Selectivity and Growth Rate Modulations for Ruthenium Area-selective Deposition by Co-Reagent and Nanopattern Design

Area-selective deposition (ASD) is a bottom-up technique that provides numerous opportunities for nanoelectronic device fabrication. For example, advanced nano-interconnect structures with barrierless metals like Ru in the contact holes can be created by Ru ASD with the bottom metals as growth surfaces and dielectrics as non-growth surfaces. This work investigates Ru ASD by chemical vapor deposition (CVD) on industrially relevant substrates and nanopatterns and reveals how selectivity and growth rate are modulated by the CVD conditions and type of nanopattern. For low-k dielectric/Cu substrate combinations, the selectivity reverses from metal-on-metal to metal-on-dielectric upon only changing the CVD co-reagent from H2 to NH3. In contrast, NH3 is the preferred co-reagent for SiO2-TiN line patterns with critical dimension (CD) of 40 nm due to the more favorable adsorption and diffusion kinetics that cause growth rate and selectivity enhancement. Consistent with a diffusion-mediated mechanism, the growth rate enhances even more for Ru CVD on nanoscale contact holes with CD of 10.5 nm, becoming 2.4 times higher as compared to unpatterned substrates. Thus, the ASD process changes drastically when pattern dimensions reach the nanoscale. The reported insights facilitate rational design of metal ASD processes for multiple applications in nanofabrication. This work reveals how the selectivity and growth rate of ruthenium area-selective deposition are modulated by the deposition conditions, substrate materials, and type of nanopatterns. The growth rate increases on nanoscale patterns, consistent with a diffusion-mediated growth mechanism. This enables to maintain selectivity up to higher thickness, which holds promise for advanced semiconductor device fabrication and other nanoscale applications.image