Enhanced patterning by tilted ion implantation

Abstract

Tilted ion implantation (TII) is proposed as a lower-cost alternative to self-aligned double patterning (SADP) for pitchhalving. 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.