Electrical evaluation of high-temperature effects on gate oxide integrity in a self-aligned CoSi₂ MOS process

Abstract

A previous investigation revealed that during annealing at high temperatures a CoSi2/polysilicon bilayer breaks down, resulting in an inverted bilayer structure because of silicon grain growth and cobalt redistribution. The present paper is devoted to the electrical effects of the observed phenomena. MOS capacitors were subjected to heat treatments in the range 750-900°C prior to the evaluation of breakdown statistics. The electrical results were compared with Rutherford backscattering spectrometry. It is concluded that the effects on gate oxide integrity are slight and reproducible even after partial inversion of the bilayer structure. © 1993.