Doping profile measurements on silicon epitaxial layers with field controlled planar diodes

Abstract

A new method was developed for doping profile determination of Si epitaxial layers based on the physical properties of a MOS structure. Thin planar diodes were formed on the epitaxial layers and its capacitance vs. field-electrode voltage curves were measured at fixed reverse bias values, C( V g )/ V g . A step in the C( V g ) curve is obtained at a specific V g0 threshold voltage inducing an inversion layer on the surface. From the function V g0 C) the dopant surface concentration of the depletion region, q ∫ 0 x N(x) dx is then determined which gives after differentiation the doping profile N( x). The evaluation of measurement results is simple and can easily be automated.