Patent ID: 6256097
Filing Date: 2001-07-03
Classification: G01J,G01N

Abstract:
An ellipsometry method comprising operating an ellipsometer to direct polarized light so that the light interacts with a sample optical system under study more than once by reflection of the polarized light from a surface of the sample optical system and re-reflection of the reflected light from said surface of the sample optical system so as to retrace its path in said ellipsometer, and measuring a change in polarization state of the light interacted with the sample optical system, wherein said polarized light includes a single beam of light which is simultaneously directed to interact with the sample optical system at different angles of incidence and wherein a change in polarization state is measured for at least one of a plurality of said angles of incidence of the multiple interactions of the light with the sample optical system, and wherein said ellipsometer is a return-path ellipsometer with a polarizer arm and an analyzer arm superimposed on said polarizer arm and wherein said step of directing said polarizer light to interact with the optical system at different angles of incidence includes reflecting said light from a surface of the sample optical system and re-reflecting said reflected light from said surface of said sample optical system so that said re-reflected light retraces its path in said arm of said ellipsometer and is then separated from the originating beam to be measured. and wherein said ellipsometer is a return-path ellipsometer with a polarizer arm and an analyzer arm superimposed on said polarizer arm and wherein said step of directing said polarized light to interact with the optical system at different angles of incidence includes reflecting said light from a surface of the sample optical system and re-reflecting said reflected light from said surface of said sample optical system so that said re-reflected light retraces its path in said arm of said ellipsometer and is then separated from the originating beam to be measured.