ENHANCED RETENTION CHARACTERISTICS OF Pb(Zr, Ti)O3 CAPACITORS BY OZONE TREATMENT

Effects of ozone treatment and charged defects on retention characteristics of Ir/IrO2/Pb(Zr, Ti)O3 (PZT)/Pt/IrO2/Ir capacitors were investigated. For these purposes, PZT thin films were exposed to ozone environment to promote enhanced surface oxidation. After baking the Ir/IrO2/PZT/Pt/IrO2/Ir capacitors at 125 C for 500 h, degradation of Qnv (non-volatile charge) value of the ozone-treated capacitors was approximately 17.6%, that is less than one fifth of that of the untreated capacitors. XPS and AES studies showed that the amount of O-vacancies near the PZT surface was dramatically decreased by the ozone treatment. The Schottky barrier height of the ozone-treated capacitors increased when compared to that of the untreated capacitors (the Schottky barrier height of the untreated and the ozone-treated capacitor was 0.29 and 0.43 eV, resp.). The retention characteristics seem to be closely associated with O related defects near the ferroelectric/electrode interface and the control of the interface properties of PZT thin film is a key technology to pursue reliable function characteristics of ferroelectric random access memory (FRAM) devices. 17 refs.