Leakage Current Mechanism of Metal ‐ Ta2 O 5 ‐ Metal Capacitors for Memory Device Applications

Abstract

Tantalum oxide is an important material for future dynamic random access memory capacitor and metal oxide semiconductor field effect transistor gate oxide applications. In this work, the electrical and material properties of amorphous metal insulator‐metal capacitors deposited by plasma‐enhanced chemical vapor deposition (PECVD) on a tungsten bottom electrode are studied. The minimum thickness of is 14 nm which is equivalent to a thickness of 2.58 nm. High‐quality dielectric characteristics such as a leakage current density of at 0.75 V for both voltage polarities, a capacitance of , and a breakdown strength of 8.23 MV/cm when the bias is negative, are obtained. These high‐quality characteristics are most likely due to the complete decomposition of the precursor by oxygen plasma during plasma deposition. The current conduction mechanism of amorphous is investigated. A comparison between deposited by PECVD and by low‐pressure chemical vapor deposition is also studied. © 1999 The Electrochemical Society. All rights reserved.