Optimized Work Function Metal Layer Damage Effect in Metal Gate BARC Etch Process by ICP Etch System

Metal gate BARC open process is considered to be more and more critical in semiconductor manufacturing in and beyond 14nm technical node, due to its important effect on WAT result through the work function metal layer damage side-effect. In this work, metal gate BARC open process is performed in ICP etch system. The pattern loading of dense/isolated area is critical for process health. The effects of work function metal layer damage are studied systemically to setup ideal process. Partial etch profile to control pressure impact is studied in detail. The effect mechanism is also discussed through polymer passivation on Fin. It is proposed that reasonable over etch window is very important to eliminate Work Function Metal damage and BARC residue in ICP etch system.