Indium tin oxide (ITO) thin films were deposited by the RF-magnetron sputtering method and the crystallization behavior of the films with no external heating as a function of deposition time was examined. The X-ray diffraction results indicated an amorphous state of the film when the deposition time is about 10 min. When the deposition time was increased to over 20 min, the crystallization of the films is observed. When the film was deposited intermittently, but the total sputtering time is equally adjusted, the film was not well crystallized compared with the case of continuous deposition. The results on the study of crystallization of ITO thin films by prolonged deposition without external heating are discussed from a viewpoint of energetic ion bombardment. (C) 2004 Elsevier B.V. All rights reserved.