METAL-ORGANIC CHEMICAL VAPOR DEPOSITION OF PbZr_xTi_{1 –x}O₃ THIN FILMS ON Ir–Ru ALLOY ELECTRODES

ABSTRACT

Surface smoothness and ferroelectric properties of PbZr_xTi_1-xO₃ (PZT) thin films, grown by metal-organic chemical vapor deposition (MOCVD), was improved by applying Ir–Ru alloy electrode. It was found that the specific composition ratio of Ir and Ru could guarantee the best quality of the alloyed films. That is 35∼55% in Ru portion called as the ‘multi-phase' because two different crystallographic structures exist. This multi-phase electrode has high thermal stability under oxygen annealing atmosphere. Moreover, PZT thin films grown on the multi-phase electrodes, have smoother surface roughness, larger remnant polarization and lower current leakage than PZT thin films on Ir electrode. It is thought think that the grain boundaries between different phases of the alloyed electrode could supply high nucleation sites of PZT to restrict large grain growth and regulate grain shape. Therefore, the multi-phase alloyed electrode can be utilized for growing ultra thin PZT film, which is necessary for high-density ferroelectric random access memory.

Keywords:

• Ir–Ru alloy
• multi-phase
• MOCVD
• PZT
• ferroelectric
• thin film
• FRAM

ACKNOWLEDGMENT

This work was supported by grant No. R01-2005-000-11167-0 from the Basic Research Program of the Korea Science & Engineering Foundation.