Investigation and modeling of the electrical properties of metal–oxide–metal structures formed from chemical vapor deposited Ta2O5 films

Amorphous Ta2O5 films were deposited by low pressure chemical vapor deposition (LPCVD) and plasma enhanced chemical vapor deposition (PECVD) at temperatures below 450 °C. These films were used to fabricate metal–oxide–metal (MOM) structures with titanium nitride (TiN) electrodes. The electrical properties of the MOM capacitance were investigated by the means of current–voltage and capacitance–voltage characteristics in the 100 Hz–1 MHz frequency range. It is shown that the conduction mechanism changed from Schottky emission, for the LPCVD material, to Poole–Frenkel current for the PECVD material. The roughness of the bottom electrode, as determined by atomic force microscopy measurements, is found to impact the leakage current. For the LPCVD material the capacitance exhibits a strong dependency on the applied bias and the frequency. For the PECVD material, only a small variation of the capacitance is observed when the bias is increased, with almost no frequency dependency. A clear correlation between the ...