Using Ni masks in inductively coupled plasma etching of high density hole patterns in GaN

Abstract

High density patterns of holes in metalorganic chemical vapor deposition grown GaN films on sapphire have been fabricated by inductively coupled plasma etching using a nickel mask. Pattern transfer from the e-beam lithographically patterned resist to the nickel etch mask was accomplished by ion beam milling. A Cl2–BCl3 inductively coupled plasma was used to anisotropically etch patterns of 200–250-nm-diam holes with 300nm center-to-center spacing through the entire thickness of a 265-nm- and a 300-nm-thick GaN film. This work demonstrates a pattern transfer technique to Ni by ion beam milling and Ni as a durable etch mask under a chlorine environment for high density patterning of GaN films.