Fabrication of high aspect ratio structures in silicon independent of crystal orientation using metal assisted etching

Metal assisted etching is a technique which can be used to etch high aspect ratio structures in silicon (Si) and has application in areas including solar cells, MEMS devices and the etching of through-silicon vias. The ability to etch in any direction on the Si wafer provides flexibility in terms of both processing and applications. Using gold as a catalyst, grooves were etched with metal assisted etching through a 650 μm-thick Si wafer with an aspect ratio of 22, independently of crystal orientation. Grooves were etched in a spiral pattern, allowing silicon segments up to 10 cm in length to be removed and unwound.