Improved lithographic performance for resists based on polymers having a vinyl ether-maleic anhydride (VEMA) backbone

ArF lithography, in combination with chemically amplified resists, has been investigated as one of the most promising technologies for producing patterns below 100 nm. In considering the polymer matrix for 193 nm photoresist applications, factors such as sensitivity, transparency to 193 nm radiation, adhesion to substrate, dry etch resistance, ease of synthesis, and availability of monomers are very critical. In these respects, remarkable progress has been made in development of ArF resist material. Polymers of acrylic and methacrylic esters show good imaging performance at 193 nm, but have insufficient dry-etch resistance under oxide or nitride etch condition. On the other hand, cyclic olefin-maleic anhydride (COMA) alternating copolymers exhibit good dry etch resistance, but have poor resolution capability. We previously reported a new platform, based on a vinyl ether-maleic anhydride (VEMA) alternating polymer system, that demonstrated both good resolution and high dry etch resistance. In this paper, VEMA systems with improved lithographic performance are presented. The new platform (VEMA) showed good performance in resolution, depth of focus (DOF), iso-dense bias, and post-etch roughness. With conventional illumination (NA=0.6, sigma=0.7), 120 nm dense line/space patterns with 0.4 muM DOF were resolved. And 90 run L/S patterns 0.6 muM DOF were resolved with off-axis illumination (NA=0.63). Another important factor to be considered for the dry-etch process is post-etch roughness. In the case of VEMA system a clean surface was observed after etch under oxide, nitride, and poly conditions. The VEMA resist system is regarded as one of the most production-worthy material for real device manufacture.