A New Breed of Wet-Developable BARC Materials

Abstract

A new family of materials has been developed to serve as a wet-developable bottom antireflective coating (D-BARC) for patterning levels that have a strong need to avoid dry-etch processes for BARC-open steps. Such include some implant levels, where dry-etch introduces surface damage that consequently affects the final electrical performance of a device. Other levels that might benefit from all-wet patterning are those using special substrates such as high-k metal-gate (HKMG) levels. Our design of D-BARC materials combines the unique properties of traditional BARC as well as those of a photoresist to deliver a D-BARC solution that is photoimageable in nature. It was found that isotropically developable (i.e., non-imageable) D-BARCs do not provide viable solutions that satisfy the resolution requirements of the current 32 nm technology node and provide the extendibility to future nodes. The optical properties of the D-BARC material are critical for reflectivity control but high optical density can negatively impact the imaging performance of the material. Therefore a balance is needed where the D-BARC is co-optimized with the photoresist as a system, achieves good reflectivity control, residue-free imaging and process gains.