Study of amorphous Ta2O5 thin films by DC magnetron reactive sputtering

The dc magnetron reactive sputtering deposition of tantalum pentoxide (Ta2O5) thin films was investigated. By combining Schiller's criterion and Reith's ''target preoxidation'' procedure, high quality Ta2O5 thin films were prepared at a high deposition rate of about 100 Angstrom/min. The deposited films were amorphous, with a refractive index around 2.07 and a dielectric constant of 20. An optical transmittance of 98.6% was obtained for a 4500 Angstrom thick film. The leakage current density is 5 x 10(-9) A/cm(2) at an electric field strength of 1 MV/cm and its breakdown field strength is above 2 MV/cm. The temperature coefficient of capacitance for capacitors fabricated using the deposited films is approximately +230 ppm/degrees C. Xray photoelectron spectroscopy shows that the films are stoichiometric tantalum pentoxide, Ta2O5, and exhibit good stability.