Dielectric Breakdown Properties of SiO2 Films Grown in Halogen and Hydrogen‐Containing Environments

Abstract

Thermal oxidation of silicon, in the presence of chlorine or bromine compounds, effectively improved the dielectric breakdown characteristics (as measured with a voltage ramp) of the resulting SiO 2 films. At high halogen concentrations the oxidation rate was erratic; the optimal initial breakdown properties were attained by oxidizing with about one‐half of the halogen‐containing additive that would cause etching of the Si. Oxidation in the presence of halides increased the resistance of SiO 2 films to dielectric breakdown under accelerated bias‐temperature stressing. The maximum time to failure varied semilogarithmically with HCl concentration and increased by 0.3 to 0.65 decade per per cent of HCl (0–3% HCl range) for applied fields from 2 to 7 MV/cm, respectively. Higher oxidation temperatures further improved the resistance of HCl oxides to dielectric wear‐out. The longer wear‐out times were attributed to hydrogen rather than the halogen and could be achieved by oxidation in small concentrations of H 2 O , annealing in H2, or.implantation of H2 or H 2 O .