Investigation of the Stress in MOS Structures with Micro-Raman Scattering

摘要

Two kinds of samples were investigated with micro-Raman spectroscopy. MOS structures having poly-silicon gates with metallic contact were made of Al with addition of 1% Cu. The other type of the sample was Si wafer subjected to surface oxidation. The position of the sample was changed along z-axis in order to maximize the Raman signal coming from different layers of the structure. Two MOS structures were studied, both prepared in the same process, and after that only one was thermally-treated at temperature 400℃. The spectra coming from different layers of the structure were analyzed numerically using Lorentzian profile. The authors want to point out that the measurements of the Raman signal performed through the metallic contact of the poly-silicon gate gave anomalously large signal coming from silicon structure. This effect was observed only for thermally threated sample. This suggest that in the case of thermally-treated structure the signal observed through the metallic contact was magnified by surface-enhanced Raman scattering phenomenon.