Inspection system utilizing dark-field illumination

Details Inspection system utilizing dark-field illumination Inspection system utilizing dark-field illumination

1984-01-25

1986-06-17

Kittle, John E.

Optics: measuring and testing

Inspection of flaws or impurities

Having predetermined light transmission regions

250563, 356392, 356446, G01B 1100, G01B 1124

Patent

active

045952892

ABSTRACT:
Integrated-circuit wafers and the lithographic masks and reticles used in their fabrication must be inspected for defects. Conventional systems accomplish such inspection by bright-field illumination and comparison of corresponding portions of two supposedly identical patterns on the workpiece. The minimum-size defect that can be so detected is set by misalignment between the patterns. Dark-field illumination of the portions to be compared significantly enhances the detection capabilities of such an inspection system. For a given misalignment, dark-field illumination permits the detection of defects at least four times smaller than those detectable in a conventional bright-field-illuminated system.

REFERENCES:
patent: 3186296 (1965-06-01), Erban
patent: 3430055 (1969-02-01), Metzger
patent: 4247203 (1981-01-01), Levy et al.
patent: 4421410 (1983-12-01), Karasaki

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