Post-annealing effects on the structural properties and residual stress of Ta₂O₅ thin films deposited by ion beam sputtering

We studied the structural properties and residual stress of Ta ₂O₅ thin films deposited by single ion beam sputtering (SIBS) and dual ion beam sputtering (DIBS) as a function of the annealing temperatures (200-800 °C). With the increase of the annealing temperatures, the refractive indexes of the Ta₂O₅ films deposited by both SIBS and DIBS processes continuously decreased. The residual stress of the post-annealed film could be minimized at an annealing temperature of 400 °C. According to the XRD analysis, the crystallization temperature of Ta ₂O₅ is found around 600 °C. As the annealing temperature was increased to 600 °C, the oxygen-concentration in the film continuously increased, but it started to saturate in the temperature range 600 °C - 800 °C.