Multibit memory devices based on the ferroelectric copolymer P(VDF‐TrFE) (poly‐(vinylidenefluoride‐trifluoroethylene)) are presented. Multilevel microstructures are fabricated by thermal imprinting of spin‐coated ferroelectric polymer film using a rigid Si template. Multibit storage in capacitors and thin‐film transistor memory is realized by implementing imprinted ferroelectric polymer films as the insulator and gate dielectric layers, respectively.

In this communication we propose a novel application for prefluorescent probes in the detection of free carbon-centered radicals in enzymatic processes. Prefluorescent probes combine a fluorescent moiety tethered to a paramagnetic nitroxide that acts as a fluorescence quencher. Trapping of a radical by the nitroxide group restores the fluorescence properties. The increase in fluorescence intensity with time reflects the formation and quenching of carbon-centered radicals and can be used for the quantitative evaluation of yields and kinetics. As a test system we used horseradish peroxidase, an oxidoreductase that is widely accepted to operate by a radical-mediated mechanism. We used the prefluorescent probe (quinoline-TEMPO), where a quinoline moiety has been tethered to 2,2,6,6-tetramethylpiperidin-1-oxyl.

The use of 157 nm as the next lower wavelength for photolithography for the production of semiconductors has created a need for transparent and radiation-durable polymers for use in soft pellicles, the polymer films which protect the chip from particle deposition. The most promising materials for pellicles are fluorinated polymers, but currently available fluorinated polymers undergo photodegradation and/or photodarkening upon long term exposure to 157 nm irradiation. To understand the mechanism of the photodegradation and photodarkening of fluorinated polymers, mechanistic studies on the photolysis of liquid model fluorocarbons, including perfluorobutylethyl ether and perfluoro-2H-3-oxa-heptane, were performed employing UV, NMR, FTIR, GC, and GC/MS analyses. All hydrogen-containing compounds showed decreased photostability compared to the fully perfluorinated compounds. Irradiation in the presence of atmospheric oxygen showed reduced photostability compared to deoxygenated samples. Photolysis of the samples was performed at 157, 172, 185, and 254 nm and showed only minor wavelength dependence. Mechanisms for photodegradation of the fluorocarbons are proposed, which involve Rydberg excited states. Time-dependent density functional theory has been used to predict the excitation spectra of model compounds.

No abstract

Acid-catalyzed deprotection of tert-butoxycarbonyl (t-Boc) pendant groups present in a polymer film is one of the most common chemical reactions in photolithography. We present here a novel method to determine the catalytic chain length of this reaction under different development conditions. We demonstrate this in model PMMA thin films containing triphenylsulphonium triflate as a photoacid generator, acid sensor coumarin 6, t-Boc protected coumarin 4, and base 2-piperidin-1-yl-ethanol (2-PE). Deprotection of the t-Boc group, catalyzed by the photogenerated acid, during the post-exposure bake leads to formation of coumarin 4, a strongly fluorescent molecule whose concentration is monitored using fluorescence. We take advantage of the change in the emission spectra of coumarin 6 upon protonation to monitor acid formation. To quantify the amount of acid, an acid–base titration is done in the polymer film using 2-PE. Knowing the amount of deprotected probe and the amount of acid, we are able to calculate the number of moles of deprotected C4-t-Boc per mol of acid, which is the actual catalytic chain length.Key words: photolithography, chemical amplification, catalytic chain length, fluorescent sensors, photoacid generator.