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

Abstract

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.

A novel water developable tetraphenyltin-based nonchemically-amplified molecular resist for sub-13 nm lithography

“…20,25,38 Our previous study also demonstrated that similar chemical reactions occur in the film of the sulfonium-based compound by e-beam and EUV light, both of which can generate secondary electrons to induce the chemical reactions. 34 Based on the XPS data and the previously reported results, we propose a mechanism for the solubility switch of the SnMSF 4 resist (Fig. 8c).…”

“…23 However, it should be noted that the sensitivity of the SnMSF 4 resist for EUVL is not significantly increased by the introduction of Sn to the molecule compared with our previous studies on other sulfonium-based n-CARs. 11,20,34 This is attributed to the following possible reasons: i) unlike the reported tin-oxo cages, 35 the cross-section of the Sn atom in the SnMSF 4 molecule is estimated to be only ∼10%, by comparing the cross-section of the Sn atom to the whole molecule, 36 which limits its contribution to EUV absorption. Thus, the yield of secondary electrons to irradiate the sulfonium is not increased significantly.…”

Increasing the Sensitivity of Nonchemically Amplified Resists by Oxime Sulfonate-Functionalized Polystyrene

“…Our previous studies have demonstrated that NTD is a practical method to achieve high-resolution patterns by using organic developers with low surface tension. ,, To demonstrate the effect of the OS ratio on the EBL, the NRT analysis of PSOS x resists for EBL was performed in the BAC developer as shown in Figure S12. The 3D image of the PSOS 100 resist pattern (Figure S12a) shows that the film thickness clearly increases from zero to almost constant with the increasing exposure dose.…”

“…Recently, our group have reported a series of n-CARs based on sulfonium-functionalized polystyrene or small molecules, resolving 13 nm half-pitch (HP) patterns with an LER of 2.5–2.8 nm by EUVL. However, the sensitivity was relatively low (exposure doses of 180–200 mJ/cm 2 ) and the sensitivity needs to be further improved. , Inspired by a previous work, we anticipate that the introduction of groups with more efficient photochemical reactions into the polymer will improve the sensitivity of resists.…”

Exceptional Lithography Sensitivity Boosted by Hexafluoroisopropanols in Photoresists

“…Researchers have recently developed a variety of candidate photoresist materials, including chemically amplified photoresists (CARs) [ 10 , 11 , 12 ], metal-based materials [ 13 , 14 ], and cleavage polymer-based non-CARs [ 15 , 16 , 17 ]. Of these, polymer-based CARs are considered the latest qualifying EUV photoresist for realizing high-volume manufacturing [ 18 ].…”