Wafer-Scale Nanoprinting of 3D Interconnects beyond Cu

Abstract

Cloud operations and services, as well as many other modern computing tasks, require hardware that is run by very densely packed integrated circuits (ICs) and heterogenous ICs. The performance of these ICs is determined by the stability and properties of the interconnects between the semiconductor devices and ICs. Although some ICs with 3D interconnects are commercially available, there has been limited progress on 3D printing utilizing emerging nanomaterials. Moreover, laying out reliable 3D metal interconnects in ICs with the appropriate electrical and physical properties remains challenging. Here, we propose high-throughput 3D interconnection with nanoscale precision by leveraging lines of forces. We successfully nanoprinted multiscale and multilevel Au, Ir, and Ru 3D interconnects on the wafer scale in non-vacuum conditions using a pulsed electric field. The ON phase of the pulsed field initiates in situ printing of nanoparticle (NP) deposition into interconnects, whereas the OFF phase allows the gas flow to evenly distribute the NPs over an entire wafer. Characterization of the 3D interconnects confirms their excellent uniformity, electrical properties, and free-form geometries, far exceeding those of any 3D-printed interconnects. Importantly, their measured resistances approach the theoretical values calculated here. The results demonstrate that 3D nanoprinting can be used to fabricate thinner and faster interconnects, which can enhance the performance of dense ICs; therefore, 3D nanoprinting can complement lithography and resolve the challenges encountered in the fabrication of critical device features.