Ellipsometric Investigations of Boron-Rich Layers on Silicon

Abstract

It is shown that exposure of a silicon substrate to sufficiently highconcentrationsof diborane results in a surface layer which most likely consistsof a silicon-boron phase. This phase, which is controlled by the diboraneconcentration and the temperature, gives rise to a prediffused layerof boronin the adjacent substrate. Good control of the phase layer affordsgood controlof the prediffused layer. When the phase layer is removed prior todrive-in, optimal control is achieved with respect to the final diffusedstructure.