Degradation of poly(methylmethacrylate) by deep ultraviolet, x-ray, electron beam, and proton beam irradiations

Choi, Jong‐Jin; Moore, James A.; Corelli, J. C.; Silverman, J. P.; Bakhru, H.

doi:10.1116/1.584071

Cited by 142 publications

(83 citation statements)

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“…5a, it is found that main-chain scission occurs from only 2.5% and 10% of the polymer radicals generated by benzoyl sidechain cleavage at 30°C and 130°C, respectively. The former value, 2.5%, is quite similar to the value of 2.6% observed with main-chain scission of PMMA after the ester side-chain removal (17). Compared with this, the ratio of 10% indicates much enhanced efficiency of main-chain scission at 130°C.…”

Section: -3supporting

confidence: 67%

“…Photosplitting of the ester side chains of PMMA generates polymer radicals, the structure of which is the same as those from PMMA-PIPK involving the benzoyl side-chain cleavage. PScission proceeds from only 2.6% of the polymer radicals and most of the radicals form C=C bonds in the main chain or the side chain (17) (Fig. 1, c (11 = 1) and d).…”

Section: Introductionmentioning

confidence: 99%

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Photodegradation mechanism of phenyl isopropenyl ketone – methyl methacrylate copolymers in the solid phase and their performance as a deep UV resist

Sugita¹,

Ishida²,

Kushida³

et al. 1995

Can. J. Chem.

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Phenyl isopropenyl ketone (PIPK) copolymer films were irradiated with a low-pressure mercury lamp, and benzoyl side-chain cleavage and main-chain scission at various temperatures were followed by UV spectral changes and gel permeation chromatography, respectively. Quantum yields of both reactions and the ratio of the latter to the former reaction increased markedly above their glass transition temperatures. The rnainchain scission continued to proceed by irradiation even after the side chain ceased to split. These experimental results suggest a new reaction mechanism of photosplitting of the methyl methacrylate ester side chain on the carbon adjacent to the C=C bond followed by p-scission, in addition to the known benzoyl side-chain cleavage followed by p-scission or C=C bond formation. The enhanced quantum yield for the main-chain scission of the PIPK copolymer at 130°C realized sensitivity of 100 mJ/crn2 as a DUV resist, which was 1200 times as high as that of poly(methy1 methacrylate) exposed at room temperature and developed under similar conditions. Key words: N o~~i s h type I cleavage, p-scission of main chain, temperature dependence, photosplitting of ester side chain, conjugated polymer radical.RCsumC : On a irradie des films de copolymtre de phCnyl(isopropCny1)cCtone (PIPK) A l'aide d'une larnpe au mercure A basse pression et on a observe le clivage de la chaine laterale benzoyle ainsi que la scission de la chaine principale, A diverses temperatures, en faisant appel respectivement aux changernents des spectres UV et A la chromatographie par permiation de gel. Les rendements quantiques des deux reactions ainsi que les rapports de la derniere reaction par rapport A la prernikre augmentent d'une faqon marquee au-dessus de leur temperature de transition vitreuse. Sous l'influence de l'irradiation, la scission de la chaine principale se produit encore m&me lorsque la chaine laterale a cesse de se cliver. Ces resultats exptrimentaux suggerent que, en plus du mecanisme connu irnpliquant un clivage de lachainelaterale benzoyle, suivi d'une scission-p ou de la formation d'une liaison C=C, il existe un nouveau mecanisme reactionnel pour la reaction de photoclivage de la chaine laterale du rnethacrylate de rnkthyle; il implique le carbone adjacent de la liaison C% et il est suivi par une scission-p. Le rendement quantique plus Clevt pour la scission de la chaine principale du copolyrnere PIPK, B 130°C, a permis d'atteindre une sensibilite de 100 rnJ/cm2 cornme resistante DUV; cette valeur est 1200 fois plus tlevte que celle du poly(rnCthacry1ate de rnethyle) expose i la ternpirature arnbiante et dCveloppC dans des conditions sernblables.Mots c l b : clivage Nonish de type I, scission-p de la chaine principale, relation avec la temperature, photoclivage de la chaine lattrale ester, radical polyrnere conjuge.[Traduit par la redaction]

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Section: -3supporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Photodegradation mechanism of phenyl isopropenyl ketone – methyl methacrylate copolymers in the solid phase and their performance as a deep UV resist

Sugita¹,

Ishida²,

Kushida³

et al. 1995

Can. J. Chem.

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“…[14][15][16][17][18][19][20][21] Although the picture is not entirely clear, there is a reasonable consensus as to the principal events that occur. 22 The initial absorption of radiation seems to lead to a scission (or chemical transformation) of the ester side chain of a monomer segment.…”

Section: Photochemistry Modelmentioning

confidence: 99%

A model for reaction-assisted polymer dissolution in LIGA.

Larson

2004

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A new chemically-oriented mathematical model for the development step of the LIGA process is presented. The key assumption is that the developer can react with the polymeric resist material in order to increase the solubility of the latter, thereby partially overcoming the need to reduce the polymer size. The ease with which this reaction takes place is assumed to be determined by the number of side chain scissions that occur during the x-ray exposure phase of the process. The dynamics of the dissolution process are simulated by solving the reaction-diffusion equations for this three-component, two-phase system, the three species being the unreacted and reacted polymers and the solvent. The mass fluxes are described by the multicomponent diffusion (StefanMaxwell) equations, and the chemical potentials are assumed to be given by the Flory-Huggins theory. Sample calculations are used to determine the dependence of the dissolution rate on key system parameters such as the reaction rate constant, polymer size, solid-phase diffusivity, and Flory-Huggins interaction parameters. A simple photochemistry model is used to relate the reaction rate constant and the polymer size to the absorbed x-ray dose. The resulting formula for the dissolution rate as a function of dose and temperature is fit to an extensive experimental data base in order to evaluate a set of unknown global parameters. The results suggest that reaction-assisted dissolution is very important at low doses and low temperatures, the solubility of the unreacted polymer being too small for it to be dissolved at an appreciable rate. However, at high doses or at higher temperatures, the solubility is such that the reaction is no longer needed, and dissolution can take place via the conventional route. These results provide an explanation for the observed dependences of both the dissolution rate and its activation energy on the absorbed dose.3

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“…Many fabrication methods of refractive micro-lens were reported (Ref [2][3][4][5][6][7][8][9][10][11][12][13], and most of which used photoresist reflow technique (Ref 2-7). Some micro-optical components were fabricated by molding (either hot embossing or injection molding) (Ref [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Optical Film for LED with Triangular-Pyramidal Array Using Size-Reducible Embossing Method

Liu

Pan

Liu

et al. 2011

J. of Materi Eng and Perform

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This study presents a modified hot-embossing process to fabricate micro-triangular-pyramidal array (MTPA). First, a tungsten (W) steel mold (as the first mold) is manufactured by precision machining including optical projection grinding, lapping, and polishing processes. The dimension of a triangular pyramid with acute angle of 85°on the W-steel mold is about 300 lm in width and 139 lm in height. The pitch between two triangular-pyramidal tips is about 170 lm. Then, only the portion of the tip area of the triangular-pyramidal patterns is transferred on bulk metallic glass (BMG, Mg 58 Cu 31 Y 11 ) using this modified multi-step hot-embossing method to reduce the pattern size. With a position-adjustable mechanism, size-reduced concaved-shaped MTPA can be selectively formed, used as the secondary mold. In this way, not only can the size of triangular-pyramidal patterns on W-steel mold be reduced down on BMG, but also the tool arc between each triangular-pyramid on W-steel mold caused by machine tool can be eliminated. This is based on the fact that amorphous glass alloys contain no dislocation that can be responsible for yielding in crystalline materials. Thus, BMG is expected to be strong and hard enough to be used as a mold material. Then the secondary mold is used to emboss convex-shaped MTPA on PolymethylMethacrylate (PMMA) optical film. Experiments with different embossing times and embossing pressures are conducted and discussed. Large-sized triangular-pyramidal array on the W-steel mold has been successfully and selectively miniaturized on BMG, and then transferred on PMMA. Finally, this optical film of PMMA with MTPA is packaged on light-emitting diode (LED) to improve its lighting uniformity and luminance. In comparison with commercial 3M Ô optical film (3M Ô Vikuiti Ô TBEF2-T-65i), the film with MTPA shows a good optical performance.

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Degradation of poly(methylmethacrylate) by deep ultraviolet, x-ray, electron beam, and proton beam irradiations

Cited by 142 publications

References 0 publications

Photodegradation mechanism of phenyl isopropenyl ketone – methyl methacrylate copolymers in the solid phase and their performance as a deep UV resist

Photodegradation mechanism of phenyl isopropenyl ketone – methyl methacrylate copolymers in the solid phase and their performance as a deep UV resist

A model for reaction-assisted polymer dissolution in LIGA.

Optical Film for LED with Triangular-Pyramidal Array Using Size-Reducible Embossing Method

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