Fabrication of High Aspect Ratio Nanopillars using Metal Assisted Chemical Etching

This report describes fabrication of 100 to 200 nm diameter silicon nanopillars with ~140:1 aspect ratio using Metal Assisted Chemical Etching (MacEtch) process giving a high etch rate of ~930 nm/min, and also discusses an area dependence of the etch uniformity and rate, using 0.5 and 1 µm diameter, and 2 mm x 2 mm Au films. It is found that the etching using the Au film with the area of 0.2 µm2 is uniform, but that with the area of more than 0.8 µm2 is not, suggesting that the diffusion length of the species in MacEtch reaction underneath the Au film is ~300 nm.