Patent ID: 6746881
Filing Date: 2004-06-08
Classification: B24B,H01J,H01L

Abstract:
A method for measuring a thickness of a first layer,said first layer to be measured being deposited on a second layer which is underneath said first layer, said first and second layers being part of an integrated circuit, said method being carried out, in real time, during an engraving reaction wherein an engraving front progresses from said first layer to said second, underneath layer, said engraving front progressing at a predetermined speed, and said engraving reaction, when applied to said second, underneath layer, generating a light emission having at least one spectral component, said method comprising the steps of: a) measuring an amplitude of light emitted during the engraving reaction, in a selected spectral range comprising said at least one spectral component; b) establishing a distribution of said amplitude as a function of time; c) determining, from said distribution, a moment of occurrence of an increase in said measured amplitude, said moment corresponding to a point in time at which the engraving front reaches the second, underneath layer; d) and computing the thickness of said first layer to be measured, on the basis of said moment and said predetermined speed of the engraving front.