Fluorinated amorphous carbon thin films (a-C:F) for low-dielectric-constant interlayer dielectrics were deposited by helicon-wave plasma-enhanced chemical vapor deposition using fluorocarbon compounds as a source material. The a-C:F films could be grown from C₄F₈ at a high deposition rate (above 400nm/min) and they were thermally stable up to 300°C. The addition of bias power to the substrate made it possible to completely fill gaps in the wiring (space 0.35μm, height 0.65μm) with the a-C:F film. To protect the a-C:F film during further processing, we deposited a SiO₂ film to add mechanical strength and resistance to the oxygen plasma used to remove resist materials. The adhesion between the a-C:F and SiO₂ films was dramatically improved by inserting an adhesion promoter consisting of a-C:H and Si-rich SiO₂.

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The effect of pore distribution on the film properties of low-dielectric-constant porous SOG material has been studied. A novel low-dielectric-constant porous material, Interpenetrated SOG (IPS), was designed to have the pore diameter range below 5nm. It is composed of pyrolic template, which is an organic oligomer, and framework made from SOG polymer and Silica sol, and it has an interpenetrated structure. Thermal decomposition of the organic component successfully resulted in films with pore diameter range below 5nm. It is found that the dielectric constant and the pore diameter are affected by the density, and the film strength is affected by average pore diameter. Practically, films with the average pore size below 5nm possessed dielectric constant as low as 2.2 and sufficient strength.

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Porous polyimide films were prepared by 2 steps. The first step is the preparation of poly(urethane-imide) films by a reaction between phenol-terminated polyurethane prepolymer and poly(amide acid). Polyurethane prepolymer was prepared from the reaction of polyethylene adipate and hexamethylenediisocyanate. Poly(amide acid) was obtained from pyromellitic dianhydride and oxydianiline. The second step is the pyrolysis of the poly(urethane-imide) films. Upon thermal treatment of the poly(urethane-imide) films at 300 to 400°C, the thermally less stable urethane domains decomposed, leaving porous polyimide films. The presence of pores was confirmed from the scanning electron microscope of the surface and the cross-section of the films. The size distribution of the pore was narrow. With the increase of urethane content, the size of the pore increased. Tensile measurements revealed that, with the increase of urethane component, tensile modulus did not vary so much, but elongation and thus tensile strength decreased. Viscoelastic analyses showed that all the porous polyimide films had high glass transition temperature at above 400°C, and storage moduli were maintained up to 400°C.

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This paper presents the science and technology developments in the field of high performance aromatic polyimides and their composites in relation to space applications as follows; 1) Development of polyimides as an high performance materials 2) High perfonnance polyimide film like materials for spacecraft applications such as the multilayer thermal blanket(MLI) and the flexible and/or rigid extendable structures, 3) Development of these heat resistant polyimide matrix resins for advanced composites. Finally, this paper describes the synthesis and properties of a newly developed phenylethynyl-terminated novel asymmetric biphenyltetracarboxylic dianhydride (a-BPDA) derived polyimide matrix resin with high Tg, good processability, and good toughness.

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New photosensitive polyimides containing pendant propargyl ester group were synthesized, and the photochemical reaction of the resulting polyimides was investigated using photo-acid generators. The reaction of 4, 4′-diamino-3, 3′-dicarboxydiphenylmethane with 1.2 times amount of propargyl bromide was performed using 1, 8-diazabicyclo[5.4.0]-7-undecene (DBU), and the targeted diamine monomer containing pendant propargyl ester group was obtained with high yield. Poly(amic acid)s were prepared by the reaction of the diamine monomer containing propargyl ester group with various tetracarboxylic dianhydrides in dimethyl sulfoxide at room temperature for 8h. Poly(amic acid)s were then converted into polyimides using acetic anhydride I pyridine as a dehydrating agent at 90°C for 24h. The photochemical reaction of polyimide films was examined with various photo-acid generators (10mol-%). It was proved that the photoinitiated cationic polymerization of pendant propargyl ester group of the polyimides with photo-acid generator proceeded smoothly under UV-light irradiation to give insoluble polymer films in organic solvents.

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The origin of coloration in aromatic polyimides was elucidated from a viewpoint of quantum chemistry. The MOs and the difference electron density between the ground and the first excited states of the model compounds were calculated using semiempirical AM1 (MOPAC97) and INDO/S (MOS-F) methods. Two model compounds of PI(PMDA-DDE) were adopted for the MO calculations. The calculated λ_max 's were around 390nm, which were in good agreement with the cut-off wavelength of the PI(PMDA-DDE) film. From the CI coefficients, the predominant electronic transition was found to be HOMO→LUMO in each model, and its contribution to the first excited state was estimated to be approximately 50%. The calculations of the MOs and the difference electron density clearly indicate that the benzene ring derived from DDE acts as an electron-donating group and the five-membered imide and the benzene rings derived from PMDA act as electron-withdrawing groups. Therefore, it is evident that a strong intramolecular CT characterizes the first excited state, and this nature of the first excited state based on the predominant HOMO→LUMO transition contributes to the coloration of aromatic polyimides.

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A poly(amic acid) having second-order nonlinear optical (NLO) properties was preparedby the ring-opening polyaddition of pyromelliticdianhydride (PMDA) with 5, 5′-(hexafluoroisopropylidene)bis{2-[2-[N-ethyl-N-(4-(4-nitro-phenyldiazenyl)phenyl)aminoethoxy]aniline]} (HNDA) and bis(4-aminophenyl) ether (BAPE). The polymer containing 30wt% of 2, 3, 4, -tris[1-oxo-2-diazona-phthoquinone-4-sulfonyloxy]benzophenone (D4SB) as a photosensitive dissolution inhibitor functioned as an alkaline developable photosensitive resist, and then was converted to polyimide by coronapoling during the thermal imidi zation process. The secondharmonic coefficient (d₃₃) of the resulting polyimide at the wavelength of 1064nm was 53pm/V(127.3×10^-9 esu) and remained unchanged at elevatedtempemtures.

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Aliphatic polyesters such as polycaprolactone are now widely utilized as a green polymer to avoid serious environmental pollution due to diffusion of plastics waste. Such a polyester contains a carbonyl group in each repeating unit. The Norrish-type photo decomposition, therefore, is expected to occur in these polyester polymers. Accordingly, photo irradiation by a medium pressure mercury lamp was done to the polyester film. It was found that the aliphatic polyester could be utilized for a photodegradable plastics. Photodegradation behavior of the aliphatic polyesters was compared with the biodegradation behavior by means of electron microscopy.

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Photochemical reactions and photochromic reactions are attractive tool as a key step of a variety of functional materials for microelectonics and photonics, and as a molecular probe investigating microstructure of various solid state polymers. Quantitative analysis of the dynamics of the photochemical and photochromic reactions in every stage of the reaction is very important because it involves valuable information on the temporal polymer matrix, while an estimation of the overall quantum yield only gives the average of the kinetics in time and space. This paper presents a basic theory on the kinetics of some photochemical and photochromic reactions. Based on the theory, quantum yield distribution of an azo compound is found to be much larger than that of a diazo compound.

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Water-soluble polyvinyl alcohol (PVA) was modified by uracil derivatives which gave photodimer by UV irradiation. Photo cross-linking of the polymer (PVA-Ura) was carried out in film state on quarz plate by irradiation at 265nm. Photo cross-linking of the polymer was evaluated by development in water The cross-linking was found to be affected by irradiated energy, degree of polymerization of PVA, and kind of uracil derivatives used. High sensitivity was obtained for the polymer having high degree of polymerization. Cross-linking occured at low conversion of photodimerization (1-3%).This result indicated that photodimerization of one uracil unit in one polymer chain caused effective cross-linking of the polymer

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Liquid crystalline (LC) polyacetylene derivative with a hexamethylene chain as a spacer in LC side chain was synthesized. The acetylene monomer substituted with LC group showed both nematic and smectic phases in the cooling process. The polymerizations of the monomers were carried out using Ziegler-Natta and metathesis catalysts. The polymers thus prepared showed smectic phases in heating and cooling processes, indicating an enantiotropic nature. We found that the mesophase of the present polymer is more stabilized with a longer methylene spacer.

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In chemically amplified resists, acid diffusion from a photo-acid generator (PAG) is one of the important factors which control their efficiency. This paper reports observation and estimation of the acid diffusion from PAG (p-nitrobenzyl 9, 10-dimethoxyanthracene-2-sulfonate, NAS, or 2, 4-dinitrobenzyl tosylate, DNBT) in polymer solids (PMMA or PEMA) by using a diffusion-controlled acid-base reaction. Nile Blue A base used as a basic indicator changes its absorption peak by protonation. The rate constants and hence the diffusion coefficients of acids from the PAG in polymer solids were estimated from second-order reaction kinetics.

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Phase-transfer photopolymenzation of methyl methacrylate (MMA) with N-cetylpyridinium chloride (CPC)-KSCN-CCl₄ was investigated in an aqueous-organic two-phase system and Schemes 1 and 2 were proposed as an initiating mechanism for the photopolymerization. At first stage the polymerization of MMA was photoinitiated by N-cetylpyridinium thiocyanate (CPT) in the interface domain to the intermediary polymer with low molecular weight, and at second stage photoinitiated by the intermediary polymer in the organic bulk phase to poly MMA with high molecular weight. Photo-oligomenzation of MMA with CPC-KSCN in the aqueous system was also performed. When ethyl acetate added to the aqueous system as a solvent, the oligomers were obtained without any formation of polymer. By chromatographic separation one of oligomers was identified to be a tetramer of MMA which has a SCN group as both end groups. These results also suggested that the photopolymerization with CPC-KSCN-CCl₄ in the aqueous-organic two-phase system would be initiated by CPT at first stage.

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Based on the rule of M/A value reported by us before, the most preferable ranges of the M/A values of different types of photosensitive compositions before photolysis, i.e. the (M/A)_cb values, the M/A values after photolysis, i.e. the (M/A)_ca values, the R_b/a values which are equal to the values of (M/A)_cb divided by (N/A)_ca and the values of dissolution inhibition index (NQ/M) have been found by the calculation and the performance evaluation of the photosensitive compositions, that is to say, the most preferable range of the (M/A)_cb values is between 8.20 and 9.00, the most preferable range of the (M/A)_ca, values is between (M/A)_B and (M/A)_B+0.5, the most preferable range of the R_b/a values is between 1.20 and 1.40 and the most preferable range of the NQ/M values is between 0.11 and 0.18.

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Six isomers of dihydroxyl benzoic acid and three isomers of trihydroxyl benzoic acid were analysed systematically with thermogravimetric analysis. They, the starting temperatures (T_S), the peak temperatures (T_P) and the end temperatures (T_e) in the decarboxylation reactions, were worked out based on the integral curves (TG) and the differential curves (DTG) in thermogravimetric analysis of these compounds. The carbon atoms of benzene rings connected with carboxyl groups of these compounds are numbered as C₁, and the carbon atoms of carboxyl groups are numbered as C₇. The chemical shift values of C₁ (δ₁) and C₇ (δ₇) are from the NMR spectra of these compounds, and it is found that there is a linear relation between T_P and δ₁ or (δ₇-δ₁). The net charge values of C₁ (q₁) and C₇ (q₇) are from the calculations of quantum chemistry. After compared δ₁ and(δ₇-δ₁) with q₁ and(q₇-q₁) respectively, it is also found that there are linear relations between them. These prove that there is a close relation among δ_i, q_i and the reactivity of i-position on the benzene ring of a phenolic compound.

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The electronic structure of various hydroxyl substituted benzoic acids is studied by using ab initio method at HF/6-31G* level. The importance was put on the charge distribution on benzene ring and the effect of hydroxyl group. The total negative charge on benzene ring is in inverse proportion to the number of hydroxyl substituents. The net charge change on carbon atoms of benzene ring of multi-hydroxyl benzoic acids induced by hydroxyl is very close to the simple addition of that of corresponding mono-hydroxyl benzoic acids. These phenolic acids possess one to three active sites on benzene ring where the negative charges are much more than that of other sites and than that of unsubstituted benzoic acids. The relationship of electronic structure and reactivity of the compounds is discussed. The lower decarboxylation temperature is found to be well correlated with the more negative charge on the carbon atom linked to carboxyl group for most of the measured phenolic acids.

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The three long-wavelength photosensitive initiating systems which composed of photosensitizer 3-acetvl-7-N, N-diethylamino coumarin(C1) or 7-diethvlamino-3-(2′ -benzimidazolyl) coumarin(C2), or 7-diethylamino-3-(2′ -N-methylbenzimidazolyl) coumarin(C3) and photoinitiator 2-chlorohexaarylbiimidazole(o-Cl-HABI), and hydrogen donor coinitiator n-dodecyl mercaptan (SH) were studied. The results showed that when exposed to visible light, biimidazole and coumarin underwent electron transfer from coumrian to biimidazole and free radical was produced. The relationship between the photopolymerization rate of methyl methacrylate(MMA) and concentration of C1 and o-Cl-HABI was studied.

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The ultraviolet photosensitive initiating system is composed of 4, 4′ -bis(N, N′-dimethyl-amino)benzophenone(MK), 2-chlorohexaarylbiimidazole(o-Cl-HABI) and a hydrogen donor coinitiator n-dodecyl mercaptan(SH). Under the irradiation by high pressure mercury lamp, the relationship between the photopolymerization rate of MMA and the concentration of each component of the system, including MK, o-Cl-HABI and SH, was studied. The excellent results have been obtained through studying the system's application on PS lithographic printing plate.

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Calix[4]resocinarenes(C4-RAs), "C-tertaheptyl-calix[4]resorcinarene [C(7)C4-RA], C-tertaoctyl-calix[4]resorcinarene [C(8)C4-RA], C-tertanonyl-calix[4]resorcinarene [C(9)C4- RA], and C-tertaundecyl-calix[4]resorcinarene [C(11)C4-RA]", were synthesized by the acid-catalyzed condensation of resorcinol and alkylaldehyde. The obtained C4-RAs were well-dissolved in common organic solvents and their films were transparent above 300nm. Therefore, negative working photoresists based on C4-RAs, 4, 4′-methylenebis[2, 6-bis(hydroxymethyl)]phenol (MBHP) as a cross-linker, and a photo-acid generator diphenyliodonium 9, 10-dimethoxyanthracene-2-sulfonate (DIAS) has been developed. Particularly, the resist containing C(8)C4-RA had the dissolution property well-controlled by a conventional aqueous base developer [2.38wt% aqueous tetramethylammonium hydroxide(TMAH) solution]. Thus, the photoresist consisting of C(8)C4-RA (70wt%), MBHP (20wt%), and DIAS (10wt%) showed a sensitivity of 7mJ/cm^-2 and a contrast of 6.1 when it was exposed to 365nm light and postbaked at 130°C for 3min, followed by developing with the TMAH developer at room temperature.

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A positive working thermally stable and photosensitive polymer based on poly(2-hydroxy-6-methylphenol-co-2, 6-dimethylphenol)(PHP-MP) and 2, 3, 4-tris[2-diazo-1(2H)-naphthalenone-4-sulfonyloxy] benzophenone (D4SB) as a photoreactive compound has been developed. The copolymer PHP-MP was prepared by oxidative coupling polymerization of 2-(tetrahydropyran-2-yl)oxy-6-methylphenol with 2, 6-dimethylphenol, followed by acid treatment. The PHP-MP film showed excellent transparency above 300nm. The dissolution behaviour of the PHP-MP film containing 30wt% of D4SB after exposure and post exposure bake (PEB) has been studied and it has been found that the dissolution rate of an exposed area was 200 times faster than that of an unexposed area, due to the photochemical reaction of D4SB in the polymer film. This system containing 25wt% of D4SB showed a sensitivity of 75mJ/cm² and a contrast of 1.5 with 365nm light, when it was post-exposure baked at 100°C for 3min, followed by developing with a 2.38wt% aqueous tetramethylammonium hydroxide solution at 25°C.

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New negative electron-beam (EB) resists based on ring-chain tautomerism of benzoic acid derivatives have been developed. o-Acetylbenzoic acid (ABA), which converts into the ring-tautomer through a hydrogen transfer from the carboxyl group to the carbonyl group, was selected as the precursor of dissolution inhibitor for the new resist. The resist composed of ABA, diphenyliodonium triflate, and m, p-cresol novolak resin enables us to define 300-nm line and 500-nm space patterns with a dose of 75μC/cm² at 70kV. Spectroscopic studies show that the acid-catalyzed protection of hydroxyl groups of novolak resin brought about by ABA is responsible for the resist insolubilization.

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Nano-scale AFM lithography using the space area between the resist patterns of a negative-type resist was developed. A 15-nm-wide space line pattern could be fabricated on a 50-nm-thick resist film. Using this method, we fabricated a 25-nm-wide Ni line pattern.

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Novel water-soluble azide polymer (PVA-ARBB) was prepared by acetalizing poly(vinyl alcohol) (PVA, degree of polymerization(DP), 1700; 88% saponified; 1.0mol% acetalized) with the sodium salt of 5-(4-azido-2-sulfobenzylidene)-3-(4, 4′-dimethoxybutyl)rhodanine (ARBB). PVA-ARBB showed high sensitivity (E_0.5=0.8mJ/cm², d=1.0μm) under low light intensity (0.15mW/cm², UV-35). PVA-ARBB was tested as a water-soluble photoresist in comparison with an established system of base polymer and a bis-azide compound, sodium 4, 4′-diazidostilbene-2, 2′-disulfonate (DAzSTNa) and proved itself as a superb substitute for DAzSTNa. When poly(vinylpyrrolidone) (PVP) was used as basic polymer, PVA-ARBB/PVP/DAzSTNa (10/100/10 by weight) showed higher sensitivity (E_0.5=0.7 mJ/cm², d=0.7μm) than that of PVP/DAzSTNa (100/10 by weight, E_0.5=9.0mJ/cm², d=0.7μm).

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We have studied the chemical changes that result in photoresist due to various stresses that the photoresist is subjected to during the recovery and reclamation process.
(1) When the roll coater recovery photoresist is kept open at room temperature for 50 days, needle-shaped crystals formed in recovery photoresist. Examination by X-ray diffraction revealed that those crystals are ammonium zinc sulfate hexahydrate that was dissolved from the roll material of coater. It is possible to avoid this problem by appropriate selection of the material that comes in contact with recovered photoresist.
(2) When new, tightly sealed photoresist was subjected to thermal stress at 40°C for 100 days, a bead-shaped coagulated material appeared. NMR analysis showed that the coagulated material was mainly a photosensitive ester tetramer formed by a thermal change. In the case of the spin coating, although there is virtually no damage from physical stress, water content of about 1% is absorbed from the air during the spin-coating process, and the photo-active compound is decomposed by the thermal stress on the photoresist, lowering the photosensitivity. This change in the photosensitivity of the photoresist can be virtually eliminated if the photoresist contains no water so that the photo-active compound chemical change does not occur during the distillation process.
(3) In the reclamation of photoresist, (a) the photoresist is coated in a dry nitrogen atmosphere with no water content, and next (b) the photoresist in a coater cup is dissolved by a photoresist-solvent and recovered, and then (c) the viscosity of the recovered photoresist is adjusted by distillation is filtered at the end. Fresh photoresist is replenished to it. We offer the resist reprocessor herein.

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The enhancement mechanisms for photoinitiators comprising an aminostyryl dye and a radical generating reagent by a 2-mercaptobenzothiazole (MBT): aminostyryl-dye; 2-[p-(diethylamino)styryl]naphthol[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 have been investigated by laser flash photolysis using a total reflection cell.

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A dye recycled photosensitization system composed of Eosin Ethyl Ester Iodonium Salt (EOEtIPh₂) and basic H-donor has been designed. As a result of studies in the mechanism of electron transfer reaction of xanthene iodonium salt, it is proposed that the dye-recycled process consists of three-step reactions during the photosensitization: The oxidative fading product (I) of due is formed through electron transfer under irradiation; In the presence of H-donor, product (I) changes into acidic leuco dye product (II); Product (II) undergoes deprotonization under action of base to regenerate initial dye. The roles of light, H-donor and base are three major factors in the process of dye regeneration. The results obtained show that their efficiency of sensitization is 4 times higher than that of single system EOErIPh₂, and the photopolymerization rate is also significantly promoted due to multiplication of radicals formed in the dye recycled photosensitization process.

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