Low-temperature SiO2 layers deposited by combination of ECR plasma and supersonic silane/helium jet

As the semiconductor industry strives toward wafer postprocessing and three-dimensional integration, a demand has arisen for high- quality thin films deposited at temperatures below 400 degrees C. In this work, we present SiO2 films deposited at near room temperature, using a multipolar electron cyclotron resonance (ECR) plasma source, introducing the SiH4 gas by using a high-velocity jet of silane diluted in helium. The electrical properties were studied under varying deposition parameters, such as gas flow rate, deposition pressure, and postdeposition and postmetallization annealing processes. At a low pressure, low SiH4 flow and high helium flow, device-quality SiO2 layers were obtained after a deposition combined with a 5 min postmetallization annealing at 400 degrees C. These layers exhibited a refractive index of 1.46, an O/Si ratio of 2, an interface trap density in the order of 10(11) cm(-2) eV(-1), an oxide charge density down to 10(10) cm(-2), and a breakdown field up to 11 MV/cm. They are thus suitable as a gate dielectric in a thin-film transistor. (c) 2007 The Electrochemical Society.