Atmospheric Pressure Spatial Atomic Layer Deposition of Silicon Oxide Using DIPAS and Ozone

Abstract

Silicon oxide (SiOx) is a highly versatile material used in different applications. However, its conventional growth and deposition methods often require very high temperature or the use of plasma. In this work, we present a plasma-free, low-temperature process for depositing high-quality SiOx thin films using atmospheric-pressure spatial atomic layer deposition (AP-SALD). An aminodisilane precursor, diisopropylaminosilane (SiH3N(C3H7)2, DIPAS), was synthesized and tested with different oxidants such as ozone and 30% hydrogen peroxide aqueous solution. Initial attempts with hydrogen peroxide solution resulted in precursor condensation and the formation of nano crystallite SiOx contaminated with organic molecules, indicating that the deposition process is oxidant limited. In contrast, using ozone as the oxidant facilitated the deposition of high-quality amorphous SiOx films. The microstructure was highly dependent on the deposition temperature, transitioning from nano crystallites at lower temperatures to amorphous films at temperatures of 70°C to 100°C. X-ray photoelectron spectroscopy (XPS) confirmed the deposition of SiOx films at 70°C or above using ozone, and the growth per cycle was ~1 Å/cycle, consistent with ALD of SiOx. This work shows that high-quality SiOx films can be produced by AP-SALD using DIPAS and ozone, without the aid of plasma or any surface functionalization, at low growth temperatures (T >= 70°C).