Characterization of anisotropic strain relaxation after isolation for strained SGOI and SiGe/Si structure with newly developed high-NA and oil-immersion Raman method

Local anisotropic strain relaxation at the free edge of the stained SiGe layers after isolation of strained SiGe layers was evaluated using the high-NA and oil-immersion Raman method adopting high numerical aperture (NA:1.4) lens and oil immersion techniques. It was confirmed that forbidden optical phonon mode (TO) can be effectively excited with the technique, and that the anisotropic strain measurement was realized for the strained-SiGe layers. It was found that the strain was more significantly relax in St-SGOI than in St-SiGe around each edge. The result implies that the relaxation mechanism of the SiGe mesas on the SiO2-Box layer and on the Si substrate may be different from each other.

► Local strain relaxation at the free edge of the stained SiGe layers is evaluated.
► A high-NA (1.4) Raman method was utilized to enhance spatial resolution.
► The technique allows anisotropic strain measurement to be realized.
► Strain relaxation was found to be higher in strained SGOI than in SiGe on Si.