Hydrogen Plasma-Assisted Atomic Layer Deposition of Ru with Low Oxygen Content

Ru is extensively used in electrical and energy applications because of its high electrical conductivity and catalytic activity. This study reports the H₂ plasma-enhanced atomic layer deposition (PEALD) of Ru thin films using a novel carbonyl cyclohexadiene ruthenium precursor. The optimized process conditions for depositing Ru thin films by PEALD were established based on the growth per cycle (GPC), chemical formation, crystallinity, conformality, and resistivity, according to process parameters such as precursor pulse time, H₂ plasma pulse time, purge time, and deposition temperature. Pure Ru thin films (low carbon and oxygen) were deposited with low resistivity (30.8 μΩ cm) and showed high conformality (> 95%) on the Si trenches. The oxidant-free PEALD Ru process reported in this study may have implications on the fabrication of high-quality interfaces between Ru and easily-oxidized substrates.