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°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 highvelocity 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°C. These layers exhibited a refractive index of 1.46, an OSi ratio of 2, an interface trap density in the order of 1011 cm−2 eV−1, an oxide charge density down to 1010 cm−2, and a breakdown field up to 11 MVcm. They are thus suitable as a gate dielectric in a thin-film transistor.