France Telecom/cnet

French State, Minister of Post, Telecommunications and Space

Jean Galvier

Annie Tissier

Philippe Gayet

A method for determining the complete elimination of a thin layer (3) deposited on a substrate (1) includes the steps of providing on an area of the substrate (1) an optical diffraction grating (2, 2'), the thin layer deposited on the substrate also covering this diffraction grating, and the etching of the thin layer being also carried out in the area of the diffraction grating; illuminating the grating (2, 2') with a monochromatic light beam; and observing the evolution of the diffracted light during the etching of the thin layer, in order to determine the moment when the material of the thin layer is entirely removed.

Method for determining the complete elimination of a thin layer on a non

A process for measuring the dimensions of a spacer consisting in forming in a substrate (1) an array of parallel stripes (2), having a rectangular cross section; forming spacers (7) on the lateral edges (6) of the parallel stripes (2); lighting the array through a monochromatic light beam to supply a diffraction pattern, the envelope of which exhibits a major lobe and secondary lobes; measuring the sum of light intensities of a predetermined number of spots pertaining to the first secondary lobe; and deducting therefrom the width l and angle .theta. of the spacer (7) according to the following formulas:

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Saint Martin d'Heres, France

Jean Galvier