Enhanced Patterning by Tilted Ion Implantation

摘要

Tilted ion implantation (TII) is proposed as a lower-cost alternative to self-aligned double patterning (SADP) for pitch-halving. This new approach is based on an enhancement in etch rate of a hard-mask layer by implant-induced damage. Ar~+ implantation into a thin layer of silicon dioxide (SiO_2) is shown to enhance its etch rate in dilute hydrofluoric acid (HF) solution, by up to 9× for an implant dose of 3×10~(14) cm~(-2). The formation of sub-lithographic features defined by masked tilted Ar~+ implantation into a SiO_2 hard-mask layer is experimentally demonstrated. Features with sizes as small as ～21 nm, self-aligned to the lithographically patterned mask, are achieved. As compared with SADP, enhanced patterning by TII requires far fewer and lower-cost process steps and hence is expected to be much more cost-effective.