Micro-scale characterization of crystalline phase and stress in laser-crystallized poly-Si thin films by Raman spectroscopy

Laser crystallized poly-Si thin films were characterized using micro-Raman spectroscopy. Mapping measurements of the Si optical-phonon line were carried out for large size grains generated by the super-lateral growth, where the mapping interval was as small as 0.2 mu m. It was found that the spectral intensity is extremely large at ridges located at grain boundaries. The map of peak-frequency shift indicated that the tensile stress tends to accumulate in grains and relax at grain boundaries. The map of spectral width revealed the abrupt variation of the crystalline phase from large-size grains to microcrystals.