Plasma-enhanced atomic layer deposition of low temperature silicon dioxide films using di-isopropylaminosilane as a precursor

Silicon dioxide (SiO2) films were deposited on Si (100) substrates with plasma-enhanced atomic layer deposition (PE-ALD) technique at 50, 100, and 200 °C, using di-isopropylaminosilane as a silicon source and oxygen (O2) plasma as an oxident. Self-limiting growth was confirmed with saturated growth-per-cycle (GPC) of ~1.7 Å at a constant O2 plasma time of 1.0 s while the GPC of the PE-ALD SiO2 film decreased with the O2 plasma time at a low temperature of 50 °C. In our experiment, the highest GPC of ~2.0 Å was achieved when the O2 plasma time was 0.3 s. Along the change of deposition temperature, an activation energy for thermal dehydroxylation was estimated from the gradient of the Arrhenius plot. Also, film properties were investigated with varying O2 plasma time. PE-ALD SiO2 film exhibited a disparity in wet etch rate and stoichiometric composition dependent on the in-cycle O2 plasma time. According to our experimental results, PE-ALD SiO2 film at a low temperature of 50 °C, presented high GPC and refractive index value of typical SiO2 film compared to thermal ALD SiO2.