Sublithographic Patterning of Spin-Coated SiARC Films Using Tilted Ion Implantation

Tilted ion implantation (TII) used in conjunction with preexisting masking features on the surface of a wafer is a relatively low-cost method for sublithographic patterning. Previous demonstrations of this method utilized a thin thermally grown layer of silicon oxide (SiO2) as the implanted layer, with amorphous-silicon masking features, to form patterns with feature sizes as small as 9 nm. In this article, this method is adapted to be compatible with back-end-of-line (BEOL) processing using silicon-containing antireflection coating (SiARC) as the implanted layer, with photoresist masking features formed using deep-ultraviolet (DUV) lithography. Negative-tone patterning of an ~15-nm-thick SiARC film is achieved by implanting Ar
⁺
ions to selectively reduce its wet etch rate, allowing for the subsequent selective removal of the SiARC material from unimplanted regions. Patterned features down to 20 nm in lateral dimension are demonstrated.