Plasma nitride hydrogen source encapsulation method to hydrogenate polysilicon thin film transistors

A novel, commercially attractive process has been developed to hydrogenate polysilicon thin film transistors (poly-Si TFTs). Active device regions of TFTs are encapsulated by two nitride layers; one underneath the poly-Si cha nnel but separated by a thin oxide, and the other capping the device. Durin g the dopant activation anneal, hydrogen is driven from nitride layers, thr ough intermediate oxide layers, and into the channel passivating trap sites . On test samples, secondary ion mass spectroscopy suggests this treatment introduced up to 10(20) cm(-3) hydrogen into poly-Si. After hydrogenation, the threshold was reduced by 43 V and the saturation on-current improved by two magnitudes, approaching the performance of electron cyclotron resonanc e hydrogenated TFTs. (C) 1999 The Electrochemical Society. S1099-0062(98)07 -085-0. All rights reserved.