The effect of pulse width on asymmetric bipolar pulse DC sputtered tantalum pentoxide thin films

The effect of pulse width in asymmetric bipolar pulse DC (ABPDC) sputtering technique is studied by depositing a set of Ta2O5 dielectric thin films under varying pulse widths from 496-1616 ns. Structural studies showed no distinction among the deposited samples. Optical properties of the samples have been characterized by transmission spectrophotometry and spectroscopic ellipsometry which reveal that with increase in pulse width, the deposition rate and hence total thickness of the samples decreases while the percentage of substrate-film interface thickness increases. The void percentage in interface layers were found to be almost constant up to 1296 ns pulse width and increases substantially beyond this. The study is important from the point of pulse width optimization for depositing Ta2O5 thin films by ABPDC sputtering technique for optical multilayer thin film application.