Characterization of Metal Insulator Metal Electrical Properties of Electron Cyclotron Resonance Plasma Deposited Ta2O5

The electrical properties of tantalum pentaoxide (Ta 2 O 5 ) films deposited by an electron cyclotron resonance (ECR) plasma sputtering have been investigated using metal–insulator–metal (MIM) capacitor structures. The deposition conditions of Ta 2 O 5 films and the bottom electrode materials of the MIM have been examined from the point of view of both the low leakage current and the high capacitance. On the TiN bottom electrode, additional postdeposition plasma irradiation on the first thin Ta 2 O 5 layer was effective in ensuring a high breakdown strength of the MIM, because of the stabilization of the interlayer between the Ta 2 O 5 film and the TiN bottom electrode film. However, the MIM using a Ru bottom electrode, which shows the characteristics of conductive films even for oxides, showed the high breakdown characteristics of approximately 4.5 MV/cm for as-deposited Ta 2 O 5 in metal-mode deposition in ECR sputtering. In both cases, the dielectric constant of Ta 2 O 5 was approximately 25, so that a high capacitance of approximately 3 fF/µm 2 was for frequencies of up to 1 MHz for a MIM with a Ru bottom electrode and 20-nm-thick Ta 2 O 5 film.