Patent ID: 7130373

Claim:
A method of measuring a film thickness comprising the steps of: (a) preparing a thin film made of a polycrystalline material; (b) assuming an orientation density distribution function ρ which is axisymmetric about a normal direction of a surface of said thin film, said orientation density distribution function ρ being a function of an angle φ at which a normal of a measurement lattice plane of a crystallite of the thin film is inclined to a normal of the surface of the thin film, and said orientation density distribution function ρ containing at least one characteristic parameter characterizing a form of the function; (c) allowing an X-ray to be incident upon the surface of the thin film at an incident angle α, measuring an intensity of a diffracted X-ray which is reflected at said measurement lattice plane of the thin film, and determining a variation of the intensity of the diffracted X-ray from said measurement lattice plane with the incident angle α being changed to obtain a measured rocking curve; (d) calculating a theoretical diffracted X-ray intensity, based on (i) a scale factor which is predetermined for a standard sample having a known film thickness, (ii) said orientation density distribution function ρ and (iii) a film thickness t of said thin film, to obtain a theoretical rocking curve about a variation of the intensity of the diffracted X-ray from said measurement lattice plane with the incident angle α being changed; and (e) carrying out a parameter fitting operation in which said characteristic parameter and said film thickness t are adjusted so that said theoretical rocking curve can approach said measured rocking curve as closely as possible, whereby said film thickness t is determined.