A kinetic model for solid-state silicide nucleation

Abstract

We present a model for solid-state silicide nucleation at the interface of a thin metal film and a silicon substrate, starting with the assumption that compound nucleation in these systems is a kinetically controlled process. We consider the work being done on other systems, such as dendrite nucleation and growth, and snowflake generation, where the processes are kinetically self-limited by the structures that form. We show that the requirements for kinetically self-limited systems can be formally satisfied at the interfaces for silicide forming systems. In particular, in analogy with the selection of metastable shapes for snowflake structures, we would in general expect metastable chemical structures to form at metal-semiconductor interfaces under conditions of large supercooling. We discuss the selection criteria (maximum energy degradation rate), the probable forms of these structures, and the conditions required for their growth. We then discuss an interpretation of phenomenological rules for selection of first-phase nucleation in terms of these structures.