Method of detecting pattern defect and its apparatus

Claim 3

A method of detecting a pattern defect according to Claim 1, wherein said binary signals are simultaneously extracted from said first and second binary signals which have been corrected, in accordance with an axially asymmetric, picture element pattern (Figs. 10A to 10H).

Claim 4

A method of detecting a pattern defect according to Claim 1, wherein each of said patterns is a wiring pattern (58) formed on a wafer (1).

Claim 5

A method of detecting a pattern defect according to Claim 3, wherein said wafer (1) is illuminated with both vertical illumination light (54) and dark field illumination light (54 1 ).

Claim 6

A pattern defect detecting apparatus including imaging means (.18) for scanning and imaging one of two patterns, and binary digitizing means (20) for converting an image signal from said imaging means into a first binary signal, to detect a difference between said patterns by two-dimensionally comparing said first binary signal with a second binary signal corresponding to the other pattern, said second binary signal being formed by another imaging means (19) and another binary digitizing means (21) or being previously stored in storage means, said apparatus comprising: delay means (23, 24) for delaying two-dimensionally said first and second binary signals by a predetermined amount; means (22) for two-dimensionally detecting a positioning error between said patterns, in a period when said first and second binary signals are delayed by said predetermined amount, in such a manner that each of picture elements included in a predetermined area of a two-dimensional image corresponding to said one pattern which has been two-dimensionally delayed, is compared with a specified picture element included in an image corresponding to said other pattern which has been similarly delayed, the result of comparison is summed at each of the former picture elements, to statistically and two-dimensionally detect said positioning error; correction means (25) for correcting said positioning error by shifting said first and second binary signals from said delay means two-dimensionally according to the detected positioning error, and for two-dimensionally extracting binary signals from said first and second binary signals which have been corrected, in accordance with a picture element pattern for comparison; and comparison means (26) for comparing the extracted binary signals from said correction means to compare said patterns with each other.

Claim 7

A pattern defect detecting apparatus including imaging means (.18) for scanning and imaging one of two patterns, and binary digitizing means (20) for converting an image signal from said imaging means into a first binary signal, to detect a difference between said patterns by two-dimensionally comparing said first binary signal with a second binary signal corresponding to the other pattern, said second binary signal being formed by another imaging means (19) and another binary digitizing means (21) or being previously stored in storage means, said apparatus comprising: delay means (23, 24) for delaying two-dimensionally said first and second binary signals by a predetermined amount; means (22) for two-dimensionally detecting a positioning error between said patterns, in a period when said first and second binary signals are delayed by said predetermined amount, in such a manner that each of picture elements included in a predetermined area of a two-dimensional image corresponding to said one pattern which has been two-dimensionally delayed, is compared with a specified picture element included in an image corresponding to said other pattern which has been similarly delayed, the result of comparison is summed at each of the former picture elements, to statistically and two-dimensionally detect said positioning error; correction means (25) for correcting said positioning error by shifting said first and second binary signals from said delay means two-dimensionally according to the detected positioning error, and for two-dimensionally extracting binary signals from said first and second binary signals which have been corrected, in accordance with a picture element pattern for comparison; and comparison means (26) for comparing the extracted binary signals from said correction means to compare said patterns with each other.

Claim 8

A pattern defect detecting apparatus according to Claim 5, wherein said binary signals are simultaneously extracted from said first and second binary signals which have been corrected, in accordance with an axially asymmetric picture element pattern (Figs. 10A to 10H) for comparison.

Claim 9

A pattern defect detecting apparatus according to Claim 5, further comprising illumination means in which a lamp (63) for vertical illumination and a lamp (62) for dark field illumination are severally provided, means (66) for adjusting the quantity of vertical illumination light (54) from said lamp (63) for vertical illumination is provided to adjust a ratio of the quantity of vertical illumination light to the quantity of dark field illumination light, a first parabolic mirror (69) is disposed so as to reflect light from the lamp (62) for dark field illumination in directions parallel to the optical axis of an object lens (6, 5), and a second parabolic mirror (68) is disposed in the vicinity of an end portion of said object lens so that light travelling in the directions parallel to the optical axis of the object lens is reflected from said second parabolic mirror and the reflected light from the second parabolic mirror impinges obliquely on a portion to be illuminated, said illumination means being disposed so that the image of said one pattern illuminated with said illumination means is formed on said imaging means (18) by reflected light from said pattern.