Poly(aryline imide)s as E-beam resist: Sensitivity and resolution

Polyamic acids synthesized from di-trifluoromethyl methane bis(phthalic anhydride) and 4,4′-diaminophenyl sulfone and 4,4′-diaminophenyl ether were found to have excellent negative E-beam resist properties. The best materials contain about 90% imidized structural units having sensitivities of 1.5–2.5 μC cm^?2 and contrast of 1.0–1.3. Polyamic acid of pyromellitic dianhydride and 4,4′-diaminophenyl sulfone imidized to 97% exhibits useful positive E-beam resist properties. Radiation induces imidization or chain scission to alter the solubility of the resist polymers resulting in the formation of latent images.     

A new type of eco‐friendly resist based on nonchemically amplified system

Novel water‐processable photopolymers were designed to be useful as environment‐friendly photolithographic materials. By copolymerization of 2‐(2‐diazo‐3‐oxo‐butyryloxy)ethyl methacrylate (DOBEMA), hydroxyethyl methacrylate (HEMA), methacryllic acid (MAA), and sodium 4‐vinylbenzenesulfonate (SVBS), two kinds of polymers, poly(DOBEMA‐co‐HEMA‐co‐SVBS) for negative‐tone resist and poly(DOBEMA‐co‐MAA) for positive‐tone resist, were synthesized and their photolithographic properties were investigated. The single component negative‐tone resist produced 0.8 μm line and space patterns using a mercury‐xenon lamp in a contact printing mode using pure water as casting and developing solvent at a exposure dose of 25 mJ cm^?2. On the other hand, the single component positive‐tone resist produced 0.8 μm line and space patterns at a much higher dose of 150 mJ cm^?2. Thus, the negative resist showed much improved sensitivity when compared with the positive resist and the reported nonchemically amplified resists. This sensitivity is comparable with those of typical chemically amplified resists. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7534–7542, 2008     

The synthesis and lithographic evaluation of a new organosilicon novolac-based resist

A novel material, bis(trimethylsilylmethoxy resorcinol) was synthesized by a phenoxide alkylation method. The new substituted resorcinol was then terpolymerized with 2-methyl resorcinol and formaldehyde. We evaluated the preparation of this new polymer in terms of feed ratio of the reactants, reaction time, and temperature; and prepared a series of materials with different silicon content. Polymers which retained base solubility at high silicon content were blended with a dissolution inhibitor, and studied for their lithographic capabilities as positive, photo- or electron-beam bilevel resists. When used in a photoresist formulation a dose of 120 mJ/cm² allowed formation of submicron features. When used in an electron-beam resist formulation 0.5 μm line/space patterns were obtained at a dose of 10 μC/cm². Furthermore, these materials displayed etching ratios relative to hardbaked HPR206 of ? 1 : 10. This value is believed to be large enough to allow these resists to withstand reactive ion etching conditions for pattern transfer in a bilevel scheme.     

Action du chlorure d'acetyle et de l'anhydride acetique sur le nitronate de lithium derive du phenyl-2 nitroethane : Reactivite electrophile ou dipolaire,en fonction du milieu,de l'oxyde de nitrile intermediairement forme

The lithium nitronate salt derived from 2-phenyl nitroethane reacts with acetic anhydride and with acetyl chloride to give an intermediate nitrile oxide. Depending on the protonating character of the medium, this latter can react either as a 1,3 dipole to give the furoxan or, in the presence of a dipolarophile, the corresponding adduct ; or as an electrophile leading to the chlorooxime or to derivatives of benzohydroxamic acid. The formation of the nitrile oxide, by loss of acetic acid from a nitronic-acetic mixed anhydride, appears to be the most plausible reaction pathway accounting for the above observations.     

Synthesis of photoreactive poly(ether ether ketone)s containing alkyl groups

Poly(ether ether ketone)s containing alkyl groups were prepared by nucleophilic substitution reaction of alkyl-substituted difluoro diaryl ethers with hydroquinone or by electrophilic substitution reaction of alkyl-substituted diaryl ether with 4,4′-oxydibenzoic acid in PPMA. Polycondensations proceeded smoothly and produced polymers having inherent viscosities up to 0.5-–1.6 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, and chloroform at room temperature. Thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight loses of the polymers were observed in the range above 450°C in nitrogen atmosphere. The glass transition temperatures of the polymers ranged from 128 to 146°C. Furthermore, Polymer 3b functioned as a photosensitive resist of negative type for UV radiation. The resist had a sensitivity of 42 mJ/cm² and a contrast of 2.5, when it was postbaked at 100°C for 10 min, followed by development with THF/acetone at room temperature. © 1996 John Wiley & Sons, Inc.     

Chiral Brønsted Acid Catalyzed Enantioconvergent Propargylic Substitution Reaction of Racemic Secondary Propargylic Alcohols with Thiols

Despite the significant progress of the enantioselective reaction using chiral catalysts, the enantioselective nucleophilic substitution reaction at the chiral sp³-hybridized carbon atom of a racemic electrophile has not been largely explored. Herein, we report the enantioconvergent propargylic substitution reaction of racemic propargylic alcohols with thiols using chiral bis-phosphoric acid as the chiral Brønsted acid catalyst. The substitution products were formed in high yields with high enantioselectivities in most cases. The cation-stabilizing effect of the sulfur functional group introduced at the alkynyl terminus is the key to achieving the efficient enantioconvergent process, in which chiral information originating from not only the racemic stereogenic center but also the formed contact ion pair is completely eliminated from the present system.     

Chemistry of geminal-dithiolates derived from cyano-substituted tetrathiafulvalenes

Tetracyanotetrathiafulvalene reacts with two equivalents of thiol salts (RS^?) to give 1,2-dicyano-1,2-di RS ethene and a geminal dithiolate intermediate which reacts with a variety of reagents to provide novel tetrathioethene derivatives, such as reaction with 3-chloro-2-butanone and acid to give dimethyldicyanotetrathiafulvalene.     

Abiotic reaction of iodate with sphagnum peat and other natural organic matter

Previous studies have shown that iodine (including ¹²⁹I) can be strongly retained in organic-rich surface soils and sediment and that a large fraction of soluble iodine may be associated with dissolved humic material. Iodate (IO₃⁻) reacts with natural organic matter (NOM) producing either hypoiodous acid (HIO) or I₂ as an intermediate. This intermediate is subsequently incorporated into the organic matter. Based on reactions of model compounds, we infer that iodine reacts with peat by aromatic substitution of hydrogen on phenolic constituents of the peat. Alternatively, the intermediate, HIO or I₂, may be reduced to iodide (I⁻). The pH (and temperature) dependence of the IO₃⁻ reaction (reduction) has been explored with sphagnum peat, alkali lignin, and several model compounds. The incorporation of iodine into NOM has been verified by pyrolysis gas chromatography/mass spectrometry (GC/MS). Model compound studies indicate that reduction of IO₃⁻ to HIO may result from reaction with hydroquinone (or semiquinone) moieties of the peat.     

Sequential coupling of zincated hydrazone, alkenylboronate, and electrophile that creates several contiguous stereogenic centers

A zincated N,N-dimethylhydrazone of a ketone undergoes stereospecific syn addition to E- or Z-alkenylboronate to generate a gamma-Zn/B dimetallic intermediate, which reacts with a carbon electrophile to give a gamma-borylhydrazone in good yield with excellent diastereoselectivity, creating two to four contiguous stereogenic centers in a one-pot reaction.     

Reactions of triphenylphosphine with 2,3-dihalo-2-methylpropionic acids and their methyl esters

Triphenylphosphine reacts with 2,3-dichloro-2-methylpropionic acid and its ester along the dehydrochlorination pathway with the participation of the less labile hydrogen atom from the methyl group. The subsequent reaction of the unsaturated product with triphenylphosphine yields 2-carboxypropane- and 2-methoxycarbonylpropane-1,3-diylbis(triphenylphosphonium) dichlorides, respectively. The unusual course of dehydrochlorination may be due to easier electron density transfer from the C-H bond of the methyl group as compared to the chloromethyl group in the carbocationoid intermediate. With the bromine analogs, the reaction pathways are different. The ester reacts similarly to dibromopropionic acid and its derivatives, following the debromination scheme, whereas the free acid gives the product of double nucleophilic substitution.     

Enantioselective synthesis of alpha-substituted ketones by asymmetric addition of chiral zinc enamides to 1-alkenes

A zinc enamide of a chiral imine derived from a ketone and (S)-valinol or (S)-t-leucinol undergoes addition to 1-alkene to generate a gamma-zincioimine intermediate, which reacts with a carbon electrophile to give upon hydrolysis an optically active alpha-substituted ketone in good yield. The stereoselectivity of the addition reaction may reach 99% for the reaction of a cyclohexanone imine with ethylene.     

Acid-catalyzed degradation mechanism of poly(phthalaldehyde): Unzipping reaction of chemical amplification resist

The acid-catalyzed degradation mechanism of chemical amplification resists based on end-capped poly(phthalaldehyde) has been elucidated by semi-empirical molecular orbital calculations. It is concluded that: (i) two different starting points exist in the degradation of end-capped poly(phthalaldehyde), the central part of the polymer as well as the polymer end; (ii) in both cases, after the first protonation, cationic hydroxyl compounds generated decompose to the identical cation intermediate, which can unzip itself to phthalaldehyde monomers successively (unzipping reaction); (iii) the hemiacetal type intermediates hardly degrade to the same intermediate without acid catalyst; (iv) the overall activation energy for the degradation reaction is less than 14 kcal/mol in all the cases. Thus, the poly(phthalaldehyde) resist can easily self-develop below 100°C, as reported in the literature. © 1997 John Wiley & Sons, Inc.     

Reactions in the presence of organic phosphites,II: Low-temperature amidatior in solvent

Polyamides and related model compounds were prepared from carboxy acids and primary amines by reacting them with triphenylphosphite in an appropriate solvent at 100°C. The reactions proceeded in the absence of organic base but were accelerated by the addition of bases such as pyridine. Nevertheless, even the powerful combination of ¹³C and ³¹P NMR failed to indicate the presence of pyridinium phosphite in the reaction mixture. In the reaction of a primary amine and carboxyl groups a detectable amount of the diphenoxy aminophosphine intermediate was observed. The end products are the amides, phenol, and diphenyl phosphite. When primary amine was not present a slow formation of a phenyl ester of the carboxylic acid was evident. All the intermediate species and the end products were formed with or without added pyridine. A mixed anhydride of carboxylic acid and phosphite was never seen. The results in this article are fundamentally the same as those in the companion article (I) for which the data were obtained at 280°C in the absence of solvent and base. However, because the reaction went quickly to completion at 280°C, the diphenoxy aminophosphine intermediate was not observed. A mechanism for the amidation in which the diphenoxy aminophosphine is an initial reaction intermediate is proposed. This species reacts with the carboxylic acid through an intramolecular substitution to give an amide. This mechanism may be valid for the high-temperature reactions as well. Several minor unclear points are indicated.     

Synthesis of photoreactive isopropyl-substituted poly(phenylene ether ether ketone)

Isopropyl substituted poly(phenylene ether ether ketone) with a high molecular weight was prepared by nucleophilic substitution reaction of isopropyl-substituted difluoro diaryl ether with hydroquinone. This polymer was amorphous and soluble in common organic solvents, such as THF, chloroform, and cyclohexanone. Thermogravimetry of the polymer showed good thermal stability, indicating that a 10% weight loss of the polymer was observed at 470°C in nitrogen. The glass transition temperature of the polymer was 145°C. The polymer had a broad UV absorption band over 250–380 nm. The polymer acted as a photosensitive resist of negative type for UV radiation. The resist had a sensitivity of 40 mJ/cm² and a contrast of 2.8, when it was developed with DMF at room temperature. © 1997 John Wiley & Sons, Inc.     

Deep UV photoresists based on poly(dl-tert-butyl fumarate)

Poly(di-tert-butyl fumarate) was prepared and evaluated as a potential candidate as a deep UV photoresist. Although this polymer displayed excellent sensitivity, the polymer was found to exhibit poor dry etch resistance. Copolymers of di-tert-butyl fumarate with either allyltrimethylsilane or styrene, and an onium salt as a photoacid generator were synthesized and subsequently evaluated using a 248-nm KrF excimer laser step-and-repeat system (stepper). At 248 nm, the absorbance of ～ 1 μm thick resist films was only 0.156-0.211. The sensitivities of these resists were 1-4 mJ/cm². The dry etch resistance of these photoresists was comparable to that of conventional positive photoresists based on novolac resins. © 1995 John Wiley & Sons, Inc.     

Benzyl N‐[(Benzyloxy)methyl]carbamate: An Improved Aminomethylation Electrophile for the Synthesis of (Benzyloxy)carbonyl (Cbz)‐Protected Chiral β2‐Amino Acids

α‐Aminomethylation of (R)‐DIOZ‐alkylated (DIOZ=4‐isopropyl‐5,5‐diphenyloxazolidin‐2‐one) substrates is a key step in the asymmetric synthesis of β²‐amino acids, but it is unfortunately often accompanied by formation of transcarbamation by‐products. Aminomethylation was tested using a range of electrophiles, and the amount of by‐product formation was assessed in each case. Benzyl N‐[(benzyloxy)methyl]carbamate electrophile 3d is unable to form this by‐product due to its inherent benzyl substitution. Use of electrophile 3d showed an improved impurity profile in aminomethylation, thus leading to easier intermediate purification.     

Acid generation and deprotecting reaction by diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate in a novolak positive photoresist based on chemical amplification

In a positive photoresist composed of diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate as a novel photoacid generator, bisphenol A protected with tertbutoxycarbonyl group as a dissolution inhibitor, and a novolak resist matrix, the efficiency of photo-acid generation and deprotective reaction were investigated by means of UV-visible and IR spectroscopies. The quantitative measurement of photogenerated acid by using the acid-sensitive dye exhibited 0.18 as the quantum yield of acid generation in novolak resin film. The lithographic evaluation of this system as a chemically amplified resist was studied. The catalytic chain length for the acid-catalyzed deprotection step was determined as about 100 when 10 min post-exposure bake (PEB) at 80°C was given. The sensitivity and the resolution as a positive resist are 180 mJ/cm² and higher than 1 μm, respectively under the PEB conditions mentioned above.     

Preparation and Reactivity of Acyclic Chiral Allylzinc Species by a Zinc‐Brook Rearrangement

The zinc‐Brook rearrangement of enantiomerically enriched α‐hydroxy allylsilane produces a chiral allylzinc intermediate, which reacts with retention of configuration in the presence of an electrophile. Two remarkable features of this transformation are the stereochemical outcome during the formation of the allylzinc species and the complete stereocontrol in the organized six‐membered transition state, which leads to an overall and complete transfer of chirality within the reaction sequence.     

Hammett-korrelation von phenylchlorcarben — temperaturabhängigkeit,selektivität

Phenylchlorcarbene $\text{2}$ reacts as an electrophile as deduced from a Hammettplot; the ?-values in the addition reaction with styrenes are clearly temperature dependent.     

Positive working resists sensitive to visible light,I: poly(tert-butyl and 2-phenylpropyl-2 methacrylates) sensitized with diphenyliodonium salt — p-aminobenzylidene dye system

Visible-light-sensitive positive type resists have been developed. The chemistry to form images is based on the cleavage of side chain ester bonds of poly(methacrylates) catalyzed by an acid which is generated on sensitized photodecomposition of a diphenyliodonium (DPI) salt. Homopolymers and copolymers of tert-butyl methacrylate (BMA) and 2-phenylpropyl-2 methacrylate (PPMA) were used as acid labile polymers. Exposure of thin films of the poly(methacrylates) containing DPI salt and p-dimethylaminobenzylidene derivatives to an Ar laser beam emitting 488 nm light and subsequent heat treatment resulted in solubility alteration of the polymers, which became soluble in a protic solvent system. Considerable reduction of film thickness was observed after heating an image-wise exposed thin film of PPMA polymers. The minimum exposure energies of 488 nm light for the positive image formation were 60 mJ/cm² and 40 mJ/cm² for BMA and PPMA homopolymers, respectively.