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Published online by Cambridge University Press: 25 February 2011
Titanium silicide (TiSix), used as polycide gate consists of TiSi1.1 and amorphous silicon (a-Si), was deposited by Plasma Enhanced Chemical Vapor Deposition method (PE-CVD). The effect of a-Si layer in PE-CVD Ti polycide gate dielectrics has been studied. In order to evaluate the a-Si layer effect, three types of samples were prepared on gate SiO2 film with following structures : a) a-Si / TiSi-1.1 / a-Si / phosphorus (P) doped poly-Si, b) a-Si / TiSi-1.1 / non-doped poly-Si / P doped poly-Si and c) a-Si / TiSi1.1 / P doped poly-Si, respectively. Furthermore, in order to avoid the influence of native oxide existence at the interface, the pre-cleaning treatment was performed in-situ on the poly-Si film surface before TiSi1.1 film deposition. The gate dielectric strengths of these samples indicate that the gate dielectric degradation in PE-CVD Ti polycide gate is greatly dependent on Si under layer crystallization. It is effective using a-Si film as the under layer in decreasing the gate dielectric degradation . This is due to the Ti oxide interlayer, formed at the interface of TiSi2.0 and poly-Si films, which restrains the TiSix local penetration.