ICP Etching of Silicon for Micro and Nanoscale Devices

Citation

Henry, Michael David (2010) ICP Etching of Silicon for Micro and Nanoscale Devices. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9MW2FBC. https://resolver.caltech.edu/CaltechTHESIS:05262010-152815609

Abstract

The physical structuring of silicon is one of the cornerstones of modern microelectronics and integrated circuits. Typical structuring of silicon requires generating a plasma to chemically or physically etch silicon. Although many tools have been created to do this, the most finely honed tool is the Inductively Couple Plasma Reactive Ion Etcher. This tool has the ability to finesse structures from silicon unachievable on other machines. Extracting structures such as high aspect ratio silicon nanowires requires more than just this tool, however. It requires etch masks which can adequately protect the silicon without interacting with the etching plasma and highly tuned etch chemistry able to protect the silicon structures during the etching process.

In the work presented here, three highly tuned etches for silicon, and its oxide, will be described in detail. The etches presented utilize a type of etch chemistry which provides passivation while simultaneously etching, thus permitting silicon structures previously unattainable. To cover the range of applications, one etch is tuned for deep reactive ion etching of high aspect ratio micro-structures in silicon, while another is tuned for high aspect ratio nanoscale structures. The third etch described is tuned for creating structures in silicon dioxide. Following the description of these etches, two etch masks for silicon will be described. The first mask will detail a highly selective etch mask uniquely capable of protecting silicon for both etches described while being compatible with mainstream semiconductor fabrication facilities. This mask is aluminum oxide. The second mask detailed permits for a completely dry lithography on the micro and nanoscale, FIB implanted Ga etch masks. The third chapter will describe the fabrication and in situ electrical testing of silicon nanowires and nanopillars created using the methods previously described. A unique method for contacting these nanowires is also described which has enabled investigation into the world of nanoelectronics. The fourth and final chapter will detail the design and construction of high magnetic fields and integrated planar microcoils, work which was enabled by the etching detailed here. This research was directed towards creation of a portable NMR machine.

Thesis Files