Dry Etching of Al-Rich AlGaAs for Photonic Crystal Fabrication

Abstract

We investigate inductively coupled plasma deep dry etching of Al0.8Ga0.2As for photonic crystal (PC) fabrication using Cl2, BCl3, and CH4 chemistry. The characteristic AlOx deposition is observed during the etching, resulting in the reduction of etching rate. BCl3 is considered to scavenge the deposited AlOx by its reductive reaction. CH4 passivates the etching sidewall, as well as enhances the deposition of AlOx. Concerning the impact of pattern size, a pronounced inverse reactive ion etching (RIE) lag is observed, which is beneficial for small-size PC fabrication typically with a hole diameter of 100–500 nm. From the findings, we successfully fabricated a PC structure with air holes having an aspect ratio of 8 and a diameter of 110 nm.