Characterisation of macro-porous silicon for electronic applications

Micro-Raman spectroscopy was used in this study for the analysis of the influence of process conditions on the strain and stress in macro-porous layers. As expected, it was found that oxidation results in significant wafer bending, depending on the layer porosity. The magnitude of stress of about 0.33 GPa was found for ma-PS sample with lattice constant of 4 mum while for sample with the lattice constant of 12 mum it was only 0.175 GPa. Dissolution of the oxide layer restores the flatness of the samples after the first oxidation. Repetition of the oxidation cycles leads to a "memory effect", as the residual deformation increases. The results are consistent with results obtained for similar samples using X-ray diffractometry and topography and curvature measurements.