High-performance RSD poly-Si TFTs with a new ONO gate dielectric

Abstract

This paper developed a novel polycrystalline silicon (poly-Si) thin-film transistor (TFT) structure with the special features: 1) a new oxide-nitride-oxynitride (ONO) multilayer gate dielectric to reduce leakage current, improved breakdown characteristics, and enhanced reliability; and 2) raised source/drain (RSD) structure to reduce series resistance. These features were used to fabricate high-performance RSD-TFTs with ONO gate dielectric. The ONO gate dielectric on poly-Si films shows a very high breakdown field of 9.4 MV/cm, a longer time dependent dielectric breakdown, larger QBD, and a lower charge-trapping rate than single-layer plasma-enhanced chemical vapor deposition tetraethooxysilane oxide or nitride. The fabricated RSD-TFTs with ONO gate dielectric exhibited excellent transfer characteristics, high field-effect mobility of 320 cm(2) /V . s, and an on/off current ratio exceeding 10(8).