METHOD TO MEASURE THICKNESS OF THIN FILMS ON SUBSTRATE Russian patent published in 2010 - IPC G01B11/06 

FIELD: physics.

SUBSTANCE: proposed contactless method consists in irradiating the surface by optical radiation on various sounding wavelengths, registering signal reflected from said surface and determining film thickness by analyzing dependence of reflected signal intensity upon sounding wavelengths. Note that here is used laser source, smoothly or discretely (over six sounding wavelengths) readjustable in narrow range of wave length λ. Reflected signal measurement results are used to additionally determine first R'ref(λ,d) and second R"ref(λ,d) derivatives of coefficient Rref(λ,d) of reflection of three-layer system "air-film-substrate" to calculate film thickness d by the formula: , where n₂ is refractivity index of film material; r₁₂, r₂₃ are coefficients of reflection on the boundary of spheres "air-film" and "film-substrate"

EFFECT: higher accuracy of measurement.

2 dwg