Indium-tin oxide deposition by d.c. reactive sputtering on a low softening point material

Abstract

The resistivities of indium-tin oxide (ITO) films produced by d.c. reactive magnetron sputtering and subsequently air baked were determined over a range of deposition rates and oxygen flow rates. The dependence of resistivity on deposition rate and oxygen flow rate of ITO sputtered film on glass formed a family of straight lines of constant resistivity emanating from the origin. These lines of constant resistivity were used to provide the form of the boundaries of the operating window for low resistance ITO films deposited on fused, pigmented glass frit substrate with a softening point (370 °C) lower than the air-bake temperature (490 °C) used to convert the sputtered ITO from a soft, dark film to a hard, transparent film. Inside the boundaries the air-baked ITO formed low resistance, conformal films. Outside the boundaries at higher deposition rate:oxygen flow ratios the air-baked film would fold (buckle) along with the underlying frit glass substrate to form higher resistance films. At lower deposition rate:oxygen flow rate ratios the air-baked films would crack along with the underlying frit glass substrate to form higher resistance, sometimes electrically open films.