Deblocking reaction mechanisms of two kinds of chemically amplified resist systems were studied using the in-situ FT-IR measurement system. From the measured results, photoacid generation reaction constants, deblocking reaction orders for the acid concentration and deblocking reaction rate constants were estimated. In the case of 1-ethoxyethyl group, the deblocking reaction order for the acid concentration was very small (10^-4). The activation energies of the deblocking reactions in an acetal type resist and a t-Boc type resist were calculated from the Arrhenius plots of deblocking reaction constants and these values were agreeable with the results of molecular orbital calculations.

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The sensitization mechanisms for photoinitiations comprising a 2, 8-diethyl-1, 3, 5, 7, 9-pentamethylbipyrromethene difluoroborate (EBP) and a 1, 3, 5, 7, 9-pentamethylbipyrromethene difluoroborate (HBP), and a radical generating reagent, 3, 3′, 4, 4′-tetrakis(t-butylperoxycarbonyl)benzophenone (BTTB) in a poly(methyl methacrylate) (PMMA) film have been investigated by laser flash photolysis using a total reflection cell and cyclic voltammetry. Effect in sensitization mechanisms with incorporating ethyl group into bipyrromethene dye was discussed.

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The sensitization mechanisms for photoinitiators comprising a subphthalocyanine dye and a radical generating reagent; 2, 4, 6-tris(trichloromethyl)-1, 3, 5-triazine (TCT) in a poly(methyl methacrylate) film have been invesigated by laser flash photolysis using a total reflection cell.

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The sensitization mechanisms for photo-initiations comprised a sensitizer dyes such as 2, 8-diethyl-1, 3, 5, 7, 9-pentamethylbipyrromethene difluoroborate (EBP), 1, 3, 5, 7, 9-pentamethyl-bipyrromethene difluoroborate (HBP), and 2, 8-diethyl-1, 3, 5, 7-teramethyl-9-phenylbipyrromethene difluoroborate (PBP), and a radical generating reagent 3, 3′, 4, 4′-tetrakis(t-butylperoxycarbonyl) benzophenone (BTTB) in acetonitrile have been investigated by singe photon counting.

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Photoinitiation mechanisms of photopolymer coating layer containing a heptamethine cyanine dye and a radical generating reagent were investigated by laser flash photolysis using a total reflection cell. From fluorescence quenching studies, it was found that singlet static sensitization process was predominant for CDB-TCT systems.

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The cyclized copolymers from N-cyclohexyldimethacrylamide (CHDMA) with t-butyl methacrylate (tBuMA) or tetrahydropyranyl methacrylate (THPMA) were synthesized. These copolymerizations occurred by general technique of radical polymerization and CHDMA mainly proceeded the cyclized reaction. The copolymers have high transmittance at 248nm. These copolymers indicated high thermal property due to the cyclic structure in the main chain. The ester unit of the side chain was easily cleaved by baking with acid catalyst. The acid reaction was dependent on a number of methacrylate units and a kind of ester group. However, the cyclized unit from CHDMA was no changed on this process. We applied these copolymers to photoresist based on the chemically amplified system with PAG and obtained patterns of positive-tone image.

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A series of different acid value polyimides with carboxyl groups in the ends of main chain was synthesized and used for the three-component photopolymers, consisting of the polyimide, a vinyl ether monomer, and a photo-acid generator (PAG). This polyimide acts as a positive-type resist with the process of prebaking (PB), exposure to light, and post-exposure baking (PEB). The effect of the acid value correspond to molecular weight on the characteristics of the photopolyimide, such as sensitivity and contrast, was investigated. An increase in the acid value and a decrease in the molecular weight enhance the increment of sensitivity based on solubilization rate by cleavage reaction. This positive-type photopolyimide showed a sensitivity of 137mJ/cm² and a gamma value of 2.9.

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Free volume characteristics in poly(n-alkylphenylsilane)s whose n-alkyl side-group was changed from methyl to n-dodecyl were investigated by positron annihilation technique at room temperature. The average radii of free volume increase in two steps, one is observed with an increase in the length of n-alkyl side-groups from methyl to n-pentyl, the other from n-hexyl to n-dodecyl with an interruption between n-hexyl and n-pentyl. The radius in poly(n-hexylphenylsilane) is smaller than that in poly(n-pentylphenylsilane). This agrees with the result of the theoretical calculation that n-hexyl side chain is entangled leading to suitable packing in the literature.

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For development and improvement of chemically amplified resists, the mechanisms of acid-generation reactions and the matrix effects were studied by using a pulse radiolysis technique. Ionic and nonionic acid generators act as electron scavengers when irradiated with an ionizing radiation in methanol solutions, resulting in the formation of Brφnsted acids. Rate constants for the reactions of the acid generators with a solvated electron have been determined. The rate constants of the onium salts were in the range of (1.6-2.7)x10¹⁰M^-1 s^-1. The nonionic acid generators were also found to be highly reactive to the solvated electron. Regardless of the structures and the polarities, the acid generators contribute to the acid generation by scavenging the solvated electron with the rates close to the diffusion-controlled limit. The reaction of acid generator with electrons trapped by base polymer was clarified. It would appear that electron scavenging reaction by acid generator in chemically amplified EB resist have two processes, and both process contribute to acid generation mechanism.

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Water-soluble polyvinyl alcohol (PVA) was modified by thymine derivatives, which gave reversibly photodimer by UV irradiation. Photo-cross-linking of the polymer (PVA-Thy) was carried out in film state on quartz plate by irradiation at 280nm.PVA containing thymine had good sensitivity compared with uracil. Photodimerization of the ester derivative was faster than the acetal derivatives, but the sensitivity was lower because solubility in water was high. Reverse reaction of photodimerization was almost complete, but the reversibility of solubility was not complete. This fact indicated that hydrogen bonding between PVA was formed during photodimerization reactions.

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Photodegradation of acrylate, methacrylate, and styrene type polymers was investigated under nitrogen using 146nm light from Kr₂ excimer lamp. Photochemical reactivity of poly(methacrylates) and poly(acrylates) was dependent on the structure of the ester units. Cleavage of ester units and formation of double bonds were observed. Decrease of film thickness due to ablation was observed. Poly(methacrylates) films irradiated at 146nm were soluble in tetrahydrofuran (THF) but irradiated poly(acrylates) films were not soluble. Thickness decrease of styrene based polymer films did not occur on irradiation with 146nm light. The irradiated polystyrene film was insoluble in THF but poly(α-methylstyrene) film was soluble in THF after irradiation. The irradiated poly(p-hydroxystyrene) and poly(p-hydroxy-α-methylstyrene) films were insoluble in THF. It was found that tertiary hydrogen atoms in the main chain and phcnolic OH groups participated in crosslinking of the polymers.

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