Insulator-semiconductor interface formation by electronic promotion using alkali metal and removal of the catalyst

Abstract

Core level photoemission spectroscopy experiments using synchrotron radiation is performed to study the effect of alkali metal overlayers on the oxidation and the nitridation of silicon. At room temperature, the presence of an alkali metal monolayer enhanced dramatically the oxidation rate of silicon by several orders of magnitude. A rapid thermal annealing at moderate temperature results in the formation of a SiO2-Si interface at lower temperature than by direct thermal oxidation. The catalytic mechanism is found to be non-local in nature. A similar behaviour is observed for nitridation using molecular nitrogen with formation of a Si3N4-Si interface at much lower temperature than with other thermal processes. In both cases the alkali metal catalyst is removed by thermal desorption at moderate temperature.