The present invention provides a method of using organic polymer as a covering layer for a device lightly doped drain (LDD) structure, wherein a photo resist is covered by organic polymer, and ion implantation of different energies and kinds are performed to the same region of different line widths, thereby achieving the effect of LDD. Additionally, the covering layer of organic polymer is removed by means of simple and easy oxygen plasma etch so as not to increase the complexity of fabrication process. The complex fabrication process of a device LDD structure in the prior art is thus greatly improved.