WAFER READER INCLUDING A MIRROR ASSEMBLY FOR READING WAFER SCRIBES WITHOUT DISPLACING WAFERS

摘要

A wafer reader (10) for reading scribes from the surface of semiconductor wafers (28, 30, 32) uses a mirror assembly (42) with a series of stationary mirrors (48A-48D) spaced apart so that the mirrors can be inserted between wafers (28, 30, 32) in a cassette (12). The mirror assembly (42) enables a reader unit (10) to read each scribe without displacing the wafer that it is reading or the adjacent wafers. The reader unit (10) can include a single camera (34) that moves relative to a stationary cassette assembly (12) for holding a cassette or a moving cassette that moves past a fixed reading position of a single, stationary camera (34). Alternatively, the reader unit can include more than one stationary camera (300-308, figure 6), each capable of reading more than one wafer (352, 354, 356, figure 6) in a cassette (252, figure 6). The reader (10) can use either bright (110) or dark field lighting (122). In either case, each mirror in the mirror assembly re-directs light depicting a wafer scribe from the surface of an adjacent wafer to the camera assembly (34).