Interface engineering for InGaAs n-MOSFET application using plasma PH 3-N2 passivation

Abstract

To realize high electron mobility metal-oxide-semiconductor field effect transistors (MOSFETs) on In0.53Ga0.47 As with unpinned Fermi level, a PH3- N2 plasma treatment is proposed and preliminarily studied as a novel interface engineering technique, which passivates the InGaAs surface by depositing a phosphorus nitride (P xNy) layer to suppress AsOx and free As. Comparative X-ray photoelectron spectroscopy and atomic force microscopy studies reveal that a low pressure PH3- N2 plasma treatment of In0.53Ga0.47 As results in a smooth and atomically thin (∼1 monolayer) PxNy film as a main product, with a P-for-As anion exchanged layer found beneath the PxNy layer in a practically wide range of process window. The process conditions affect the stoichiometry of the PxNy layer, the amount of phosphorus and nitrogen atoms incorporated, and the degree of the P-for-As exchange reaction. MOSFET devices integrated with metalorganic chemical vapor deposited HfO2 /TaN metal gate on the passivated In 0.53Ga0.47 As substrates have been fabricated by the conventional self-aligned gate-first process and compared to nonpassivated MOSFETs. The excellent interface quality of PxNy passivated In0.53Ga0.47 As/ HfO2 /TaN gate stack has been proven showing suppressed frequency dispersion in inversion capacitance by 82-94% compared to the nonpassivated device and a low subthreshold slope approaching the theoretical value of 60 mV/dec. © 2010 The Electrochemical Society.