The material design to reduce outgassing in acetal-based chemically amplified resist for EUV lithography

Masuda, Seiya; Kawanishi, Yasutomo; Hirano, Shuuji; Kamimura, Sou; Mizutani, Kazuyoshi; Yasunami, Shoichiro; Kawabe, Yasumasa

doi:10.1117/12.656238

Cited by 14 publications

(11 citation statements)

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“…13 Although outgassing has received a great deal of attention due to its impact on throughput and damages to optics, only several studies have been reported regarding chemistry of outgassing. [19][20][21][22][23] There have been only one report that deals with influence of Ea on outgassing. 23 Therefore, we have investigated, in particular, effects of Ea on outgassing using a wide variety of polymers with a different acid labile groups (ALG).…”

Section: Outgassing Issue Of Low Ea Polymermentioning

confidence: 95%

Novel EUV resist materials design for 14nm half pitch and below

et al. 2014

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Polymers with a different Tg and activation energy were prepared to clarify influences of acid diffusion on resolution at 15 nm half-pitch (hp) and 14 nm hp using a EUV micro-field exposure tool (MET) at LBNL. Resolution on such a narrow pattern was limited by collapse and pinching. Clear relationship between pinching numbers and polymer Tg indicates that acid diffusion is one of major contributors on the pinching. In addition, polymers with a low thermal activation energy (Ea) on deprotection were effective for reducing pinching. This is probably originated from its high chemically amplification character even in low post-exposure bake (PEB) temperature to obtain both large chemical contrast and short acid diffusion. On the other hand, a good correlation between a cleanable outgassing amount and Ea indicates trade-off relationship between outgassing and resolution. Advantages of n-butyl acetate (nBA) developer have been investigated in viewpoint of dissolution uniformity. Surface roughness of a non-patterned resist film at half-exposed area, which was well correlated with LWR, was measured by AFM as indicator of uniformity in development process. To avoid any differences in resist chemistry other than development process, cross linking negative tone resist was applied for this study. The surface roughness obtained by nBA, which is conventional negative-tone imaging (NTI) developer, was 32 % lower than that obtained by 2.38 % TMAH solution. NTI resist system with a nBA developer and optimized resist reduced LWR from 4.8 nm to 3.0 nm in comparison with conventional positive tone resist with a 2.38 % TMAH developer. In addition, advantage on semi-dense trench patterning was well defined. New EUV sensitizer with 1.15 times higher EUV absorption resulted in 1.15 times higher acid yield by EUV exposure. Lithography performance of the new EUV sensitizer has been investigated by MET at SEMATECH Albany. Sensitivity was indeed improved from 20 mJ/cm 2 to 17 mJ/cm 2 according to the acid yield increase, but resolution was significantly degraded.

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Section: Outgassing Issue Of Low Ea Polymermentioning

confidence: 95%

Novel EUV resist materials design for 14nm half pitch and below

et al. 2014

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“…The dependence of acid generation efficiency on the molecular structure of acid generators has been investigated using -rays from 60 Co, 124,125) EB, 113,126) and EUV radiation. 118,127,128) The relationship between reductive potential and relative acid yield has been reported for sulfonium and iodonium salts as well as for nonionic acid generators.…”

Section: )mentioning

confidence: 99%

“…118,127,128) The relationship between reductive potential and relative acid yield has been reported for sulfonium and iodonium salts as well as for nonionic acid generators. 125,126) Also, the reactivity of acid generators with solvated electrons formed in solutions has been measured from the viewpoint of molecular structure dependence. 115,116) The reactivity estimated from the rate constant for the reaction with methanol-solvated electrons well explains the acid generation efficiency of TPS-tf upon exposure to EB 90) and EUV radiation 79,129) as discussed above.…”

Section: )mentioning

confidence: 99%

Radiation Chemistry in Chemically Amplified Resists

Kozawa

Tagawa

2010

Jpn. J. Appl. Phys.

336

319

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Historically, in the mass production of semiconductor devices, exposure tools have been repeatedly replaced with those with a shorter wavelength to meet the resolution requirements projected in the International Technology Roadmap for Semiconductors issued by the Semiconductor Industry Association. After ArF immersion lithography, extreme ultraviolet (EUV; 92.5 eV) radiation is expected to be used as an exposure tool for the mass production at or below the 22 nm technology node. If realized, 92.5 eV EUV will be the first ionizing radiation used for the mass production of semiconductor devices. In EUV lithography, chemically amplified resists, which have been the standard resists for mass production since the use of KrF lithography, will be used to meet the sensitivity requirement. Above the ionization energy of resist materials, the fundamental science of imaging, however, changes from photochemistry to radiation chemistry. In this paper, we review the radiation chemistry of materials related to chemically amplified resists. The imaging mechanisms from energy deposition to proton migration in resist materials are discussed.

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“…There are a number of known techniques that are typically used to quantify resist outgassing, which include the pressure rise method using an ion gauge, accumulation method using gas chromatograph mass spectroscopy, summing method using quadropole mass spectrometer and witness plates. [7][8][9][10][11] ASML protocol requires the use of X-ray photoelectron spectroscopy (XPS) technique on witness plate samples to quantify the noncleanable contamination residue from the resist on the witness plates, [12] and optimizing sensitivity and speed simultaneously for this XPS measurement is the focus of our study. There are a number of studies pertaining to the estimation of uncertainties associated with the XPS technique and its impact on the data acquisition strategy.…”

Section: Introductionmentioning

confidence: 99%

X-ray photoelectron spectroscopy process optimization for characterization of trace contamination elements for extreme ultraviolet resist outgassing study

et al. 2013

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X-ray photoelectron spectroscopy (XPS) is used for elemental identification and quantification in a number of fields, and the optimization of XPS performance can help in making better use of the limited XPS tool availability. In the field of extreme ultraviolet (EUV) lithography, one of the requirements is having a clean vacuum environment to minimize contamination of the EUV optics. EUV resist outgassing is viewed as one of the main issues that could affect the vacuum environment. There is a program underway to measure the relative contamination rates from different resists following the ASML (provider of lithography systems) approved protocols for witness plate testing. One of the key steps is the XPS measurement of residue on the optics after cleaning. The role of XPS in quantification of species that adhere to the ruthenium-coated silicon witness plate sample is discussed. The various XPS tool parameters like the pass energy and source setting were optimized for our application of witness plate analysis. The statistics of our XPS tool were studied, and combined with the fundamental XPS equations, a simple mathematical model was developed to optimize the number of scans for the various elements of interest in our witness plate study. Using the optimized number of scans, the acquisition time to measure the contaminant elements to a precision better than 0.1 at.% was minimized. The model devised in the paper can be adapted to other XPS measurements requiring different levels of precision.

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The material design to reduce outgassing in acetal-based chemically amplified resist for EUV lithography

Cited by 14 publications

References 0 publications

Novel EUV resist materials design for 14nm half pitch and below

Novel EUV resist materials design for 14nm half pitch and below

Radiation Chemistry in Chemically Amplified Resists

X-ray photoelectron spectroscopy process optimization for characterization of trace contamination elements for extreme ultraviolet resist outgassing study

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