Yttrium carbide thin film as an emerging transition metal carbide Prepared by plasma-enhanced atomic layer deposition for Dual diffusion barrier applications into Cu and Ru metallization

Abstract

Transition metal carbides (TMCs) often possess superior properties to transition metal nitrides (TMNs) in hardness, thermal stability, electrical conductivity, and chemical stability. However, developing an atomic layer deposition (ALD) process for these materials remains in its early stages, especially yttrium carbide (YCx) thin films, which remained largely unexplored. This study focuses on developing a plasma-enhanced ALD-YCx process for high-quality, uniform, and conformal thickness control TMCs while highlighting the advanced properties to utilize as advanced diffusion barriers via a novel Y-precursor. The critical experimental process parameters, Y-precursor, and H-2 plasma exposure times are thoroughly optimized to achieve highly conductive (similar to 415 mu Omega<middle dot>cm), high crystalline PEALD-Y2C thin films with a growth rate of similar to 0.13 nm/cycle at 250 degrees C within the ALD temperature window (150-350 degrees C). Advanced aberration-corrected electron microscopies, electron diffractions, and spectroscopic techniques confirmed the formation of a nanocrystalline rhombohedral phase, C-to-Y ratio similar to 0.46, 4.63 g/cm(3) density, and excellent step coverage (95%) of a trench structure with an aspect ratio of similar to 1.5 and a bottom width of similar to 265 nm. The post-annealed PEALD-Y2C films maintained stable thermal and crystallographic properties, exhibiting effective dual diffusion barrier performance for Cu and Ru (similar to 40 nm) up to 900 degrees C, emphasizing its importance as interconnects in advanced semiconductor devices.