We have auditioned a new self-immolating polyester as a highly sensitive resist system for next-generation lithography. Upon exposure to either UV or electron beam radiation, the polymer irreversibly depolymerizes to generate toluene and carbon dioxide. When blended with Novolac, the polyester functions as a dissolution inhibitor and displays both high contrast and sensitivity when compared to a positive-tone, high resolution resist such as PMMA. Our research for this material is motivated by new advances in next-generation patterning techniques, such as extreme ultraviolet (EUV) lithography. An ideal EUV resist system must have both high sensitivity and low LER to compensate for the weak intensity of the light source. Unfortunately, traditional chemically amplified resist (CAR) systems suffer from blur caused by acid diffusion which results in poor image quality. To achieve sensitivity without the blur caused by catalyst diffusion, our resist system leverages the amplification power of a self-immolating polymer, which can fully depolymerize in response to a single photochemical event. Combined with the high etch selectivity of a phenolic resin such as Novolac, we can achieve high contrast and sensitivity in a non-CAR system that is compatible with current photolithographic processes. We have optimized our polyester resist system using electron beam lithography (EBL) as a substitute for EUV and compared its lithographic performance to high resolution EBL resists such as PMMA and ZEP as well as a commercial chemically amplified resist for 193 nm lithography.

Self-immolative aromatizing polyester for next-generation lithography

251st National Meeting (2016)

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