Leakage Current Characteristics of Atomic Layer Deposited Al-Doped TiO2 Thin Film for Dielectric in DRAM Capacitor

Abstract

We researched the reduction of leakage current by Al doping in TiO2 thin film. During the TiO2 thin film deposition process, Al2O3 thin film deposition was used for Al doping. XPS analysis showed that the greater the amount of Al doping in TiO2 thin film, the fewer oxygen vacancies were found. The n-type characteristic of TiO2 thin films is reduced as oxygen vacancies are reduced. An anatase (211) peak was detected by GIXRD analysis, and crystallinity was reduced with greater Al doping; the full width half maximum showed the crystalline size was reduced. UV-visible analysis showed the energy bandgap increased as the crystalline size became smaller, and I-V measurements showed the current density decreased to 3 x 10(-4 )A cm(-2) (As-dep TiO2: 10(-1) A cm(-2)) with Al doping. The dielectric constant remained above 20 even when doped with Al, confirming the superior properties of Al-doping TiO2 thin film over conventional TiO2 thin films.