A novel low-temperature method of SiO2 film deposition forMOSFET applications
Silicon dioxide dielectric films were deposited at low temperatures (250–300°) using a novel plasma enhanced MO-CVD process. In this process, the substrate was kept remote from the plasma region and the deposition of the film was achieved at low pressure (0.8-1.0 Torr) and low dc plasma power (0.3 W· cm−2). Films deposited using tetraethyloxysilane (TEOS) and nitrous oxide (N2O) as reactant material had, under optimum deposition conditions, resistivities of ≥ 1015 ohm-cm, a refractive index of 1.46, a dielectric constant of 3.98 and a breakdown field strength ≥ 5x 106 V·cm−1. AES and SIMS analysis indicated that the films were of high purity and were stoichiometric with no metallic silicon present. MOS-capacitors fabricated on Si-substrates showed no hysteresis and no frequency dispersion of capacitance in the accumulation region. An interface state density in the range of 1011 cm−2eV−1 was achieved for these MOS devices using our deposited SiO2dielectric films.