Wet chemical method to etch sophisticated nanostructures into silicon wafers using sub-25nm feature sizes and high aspect ratios

Abstract

There are a number of emerging technologies such as metamaterials, photonic wave-guides, nano-imprint lithography (NIL), field emission devices and through silicon via (TSV), that require high resolution and high aspect ratio nanofabrication techniques for good performance. Unfortunately, current nanofabrication techniques, including photolithography and e-beam lithography, are limited to low aspect ratios on the order of 7:1 and cannot fabricate the high aspect ratio nanostructures needed for these emerging nanotechnologies. Deep reactive ion etching has traditionally been used to increase the aspect ratio nanostructures produced from traditional lithography techniques; however, the process is expensive, time consuming and cannot produce smooth sidewalls, lowering device performance. To overcome these obstacles our group has developed a new wet chemical nanofabrication technique that uses shaped catalysts to etch high aspect ratio nanostructures into silicon. The process is fast, does not require expensive equipment and has been used to produce features less than 25 nm wide, 25 µms long and microns deep in silicon using nanorod catalysts. 10 nm wide features were also fabricated using nano-donuts. This new, patented technique is compatible with existing silicon fabrication technologies and could be used for a wide variety of applications that require nanometer sized features and high aspect ratios.