Improved Properties of Atomic Layer Deposited Ru Films by Providing Additional Reactant for Cu Alternative Nanoscale Interconnects

Abstract

This study designed the ABC-type Ru ALD process using 02 and NH3 consecutively as counter-reactants to achieve a low resistivity of 13.4 u Omega center dot cm and superior film properties, including enhanced crystallinity. Compared to conventional AB-type Ru films, this process resulted in improved properties, with grain size increasing from 12 nm to 25 nm, impurity concentration decreasing from 1.5 at.% to 0.3 at.%, and surface roughness reducing from 2.0 nm to 1.2 nm. To investigate the effect of the additional reactant gas NH3, machine-learning potential (MLP) analysis was performed. The results revealed that NH3 dissociatively adsorbs on the Ru surface, generating atomic hydrogen, which reduces surface oxygen and removes 0 and C impurities. Fuchs-Sondheimer (FS) and Mayadas-Shatzkes (MS) modeling demonstrated that grain size significantly impacts resistivity, while the influence of surface scattering is relatively minor. These findings suggest that NH3 plays a crucial role in improving Ru film properties in the ABC-type Ru ALD process, highlighting its potential for next-generation Cu replacement interconnect applications.