A constitutive single crystal model for the silicon mechanical behavior: Applications to the stress induced by silicided lines and STI in MOS technologies.

In this study, a single crystal model for the silicon mechanical behavior is used in finite element simulation, performed with the FEM code ZeBuLon. The constitutive equations are taken from the well known model of Alexander and Haasen applied to each slip system along the {111} planes in the (110) directions. After calibration, thermal-softening and strain rate-softening have been investigated. Two applications are reviewed. The effect of silicide-induced stress is studied with the model. During the cooling down, simulation shows that gliding is activated in a narrow temperature window. This viscoplastic regime enables strain localization. The residual stress field is compared with an elastic simulation. Then, in a second application two layouts, where the STI pattern is different, are simulated and the results are checked against the leakage current measured.