Inductively coupled high-density plasma-induced etch damage of GaN MESFETs

The fabrication of a wide variety of GaN-based photonic and electronic devi ces depends on dry etching, which typically requires ion-assisted removal o f the substrate material. Under conditions of both high plasma Aux and ener getic ion bombardment, GaN etch rates greater than 0.5 mum min(-1) and anis otropic etch profiles are readily achieved in inductively; coupled plasma ( ICP) etch systems. Unfortunately, under these conditions, plasma-induced da mage often occurs. Attempts to minimize such damage by reducing the ion ene rgy or increasing the chemical activity in the plasma often result in a los s of etch rate or profile control which can limit dimensional control and r educe the utility of the process for device applications requiring anisotro pic etch profiles. It is therefore necessary to develop plasma etch process es which couple anisotropy For critical dimension and sidewall profile cont rol and high etch rates with low-damage for optimum device performance. In this study, we report changes in source resistance, reverse breakdown volta ge, transconductance, and drain saturation current for GaN MESFET structure s exposed to an Ar ICP plasma. In general. plasma-induced damage was more s ensitive to ion bombardment energies as compared to plasma flux. (C) 2001 E lsevier Science Ltd. All rights reserved.