Internal Stress of ITO, IZO and GZO Films Deposited by RF and DC Magnetron Sputtering

Abstract

ABSTRACTMechanical properties such as internal stress or adhesion of transparent conductive oxide (TCO) films are quite important to guarantee the patterning accuracy and the durability for various kinds of commercial applications. In this study, representative TCO films with the thickness of about 200 nm, such as tin-doped indium oxide (ITO), indium-zinc oxide (IZO), and gallium-doped zinc oxide (GZO) films were deposited on unheated glass substrate by rf and dc magnetron sputtering using corresponding oxide targets under various total gas pressure (Ptot) from 0.3 to 3.0 Pa. The internal stress of these TCO films was measured by cantilever method using 50 µ m thick 50mmx5mm micro-sheet glass substrates in relation to the Ptot during the deposition. The ITO films deposited at Ptot lower than 0.7 Pa were polycrystalline and showed large compressive stress, while the amorphous ITO films deposited at 1.5-3.0 Pa showed a very slight tensile stress. On the contrary, the all the IZO films with various thicknesses (50-750 nm) deposited at Ptot of 0.3-3.0 Pa showed entirely amorphous structure, where the compressive stress of IZO films was lower than that of ITO films. Whereas, all the GZO films deposited under Ptot from 0.3 to 5.0 Pa showed polycrystalline structure with <001> preferred orientation, where the compressive stress showed almost constant for all the films.