Metal Assisted Chemical Etch of Polycrystalline Silicon

Abstract

Metalassisted chemical etching (MacEtch) of silicon shows reliable vertical anisotropic wet etching only in singlecrystal silicon, which limits its applications to a small number of devices. This work extends the capabilities of MacEtch to polysilicon which has potential to enable highvolume and costsensitive applications such as optical metasurfaces, anodes for high capacity and flexible batteries, electrostatic supercapacitors, sensors, nanofluidic deterministic lateral displacement devices, etc. This work presents a MacEtch of polysilicon that produces nanostructure arrays with sub50 nm resolution and anisotropic profile. The three demonstrated structures are pillars of 5:1 aspect ratio and 50 nm spacing for comparison to single crystal silicon MacEtch literature, pillars of 30 nm spacing, and a diamond pillar array with sharp corners to establish resolution limits of polysilicon MacEtch.