Area-Selective Atomic Layer Deposition on Chemically Similar Materials: Achieving Selectivity on Oxide/Oxide Patterns

Area-selective atomic layer deposition (AS-ALD) is attracting increasing interest, but the process usually requires substrate materials with substantially different chemical properties. We introduce a process that expands the application to more general material systems by demonstrating AS-ALD on patterns with chemically similar materials. The substrate materials investigated are Al2O3, HfO2, TiO2, Ta2O5, and SiO2. By taking advantage of differential reactivity of octadecylphosphonic acid (ODPA) self-assembled monolayers (SAMs) on the various dielectric surfaces, we use the SAMs as ALD inhibitors to achieve selective ALD of both ZnO and Al2O3. With SiO2 as the growth surface, the best blocking performance against ZnO and Al2O3 ALD is achieved on ODPA-protected Al2O3 and HfO2 substrates which reach selectivities above 0.9 after 14 nm ZnO and 2.5 nm Al2O3 growth, respectively, on control Si wafers. Selectivity between different metal oxides is also explored, including HfO2/Al2O3 patterns. With the optimization of solvent and ODPA SAM deposition time, selectivity above 0.9 can be achieved for at least 4 nm ZnO ALD on a HfO2 growth surface, while preventing growth on an Al2O3 nongrowth surface. This study introduces a strategy for achieving more general selectivity and opens up the possibility for new applications in next generation electronic devices.