Ta₂O₅ Thin Film Deposited By Arc Ion Plating Technique

Ta2O5 films have attracted increasing interest for optical and microelectronics field because of their high refractive indexes and high transmittance at the visible and near infrared band. Cathodic vacuum arc is a deposition technique which exhibits high ion energy, high ionization and high deposition rate. The content of metal particles of films is reduced by using magnetic filter technology and the quality of films meets the requirements of optical films. This topic is concentrate on the fabrication of optical films by arc source technology and research the advantage of this technology rely on the superiority of arc source.In this papers, the Ta2O5 thin film is deposited by FCVA, the influence of electromagnetic field on working stability of arc source is also studied. Keeping the target current as 90A, the base pressure as 5.0×10-3Pa and the target-substrate distance uncharged, the microstructural, morphology and optical properties of films prepared under different oxygen component are studied. The film is annealed in the oxygen atmosphere followed. In this paper, the phase structural and stoichiometric ratio of films are tested by XRD and XPS respectively, the spectral characteristic and optical constant are measured by UV-PDA spectrophotometer and ellipsometer, and the surface roughness is tested by white-high interferometer. The experimental results shows that the adjustment of electromagnetic around cathode target has a great influence on the working stability of arc source. The shifting magnetic affects the translation of discharge region in a radial direction, the focusing magnetic affects the size of discharge region, and the adjustment of arc stabilizing magnetic can further improves the working stability. By adjusting the electromagnetic field, the best working stability is obtained while the shifting magnetic and focusing magnetic and arc stabilizing magnetic at 14mV,0.75A and 23.2V respectively. The amorphous Ta2O5 thin film is obtained under different oxygen component. With the increasing of oxygen component, the stoichiometric ratio of films presents a raising trend and reaches 2.05 while the oxygen component is 32.03%. The film has a high transmittance at the visible and near infrared band. The refractive index decreases with the increasing of the oxygen component and as 2.14 at 550nm. The extinction coefficient is lower than 10-4 while λ is more than 400nm. The deposition rate increases at first and then decreases, when oxygen component is 26.11% it reaches 0.84nm/s. The surface roughness decreases firstly and decreases then, when oxygen component is 26.11% it meets the minimum value as 0.88nm. After annealing in the oxygen atmosphere for 2h at 773K(500℃), the stoichiometric ratio shows an increase, the transmission spectra has a slight shift, the refractive index and extinction coefficient show little change and the surface roughness has an increase.