Sulfonium-Functionalized Polystyrene-Based Nonchemically Amplified Resists Enabling Sub-13 nm Nanolithography

Abstract

Nonchemically amplified resists based on triphenyl sulfonium triflate-modified polystyrene (PSTS) were prepared by a facile method of modification of polystyrene with sulfonium groups. The uploading of the sulfonium group can be well-controlled by changing the feed ratio of raw materials, resulting in PSTS0.5 and PSTS0.7 resists with sulfonium ratios of 50 and 70%, respectively. The optimum developer (methyl isobutyl ketone/ethanol = 1:7) is obtained by analyzing contrast curves of electron beam lithography (EBL). PSTS0.7 exhibits a better resolution (18 nm half-pitch (HP)) than the PSTS0.5 resist (20 nm HP) at the same developing conditions for EBL. This novel resist platform was further evaluated by extreme ultraviolet lithography, and patterning performance down to 13 nm HP at a dose of 186 mJ cm–2 with a line edge roughness of 2.8 nm was achieved. Our detailed study of the reaction and patterning mechanism suggests that the decomposition of the polar triflate and triphenyl sulfonium groups into nonpolar sulfide or polystyrene plays an important role in the solubility switch.

Nonchemically Amplified Molecular Resists Based on Sulfonium-Functionalized Sulfone Derivatives for Sub-13 nm Nanolithography

“…The etch selectivity of the BPSS4 resist to the silicon substrate was 21:1, which was two times that of conventional ZEP resist under the same etching conditions. 45 These results demonstrate that the BPSS4 resist is excellent for dry-etching resistance. The high-resolution pattern transfer capability was examined under the same conditions.…”

“…The BPSSn (n = 2, 3, and 4) with different ratios of the sulfonium group were prepared according to our previous report. 45 The details of the synthesis are provided in the Supporting Information.…”

A Single-Component Molecular Glass Resist Based on Tetraphenylsilane Derivatives for Electron Beam Lithography

“…One approach to solving the limitation of resolution is the development of nonchemically amplified resists (n-CARs). Some novel n-CARs based on polycarbonates, metal-containing clusters, − metal–organic complexes, − polymer containing sulfonium salt, , have been investigated to achieve sub-20 nm patterning under e-beam exposure. Although the resolution has been greatly increased, the sensitivity still needs to be further improved.…”

“…One approach to solving the limitation of resolution is the development of nonchemically amplified resists (n-CARs). Some novel n-CARs based on polycarbonates, 14 metal-containing clusters, 15 − 17 metal–organic complexes, 18 − 21 polymer containing sulfonium salt, 22 , 23 have been investigated to achieve sub-20 nm patterning under e-beam exposure. Although the resolution has been greatly increased, the sensitivity still needs to be further improved.…”

Towards environmentally friendly processing of ionic liquid-based photoresists with a boosted lithography performance

“…Wang et al 10 have recently proposed a highly sensitive photoresist based on ZrO 2 -MAA MOC, but it still requires the use of environmentally unfriendly toluene as the developer. Yang et al 11 synthesized polystyrene-based nonchemically amplified resists, but they still faced the challenge of using complex organic reagents such as MIBK/EtOH as developers during the development process. Therefore, developing a hydrophilic and water-soluble photoresist is crucial for achieving mild lithography, as it eliminates the need for HMDS vapor.…”