Study of stress distribution in a cleaved Si shallow trench isolation structure using confocal micro-Raman system

Abstract

We measured local stress distributions in a cleaved Si shallow trench isolation (STI) structure. We used a high-spatial-resolution confocal UV micro-Raman system with an excitation wavelength of 364 nm. The polarization dependence of Raman spectra enabled us to quantitatively estimate the stress direction and intensity on the (1¯10) cross-section. We observed stress relaxation due to the cleavage resulted in an abrupt change in the intensity and polarity of stress around the cross-sectional surface. Finite element method simulations reproduced well the measurement results and confirmed that this change was due to out-of-plane elastic deformation of the cleaved surface. This accurate comparison of the measurement data and the simulation is based on the feature that the UV Raman measurement selectively detects the surface regions, making this method particularly useful in stress distribution analyses.