Microstrain in laser-crystallized silicon islands on fused silica

Residual strain in cw laser-crystallized silicon thin films has been measured with high spatial resolution (∼5 μm) by Raman spectroscopy. Thin films of polycrystalline silicon were defined into moated islands and patterned stripes on fused silica substrates and encapsulated with silicon nitride. Raman scattering was used to measure local strain at various points in and near crystallized islands, and the results reveal that the silicon film is under tension. The observations indicate that a major component of the stress in the film arises from pinning of the silicon at the silicon-fused silica interface at the solidification temperature followed by differential thermal contraction.