Indium–tin oxide films radio frequency sputtered from specially formulated high density indium–tin oxide targets

High density ITO (indium–tin oxide) targets doped with Al2O3 and SiO2 manufactured in the Tektronix Ceramics Division have been used to rf sputter ITO films of various thicknesses on borosilicate glass substrates. Sputtering in an oxygen–argon gas mixture and annealing in forming gas, resulted in ITO films exhibiting 90% transmission at 550 nm and a sheet resistance of 15 Ω/sq for a thickness of 1100 A. Sputtering in an oxygen–argon gas mixture and annealing in air increased sheet resistance without a large effect on the transmission. Films sputtered in argon gas alone were transparent in the visible and the sheet resistance was found to be 100–180 Ω/sq for the same thickness, without annealing.