Evaluation of high-resolution and sensitivity of n-CAR hybrid resist for sub-16nm or below technology node

Abstract

MAPDST (4-(methacryloyloxy)phenyl)dimethylsulfoniumtrifluoromethanesulfonate)) based resist analogous are reported to pattern high-resolution nano features (20 nm) under wide range of lithography tools including electron beam lithography (EBL), extreme ultraviolet lithography (EUVL), 193 nm immersion lithography etc. However, these resists have not yet patterned lower node features, especially at sub-15 nm regime with ultra-low line edge roughness (LER) and line width roughness (LWR). One of the methods to improve the resolution of a resist is the structural modification. Towards this, we have developed two new hybrid copolymer resists i.e MAPDST-co-ADSM and MAPDST-co-TPMA by the copolymerization of radiation sensitive organic MAPDST with hybrid tin monomers ADSM and TPMA (ADSM = acetyldibutylstannyl methacrylate; TPMA = triphenyl tin methacrylate) for high-resolution EBL applications. The developed resists were studied for their sub-15 nm line patterns with low LER and LWR features. Various line features, starting from 30-12 nm with different line/space (L/S to L/10S) characteristics were studied at various e-beam doses 200- 1200 μC/cm2. Isolated 12 nm line features have been achieved with the resist MAPDST-co-ADSM at a dose 1200 μC/cm2. Meanwhile, the MAPDST-co-TPMA resist patterned 15 nm features at the dose 700 μC/cm2. The estimated sensitivity and contrast of resists MAPDST-co-ADSM and MAPDST-co-TPMA were 1.60; 450 μC/cm2 and 1.55; 380 μC/cm2 respectively. Similarly, the computed LER and LWR parameters exhibited by the resists MAPDST-co-ADSM and MAPDST-co-TPMA for sub-30 nm features were 0.99; 1.22 and 1.8; 3 nm respectively. The e-beam studies revealed a resolution enhancement of the hybrid resists at 12 nm regime as compared to the neat poly(MAPDST) resist (where the resist resolution was 20 nm) indicating improvements in the lithography properties of these resists.