Effects of radiation and charge trapping on the reliability of high- κ gate dielectrics

Abstract

The radiation response and long term reliability of alternative gate dielectrics will play a critical role in determining the viability of these materials for use in future space applications. The total dose radiation responses of several near and long term alternative gate dielectrics to SiO 2 are discussed. Radiation results are presented for nitrided oxides, which show no change in interface trap density with dose and oxide trapped charge densities comparable to ultra thin thermal oxides. For aluminum oxide and hafnium oxide gate dielectric stacks, the density of oxide trapped charge is shown to depend strongly on the film thickness and processing conditions. The alternative gate dielectrics discussed here are shown to have effective trapping efficiencies that are up to ∼15 to 20 times larger than thermal SiO2 of equivalent electrical thickness. A discussion of single event effects in devices and ICs is also provided. It is shown that some alternative gate dielectrics exhibit excellent tolerance to heavy ion induced gate dielectric breakdown. However, it is not yet known how irradiation with energetic particles will affect the long term reliability of MOS devices with high-κ gate dielectrics in a space environment. © 2003 Elsevier Ltd. All rights reserved.