A Model for Dopant Incorporation into Growing Silicon Epitaxial Films: II . Comparison of Theory and Experiment

Abstract

In the preceding paper, a physicochemical model describing the incorporation of arsenic atoms into growing silicon epitaxial films was presented. An equivalent RC circuit, described by a series of mathematically similar equations, was also introduced. In this paper both the steady‐state and the transient behavior of the epitaxial doping process predicted by the model are described and compared to experimental results using the equivalent circuit. In steady state the model indicates that the doping process is controlled by thermodynamics at very low growth rates and by reaction kinetics at high growth rates. The decrease in the epitaxial‐layer arsenic concentration observed with increasing deposition temperature at high growth rates is used to show that the dominant mechanism occurs at the growing surface. According to the model, at low growth rates the transient response is controlled by the RC time constant associated with the relaxation time of the slowest step in the kinetic sequence. At high growth rates it is controlled by the rate at which arsenic atoms occupying incorporation sites on the growing surface are covered by subsequently arriving silicon atoms. The decay time associated with the transient is independent of the growth rate at very low rates and is inversely proportional to the growth rate at high rates, in agreement with experimental results.