Development of electron beam resists based on amorphous polyphenols with low molecular weight and narrow dispersion

We have investigated the possibility of amorphous low molecular weight polyphenols as a chemically amplified positive-tone electron-beam (EB) resist. Low molecular weight polyphenol, 4'4-methylenebis{2-[di(2-methyl-4-hydroxy-5-cyclohexylphenyl)]methyl} phenol (3M6C-MBSA) as a base matrix, was protected by 1-ethoxyethyl (EE) groups to control the dissolution rate in 0.26 N tetramethylammonium hydroxide aq. developer. The film distribution in the depth direction for resist components with a Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and the Fourier amplitude spectra of line-edge roughness (LER) have been investigated to understand the relationship between them for the resists formulated with 3M6C-MBSA and two types of photo acid generator (PAG), triphenylsulfonium perfluoro-1-butanesulfonate (TPS-PFBS) and triphenylsulfonium n-octanesulfonate (TPS-nOS). From these results, it was found that the resist film consisting of TPS-nOS showed more homogeneous in the depth film distribution than that with TPS-PFBS, and the resist with TPS-nOS also indicated the suppressed LER value of 5.1 nm in the wide frequency range. Therefore, the homogeneity of the resist film may affect the pattern LER.