Masumi Suetsugu

Negative tone chemically amplified resist formulation optimizations for ultra high-resolution lithography

Starting from the Sumitomo commercial platform NEB-33 resist, three new experimental negative tone chemical amplified resist (CAR) formulations have been developed, to push resolution below 40 nm in direct electron beam lithography. PEB temperatures and times have been optimized between 60 and 100 °C and, respectively, 20 and 120 s. Fourier transform infra red spectra have been performed and allowed us to follow the solvent and PAG concentration in order to optimize processes on all samples. As a consequence, 25-nm isolated lines have been resolved with these new chemical amplified resists.

Resist composition effects on ultimate resolution of negative-tone chemically amplified resists

Chemical Amplification Resists (CAR) are now widely used in optical lithography since the introduction of the deep UV era. One advantage of the CARs is also their full compatibility with electron beam writing. This paper is focused on the development work of a negative tone resist. The influence of resist compounds such as polymer matrix composition and PAG size on diffusion and ultimate resolution is detailed. Finally the pattern transfer capabilities of a 30 nm isolated line into a polysilicon layer is presented.

Negative-tone CAR resists for e-beam lithography: modification of chemical composition for R&D application (high resolution) or production application (high sensitivity)

In this study, it is investigated how chemical modifications of a given resist platform can induce improvements in e-beam lithographic performances. Molecular weight (Mw) as well as photo-acid generator (PAG) modifications will act as fine tuners for Sumitomo NEB-33 negative resist to match specific applications: preparation of advanced CMOS R&D architecture (highly resolving resists needed) and fast patterning for production environment (highly sensitive resists needed).

Tandem type resin for chemically amplified KrF positive resist

A mixture of high Mw fractionated novolac resin and 2EAdMA (2-ethyl-2-adamantyle methacrylate)/HST (hydroxy styrene) copolymer brought about high resolution almost comparative to simple 2EAdMA/HST copolymer. Dry etching resistance was higher than 2EAdMA/HST copolymer. A mixture of unfractionated novolac resin and 2EAdMA/HST copolymer showed low resolution. Discrimination curve was measured by DRM on each case. Dissolution contrast of fractionated mixture was almost same as unfractionated one. Dissolution characteristics cannot tell the difference of resolution between fractionated and unfractionated novolac mixture.