In
this study, a series of molecular resists based on a bis(4-butoxyphenyl)
sulfone core attached to a varying number of radiation-sensitive triphenylsulfonium
units (BPSSn, where n = 2, 3, and
4) were designed and synthesized. We evaluated the physical properties
of these resists, including solubility, film-forming ability, and
thermal stability, to assess their viability as photoresist materials.
The materials allowed for negative patterning through organic development
in both e-beam and extreme ultraviolet (EUV) lithography. Through
manipulating the average number of triphenylsulfonium units in the
molecule and optimizing the developing agents, BPSS4 resists demonstrated
high resolution (16/13 nm) and low line edge roughness (2.5/2.5 nm)
in e-beam and EUV dense line patterning, respectively. We further
explored the EUV and e-beam exposure mechanisms of BPSS4 resist using
X-ray photoelectron spectroscopy. We also investigated the outgassing
behavior of the film during EUV irradiation via in situ mass spectroscopy.
Remarkably, this nonchemically amplified resist exhibited high etch
resistance and accurate pattern transfer capabilities. The etch durability
of BPSS4 (under SF6/O2 plasma chemistry) with
respect to the Si wafer was 21:1, highlighting its significant potential
for practical applications in high-resolution lithography.