Two-dimensional micro-Raman mapping of stress and strain distributions in strained silicon waveguides

Micro-Raman scattering experiments were performed on strained silicon waveguides designed for nonlinear optical experiments. Thin stressing silicon nitride (Si3N4 or SiNx) cladding layers, deposited on a light-guiding silicon core layer, strain silicon to enable chi((2)), the second-order nonlinear susceptibility. Different deposition treatments allow varying the applied stress. The resulting strained waveguides are investigated by micro-Raman confocal spectroscopy performed on the waveguide facet. By modelling the measured Raman shifts, the local stress and strain are extracted. Thus, two-dimensional maps of the stress distribution as a function of the SiNx deposition parameters are drawn. A comparison of different samples allows underlying the non-uniformity of resulting strain.