Characteristics of CMOS devices fabricated using high quality thin PECVD gate oxide

Abstract

n- and p-channel FETs at 0.25-μm channel length were fabricated utilizing very thin (35-70 angstrom) PECVD (plasma-enhanced chemical-vapor-deposited) oxide as the gate dielectric. This oxide can be deposited at very low substrate temperature (≤350°C) in a low-pressure PECVD system. A helium plasma treatment is applied prior to the deposition in order to reduce the surface roughness and lower the surface state induced mobility degradation. Measured oxide quality is similar to that of thermally grown SiO2 in terms of the oxide charges and breakdown characteristics. The device characteristics are similar to those of the same devices fabricated with thermally grown gate oxide, although the device transconductances are slightly reduced. The potential of using this kind of oxide for deep submicron devices is discussed.