Influence of RTA parameters on residual stress and stress gradient of multilayered LPCVD polysilicon film

This paper reports the experimental results of examining the residual stress and stress gradient of low-pressure chemical vapor deposition (LPCVD) multilayered polysilicon film according under various rapid thermal annealing (RTA) conditions in a nitrogen atmosphere. In particular, the stress gradient of multilayered polysilicon film, which ranges from -17.1 to +1.5 MPa/μm as the RTA processing time increases, could be reduced to nearly zero by selecting the appropriate RTA time. The mechanism responsible for this dependence was examined using both experimental data and material analysis using secondary ion mass spectroscopy (SIMS) and transmission electron microscopy (TEM). It is concluded that the shift of the stress gradient is mainly caused by thin nitrided layers at the surface and interface of multilayered polysilicon film.