Large Area Nano-patterning by Masked Ion Implantation Using Anodic Porous Alumina

Abstract

Large area nano-patterning has been conducted by masked ion implantation with anodic porous alumina. The purpose of this work is to develop a nano-patterning method leading to 3D control for device fabrication. Aluminum anodic oxidation is one of the best controllable self-assembing processes to fabricate large-area pore patterns. An anodic porous alumina was fabricated by two-step anodization process in 0.3 M oxalic acid and phosphoric acid. The two-step anodization process attained periodic porous arrays. The porous a1umina was delaminated from the base aluminum by chemical etching and was mounted onto a crystalline Si02 substrate, removing the residual barrier layer by Ar sputtering. Subsequently, negative Cu ions of 60 keV were irradiated to the substrate. After the irradiation, surface morphology of the Si02 substrate was observed by SEM. The patterned irradiation was successfully conducted with the anodic porous-alumina mask to 1 x 1016 ions/cm2• Beyond this tolerance limit, the pore size decreased with increasing ion fluence, because of ion-induced deformation. In order to reduce the deformation, we also employed Au or carbon coating on the mask surface. The carbon coating significantly improved the radiation resistance of the mask.