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

Silicon oxide (SiO_x) is a highly versatile material used in different applications. However, its conventional growth and deposition methods often require a very high temperature or the use of plasma. In this work, we present a plasma-free, low-temperature process for depositing high-quality SiO_x 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 nanocrystallite SiO_x 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 SiO_x films. The microstructure was highly dependent on the deposition temperature, transitioning from nanocrystallites at lower temperatures to amorphous films at temperatures of 70–100 °C. X-ray photoelectron spectroscopy (XPS) confirmed the deposition of SiO_x films at 70 °C or above using ozone, and the growth per cycle was ∼1 Å/cycle, consistent with ALD of SiO_x. This work shows that high-quality SiO_x 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).