Newly developed polymer bound photoacid generator resist for sub-100-nm pattern by EUV lithography

Gonsalves, Kenneth E.; Thiyagarajan, Muthiah; Dean, Kim

doi:10.1117/12.602087

Cited by 10 publications

(5 citation statements)

References 10 publications

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“…In the past decades, the miniaturization and improvement of electronic devices were mainly enabled by the rapid development of lithography technology and the improvement of resist performance . Electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL), as the most advanced high-resolution lithography technologies, are widely used in research and high-volume production for feature sizes lower than 20 nm half-pitch (HP). − Accordingly, the development of resist materials fulfilling the stringent requirements of high resolution ( R ), sensitivity ( S ), and low line edge roughness (LER) is still a great challenge for advanced lithography. ,, Although traditional chemically amplified resists (CARs) have been widely used in the semiconductor industry due to their high sensitivity, the stochastic distribution of photoacid generators (PAGs) and the diffusion of acids in the resist film result in poor LER and limit the resolution of CARs. ,, To overcome these limitations, researchers have proposed methods to accomplish the uniform distribution of PAGs and diffusion minimization of acids in a resist film. , It has been demonstrated that incorporating the PAGs into the polymer backbone and increasing the volume of anions of PAG can effectively improve the uniformity of PAG distribution and control the acid diffusion. − However, as the feature size becomes smaller and smaller, it is difficult to achieve the required resolution due to the acid diffusion blur, which is intrinsic for CARs.…”

Section: Introductionmentioning

confidence: 99%

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

Wang

Chen

et al. 2022

ACS Appl. Mater. Interfaces

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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.

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Section: Introductionmentioning

confidence: 99%

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

Wang

Chen

et al. 2022

ACS Appl. Mater. Interfaces

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“…The second established method of overcoming the RLS trade-off is to increase the PAG concentration, thereby increasing the efficiency of the exposure process and reducing shot noise effects. ,,, However, this approach is restricted as EUV resists almost exclusively implement ionic PAGs that may segregate from the polymer, especially at concentrations above 20 wt % . While nonionic PAGs have been thoroughly investigated − and shown to outperform ionic PAGs in several areas including dark loss, , acid generation under e-beam conditions, , outgassing, and PAG phase separation, a few nonionic PAG are capable of achieving sub-20 mJ/cm 2 sensitivity under EUV exposure. This sensitivity challenge has been exacerbated by the limited mechanistic knowledge of the EUV process, especially with respect to the behavior of nonionic PAGs.…”

Section: Introductionmentioning

confidence: 99%

High-Performance Chain Scissionable Resists for Extreme Ultraviolet Lithography: Discovery of the Photoacid Generator Structure and Mechanism

et al. 2022

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Extreme ultraviolet (EUV) lithography currently dominates the frontier of semiconductor fabrication. Photoresists must satisfy increasingly strict pattern fidelity requirements to realize the significant enhancements in resolution offered by EUV technology. Traditional chemically amplified resists (CARs) have hit a barrier in the form of the resolution, line edge roughness, and sensitivity trade-off. This has been compounded by a lack of understanding of the chemical mechanism associated with the EUV process. Here, we synthesize a series of novel EUV photoresists based on a self-immolative, acid-labile poly(acetal) system. These systems are shown to be commercially viable under current EUV requirements. Careful study of the resists’ degradation pathways has enabled the identification of a remarkable photoacid generator (PAG) that functions as both an acid generator and base quencher, enabling further improvements over previous resists. density functional theory calculations reveal, for the first time, the connection between the PAG activation barrier and resist sensitivity and suggests why attempts to use electron-beam lithography to predict EUV performance have failed.

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“…Both electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL) are advanced lithography technologies that are capable of achieving high-resolution patterns below 20 nm. , Consequently, steady improvement of resist materials for high-resolution lithography is of paramount importance. − Chemically amplified resists (CARs) have been the primary materials used in the semiconductor industry due to their excellent sensitivity for lithography. ,, In CARs, photoacid generators (PAGs) produce acid after exposure, which catalyzes the deprotection reaction of the acid-sensitive group, resulting in the solubility switch. − However, the poor line-edge roughness (LER) due to the acid diffusion and the uneven distribution of PAGs leads to the resolution limitation . The trade-off relationship among resolution, LER, and sensitivity demonstrates the limitations of CARs. , Researchers have attempted to bind PAG to the skeleton of materials to avoid nonuniform acid distribution and uncontrolled diffusion. − Yamamoto et al reported a series of polymer-bound PAG resists, achieving a 50 nm HP pattern with a line width roughness (LWR) of 3.9 nm. The patterning ability of the resist was significantly improved compared with the polymer-blended PAG resist (75 nm HP and LWR = 6.1 nm) .…”

Section: Introductionmentioning

confidence: 99%

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

An,

Chen,

Zeng

et al. 2024

ACS Appl. Polym. Mater.

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Nonchemically amplified resists (n-CARs) based on oxime sulfonate-functionalized polystyrene (PSOS) were designed and prepared. The component ratios of the oxime sulfonate (OS) group in the polymer were well-controlled by changing the molar ratios of monomers, affording PSOS x (x = 100, 90, 60, and 40) polymers with oxime sulfonate ratios of 100, 89, 60, and 40%, respectively. The solubility, thermal stability, and film-forming ability for all of the polymers were evaluated, confirming the feasibility to use them as resist materials. The lithographic performances of PSOS x resists were studied by electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL). PSOS x resists were demonstrated as dual-tone resists by using tetramethylammonium hydroxide (TMAH) as a positive tone developer and n-butyl acetate as a negative tone developer, respectively. Increasing the ratio of oxime sulfonate groups contributes to the negative tone development (NTD) patterns, while decreasing the ratio is conducive to the positive tone development (PTD) patterns. PSOS 100 resists can resolve 20 nm half-pitch (HP) patterns at a dose of 920 μC/cm 2 for NTD, and PSOS 40 resists can resolve 40 nm HP patterns at a dose of 1214 μC/cm 2 for PTD for EBL, respectively. The PSOS 100 resist was further evaluated by EUVL, achieving patterning performance down to 18 nm HP at a dose of 87.1 mJ/cm 2 with an LER of 2.3 nm for NTD. A comprehensive analysis of the patterning mechanism indicates that the decomposition of the oxime sulfonate group into sulfonic acid and other fragments upon exposure plays an important role in the solubility switch.

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Newly developed polymer bound photoacid generator resist for sub-100-nm pattern by EUV lithography

Cited by 10 publications

References 10 publications

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

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

High-Performance Chain Scissionable Resists for Extreme Ultraviolet Lithography: Discovery of the Photoacid Generator Structure and Mechanism

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

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