Optimization of Sputtering Parameters for the Deposition of Low Resistivity Indium Tin Oxide Thin Films

Indium tin oxide (ITO) thin films have been deposited using RF sputtering technique at different pressures, RF powers, and substrate temperatures. Variations in surface morphology, optical properties, and film resistances were measured and analyzed. It is shown that a very low value of sheet resistance (1.96 Omega/sq.) can be achieved with suitable arrangement of the deposition experiments. First, at constant RF power, deposition at different pressure values is done, and the condition for achieving minimum sheet resistance (26.43 Omega/sq.) is found. In the next step, different values of RF powers are tried, while keeping the pressure fixed on the previously found minimum point (1-2 Pa). Finally, the minimum resistivity is obtained by sweeping the substrate temperatures, while keeping RF power and the working pressure at their optimum values. Furthermore, the effects of process parameters on properties, such as the surface morphology and the optical transmission, are discussed. Although the point of minimum resistivity does not coincide with that of the maximum transparency of ITO film, relatively acceptable values of transmittance (approximately 75% on a glass substrate with intrinsic transparency of 89%) can be obtained.