Atomic layer deposition of zirconium oxide on copper patterned silicon substrate

Abstract

Atomic layer deposition (ALD) was performed on copper patterned silicon substrates using zirconium precursor and ethanol as both an oxygen source and reducing agent. Ethanol targeted copper oxide formed on the copper surface, reverting it back to metallic copper. Selective ALD (SALD) of metal oxides on silicon surfaces over copper surfaces has been demonstrated up to 2-3 nm, though the process seems to lose its selectivity afterwards. We strive to maintain selectivity to thicker films by stepping away from conventional ALD processes utilizing oxidants. From previous studies with HfO2 and TiO2 SALD, we speculate that the oxidation of copper to copper oxide spoils selectivity. In this present study, we carried out oxidant-free ALD by using ethanol as a co-reactant solely on the silicon portion of these substrates. This process will occur in-situ every 20-30 ALD cycles for ALD of ZrO2. As expected, reduced ALD growth rate was observed with ethanol compared to that of water or ozone, with a growth rate of about 0.04 nm/cycle on the silicon portion of the substrate.