Apparatus for detecting the defects of a pattern with directional characteristics using a filter having arm sections of curved shape

Claim 1

An apparatus for detecting defects in a pattern having linear straight line features and nonlinear defects comprising: (a) a coherent light source for radiating coherent light; (b) a collimator for collimating the coherent light radiated from said coherent light source into a light beam with a predetermined diameter and for directing it to said pattern; (c) a transform lens for transforming the intensity distribution of transmitted or reflected light from said pattern into a Fourier-transformed pattern; and (d) a spatial filter placed in the Fourier-transform plane of said transform lens which prevents transmission of the coherent light containing information of said linear straight line features of said pattern, said filter having a light intercepting area including a plurality of arm sections extending in the horizontal and vertical directions from a common point of intersection corresponding to the linear straight line features of said subject pattern and a portion lying between the two adjacent arm sections being of a circular shape protruding toward the center of said filter wherein the coherent light intercepting area of said spatial filter is defined according to the following four equations ##EQU3## where X and Y indicate the X-axis and Y-axis of said filter respectively, said X- and Y-axes corresponding to the respective axes of the arm sections of said filter extending in the horizontal and vertical directions, X=Y=0 is indicative of the center of said filter and, in the situation where the effective pupil is circular, 9√2/32 L×0.85≦R≦9√2/32 L×1.05 where L is a diameter of an effective pupil of the lens or in the situation where the effective pupil is square √2/4 L×0.85≦R≦√2/4 L×1.05 where L is a length of each side of an effective pupil of the lens.

Claim 2

An apparatus for detecting defects in a pattern having linear straight line features and nonlinear defects comprising: (a) a coherent light source for radiating coherent light; (b) a collimator for collimating the coherent light radiated from said coherent light source into a light beam with a predetermined diameter and for directing it to said pattern; (c) a transform lens for transforming the intensity distribution of transmitted or reflected light from said pattern into a Fourier-transformed pattern; and (d) a spatial filter placed in the Fourier-transform plane of said transform lens which prevents transmission of the coherent light containing information of said linear straight line features of said pattern, said filter having a light intercepting area including a plurality of arm sections extending in the horizontal and vertical directions from a common point of intersection corresponding to the linear straight line features of said subject pattern and a portion lying between the two adjacent arm sections being of a circular shape protruding toward the center of said filter wherein the coherent light intercepting area of said spatial filter is defined according to the following four equations ##EQU3## where X and Y indicate the X-axis and Y-axis of said filter respectively, said X- and Y-axes corresponding to the respective axes of the arm sections of said filter extending in the horizontal and vertical directions, X=Y=0 is indicative of the center of said filter and, in the situation where the effective pupil is circular, 9√2/32 L×0.85≦R≦9√2/32 L×1.05 where L is a diameter of an effective pupil of the lens or in the situation where the effective pupil is square √2/4 L×0.85≦R≦√2/4 L×1.05 where L is a length of each side of an effective pupil of the lens.

Claim 10

An apparatus for detecting defects in a pattern having linear straight line features and nonlinear defects comprising: (a) a coherent light source for radiating coherent light; (b) a collimator for collimating the coherent light radiated from said coherent light source into a light beam with a predetermined diameter and for directing it to said pattern; (d) a transform lens for transforming the intensity distribution of transmitted or reflected light from said pattern into a Fourier-transformed pattern; and (d) a spatial filter placed in the Fourier-transform plane of said transform lens which prevents transmission of the coherent light containing information of said linear straight line features of said pattern, said filter having a light intercepting area including a plurality of arm sections extending in the horizontal and vertical directions from a common point of intersection corresponding to the linear straight line features of said subject pattern and a portion lying between the two adjacent arm sections being of an elliptical-shape protruding toward the center of said filter wherein the coherent light intercepting area of said spatial filter is defined according to the following four equations ##EQU4## where X and Y indicate the X-axis and Y-axis of said filter respectively, said X- and Y-axes corresponding to the respective axes of the arm sections of said filter extending in the horizontal and vertical directions and, in the situation where the effective pupil is circular 21.2/64 L×0.85≦r 1 ≦21.2/64 L×1.05 and 25.5/64 L×0.85=r 2 ≦25.5/64 L×1.05 where L is a diameter of an effective pupil of the lens or in the situation where the effective pupil is square 20.9/64 L×0.85≦r 1 20.9/64 L×1.05 and 22.6/64 L×0.85≦r 2 ≦22.6/64 L×1.05 where L is a length of each side of an effective pupil of the lens.

Claim 11

An apparatus for detecting defects in a pattern having linear straight line features and nonlinear defects comprising: (a) a coherent light source for radiating coherent light; (b) a collimator for collimating the coherent light radiated from said coherent light source into a light beam with a predetermined diameter and for directing it to said pattern; (d) a transform lens for transforming the intensity distribution of transmitted or reflected light from said pattern into a Fourier-transformed pattern; and (d) a spatial filter placed in the Fourier-transform plane of said transform lens which prevents transmission of the coherent light containing information of said linear straight line features of said pattern, said filter having a light intercepting area including a plurality of arm sections extending in the horizontal and vertical directions from a common point of intersection corresponding to the linear straight line features of said subject pattern and a portion lying between the two adjacent arm sections being of an elliptical-shape protruding toward the center of said filter wherein the coherent light intercepting area of said spatial filter is defined according to the following four equations ##EQU4## where X and Y indicate the X-axis and Y-axis of said filter respectively, said X- and Y-axes corresponding to the respective axes of the arm sections of said filter extending in the horizontal and vertical directions and, in the situation where the effective pupil is circular 21.2/64 L×0.85≦r 1 ≦21.2/64 L×1.05 and 25.5/64 L×0.85=r 2 ≦25.5/64 L×1.05 where L is a diameter of an effective pupil of the lens or in the situation where the effective pupil is square 20.9/64 L×0.85≦r 1 20.9/64 L×1.05 and 22.6/64 L×0.85≦r 2 ≦22.6/64 L×1.05 where L is a length of each side of an effective pupil of the lens.