The formation process of nodules (small black projections) on the surface of tin-doped In₂O₃ (ITO) targets during magnetron sputtering was studied by observing the surface morphologies of ITO films prepared within etching time of 2?50 h. The effects of etching time on the electrical and optical properties of the deposited ITO films were explored. Results show that the distribution of In and Sn on the surfaces of the ITO targets changes with the etching time, resulting in uneven ITO films. The electrical and optical properties of the films are degraded significantly due to nodule formation. The photoelectric properties of the ITO films are not affected significantly by etching time within 40 h. However, a rapid deterioration is recorded when longer etching time is applied.