Process for inspecting patterned wafers

Details Process for inspecting patterned wafers Process for inspecting patterned wafers

1993-07-19

1994-10-11

McGraw, Vincent P.

Optics: measuring and testing

Inspection of flaws or impurities

Having predetermined light transmission regions

356394, G01N 2188

Patent

active

053552121

ABSTRACT:
A method of locating particle and defect features on a periodically patterned surface uses multiple threshold intensity levels to identify features in the data stream produced by scanning the surface with a light beam and detecting the light scattered from the surface. High thresholds are assigned to regions of the surface with high background scatter, while low thresholds are assigned to regions of the surface with low background scatter. The scattered light is detected with a wide dynamic range detector producing high resolution 12-bit pixel data capable of resolving the smallest particles and defects of interest in low scatter regions, while avoiding saturation in high scatter regions. Periodic pattern features are removed from the data by mapping features from a plurality of periodically repeating die on the surface to a single die map and looking for overlapping features. Unique, nonoverlapping features are determined to correspond to particles and defects. In one embodiment, only a portion of all the die on the surface are mapped at one time to reduce the possibility of accidental overlap of particle and defect features.

REFERENCES:
patent: 4641967 (1987-02-01), Pecen
patent: 4898471 (1990-02-01), Stonestrom et al.
patent: 5076692 (1991-12-01), Neukermans et al.
patent: 5189481 (1993-02-01), Jann et al.

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