Patent ID: 7307735

Claim:
A method for determining a thickness of a structured layer in a semiconductor wafer, wherein the structured layer has structure elements arranged in a regular pattern, comprising: irradiating the semiconductor wafer over a large area at a predetermined angle of incidence with respect to a surface of the semiconductor wafer with electromagnetic radiation extending over a wavelength range, wherein the irradiated area comprises a plurality of the structure elements of the structured layer, and the wavelengths of the electromagnetic radiation are substantially greater than lateral dimensions of the structure elements of the structured layer so that the electromagnetic radiation suppresses scattering effects at the structure elements and, thereby, the structured layer appears homogeneous to the electromagnetic radiation with regard to optical properties; recording the intensity of the reflected radiation depending on a wave number of the wavelength range of the radiated-in electromagnetic radiation at an angle of reflection, corresponding to the angle of incidence, with respect to the surface of the semiconductor wafer; and determining the thickness of the structured layer from the recorded intensity depending on the wave numbers.