Effective Control of Strain in SOI by SiN Deposition

Strain introduction in SOI substrates by SiN capping film was evaluated by UV-Raman spectroscopy. Induced strain became larger with increasing SiN film thickness. SOI substrates originally had tensile strain and the SiN cap shifted the strain toward the compressive direction. The induced strain was larger in the thinner SOI substrates with the same thickness of the SiN capping film. We also evaluated a substrate after SiN patterning with a high spatial resolution of 200-nm, and found strain enhancement at the pattern edge.