Using Anodization to Oxidize Ultrathin Aluminum Film for High-k Gate Dielectric Application

Abstract

Very low cost room-temperature process to fabricate ultrathin high-k gate dielectrics with equivalent oxide thickness of 10 to 35 Å was studied in this work. Anodic oxidation (anodization) in deionized water followed with rapid thermal annealing was used to oxidize ultrathin aluminum film. Unlike thermal oxidation, anodic possesses a speciality of self-limited oxide thickness. This work also demonstrated that the anodic exhibits gate dielectric quality characteristics, including low gate leakage current, low interface states, and low bulk trap density. The dielectric constant of anodic is estimated to be 9.7. In addition, the gate current density, is almost independent of the measurement temperature, revealing a low trap density and high thermal stability. These good insulator characteristics are believed to be related to the leakage path self-readjustment nature under electric field influence in liquid during anodization. © 2003 The Electrochemical Society. All rights reserved.