Importance

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Abstract

An automated inspection system and method replaces human visual inspection of the surface of a specimen having distinguishing features or anomalies that are detectable under either one or a combination of bright field and dark field illumination. A preferred embodiment is an after develop inspection macro (ADI Macro) defect inspection system that inspects the patterned surface of a semiconductor wafer for large scale (i.e., greater than about 25 micron minimum dimension range) defects. The ADI Macro inspection system detects defects that appear after the photolithography development step and include regions of defocus ('hot spots'), scratches, pattern blemishes, large particles, (i.e., particles greater than about 25 micron minimum dimension range), extra deposited photoresist, nonuniform photoresist deposition, and edge bead removal inconsistencies. Two fluorescent lamp tubes are used to illuminate the target area in dark field, and one fluorescent lamp tube is used in an oblique configuration to illuminate the target area in bright field. First and second imaging systems collect, respectively, bright field light rays and dark field light rays propagating from the illuminated target area of the wafer surface. Each of two light sensor arrays optically communicates with a different one of the first and second imaging systems. The light sensor array outputs provide a stream of digital data that is processed by an imaging computer. Defect detection from these data is accomplished by analyzing a difference image among nearby reticle fields of the specimen wafer.

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First Claim