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 LPCVD multilayered polysilicon film according to various rapid thermal annealing (RTA) in a nitrogen atmosphere. In particular the stress gradient of multilayered polysilicon film ranging from -17.1 to +1.5 MPa//spl mu/m as the RTA processing time increased could be reduced to nearly zero by selecting the appropriate RTA time. The mechanism responsible for this dependence was examined by 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 the thin nitrided layers at surface and interface of multilayered polysilicon film.