Characteristics of maskless patterning of Cr films using focused Sb+ ion implantation have been investigated.Dose and depth dependence of the etching rate of Sb-implanted layers during plasma etching using CC1 4 were measured.Sb profiles were also measured by Rutherford backscattering techniques.It was found that a sharp threshold dose exists to form an etch-resistant layer by Sb implantation.It was also fotind that a latent image of an Sb implanted pattern at a dose Ž 3.8x10 5 /cm 2 was developed by the plasma etching, and that Cr patterns with a thickness of a few hundred nanometers were formed by the present maskless patterning technique.