the predetermined wavelength toward a sample; a second lens that forms an image of the light transmitted through or reflected by the sample via the first lens; an image sensor that obtains multiple optical image data of a pattern formed on the sample from the light of which the image is formed by the second lens, each optical image data in the multiple optical image data including a gradation value for each of a plurality of pixels; a focal position detector that determines, for each of the multiple optical image data, a variance or a standard deviation of the gradation values in the corresponding optical image data, detects a reference focal position of an image plane of the sample from the variance or the standard deviation of the gradation values in each of the multiple optical image data of the sample obtained by the image sensor, each of the multiple optical image data being acquired by changing a distance between the first lens and the sample, and detects an optimum focal position of an inspection from the reference focal position; an image processor that obtains at least one of either an average gradation value in each predetermined unit region or a variation of a gradation value in the unit region with respect to the optical image data obtained at the optimum focal position; and a defect detector that detects a defect of the sample based on at least one of either the average gradation value or the variation of the gradation value, wherein a resolution limit determined by a wavelength of the light source and a numerical aperture of the second lens is a value in which the pattern is not resolved.