Synthesis and properties of new anionic photoacid generators bound polymer resists for e-beam and EUV lithography

Abstract

A new series of methacrylate substituted benzene sulfonic photoacid generators (PAGs) and a perfluoro alkanesulfonic PAG, bound polymeric resists based on hydroxystyrene (HS) and 2-ethyl-2-adamantyl methacrylate (EA) were prepared and characterized. The acid yield of these PAG bound polymer resists was among the range of 54-81% under deep ultraviolet exposure (254 nm) that agrees well with the electron withdrawing effect of the substituents on the PAG anion for enhancing acid generation efficiency. The intrinsic lithography performance of these polymer-bound PAG resists showed sub-50 nm half-pitch resolution and < 5 nm LER (3σ).

Radiation-Sensitive Novel Polymeric Resist Materials: Iterative Synthesis and Their EUV Fragmentation Studies

“…The development in the photoresist system greatly influences the achievable lithographic CD (critical dimension) as well as the quality of patterns transferred to the substrate through the mask. Recently, a variety of radiation-sensitive polymeric resist materials have been developed to satisfy several lithographic requirements such as low outgassing, high resolution, high sensitivity and reduction in line-edge roughness (LER)/line-width roughness (LWR). − Nonetheless, significant improvements are still required.…”

Challenges of 22 nm and beyond CMOS technology

“…PAG aggregation is detrimental to LER. Work along this line has successfully demonstrated simultaneous improvements in sensitivity and LER without deteriorating resolution [34] . LER is generally considered to be related to the randomness in the positions of the acids released during exposure combined with the superposition of the resist deprotection "blurs" generated around each released acid during PEB, which directly results from inhomogeneous distribution of PAG and protection group in a polymer.…”