Microstructure evolution and grain orientation in ITO targets and their effects on the film characteristics

ITO targets sintered at 1560–1600 °C were selected to deposit ITO films at 25 and 150 °C with a purpose of investigating the relationship between microstructure evolution and grain orientation in ITO targets and the film characteristics. It is found that, with increasing the sintering temperature, the triangle grains of In4Sn3O12 (secondary phase) transform into the dendritic grains of In2SnO5 (secondary phase), following by the increase of the solid solubility of tin oxide in In2O3 phase (main phase). Besides, the sintering temperature has a great influence only on the texture of secondary phase. More solid solubility of tin oxide in In2O3 phase, stronger texture intensity of secondary phase and higher sputtering temperature were found to promote the crystallinity of ITO films resulting in the lower sheet resistance and obtain the films with lower compression stress and strong adhesion. The transmittance of ITO films deposited at 25 °C is closely related to the film surface roughness, while it is mainly associated with the crystal structure for ITO films deposited at 150 °C.