Southampton Nanofabrication Centre

Silicon epitaxy is the growth of a layer of single-crystal silicon on top of a single-crystal silicon substrate. Epitaxial growth can be achieved at a temperature much lower than the melting point because the substrate provides a template for the ordering of deposited silicon atoms into a single-crystal lattice. Hetero-epitaxy is the growth of a single-crystal layer of one material on a substrate comprising a different single-crystal material. This can only be successfully achieved if the lattice mismatch between the two crystalline materials is small (4.2% between Si and Ge).

ASM Epsilon Epitaxy System

The Epsilon can be used to grow epitaxial silicon layers, boron and phosphorus marker layers, compressively strained silicon-germanium layers on a silicon substrate, tensile strained silicon layers on a relaxed silicon-germanium buffer, silicon-germanium multi quantum wells and germanium quantum dots. Epitaxial growth is typically performed at 500-600C using dichlorosilane for silicon, germane for germanium and both for silicon-germanium. Layers can be doped during growth using diborane for p-type layers and phosphine for n-type. If a small percentage of chlorine is introduced into the growth process, selective epitaxy can be achieved in which single-crystal silicon or silicon-germanium is grown in a window etched in a silicon dioxide or silicon nitride layer.