Fabrication of Silicon Nanowires using Scanning Electron Microscope based Electron Beam Lithography method

Abstract

Nanowires is a new class of materials that have attracted attention and great research interest in the last few years because of their potential applications in nanotechnology such as nanoelectronic, nanomechanical and biomedical engineering. Fabrication of Nanowires is one of the great challenges today. Conventional lithography methods are not capable to produce Nanowires and even with advance nanolithography sizes below 100 nm may not easily be achieved. The goal of this research work is to form and produce very small nanowires using a Top-Down Nanofabrication Method which involved Scanning Electron Microscope (SEM) based Electron Beam Lithography (EBL) method. Initially, the Top-Down Nanofabrication Method based on EBL was the design of the Nanowires Pattern Design (NPD). The NPD has been done by software called RAITH ELPHY Quantum GDSII Editor. The software package provides all the features needed to produce micro and nano scale structures starting from a structure design, post processing and design modification. The NPD is designed in various nanowires scale size from 100 nm down to 20 nm. Next, the nanofabrication process flow development which consists of the detailed parameters and recipes are developed for nanowires formation. Two (2) types of resist masks and three (3) types of nanowires are involved in the process flow development. The Resist Masks consist of PMMA Resist Mask and ma-N 2400 Series Resist Mask. It is used as a mask material or etches mask during Silicon Dioxide etching process. Fabrication of Nanowires is the main focus in this research work which consists of SiO2, Si, a-Si Nanowires. SiO2 Nanowires is used as insulation and hard mask for silicon etching in order to form Si Nanowires. Si Nanowires and a-Si Nanowires are widely used as semiconducting nanowires and has great potential in nanoelectronic devices. In order to produce very small nanowires, the dimensions, developments, etch profiles of nanowires and size-reduction by thermal oxidation was investigated. Finally, the combination on Top-Down Nanofabrication Method and size-reduction has resulted in successful reduction of Si Nanowires reduced from 100 nm to approximately 20 nm.