Ionic species in irradiated poly(methyl methacrylate). A pulse radiolysis and ESR study

Tabata, Masayoshi; Nilsson, G.; Lund, A.; Sohma, Junkichi

doi:10.1002/pol.1983.170211122

Cited by 27 publications

(13 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since no methyl radical is detected, it is evident that the photo-induced elimination of alkyl groups takes place only at the side-chain alkyl-ester group. Photo-induced elimination of ix-methyl groups once postulated 10 both for the y-irradiated PMMA and PEtMA. As shown in Figure 3c, UV-irradiation of the visible light-illuminated sample leads to the conversion of the -COOCHCH3 radicals to acyl-type radicals by reaction, -COOCHCH3 ---+-C = 0 + CH 3 CHO…”

mentioning

confidence: 94%

Thermal and Photo-Induced Reactions of Polymer Radicals in γ-Irradiated Poly(alkyl methacrylate)

Tanaka

Yoshida

Ichikawa

1990

Polym J

View full text Add to dashboard Cite

ABSTRACT:Thermal and photo-induced reactions of radical species generated by y-irradiation of poly(methyl methacrylate) and poly(ethyl methacrylate) have been investigated by means of ESR spectroscopy. The y-irradiation at cryogenic temperature leads to the formation of three major radical species, side chain ---COOC.H 2 • + 1 · -anion radicals and---COOCHC._ 1 H 2 • _ 1 radicals, and main chain -CH-radicals. Cation radicals are immediately converted to the neutral radicals by proton transfer to the polymer molecules. Illumination of the polymer anion radicals with visible light leads to electron detachment or the elimination of ester alkyl groups to form alkyl radicals. Illumination with UV light leads to the conversion of the ---COOCHC. _ 1 H 2• _ 1 radicals to acyl-type-C = 0 radicals. Both the---COOCHC. _ 1 H 2.-1 and the-C = 0 radicals are the precursor of scission-type ·qCH3)(COOC.H2.+ 1)CH 2-radicals.KEY WORDS Poly(methyl methacrylate) / Poly(ethyl methacrylate) /Resist/ Lithography / Radiolysis / Degradation / Chain scission / Radical / ESR / Since poly(alkyl methacrylate)s are typical positive-resist materials in deep UV, electron beam and X-ray lithography, many studies have been carried out for clarifying the mechanism of radiation-induced degradation of poly(alkyl methacrylate)s. It is well known that the irradiation of poly(alkyl methacrylate)s with Ionizing radiations results in the formation of scission-type radicals 1 -3 ·c-(CH3)(COOC.H2.+ 1)CH 2-. The formation of the scission-type radicals strongly suggests that the degradation is induced by the reaction of polymer radicals.Since ionization is the main action of ionizing radiations, radiation-generated positive and negative ion radicals are thought to play important roles in the degradation of the polymers. A considerable amount of spectroscopic studies have been carried out for elucidating the nature and the roles of primary ion rad-* To whom correspondence should be addressed. icals in the degradation of the polymers. 4 -10 However, there have been few consistencies between investigators even for the spectroscopic assignment of the ion radicals. We have recently made the pulse radiolysis studies of poly(alkyl methacrylate) solutions, and determined the optical absorption bands of the polymer anion radicals. 11 We have also made the ESR and electron spin echo studies of yirradiated poly(methyl metacrylate) (PMMA) and found that the y-irradiation at cryogenic temperature leads to the formation of three major radical species, side chain -COOCH 3 ·-anion radials and -COOCH 2 radicals, and main chain -CH-radicals. 12 Upon annealing the polymer to room temperature, the -COOCH 2 radicals were disappeared accompanied by the formation of scission-type ·qcH 3 )(COOCH 3 )CH 2 -radicals, which suggests that the -COOCH2 radicals are respon-835

show abstract

mentioning

confidence: 94%

Thermal and Photo-Induced Reactions of Polymer Radicals in γ-Irradiated Poly(alkyl methacrylate)

Tanaka

Yoshida

Ichikawa

1990

Polym J

View full text Add to dashboard Cite

show abstract

“…193) They later turned out to be PMMA radical anions. 191) This elusiveness of PMMA radical cations is widely believed to be due to their short lifetime.…”

Section: Methacrylate Polymermentioning

confidence: 99%

“…143,191) An excited state of PMMA is also formed through the recombination of an electron with its parent radical cation. The radical cations, 192) radical anions, 193,194) and excited PMMA molecules [195][196][197] are reported to decompose. In either case, the side chain first detaches and a macroradical is formed.…”

Section: Methacrylate Polymermentioning

confidence: 99%

Radiation Chemistry in Chemically Amplified Resists

Kozawa

Tagawa

2010

Jpn. J. Appl. Phys.

336

319

View full text Add to dashboard Cite

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.

show abstract

“…For the calculation, the film was partitioned into 10 layers (rn = 1, 2, -10) from the surface to bottom, and each layer was assumed to have a constant [TMPD?] which was calculated from equation (11) with 1 = (rn -0.5)d. [TMPD~Jtota1 used in simulation was the average of two absorbances of TMPD? at the first and the last irradiation, since [TMPD?]…”

Section: Gpc Curve Simulationmentioning

confidence: 99%

Main chain scission reaction of poly(methyl methacrylate) caused by two‐photon ionization of dopant

Sakai

Tsuchida

Yamamoto

et al. 1995

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

The main chain scission reaction of poly(methyl methacrylate) (PMMA) doped with N,N,N,′,N′‐tetramethyl‐p‐phenylenediamine (TMPD) was examined by ESR spectroscopy and GPC measurement, and the scission mechanism was analyzed. The two‐photon ionization of TMPD with excimer laser excitation at 77 K produced an ester radical anion of PMMA (PMMA·m̌), which becomes the main chain tertiary radical CH2C˙(CH3)CH2after the detachment of the ester side group by annealing of the sample at room temperature. The main chain scission radical ˙C(CH3)(COOCH3)(PMMA˙) which was produced by the β‐scission fromCH2˙C(CH3)CH2showed the 13‐line ESR spectrum instead of the ordinary 9‐line, due to the fast quenching of the sample to 77 K. The change of the molecular weight distribution was measured by GPC after several irradiation‐and‐annealing operations. The simulation of the GPC curve confirmed that the scission re‐action occurs at random in the PMMA chain in the solid and the main chain scission yield from the ester radical anion, [PMMA˙]/[PMMA·m̌], is 0.30. © 1995 John Wiley & Sons, Inc.

show abstract

Ionic species in irradiated poly(methyl methacrylate). A pulse radiolysis and ESR study

Cited by 27 publications

References 11 publications

Thermal and Photo-Induced Reactions of Polymer Radicals in γ-Irradiated Poly(alkyl methacrylate)

Thermal and Photo-Induced Reactions of Polymer Radicals in γ-Irradiated Poly(alkyl methacrylate)

Radiation Chemistry in Chemically Amplified Resists

Main chain scission reaction of poly(methyl methacrylate) caused by two‐photon ionization of dopant

Contact Info

Product

Resources

About