Local anisotropic strain evaluation in thin Ge epitaxial film using SiGe stressor template grown on Ge substrate by selective ion implantation

Abstract

Uniaxial strain states in a Ge epitaxial film were evaluated by oil-immersion Raman spectroscopy. The Ge epitaxial film used in this study was fabricated using a SiGe stressor template grown on a Ge substrate by selective ion implantation. The one-dimensional strain distribution in the Ge epitaxial film was evaluated by Raman spectroscopy, and large compressive strains and strain relaxations in implanted and unimplanted areas were confirmed, respectively. For further analysis of the strain states in the Ge epitaxial film in the unimplanted area, we obtained transversal optical phonon (TO1 and TO2) peaks by liquid-immersion Raman spectroscopy with a high-numerical-aperture objective lens. The stress states calculated from these peaks were clearly anisotropic. A uniaxially strained Ge epitaxial film, which is an appropriate high-performance transistor channel material, was achieved by using a SiGe template epitaxially grown on a selectively implanted Ge substrate.