Method and device for controlling the thickness of a layer of an integrated circuit in real time

A device 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;
• the measuring of the thickness of said first layer, 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 device comprising:
• first means for measuring an amplitude of light emitted during the engraving reaction, in a selected spectral range comprising said at least one spectral component;
• and second means for:
• establishing a distribution of said amplitude as a function of time;
• determining, from said distribution, a moment of occurrence of an increase of said measure amplitude, said moment corresponding to a point in time at which the engraving front reaches the second underneath layer;
• 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.