Direct Observation of Dry Etch‐Induced Selectivity Tailoring of Alkylate Inhibition Layer Using DMATMS Vapor

Abstract Area‐selective deposition is a key method for enhancing precision in nanofabrication, particularly for next‐generation semiconductor devices. (N,N‐dimethylamino)trimethylsilane (DMATMS) is attracting increasing attention for its ability to form a selective inhibition layer on technologically important surfaces. However, direct observation of this molecular layer is challenging because of the limited analysis methods available for tracing the monolayer chemistry. This study employs in situ spectroscopy to investigate surface chemistry before and after dry etching, revealing the significant chemical forms influencing the reactivity of DMATMS vapor on both surfaces. Using absorption spectroscopy, the presence of ─OH groups on SiO 2 and SiN x are traced. The adsorption reactivity of DMATMS is notably diminished on SiN x due to the exposure of surface NH species after the removal of ─OH groups through dry etching. Conversely, the oxygen‐rich SiO 2 surface retains some ─OH groups, leading to no significant change in DMATMS adsorption strength. Tailoring surface ─OH groups through dry etching has minimal impact on SiO 2 but significantly suppresses DMATMS adsorption on SiN x , leading to 92.2% selectivity in the subsequently deposited ruthenium (Ru) layer. These results provide a new direction toward increasing area selectivity by directly tracing and controlling the key surface molecules.