Understanding Growth Mechanism of Atomic Layer Deposition of Tisiox for Spacer in Double Patterning Process

Abstract

The aggressive scaling down of patterning technology in semiconductor industry is challenging owing to the limitation of current extreme ultraviolet EUV lithography technique, thus applying self-aligned double patterning (SADP) is essential. In this regard, TiSiOx may be a promising spacer material for SADP, which is beneficial to tolerate high aspect ratio structure triggered by shrinkage in patterning size. However, atomic layer deposition (ALD) of quaternary materials is usually faced to unexpected growth characteristics leading to undesired film qualities, while precise control of thickness and film properties is vital to achieve SADP. This work provide understanding of how growth characteristics of ALD TiSiOx are deviated according to process temperature. At 100 °C, hygroscopic TiSiOx surface which is originated by the presence of Ti-O-Si bond is exposed to H2O by-product leading to enhanced growth rate of TiSiOx compared to ideal case. If the process temperature is increased to 200 °C, opposite behavior is observed since hygroscopic TiSiOx surface characteristic is no more dominant to growth rate of ALD TiSiOx due to dehydroxylation. Theses nonconventional growth characteristics dramatically influence on hydroxyl concentration in TiSiOx films resulting in different spacer qualities such as dry etch rate and elastic modulus. These correlative results suggest that the process conditions should be modulated to suppress hydroxyls incorporation into growing TiSiOx surface during ALD to obtain a high-quality TiSiOx thin films for SADP.