Oxidation resistance of sputtered Ti_1-xAl_xN films for complementary metal oxide semiconductor storage node electrode barriers

Oxidation resistance of sputtered Ti_1-xAl_xN thin films was investigated using cross-sectional transmission electron microscopy, Auger electron spectroscopy, and current-voltage measurement by comparing characteristics with those of sputtered TiN and metallorganic chemical vapor deposited (MOCVD) TiN. For this study, barrier layers were deposited on TiSi₂/poly-Si/SiO₂/Si stacks followed by bottom Pt electrode deposition and patterning. After furnace postannealing at 600°C for 30 min in O₂, we examined interface reaction and electrical properties of the electrode barrier layers. A variety of surface treatment methods, such as rapid thermal oxidation (RTO) and N₂ plasma treatment, and sputtering conditions were employed to minimize oxidation reaction at interfaces between TiAlN barriers and Pt electrodes. MOCVD and physical vapor deposited TiN barriers showed complete oxidation and nonohmic electrical behavior after postannealing, whereas TiAlN barriers were partially oxidized only at the top surface. When RTO treatment was adopted for TiAlN barriers, excellent ohmic characteristics for Pt electrodes were obtained at -5/+5 V voltage sweeps showing minimized oxidation at barrier interfaces.