Patent ID: 7088448

Claim:
An ellipsometer measurement apparatus for determining a thickness of a film applied on a substrate, comprising: a light source emitting a beam; a transmitting optical system conveying the beam to an incidence point on the substrate, the substrate reflecting the beam from the incidence point; a photodetector device; a receiving optical system conveying the reflected beam to the photodetector device, the receiving optical system including an analyzer, a polarization direction of the beam and of the analyzer being modified in time relative to one another; an evaluation device evaluating intensity changes in the reflected beam and determining the film thickness as a function of the intensity changes; and an angle measurement device sensing an angle of the reflected beam relative to a tangential plane that does not intersect the substrate at the incidence point, the evaluation device determining the film thickness as a function of the sensed angle, wherein: the angle measurement device includes a photodetector unit that is position-sensitive in at least one of an X and Y direction, an angle of reflection being calculated from position data and distance data with an evaluation stage, and the intensity changes and the position data are sensed with a same photodetector.