Samsung Advanced Institute of Technology

Area-selective deposition is an important technology for the advancement of precision in nanofabrication for developing next-generation semiconductor devices. (N,N-dimethylamino)trimethylsilane (DMATMS), which is a short alkylating agent, is attracting increasing attention for its ability to form a selective inhibition layer on technologically important silicon dioxide (SiO₂) and silicon nitride (SiN_x) surfaces. However, direct observation of the formation process of this molecular inhibition layer is challenging because of the limited analysis methods available for tracing the chemical transformation of DMATMS into the inhibition monolayer by its interaction with hydrogenated groups present on the surface of the substrate. In this study, we observed the surface chemistry before and after dry etching using in-situ spectroscopy, which revealed the tailorable chemical forms that play a crucial role in the reactivity of pure DMATMS vapor on the two types of surfaces. The ？OH groups present on the surfaces of SiO₂ and SiN_x were traced using absorption spectroscopy. The adsorption reactivity of DMATMS was [A1]？significantly reduced on the SiN_x surface because the surface NH species were exposed owing to the complete removal of the ？OH groups by dry etching. In the case of the oxygen-rich SiO₂ surface, the ？OH groups could not be removed completely by dry etching, and hence, no significant change in the adsorption strength of DMATMS was observed. ？OH group tailoring by dry etching considerably increased the inhibition selectivity of DMATMS on both the SiN_x and SiO₂ surfaces, and the selectivity of the subsequently grown Ru layer was 92.2%. These results provide a new direction toward increasing area selectivity by directly tracing and controlling the key surface molecules.

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