Decoupling Diameter and Pitch in Silicon Nanowire Arrays Made by Metal‐Assisted Chemical Etching

Abstract

The fabrication of well‐separated, narrow, and relatively smooth silicon nanowires with good periodicity is demonstrated, using non‐close‐packed arrays of nanospheres with precisely controlled diameters, pitch, and roughness. Controlled reactive ion etching in an inductively coupled plasma reduces the self‐assembled nanospheres to approximately a tenth of their original diameter, while retaining their surface smoothness and periodic placement. A titanium adhesion layer between the silicon substrate and gold film allows much thinner catalyst layers to be continuous, facilitating the film liftoff and formation of the perforated pattern without influencing catalyzed etching of silicon. Using these methods, a periodic array of silicon nanowires with a large pitch and small diameter (e.g., a 490 nm pitch and 55 nm diameter) is created, a combination not typically found in the open literature. This approach extends the types and quality of silicon nanostructures that can be fabricated using the combined nanosphere lithography and metal‐assisted chemical etching techniques.

Evidences for redox reaction driven charge transfer and mass transport in metal-assisted chemical etching of silicon

“…In particular, there is still a lack of understanding in the fundamental reasons behind the stop-etch phenomenon shown by metals like chromium (Cr)22232425, and also debates about the mass transport during etching415182023262728. This knowledge is important to understand the basic MacEtch mechanism.…”

Polyelectrolyte multilayer-assisted fabrication of non-periodic silicon nanocolumn substrates for cellular interface applications

“…31 In this work, the density and diameter of the nanospheres remaining on the silicon surface can be directly translated into the density and diameter of the vertical nanocolumns, respectively. 31 In this work, the density and diameter of the nanospheres remaining on the silicon surface can be directly translated into the density and diameter of the vertical nanocolumns, respectively.…”

“…24 Moreover, the geometry, surface morphology, and spatial pattern of the vertical nanostructures could be delicately controlled by the oxidant concentration, 25 crystalline silicon orientation, 26 wafer doping level, 27 and metal film patterning. 31,32 This is mainly due to the difficulty in uniformly covering the silicon substrates with a monolayer of nano-mask materials, for example, close-packed colloidal nanospheres, block copolymers, or anodic aluminum oxides. 31,32 This is mainly due to the difficulty in uniformly covering the silicon substrates with a monolayer of nano-mask materials, for example, close-packed colloidal nanospheres, block copolymers, or anodic aluminum oxides.…”

Wet etching of deep trenches on silicon with three-dimensional (3D) controllability

“…High-aspect ratio silicon nanowires [27], pillars [28], pores [29] and 3D-complicated cavity [30] have been successfully fabricated by MaCE in the past decade. Due to the nature of wet etching, MaCE shows promising result in deep trenches etching that may fulfill the merits mentioned above [31].…”