Patent ID: 6985237
Filing Date: 2006-01-10
Classification: G01B

Abstract:
1. A method for determining layer thickness ranges of a plurality of layers (S i ) of a specimen, the method comprises the steps of: generating for each of the layers (S measuring a reflection spectrum of the specimen in a wavelength range (λ smoothing the reflection spectrum by diminishing noise caused predominantly by external influences and thereby generating a smoothed reflection spectrum; determining the number of extremes in the smoothed reflection spectrum, wherein two adjacent extremes, of which the one must be a minimum and the other a maximum, being evaluated only if they differ at least by a specified contrast criterion; determining the layer thickness ranges based on the number of extremes, such that for each layer (S specifying the wavelength range (λ limiting the wavelength range to a continuous range (λ selecting (λ calculating the increments (dT repeating until the wavelengths (λ