An ellipsometric apparatus provides two impinging focused probe beams directed to reflect off the sample along two mutually distinct and preferably substantially perpendicular directions. A rotating stage rotates sections of the wafer into the travel area defined by two linear axes of two perpendicularly oriented linear stages. As a result, an entire wafer is accessed for measurement with the linear stages having a travel range of only half the wafer diameter. The reduced linear travel results in a small travel envelope occupied by the wafer and consequently in a small footprint of the apparatus. The use of two perpendicularly directed probe beams permits measurement of periodic structures along a preferred direction while permitting the use of a reduced motion stage.
CLAIM OF PRIORITY
The present application is a continuation of U.S. patent application Ser. No. 10/042,592, filed Jan. 9, 2002, now U.S. Pat. No. 6,798,512 which claims priority to U.S. Provisional Patent Applications Ser. No. 60/311,035, filed Aug. 9, 2001, and Ser. No. 60/336,437 filed, Nov. 1, 2001, each of which is hereby incorporated herein by reference.
