Development of New Negative-tone Molecular Resists Based on Calixarene for EUV Lithography

We have developed new negative-tone molecular resists based on phenyl calix[4]resorcinarene derivatives, and evaluated their EUV patterning performance. EUV imaging experiments were performed using the high-numerical-aperture (NA = 0.3), small-field EUV exposure tool (HINA). Patterning results showed the resolution of the resist on an organic layer substrate to be 29 nm at an EUV exposure dose of 22.2 mJ/cm2 and the obtainable aspect ratio to be as high as 2, with pattern collapse being markedly suppressed. In addition, we analyzed the outgassing of the resists during EUV exposure. The outgassing rates of the new resins were on the same order as that of conventional poly(p-hydroxystylene) (PHS) resin. On the other hand, the outgassing rates of the new resists were about five times higher than that of conventional PHS-based resist. Quadropole mass spectra showed the main source of resist outgassing to be EUV-induced decomposition of the photoacid generator.