We have examined four molecular glasses (MGs) which are candidates for EUV photoresist formulations. These derivatized glasses and their unprotected precursors were investigated by both 1H and 13C solid state NMR in the bulk state as pure materials and mixtures with a photoacid generator (PAG). The 13C techniques gave information about crystallinity and purity. The main focus of the paper is a characterization of the intimacy of mixing of the PAG and the MGs using proton spin diffusion methods. The PAG was always finely distributed with a maximum cluster size estimated to be 3.8 nm, which is too small to reflect thermodynamic incompatibility. Hence, these blended samples are deduced to be thermodynamically compatible, with differential solubility in the preparation solvent the most likely candidate for producing the significant inhomogeneities observed in a few samples.For one of the unprotected crystalline calix resorcinarenes precursor materials, the solvent, N-methyl 2-pyrrolidinone (NMP) was used. The resulting solid was crystalline with a segregation of isomers, one of which formed a solid adduct with a 1:1 molecular ratio with NMP. Qualitatively, the strong NMP affinity for the calixresorcinarenes is also evident in a) the immobility of the NMP, b) the fact that the 14N quadrupolar interaction changes when NMP goes from the crystalline, unprotected host to a glassy, protected host, and c) that NMP tends to remain as a significant residue. Only the underivatized materials display crystallinity implying that the mixing of the PAG with any derivatized MG is not restricted by crystallization, at least not before the post-exposure baking. As a final note, very strong hydrogen bonds exist in three of the four underivatized materials which is reduced or eliminated with partial protection with t-BOC.
Proceedings Title: Proceedings of SPIE
Conference Dates: February 22-27, 2008
Conference Location: San Jose, CA
Conference Title: SPIE Advanced Lithography
Pub Type: Conferences
chemically amplified photoresists, molecular glass, nuclear magnetic resonance, photolithography, spin diffusion