Low Resistivity Scaling of RuAl-Based Medium-to-High-Entropy Intermetallic Compounds as Potential Interconnect Metallization

Abstract

Thin films of multicomponent doped, B2-ordered ruthenium aluminide (RuAl) intermetallic compounds incorporating refractory elements were deposited by magnetron co-sputtering. A crystalline, ordered B2 (body-centered cubic) structure was retained after rapid thermal annealing at 800°C for 1 min, accompanied by grain refinement to ∼10 nm. Data fitting using the Fuchs-Sondheimer (FS) and Mayadas-Shatzkes (MS) models, combined with first-principles calculations using special quasi-random structures (SQS), revealed that increasing compositional complexity shortened the electron mean free path. The calculations further indicated that this reduction is primarily driven by chemical disorder and a rugged atomic potential landscape, rather than simple lattice distortion alone. This short mean free path suppressed the resistivity scaling in the doped films relative to pure RuAl, despite their higher absolute resistivity. Furthermore, the multicomponent doped films demonstrated good thermal stability and a low temperature coefficient of resistance, attributed to the dominance of static disorder scattering.