Patent ID: 7206071
Filing Date: 2007-04-17
Classification: G01B,G01J,G01N

Abstract:
1. A method of evaluating the geometry of small structures having critical dimensions formed on a semiconductor wafer comprising the steps of: focusing a probe beam onto the surface of the wafer in manner to create a spread of angles of incidence at a plurality of planes of incidence; retarding the phase of one polarization state of the probe beam with respect to the phase of the other polarization state; interfering the two polarization states in the probe beam after the probe beam has been reflected from the surface of the sample; measuring the power of the reflected probe beam using a detector defined by a two dimensional array of detector elements, each element generating output signals, said array including at least three rows and three columns with at least three detector elements in each row and in each column allowing measurement along at least three planes of incidence with respect to the sample; and evaluating the geometry of the critical dimension structures using output signals from a plurality of detector elements corresponding to a plurality of angles of incidence and a plurality of planes of incidence.