UV-Raman imaging of the in-plane strain in single ultrathin strained silicon-on-insulator patterned structure

摘要

Confocal UV-Raman with glycerin-immersed high numerical aperture objective lens was used to probe the local strain in individual strained Si structures. The investigated structures were fabricated from 15 nm thick strained silicon-on-insulator substrates with a tensile strain of 0.8%. Two-dimensional maps of the postpatterning strain were obtained for single structures with lateral dimension of 500 nm. We found that the strain measured at the center partially relaxes and drops to 0.67% as a result of patterning-induced free surfaces. This relaxation increases toward the edges following nearly a parabolic behavior. A different strain behavior was observed for larger structures.