METHOD OF SCANNING SEMICONDUCTOR WAFERS TO INSPECT FOR DEFECTS

摘要

A patterned semiconductor wafer (60) is centered on a vacuum chuck (20) that is capable of being rapidly rotated about an axis normal to the wafer (60) surface. The vacuum holds the wafer (60) flat to the chuck (20). As the chuck (20) is rotated, the wafer (60) rotates and the surface of the wafer (60) is scanned (10) with an optical head (30). The output is fed through a signal line (47) of the read head (30) and is compared to a reference file in a processor (50) or signal representing what a perfectly pattern wafer should look like. Differences between the reference standard and the patterned wafer (60) indicate flaws in the patterning. In the case of an unpatterned surface such as a wafer, glass substrate for a liquid crystal display, or a magnetic memory, the reference signal is a null signal and any signal from the read head (30) would signify a flaw in the unpatterned surface.