Advanced Wet-Etch-Only Process for Complete Tri-Layer Rework

A tri-layer patterning technique is used for high numerical aperture immersion lithography at 28 nm node. The tri-layer consists of a photoresist (PR) deposited on a silicon-containing anti-reflective coating (SiARC) above an organic planarization layer (OPL). Defective PR processes (e.g. overlay, over-exposure, residues) are repeatedly being reworked in high volume manufacturing. Due to the different chemical composition of the three layers, multiple etch processes are necessary. In this work, we investigate a wet-etch-only tri-layer rework approach that has the advantage of lower material damage, cost reduction and increased throughput. Complete stack removal and low defect levels on patterned 300 mm wafers could be achieved.