METHOD FOR DETERMINING FILM THICKNESS BY WHITE LIGHT INTERFEROMETRY Russian patent published in 2017 - IPC G01B9/02 

FIELD: physics.

SUBSTANCE: method for determining the film thickness by white light interferometry, in which a substrate containing a measurable film is exposed to white light with limited coherence in the interferometer and correlograms are measured, is characterized in that a pre-substrate not containing the measurable film is exposed to white light with limited coherence, and a set of correlograms is determined, in addition, a set of correlograms is determined for each pixel of the optical field, after which a nonlinear phase spectrum depending on the wave number is determined, the phase spectra are approximated by the known theoretical nonlinear phase shift spectrum caused by the film, determining the local film thickness as the best approximation parameter, resulting in a set of film thicknesses and the positions of its substrate, which result in maps of surface topography and the film thickness, wherein the nonlinear phase spectrum of the object correlogram of the surface containing the film is corrected by subtracting the nonlinear phase spectrum of the reference correlogram.

EFFECT: reducing the lower limit of the measured thin film thickness range and increasing the noise immunity of the method.

4 cl, 5 dwg