New Photosensitive High Temperature Polymers for Electronic Applications

A new photosensitive high temperature polymer stable up to 500%deg;C with high photosensitivity and high resolution has been developed. The trend toward a high degree of integration in solid-state technology requires the use of new high temperature photosensitive insulating materials. Toray's Photoneece system provides such versatile polyimide pattern-generation techniques, containing a unique photosensitive polyimide precursor which can be spun or coated on the substrate. The resultant relief of photosensitive polyimide precursor, after exposure to UV light with a mask, development, and cure processing, is transformed into a cyclized aromatic polyimide. The new system has higher photosensitivity and resolution and eliminates three steps in the conventional pattern-making process for integrated circuits, resulting in a significant cost reduction. The characterization of pattern generation, the conversion to polyimide patterns, and the properties of both Photoneece and the patterns are discussed.     

Development and commercialization of ionic-type photosensitive polyimides

Toray's ionic-type photosensitive polyimide, “Photoneece”, is widely used as an interdielectric and as a protection layer for microelectronics, because of its properties, such as the removal of photoreactive groups at low temperature, excellent thermal, mechanical and electrical film properties and excellent adhesion to various substrates. Toray has developed a new type of “Photoneece”, UR-5100, which is a low-stress photosensitive polyimide. In addition to a low thermal expansion coefficient (25 ppm/°C), “Photoneece” UR-5100 also features high resolution with an aspect ratio of more than 2.0 in 40 μm imaged film, and excellent mechanical properties in the cured film such as high elongation (>20%) and tensile strength (>200 MPa), even after 60 hr heat treatment at 350°C. “Photoneece” UR-5100 can be applied in multichip modules (MCMs), hybrid circuits, ICs and LSIs. In this paper the characterization and processing of this “Photoneece” UR-5100 are described.     

Adhesive interface interactions between primary aliphatic amine surface conditioners and polyamic acid/polyimide resins

The interface reactions of 3-aminopropyltriethoxysilane treated surfaces, with the polyamic acid/polyimide resin formed from pyromellitic dianhydride and oxydianiline, were defined in bulk reactant systems and by FTIR analysis on the surface layers of germanium internal reflection plates. Adhesion between these interfacial layers is the result of chemical bonding, which proceeds through initial carboxylate salt formation between the amino function of the silylated surface and the car-boxylic acid present in the polyamic acid. Heating results in dehydration and amide formation, which is followed by preferential incorporation of the alkyl, surface-bound amine (stronger base), over the aromatic polymer amine, in an imide linkage. Aromatic imides formed before or during thermal curing may also be preferentially opened in a modified Ing-Manske reaction and reclosed to the more stable surface-bound alkylimide. Apparently polymer scission at the aromatic amide linkages occurs in this adhesion process, preferentially bonding surface-bound alkyl amines to one end of a shortened polymer chain.     

Adhesive interface interactions between primary aliphatic amine surface conditioners and polyamic ester/polyimide resins

The interface reactions of 3-aminopropyltriethoxysilane treated surfaces, with a polyamic alkyl ester/polyimide resin formed from pyromellitic dianhydride and oxydianiline, were defined by Fourier Transform Infrared (FTIR) analysis on the surface layers of germanium internal reflection plates. Adhesion between these interfacial layers is the result of chemical bonding, which apparently proceeds through initial amide formation between the amino function of the silylated surface and the alkyl ester group present in the polyamic ester. Heating results in diamide formation by a second alkyl, surface-bound amine displacing the aromatic polymer amine. Heating the more stable dialkyldiamide to 300°C imidizes both the polymer and the interfacial region, producing a strong laminate composite. Polymer scission at the aromatic amide linkages occurs in this adhesion process, bonding surface-bound alkyl amines to one end of a shortened polymer chain.     

Light-induced ESR Studies of Electron Transfer Mechanism of Triazo Pigments

Triazo pigment is a new class of excellent organic photoconductive materials, which is synthesized with tertiary aromatic amines and different couplers. The tertiary aromatic amine is a typical electron donor^[1]. After irradiation, the electron-donating ability of excited states becomes stronger than that of ground states, radical pair and radical ions are considered to be key intermediates. In the present work, the light-induced ESR spectra of 3-As-SG under different conditions are investigated. It is verified that an electron-transfer process occurred.     

Synthesis and Properties of Hyperbranched Polyimides Combined with Silica

Summary: The novel hyperbranched polyimide - silica hybrid materials containing theoretically 16 wt% of an inorganic phase were prepared via a sol-gel process. An amine terminated polyimide precursor (hyperbranched polyamic acid) was prepared from commercially available monomers 4,4′,4″-triaminotriphenylmethane and 4,4′-oxydiphthalic anhydride in molar ratio 1:1. Tetramethoxysilane and/or 3-glycidoxypropyltrimethoxysilane (also used as a coupling agent) were used as silica precursors. During thermal exposition the polyimide precursor was transformed to hyperbranched polyimide and hydrolyzed alkoxy groups reacted mutually to form silica. The final products were self-standing films, whose structure was characterized by using IR and ¹³C and ²⁹Si solid state NMR spectroscopy. The influence of the amount of silica and/or coupling agent on their structure and thermal properties was described.     

新的离子型光敏聚酰亚胺

合成了新的复合光敏聚酰胺酸季铵盐，研究了光敏剂、交联剂以及化学结构对感光度的影响，并考察了其热稳定性。结果表明以3，3′，4，4′－联苯四酸二酐－间苯二胺为主链的聚酰胺酸合成的光敏聚酰胺酸季铵盐有较高的感光度，光敏剂米氏酮的含量在3－5％，交联剂2，6－双（4－叠氨苄基）－4－甲基环己酮的含量在8－10％为宜；光敏性叔胺二甲氨基乙醇肉桂叉乙酸酯的含量不可超过8％；由这种复合季铵盐合成的新的光敏聚酰胺酸盐在较低的温度200℃以下就可以完全酰亚胺化，但接近550℃才达到理论失重量。     

Molecular orbital analysis of the XPS spectra of PMDA-ODA polymide and its polyamic acid precursor

The calculated carbon 1s (C1s) core energy-level positions of PMDA-ODA polymide and of its polyamic acid precursor are compared with the level positions inferred from XPS measurements. For the polyamic acid, calculation and experiment both yield a difference of approximately 1 eV between the carboxylic acid and the amide carbonyl C1s level positions. The difference in shape between the main C1s XPS peaks of the polyamic acid and polyimide is shown to be related to the difference in C1s core energy-level shifts of the carbon atoms composing the benzene ring adjacent to the amide or imide group. The planar imide or PMDA structure apparently yields larger core level shifts for these atoms. We have previously designated these atoms as “imide carbon atoms” (C-Im) to distinguish them from the aromatic carbon atoms (C-C) of the ODA part of the polymeric repeat unit. Comparison of the carbonyl XPS band intensities with the main peak intensities for the polyamic acid, as well as for the polyimide, suggests that there is a carbonyl deficiency at the surface of both of these materials.     

Synthesis of New Functional Silicon-Based Condensation Polymers

A new class of photosensitive aromatic polymers containing disilane units was successfully synthesized from new disilane-based monomers such as 1,2-bis(diethylamino)tetramethyldisilane and 1,2-bis(p-aminophenyl)tetrarnethyldisilane. The disilane-contain-ing aramids and polyimides had glass transition temperatures above 190°C, and all the polymers were thermally stable up to 300°C in air. The polymers were photosensitive; their molecular weight decreased rapidly upon ultraviolet light irradiation. The photosensitive polymers, especially the soluble polyimides having diphenyl sulfone units, were potential candidates for positive working photoresist materials. New highly branched polysiloxane star-burst polymers were synthesized by a siloxane synthetic reaction starting from tris[(phenyldimethylsiloxy)dimethylsiloxy]methylsilane and bis[(phenyldimethylsiloxy)methylsiloxy]dimethylsilanol as the initial core (G0-Ph) and the building block, respectively. Thus, the first generation polymer G1-Ph, second generation polymer G2-Ph, and third generation polymer G3-Ph had 6, 12, and 24 phenylsilyl groups in their exterior layers. The formation of the siloxane-based starburst polymers were confirmed by means of ¹H-, ¹³C-, and ²⁹Si-NMR spectroscopy. These polysiloxane starburst polymers were suggested to have spherical structure. Some functionalized starburst polymers were further synthesized by the introduction of functional groups in their exterior layers. New silica-polyimide hybrid materials were prepared by the sol-gel process through the hydrolysis-condensation reactions of tetraethoxysilane in the presence of the polyamic acid (polyimide precursor) in dimethylacetamide, followed by heating at 270°C. The hybrid system having silica content up to 70 wt% had good quality films. The spherical silica particles were dispersed homogeneously in the polyimide matrix. With increasing silica content, the glass transition temperature and decomposition temperature, as well as the modulus of the hybrid films, increased, while the coefficient of thermal expansion decreased.     

Facile modifications of a polyimide via chloromethylation. I. Novel synthesis of a new photosensitive polyimide

A soluble aromatic polyimide was chloromethylated via a reaction with chloromethyl methyl ether in the presence of tin(IV) chloride to produce a new starting material for the modification of aromatic polyimides. The chemical structure of the resulting polymer was confirmed by ¹H NMR and Fourier transform infrared spectroscopy. The maximum number of chloromethyl groups per repeat unit was 1.81. The chloromethylated polyimide was stable up to 250 °C and soluble in both chloroform and tetrahydrofuran. So that its utilization for further modification could be demonstrated, cinnamic acid was reacted with the formed polyimide, and it produced a new photosensitive polyimide with a cinnamoyl side chain. The photosensitivity of the resulting polyimide was investigated with ultraviolet spectroscopic methods. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 22–29, 2003     

Mono-layer of Ni(100-x)Fe(x) nanoparticles fabricated on a polyimide film under different curing atmospheres

A mono-layer of nano-sized metal particles was prepared on the surface of a polyimide film by simply depositing a thin film of Ni80Fe20 on top of the polyamic acid that was spin coated onto a Si wafer. During thermal imidization of the polyamic acid film, Fe was selectively etched by reacting with the carbonyl group of the polyamic acid to leave behind uniformly distributed Ni-rich metallic particles. The average diameter of the particles was 4 nm and the particles were confined into a single layer on top of the polymer film. Moreover, it was also shown that the morphology of the nanoparticles can be substantially altered by curing the precursor film in a hydrogen atmosphere, without significantly damaging the polymer film. Thus produced nanoparticles lay exposed on top of the electrically insulating and chemically stable polymer film so that it is possible that the nanoparticles can be directly used for fabricating a nonvolatile flash memory device or as a template for building functional nano-structures.     

Preparation and properties of new photosensitive polyimides from bis(4-aminophenyl)tetramethyldisilane and various aromatic tetracarboxylic dianhydrides

New photosensitive polymides containing photosensitive disilane unit were synthesised from 1,2-bis(4-aminophenyl)tetramethyldisilane and various aromatic tetracarboxylic dianhydrides by the usual two-step procedure that includes ring-opening polyaddition to yield the precursor polyamic acids, followed by cyclodehydration giving the respective polyimides. The polymaic acids had inherent viscosities between 0.63 and 0.85 dL/g depending on the tetracarboxylic dianhydride used. Excepting the polyimide obtained from pyromellitic dianhydride, all other polyimides were soluble in N-methyl-2-pyrrolidone, m-cresol, and pyridine. While the polyimide containing diphenyl sulfone unit was amorphous, the other polyimides were semi-crystalline polymers based on their x-ray diffractograms. The polyimides had glass transition temperatures between 235 and 304°C. They were thermally stable up to 380°C in both air and nitrogen atmospheres. All the polyamic acids showed a drastic decrease in the inherent viscosity upon UV light irradiation, implying the inherent photosensitivity of the polymers containing the disilane moiety.     

Negative-type photosensitive polyimide precursors developable with aqueous alkaline solutions

New photosensitive polyimide precursors developable with aqueous alkaline solutions were synthesized. Among diamine monomers having a photofunctional group, 2′-(methacryloyloxy)ethyl 3,5-diaminobenzoate yields high molecular weight polyamic acid. A photosensitive polymer composition consisting of Michler's ketone and a thermally stable peroxide, 3,3′,4,4′-tetrakis(t-butyldioxycarbonyl)benzophenone, results in a high photosensitivity of 200 J/m². The photosensitive coating of the composition is soluble in aqueous alkaline solutions as well as in organic aprotic polar solvents, and both solvents can be used as developers. However, the resolution of patterns is quite different, especially in thick films. Solvent developers results in poor resolution, whereas aqueous alkaline developers give patterns of high aspect ratio even in thick films. This is probably due to the difference in the diffusion efficiency and swelling properties of the polymer compared to the developers.     

SPIN-TRAPPING and ESR STUDIES OF THE DIRECT PHOTOLYSIS OF AROMATIC AMINO ACIDS, DIPEPTIDES, TRIPEPTIDES and POLYPEPTIDES IN AQUEOUS SOLUTIONS—III. TRYPTOPHAN and RELATED COMPOUNDS

Abstract— The UV photolysis of tryptophan (Trp) and Trp-containing peptides in aerated aqueous solutions has been studied by ESR and spin-trapping techniques using f-nitrosobutane as the spin-trap. The photolysis of Trp alone at 290 nm gave rise to the addition of the spin-trap to carbon 3 of the indole ring. A large ESR signal from the hydronitroxide spin-adduct was also observed revealing the formation of hydrated electrons. Generally, the photolysis of Trp-containing dipeptides generated the deamination radical of the N-terminal amino acid followed by addition to the spin-trap. In the case of lysyl-Trp, a deamination radical from the side chain of lysine was proposed. A sensitization experiment with Trp as sensitizer and glycine (Gly) as substrate led to the generation of the deamination radical of Gly. Most of the observed free radicals resulting from the photolysis of Trp-containing peptides can be explained in terms of hydrated electrons reacting with the carbonyl group followed by deamination of the N-terminus.     

高灵敏度的酯型光敏聚酰亚胺

通过液－固逐步溶解缩聚的方法,合成了几种有较高分子量的光敏聚酰胺酸酯,并对它们的光刻性能进行了研究和讨论。其中,米赤酮或双叠氮对以联苯二酐间苯二胺残在为主的链结构的光敏ＰＩ前体的感光性能有最大的影响,由这种ＰＩ前体配制的光敏聚酰亚胺光刻胶具有最高的灵敏度。     

Amine–quinone polyimide: A new high‐temperature polymer and its use to protect iron against corrosion

A new diamine monomer was synthesized by the Michael addition of 4,4′‐methylene dianiline with 1,4‐benzoquinone. The monomer was condensed with 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride to give a polyamic acid that was soluble in NMP. The polyamic acid was cast onto iron and thermally imidized to yield the amine–quinone polyimide (AQPI‐2). AQPI‐2 had a thermal decomposition temperature of 540 °C (10% TGA weight loss in N₂) and a glass transition at 292 °C, values typical of polyimides. The degradation of the coating on iron after exposure to 0.1 M NaCl electrolyte was followed by electrochemical impedance spectroscopy. Under these conditions a conventional polyimide failed after 3 days exposure, while AQPI‐2 survived more than 24 days exposure. The adhesive bond between the amine–quinone polyimide and the iron surface was so strong that it could not be broken by the electrolyte. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2893–2899, 2000     

ESR方法检测竹红菌素的半醌负离子自由基

从顺磁共振波谱检测到通过竹红菌素的光诱导还原和基态竹红菌素跟脂肪胺的电子转移两条途径所得到的自由基信号, 并由电化学还原得到同一自由基, 确认它为半醌负离子自由基。竹红菌素溶液中加入芳香胺观察不到ESR信号。它的3,10位上与醌基相邻近的羟基离解以后, 无论在基态还是在激发态都观察不到ESR信号。此外, 还从吸收光谱观察到半醌负离子自由基吸收以及竹红菌素跟脂肪胺之间的相互作用。     

Partly Imidized Polyamic Acid and Its UniaxialStretched Polyimide Films

Partly imidized polyamic acid(PAA) has been used to prepare high performance polyimide films. The behaviors of two polyamic acids derived from pyromellitic dianhydride(PMDA)/4,4′-oxydianiline(ODA) and 3,3′,4,4′-biphenyltetracarboxylic diahhydride(BPDA)/paraphenylenediamine(PPD) containing dehydrating agents composed of acetic anhydride and a tertiary amine as the catalyst were investigated. The gel point was dependent on imidization degree in despite of temperature and the molar ratio of catalyst to acetic acid. Imdization content was about 35% for PMDA/ODA and about 22% for BPDA/PPD. The effect of catalyst on imidization possessed an order of triethylamine>3-methylpyridine>pyridine>isoquinoline>2-methylpyridine. The stretching of the films greatly reduced the coefficient of linear thermal expansion(CTE) either in the longitudinal direction or transversal direction. Compared to the film from polyamic acid, the partly imidized film had greater stretching ratio, so that the uniaxial stretched polyimide film from partly imidized PAA had higher tensile strength and tensile modulus, but lower elongation in the stretching direction.     

Polyimide structure–property relationships. I. Polymers from fluorene-derived diamines

A series of fluorene and fluorenone diamines were polymerized with two aromatic dianhydrides, and the resulting polyamic acids were cyclodehydrated to aromatic polyimides. A study of the mechanical properties of the polyimide films disclosed they are among the stiffest reported to date, with an excellent retention of rigidity at elevated temperatures. Comparisons of the tensile properties and glass transition temperatures of the fluorene-derived polymer films with those from the corresponding open-chain polyimide films established that the unusual rigidity, especially at elevated temperatures, was in large part due to the contribution of the bulky, tricyclic fluorene (one) moieties in the polymer structures.     

Thermal and photo-sensitised oxidation of polypropylene: Influence of hindered piperidine compounds

The effect of two hindered piperidine compounds on the photo-sensitised oxidation of polypropylene by anthracene, anthraquinone, benzhydrol and benzophenone has been examined using infra-red, ultraviolet absorption luminescence and flash photolysis techniques. The compounds—a stable N-oxy radical and a hindered amine—are found to inhibit, to different extents, the photo-sensitised oxidation of the polymer. Neither of the compounds, however, inhibits photo-decomposition of the sensitisers, indicating that mechanisms involving excited state quenching and/or sensitiser regeneration are not operative in stabilisation. On flash photolysis of benzophenone, anthraquinone and benzhydrol, the presence of the N-oxy radical inhibits transient absorption due to the ketyl, semi-quinone and triphenyl methyl radicals. The N-oxy radical also inhibits the thermal reduction of anthraquinone in polypropylene, again indicating that excited state quenching in photo-stabilisation is unimportant. The results are discussed on the basis of a radical trapping mechanism.