Crystal quality of SiGe films fabricated by the condensation technique and characterized by medium energy ion scattering

Abstract

Highly strained SiGe-on-insulator (SGOI) channels are desired for p-type transistor performance enhancement. A fine characterization of the crystal quality as a function of depth of such films would be of great interest as the SiGe crystal quality influences its electrical properties. The crystal quality of SGOI films fabricated by the condensation technique is measured by the Medium Energy Ion Scattering technique using the channeling effect. Indeed, the presence of structural defects such as dislocations is associated with atoms displaced from their normal lattice sites that contribute as a consequence to the scattering yield in channeling conditions. This paper compares the crystal quality of low Ge content and high Ge content SGOI films fabricated by condensation. It is shown that the SiGe crystal is degraded in the top part of the film, both before and after condensation, and that the presence of Ge, even at low fraction, at the interface with the buried oxide, induces crystal damage in the immediate vicinity of the interface. We finally highlight that, except close to the interfaces with oxide films, SGOI films fabricated by condensation feature high crystal qualities up to 57% Ge concentration and 2% compressive strain.

Local defect-free elastic strain relaxation of Si1-xGex embedded into SiO2

“…The surfaces of the two samples are continuous and flat (with RMS values around 0.15nm, in the range of the AFM signal noise in air) without visible features or extended defects, demonstrating the absence of dewetting and of nucleation of dislocations. The films are then expected to be fully strained [52]. To get quantitative information on the strain, micro Raman spectroscopy was carried out on the three samples.…”