Autodoping of Epitaxial Silicon Layers (III). Theoretical Treatment of Lateral Autodoping

Abstract

AbstractSolving dopants from the silicon surface into the volume during epitaxial layer growth is commonly described as a solution equilibrium, which forms an essential part of modelling intentional silicon doping. Above buried layers a so‐called redistribution autodoping causes the inversely directed process within an initial layer growth period. When the layer begins to grow, the dopants are not totally buried by the silicon deposited, but are partially swept towards the surface to develop the redistribution equilibrium. Above that part of the layer surface located above buried layers, simultaneously a certain dopant partial pressure is established. It gives rise to a vertical and lateral dopant transport by means of gas diffusion. The flow in lateral direction is considered the source of lateral autodoping. In the present paper a theoretical model of autodoping is developed and the layer deposition parameters are discussed with regard to minimizing autodoping effects.