Scalable Fabrication and Metrology of Silicon Nanowire Arrays Made by Metal Assisted Chemical Etch

A scalable fabrication technique for silicon nanowires based on integrating nanoimprint lithography, metal assisted chemical etching (MACE), and spectroscopic scatterometry is presented in this article. The resulting wafer-scale process has demonstrated reliable and repeatable fabrication of high aspect ratio silicon nanostructures, and can provide cost-effective fabrication to enable applications in electronics, energy, point-of-use healthcare and sensing. Traditional pattern transfer using plasma etching suffers from etch taper and loss of feature fidelity at high aspect ratios, unlike MACE. However, MACE has largely been demonstrated in the literature over small areas, with scarce information on full wafer etching, critical dimension control, and etch depth uniformity. In this paper, we demonstrate a 100mm wafer high yield process to fabricate silicon nanowires. A large-area characterization of the process has been developed using imaging spectroscopic scatterometry. This scatterometry technique provides full wafer data on critical dimension control, etch depth uniformity, and presence of nanowire collapse defects. This work shows the promise of MACE as a next generation etch technology.