PECVD Bi-Layer ARC for BARC-less Immersion Lithography

Abstract

A PECVD bi-layer Dielectric Anti-Reflective Coating (DARC®) process has been developed as a cost-effective solution for immersion lithography. The proposed bi-layer DARC scheme eliminates the need for a Bottom Anti-Reflective Coating (BARC) which is commonly used in both dry and immersion lithography processes, thereby reducing manufacturing cost and improving etch margin for better CD control. The bi-layer DARC film properties are highly tunable for different underlayers to provide optimal reflectivity control. With the bi-layer DARC scheme, we have demonstrated a minimum line width of 30 nm with a wider process window and comparable line edge roughness (LER) as a BARC scheme. The patterning performance is stable after multiple rework cycles and extended queue time, proving the manufacturability of the bi-layer DARC process.