High-Quality Thin SiO2 Films Grown by Atomic Layer Deposition Using Tris(dimethylamino)silane (TDMAS) and Ozone

Abstract

Atomic layer deposition of SiO2 using tris(dimethylamino)silane and ozone were studied comprehensively. It was found that SiO2 grew linearly at different temperatures while the growth rate increased at higher temperatures. For thickness <3.5 nm, the direct tunneling current of the ALD SiO2 is comparable to that of thermally grown SiO2 when considering its equivalent oxide thickness (EOT). The frequency dispersion and hysteresis behavior of the C-V curves of the ALD SiO2 films deposited at 100°C, 200°C, and 300°C are all very small in the thickness region of <3.5 nm, suggesting excellent interfacial quality. Based on analysis of mismatch between the films’ EOT and their physical thicknesses, the ALD SiO2 thin films are likely to be silicon-rich in composition. From the EOT point-of-view, the ALD SiO2 exhibits the same breakdown electrical field as that of the thermal oxide. From the physical thickness point-of-view, the breakdown electrical field is slightly lower than that of the thermal silicon oxide. The ALD SiO2 can be used as high-quality gate insulators for thin-film MOS transistors, and insulators for sensor structures and nanostructures on non-silicon substrates.