High Capacitance Density and Thermal Leakage Improvement by Using High-kappa Al2O3-Doped SrTiO3 MIM Capacitors

Abstract

In this paper, the impact of Al2O3 incorporation on the electrical characteristics of the SrTiO3 (STO) metal-insulator-insulator (MIM) capacitor was studied. The Al2O3-doped STO (STO: Al2O3 = 3:1) MIM provides a high capacitance density (14.6 fF/mu m(2)) and a very low leakage current density (9.2 x 10(-9) A/cm(2) at -1 V) at the same time. The significant enhancement of the conduction band offset and bandgap due to Al2O3 incorporation reduces leakage current largely while maintaining the favorable properties of STO, such as a large high-kappa value, a small temperature coefficient of capacitance, and paraelectricity (no fatigue or aging problem) in the operating temperature range of devices. Meanwhile, we also made a comparison among pure STO, Al2O3-doped STO, and HfO2-doped STO MIM capacitors. Results revealed that STO MIM and HfO2-doped STO MIM capacitors both show higher capacitance densities, while the leakage current of the Al2O3-doped STO MIM is much lower than those of both the STO MIM and HfO2-doped STO MIM capacitors, which meets the strict requirement of the International Technology Roadmap for Semiconductors 2018. Therefore, the excellent result suggests that the Al2O3-doped STO film is a potential candidate material for dynamic random access memory and radio-frequency applications. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3368671] All rights reserved.