Wafer-scale strain engineering on silicon for fabrication of ultimately controlled nanostructures

Abstract

We propose a method of strain distribution control on planar Si(001) and Si(111) wafers for nanostructure self-assembly, taking a long-term view toward future Si semiconductor science and technology. Oxygen ions are implanted through patterned layers on the Si wafers. The sample is then annealed at 1325 \ifmmode^\circ\else\textdegree\fi{}C to produce bulk oxide inclusions that yield a tensile and/or compressive strain distribution on the silicon surface. We also demonstrate that strained epitaxial growth of Ge on the Si(001) substrate surface at 550 \ifmmode^\circ\else\textdegree\fi{}C in an ultrahigh vacuum produces three-dimensional islands whose location and size distribution are well controlled. The degree of localization control is in agreement with simulations of the elastic strain distribution. Additionally, we show that increasing the Ge growth temperature 50 \ifmmode^\circ\else\textdegree\fi{}C significantly reduces the density of stray dots that randomly grow on the Si surface. The samples were observed by atomic force microscopy and cross-sectional transmission electron microscopy. Strains on the silicon surface, produced by the buried silicon oxides, were measured by micro-Raman spectroscopy.