DEVICE DEGRADATION DURING LOW-TEMPERATURE ECR-CVD - PART I - GAAS-MESFETS

The effects of plasma chemistry (SiH4/NH3, SiH4/N-2 Or SiH4/N2O) and d eposition conditions (temperature, source power, pressure, SiH4 percen tage and additional Ar flow) during electron cyclotron resonance chemi cal vapor deposition of SiNx or SiO2 onto GaAs MESFETs are reported. D evice degradation, as measured by the effect on transconductance, thre shold voltage, breakdown voltage and gate ideality factor, is due to t wo mechanisms-passivation of Si dopants in the channel by atomic hydro gen, and near-surface doping or stoichiometry changes induced by ion b ombardment or preferential loss of As. Conditions which minimize hydro gen ion and neutral densities produce the least degradation in MESFET performance. (C) 1998 Elsevier Science Ltd. All rights reserved.