Self-Aligned Top-Gate Coplanar a-Si:H Thin-Film Transistors With a –Silicone Hybrid Gate Dielectric

摘要

We have made self-aligned top-gate coplanar hydrogenated amorphous-silicon (a-Si:H) thin-film transistors using a $hbox{SiO}_{2}$–silicone hybrid material as the gate dielectric. The hybrid dielectric layer is 150 nm thick and separates a chromium gate electrode from nickel silicide source and drain. The nickel silicide is formed by rapid thermal reaction of a deposited nickel film with the underlying a-Si:H. The electron field-effect mobility is $sim!! hbox{1.0} hbox{cm}^{2}/hbox{V} cdot hbox{s}$, the subthreshold slope is $sim$380 mV/decade, and the on/ off current ratio is $sim!! hbox{10}^{5}$. The gate leakage current of $sim$ 10 pA across the 150-nm-thick hybrid dielectric is $sim$1/10 of that observed across the typical 300-nm-thick $hbox{SiN}_{x}$ dielectric. The whole process needs only two masks.