Patent ID: 7339682

Claim:
A heterodyne reflectometer for measuring thickness of a target layer deposed on a substrate comprising: an optical light source for producing a split frequency, dual polarized beam; a beam path diverting optical component for propagating the split frequency, dual polarized beam toward an exposed target layer deposed on a substrate at a predetermined angle of incidence; a first heterodyne detector for receiving the split frequency, dual polarized beam and generating a reference electrical heterodyne beat signal; a second heterodyne detector for receiving a reflected split frequency, dual polarized beam from the target layer and generating a measurement electrical heterodyne beat signal; a phase detector for receiving reference electrical heterodyne beat signal and the measurement electrical heterodyne beat signal, and detecting a phase shift between said reference and measurement electrical heterodyne beat signals; and a data processor for calculating a thickness relating to the target layer from the phase shift.