Insight into Selective Surface Reactions of Dimethylamino-trimethylsilane for Area-Selective Deposition of Metal, Nitride, and Oxide

Area-selective deposition (ASD) is a promising bottom-up manufacturing solution for catalysts and nanoelectronic devices. However, industrial applications are limited as highly selective ASD processes exist only for few materials. "Passivation/deposition/defect removal" cycles have been proposed to increase selectivity, but cycling requires the passivation to be selective to the growth surface as well as the ASD-grown material. Dimethylamino-trimethylsilane (DMA-TMS) can passivate SiO2 surfaces by covering them with −Si(CH3)3 groups. However, the interaction of DMA-TMS with materials other than SiO2 and Si remains largely unknown and its compatibility with cycling is not yet understood. This work investigates the selectivity of metal, nitride, and oxide atomic layer deposition (ALD) to DMA-TMS-passivated SiO2 as well as the surface chemistry and selectivity of the DMA-TMS reaction. The ALD coreagents O2, NH3, and H2O show low reactivity with the −Si(CH3)3-terminated surface at temperatures up to 300 °C, but the selectivity of ALD strongly depends on the metal precursor and temperature. We demonstrate that DMA-TMS is a selective passivation agent for ASD of and on TiO2, TiN, and Ru selective to SiO2, by TiCl4/H2O, TiCl4/NH3, and EBECHRu/O2 ALD, respectively. We investigate the DMA-TMS reaction on Ru and TiN/TiO2 growth surfaces under conditions that passivate SiO2. At least 77% of the area of the growth surface remains reactive for ALD, confirming the compatibility of DMA-TMS with cycling for ASD. We investigate the impact of changes in surface composition due to patterning before ASD and find that DMA-TMS removes F impurities on TiN and TiO2 surfaces. DMA-TMS selectively passivates SiO2 on three-dimensional (3D) nanopatterns, allowing preferential TiO2 deposition on a nonpassivated growth surface. Thus, the selectivity of DMA-TMS shows great promise to expand the ASD material space as well as to increase selectivity during ASD cycles.