Protected surface states arising from non-trivial bandstructure topology in semimetals can potentially enable advanced device functionalities in compute, memory, interconnect, sensing, and communication. This necessitates a fundamental understanding of surface-state transport in nanoscale topological semimetals. Here, we investigate quantum transport in a prototypical topological semimetal NbAs to evaluate the potential of this class of materials for beyond-Cu interconnects in highly-scaled integrated circuits. Using density functional theory (DFT) coupled with non-equilibrium Green’s function (NEGF) calculations, we show that the resistance-area RA product in NbAs films decreases with decreasing thickness at the nanometer scale, in contrast to a nearly constant RA product in ideal Cu films. This anomalous scaling originates from the disproportionately large number of surface conduction states which dominate the ballistic conductance by up to 70% in NbAs thin films. We also show that this favorable RA scaling persists even in the presence of surface defects, in contrast to RA sharply increasing with reducing thickness for films of conventional metals, such as Cu, in the presence of surface defects. These results underscore the potential of topological semimetals as future back-end-of-line (BEOL) interconnect metals.

半金属中非平凡的能带结构拓扑产生的受保护表面态有可能实现计算、存储、互连、传感和通信方面的先进设备功能。这就需要对纳米级拓扑半金属的表面态输运有基本的了解。在这里，我们研究了原型拓扑半金属 NbAs 中的量子输运，以评估此类材料在大规模集成电路中用于超铜互连的潜力。使用密度泛函理论 (DFT) 与非平衡格林函数 (NEGF) 计算相结合，我们发现 NbAs 薄膜中的电阻面积R A乘积随着纳米尺度厚度的减小而减小，与几乎恒定的R A乘积形成鲜明对比在理想的铜膜中。这种反常缩放源于不成比例的大量表面传导态，这些态在 NbAs 薄膜中主导弹道电导高达 70%。我们还表明，即使在存在表面缺陷的情况下，这种有利的R A缩放仍然存在，相比之下，在存在表面缺陷的情况下，传统金属（例如 Cu）薄膜的R A随着厚度的减小而急剧增加。这些结果强调了拓扑半金属作为未来后道（BEOL）互连金属的潜力。