Silicon nitride encapsulation to preserve ohmic contacts characteristics in high temperature, oxygen rich environments

Roy, SK; Vassilevski, K; Wright, NG; Horsfall, AB

doi:10.4028/www.scientific.net/MSF.821-823.420

Silicon nitride encapsulation to preserve ohmic contacts characteristics in high temperature, oxygen rich environments

Lookup NU author(s): Sandip Roy, Professor Nick Wright, Dr Alton Horsfall

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Abstract

© (2015) Trans Tech Publications, Switzerland. Ohmic contacts with low contact resistance, smooth surface morphology, and a welldefined edge profile are essential to ensure optimal device performance. Ohmic contacts often require annealing under vacuum at over 1000 °C, whilst high-κ dielectrics are usually annealed in O2 rich ambient at temperatures of 800 °C or less, affecting the specific contact resistivity (ρC) and RMS surface roughness. Therefore, protection of the Ohmic contacts during the annealing of a high-κ dielectric layer is a key enabling step in the realisation of high performance MOSFET structures. In order to prevent damage during the high-κ formation, a passivation layer capable of protecting the contacts during annealing is required. In this work we have investigated the suitability of PECVD silicon nitride as a passivation layer to protect Ohmic contacts during high temperature, oxygen rich annealing.