Electrical characteristics of Ti-O/Ta2O5 thin film sputtered on Ta/Ti/Al2O3 substrate

The electrical characteristics of Ti-O/Ta2O5 films sputtered on Ta/Ti/Al2O3 substrate were investigated. Ta (tantalum) was used for the bottom and upper electrodes for the purpose of simplifying the fabrication process and Al2O3 substrates were used, which are needed in integral passive devices. Ta/Ti-O/Ta2O5/Ta/Ti/Al2O3 capacitors were annealed at 700 degreesC for 60 s in vacuum. The X-ray diffraction pattern (XRD) results showed that as-deposited Ta had a highly preferred orientation, but Ta2O5 film had amorphous structure, which was transformed to crystallization structure by rapid thermal heat treatment. We examined the log J-E and C-V characteristics of the dielectric thin films deposited on the Ta bottom electrode. From these results, we concluded that the leakage current could be reduced by introducing a Ti-O buffer layer. The conduction mechanisms of Ta/TiO/Ta2O5/Ta/Ti/Al2O3 capacitors could be interpreted appropriately by hopping conduction in lower field (E < I x 10(5) V/cm) and space-charge-limited current in higher fields (I x 10(5) V/cm < E). (C) 2003 Elsevier B.V. All rights reserved.