MOSFET TRANSISTORS FABRICATED WITH HIGH PERMITIVITY TIO2 DIELECTRICS

Layers of polycrystalline anatase TiO2 have been deposited through the thermal decomposition of titanium tetrakis-isopropoxide (TTIP). 500 A ngstrom films deposited and annealed in oxygen at 750 degrees C had av erage roughnesses (R(a)) of about 30 Angstrom. Capacitors made form 19 0 Angstrom layers of TiO2 displayed a voltage dependent accumulation c apacitance. This was postulated to be caused by finite width effects i n the accumulation layer which we have dubbed the quantum capacitance effect. N-channel transistors made with these films showed near ideal behavior, but mobilities were significantly lower than those of therma l oxide MOSFET's. This mobility reduction was believed to be caused by interface states, which fell below 10(11) cm(-2) eV(-1) at midgap, bu t rose sharply on either side, unlike the ''U'' shaped behavior in the rmal oxide MOSFET's.