Comparison of plasma etch techniques for III-V nitrides

Fabrication of group-III nitride devices relies on the ability to pattern f eatures to depths ranging from similar to 1000 A to > 5 mu m with anisotrop ic profiles, smooth morphologies, selective etching of one material over an other and a low degree of plasma-induced damage. In this study, GaN etch ra tes and etch profiles are compared using reactive ion etch (RIE), reactive ion beam etching (RIBE), electron cyclotron resonance (ECR) and inductively coupled plasma (ICP) etch systems. RIE yielded the slowest etch rates and sloped etch profiles despite de-biases > -900 V. ECR and ICP etching yielde d the highest rates with anisotropic profiles due to their high plasma flux and the ability to control ion energies independently of plasma density. R IBE etch results also showed anisotropic profiles but with slower etch rate s than either ECR or ICP possibly due to lower ion flux. InN and AlN etch c haracteristics are also compared using ICP and RIBE. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.