Wafer topography measurement by fast optical scanning deflectometry

Abstract

Fast optical scanning deflectometry has been introduced for the measurement of the surface figure of optical surfaces. The measurement principle is based on physical ray tracing by means of a narrow laser beam deflected by an oscillating mirror and a large lens arranged for telecentric scanning. A new design of an instrument capable of measuring 12-inch wafers within 60 s and with a slope resolution better 1 /spl mu/rad is presented.