Positive-tone crosslinked molecular resist based on acid-catalyzed depolymerization

Abstract

Presented here is 1,1,1-tris(4-hydroxyphenyl) ethane (THPE)-2VE, a phenol-containing depolymerization resist that demonstrates a 248-nm deep ultraviolet sensitivity (dose-to-clear) of 3 mJ/cm2 as well as a contrast ratio of 7.2 when formulated with 5 mol. % triphenyl sulfonium hexafluoroantimonate as photoacid generator. The 100 keV e-beam contrast curve shows a sensitivity of 24 μC/cm2 for methyl isobutyl ketone (MIBK) development with a contrast ratio of 6.0. A sensitivity of 20 μC/cm2 for 0.26 N tetra methyl ammonium hydroxide (TMAH) development and a contrast ratio of 10.3 was observed for 0.26 N TMAH development. THPE-2VE has been demonstrated to resolve features down to at least 35 nm lines with doses of 48 μC/cm2 in MIBK development with a line edge roughness (LER) (3σ) value of 8.4 nm. In 0.26 N TMAH development, the material required an e-beam dose of 40 μC/cm2 to pattern roughly 35 nm lines with an LER (3σ) value of 8.2 nm. This material shows improved sensitivity and shelf life compared to other depolymerization resist designs previously reported by our group. THPE-2VE has been demonstrated to resolve some of the smallest features reported to date with crosslinked depolymerization resists.