Patent ID: 6242739
Filing Date: 2001-06-05
Classification: G01B

Abstract:
A method for determining at least one parameter of a semiconductor, said method comprising the steps of:measuring an experimental reflectance spectrum R.sub.exp of the semiconductor utilizing an FT-IR instrument;constructing an analytical model of the semiconductor having a film layer, a transition layer and a substrate layer;modeling a perpendicular reflectance R.sub.s and a parallel reflectance R.sub.p of said analytical model;calculating a model reflectance spectrum R.sub.mod for said analytical model from said perpendicular reflectance R.sub.s and said parallel reflectance R.sub.p ;adjusting said model reflectance spectrum R.sub.mod to achieve a best fit relationship with said experimental reflectance spectrum R.sub.exp, wherein an adjusted model reflectance spectrum is formed; anddetermining the at least one parameter from said adjusted model reflectance spectrum;wherein said step of modeling comprises the steps of:modeling a refractive index n comprising optical constants n and k for each of said film layer and said substrate layer, wherein a refractive matrix n.sub.i comprising optical constants n.sub.i and k.sub.i is formed;calculating said optical constants n.sub.i and k.sub.i according to the following equations: ##EQU24##wherein: ##EQU25##wherein E.sub.f is determined from the following constraint:N.sub.i =.intg.f.sub.0 g(E)dE;andmodeling said perpendicular reflectance R.sub.s and said parallel reflectance R.sub.p according to the following equations:R.sub.s =r.sub.s r.sub.s.sup.*R.sub.p =r.sub.p r.sub.p.sup.*##EQU26## ##EQU27##