The demand for smaller device dimensions in microlithography drives the need to understand and control diffusion during photoresist processing.
In advanced chemically amplified systems the lithographic performance is strongly influenced by diffusion of acid and base additives. Photoacid generation efficiencies and diffusion parameters were quantitatively evaluated using an established in situ photometric method employing a pH-sensitive organic dye. [1-3] A kinetic model for the post-exposure bake (PEB) has been proposed, transferred to molecular reaction dynamics and extanded to transport properties. The experimental data for this model have been obtained from UV/VIS spectroscopy measurements. The UV/VIS data show that a photoacid loss reaction during post-exposure bake has to be taken into account. Rough estimations of the acid diffusion lengths are given by the rate of the diffusion-controlled neutralization reaction for blanket exposures. The acid diffusion range was minimized, as the temperature of pre baking was raised and the PEB temperature was reduced. Chemical kinetics around the glass transition temperature of the resist are discussed.
Furthermore, a face-to-face contact experiment (wafer-sandwich) involving the dye was used to determine acid loss during PEB. Comprehensively, the acid diffusion within the matrix and acid evaporation out of the matrix could be quantified.
Results are used to improve the lithographic performance of the dual-wavelength CARL® [4, 5] resist system presently used at Infineon Technologies.

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Quenching of imidazoyl radical (Im•) formed in photoinitiator systems comprising an aminostyryl-dye and a radical generating reagent by a 2-rnercaptobenzothiazole (MBT):aminostyryl-dye; 2-[p- (diethylamino)styryl]naphtho[1, 2-d]thiazole (NAS), radical generating reagent; 2, 2′-bis(2-chlorophenyl)- 4, 4′, 5, 5′-tetraphenyl-1, 1′-bi-1H-imidazole (BI) in a poly(methyl methacrylate) film has been investigated by laser flash photolysis using a total reflection cell.

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We studied the photochemical reaction of polymers used as resists by 146-nm light exposure. In methacrylate polymers, the main-chain scission was induced by the decomposition of the carbonyl moieties. In poly (hydroxystyrene)-type polymers, the polymer backbone was crosslinked. In norbornene carboxylate polymers, the carbonyl moieties decomposed by 146-nm light and the crosslinking of the polymers occurred.

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The cyclic bisthymine compounds were prepared in order to obtain the complete reversible photodimerization system. The photodimerizations of the bisthymine compound and the cyclic bisthymine compound in dilute solution were very fast by irradiation of UV light at 280nm, and the photodimers gave the original thymine compounds effectively by irradiation at 240nm. The GPC and the NMR data indicated that the photodimer obtained was the cis-syn isomer which was active for the photosplitting reaction. In thin solid film, however, the conversion and the rate of the photodimerization were lower than the results in dilute solution. The reason for this finding was concluded to be the presence of conformer which was inactive for the photodimerization.

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To reveal bulky-substituent effect of pyrromethene dye in sensitization mechanisms in photopolymer layer for laser-printing plate, the sensitization mechanisms of a pyrromethene dye, which has a bulky t-butylmethyl group at 5 atom, with a radical generating reagent, 1, 3, 7, 9-tetramethyl-5-t butylmethylpyrromethene-BF₂ (BHB) and with 3, 3′, 4, 4′-tetrakis(t-butyldioxycarbonyl)benzophenone (BP), in a poly(methylmethacylate) (PMMA) film were investigated by means of both laser flash photolysis using total reflection cell and a single photon counting as well as in dilute solution, and compared to the sensitization mechanisms for a pyrromethene dye, which has a non-bulky methyl group at atom 5, 1, 3, 7, 9-tetramethyl-5-methylpyrromethene-BF₂ (BHM) [l-i].

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Water dispersible microgels, ultrafine particles made of a polymer gel with a core-shell structure, were prepared by the emulsion copolymerization of lauryl methacrylate, ethylene dimethacrylate and water-soluble acrylic resin as the reactive polymer emulsifier. The core-shell type microgels were modified by glycidyl methacrylate and the amount of the methacryloyl group was controlled in the shell structure. These reactive microgels formed an emulsion with water. The minimum film forming temperature (MFT) of these emulsions varies with the composition which cosists of a different wall (core) and outside (shell). By using these reactive microgels, water-dispersible photopolymer microgels were prepared with a monomer and a photoinitiator. The amount of the methacryloyl group in the shell of the microgels affects the characteristics and properties of the microgel and the photopolymer microgels, such as viscosity, particle diameter, MFT and the rate of photopolymerization (Rp). The materials performed the pattern forming on a screen printing plate through the development process using water.

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The cyclized copolymerization of methacrylic anhydride with N phenyldimethacryl- amide and methacrylonitrile was carried out. The polymer consists of six-membered cyclic acid anhydride and five-membered imide ring. The cyclic acid anhydride was hydrolyzed by generated acid catalyst from photo-acid generator (PAG). The hydrolyzed copolymer is dissolved in an alkaline solution. We applied this copolymer with PAG to photoresist based on the chemical amplified system and obtained good patterns of positive- tone image.

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Positive-working photoresists based on poly(p-hydroxystyrene) (PHS), 2, 2-bis[4-(2- (vinyloxy)ethoxy)phenyl] propane (BPA-DEVE) has been investigated on their sensitivities to 488-nm argon ion laser using binary acid generated system. 2-(2′, 4′-dimethoxystyryl)- 4, 6-bis(trichloromethyl)-1, 3, 5-triazine (TAZ114), diphenyliodonium p-toluenesulfonate (DITS) and diphenyliodonium trifluoromethanesulfonate (DITFMS) were used as photoacid generator. Acridine orange, rose bengal, thioxanten-9-one and 3, 3′- carbonylbis(7, 7′-diethylaminocoumarin) (KCD) were used as sensitizing dye. In these photopolymers, the polymer containing of TAZ114 and acridine orange exhibits the highest sensitivity to 488-nm light at 147.5mJ/cm².

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Photochemical reaction of a new aromatic amine with dual reaction sites for the ring closure, 1, 3, 5-tris(diphenylamino)benzene (TDAB), was investigated to clarify its photochemical reaction course and the effect of oxygen on the photochemical reaction. It was found that TDAB undergoes photocyclization reaction in solution in the absence or presence of oxygen to produce N-phenyl-2, 4-bis(diphenylamino)carbazole. The product analysis and the result of laser flash photolysis indicate that the reaction mechanism for the photocyclization of TDAB is different between the deaerated and oxygen-saturated systems. Photocyclization reaction of TDAB in the absence of oxygen takes place via the electronically excited triplet state of TDAB, followed by the formation of the dihydrocarbazole. In the presence of oxygen, the dihydrocarbazole radical cation is suggested to be involved as an intermediate.

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