A fully stress-parametrized model for the dielectric function of silicon-on-insulator layers

Variable angle spectroscopic ellipsometry was used to measure the dielectric function of a silicon-on-insulator sample that was bent to induce defined stress incrementally up to about 200 MPa, as determined from the sample curvature and verified by Raman spectroscopy. The dielectric function at 1.2-6.4 eV of each stress state was modeled by four Tauc-Lorentz oscillators. By parametrizing all Tauc-Lorentz peak parameters with the induced stress, a Si dielectric function model was derived that depends solely on the stress in the layer, enabling accurate and fast stress determination by ellipsometry.