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CommunicationsFinally, it is worth noting that the oriented films were found to be extremely stable: the films could be stored under ambient conditions (exposure to air and light) for months without any noticeable change to their properties. We attribute the latter, most relevant, phenomenon to the encapsulation of the conjugated polymer in the highly crystalline PE matrix.In conclusion, we have shown that gel processing and subsequent tensile deformation of blends of different PPEs and ullra-high molecular weight polyethylene leads to an outstanding orientation of the conjugated polymer guest, resulting in state of the art polarized photoluminescence and absorption of the prepared films. Maximum orientation and polarization is obtained when the conjugated guest is of high molecular weight and derivatized with sterically hindered, rather than only linear, side chains. The orientation process used appears to induce a transformation of an initially phase-separated system into an apparent molecular dispersion of the conjugated polymer guest in the PE host.Experimental 0-OPPE, EHO-OPPE, and HMW EHO-OPPE used in this work were prepared according to previously published procedures [15,18]. UHMW-PE (Hostalen Gur 412) was obtained from Hoechst AG.Thin films were prepared by casting a solution of the PPE (5-125 mg) and UHMW-PE (0.5 g) in xylene (50 mL) (dissolution at 130 "C after degassing the mixture in vacuum at 25 "C for 15 min) into a petri dish 11 cm in diameter. The gels were dried under ambient conditions for 24 h. All resulting blend films had a homogeneous thickness of about 70 pm. The films were drawn at temperatures of 90-120 "C on a thermostatically controlled hot shoe. Draw ratios were calculated from the displacement of distance marks printed on the films prior to drawing.Polarized UV-vis spectra were recorded with a Perkin Elmer Lambda 900 instrument, fitted with motor driven Glan-Thomson polarizers. PL spectra were recorded on a SPEX Fluorolog 2 (Model F212f), using unpolarized light (350 nm) for excitation and a Glan-Thomson polarizer on the detector side. For the photophysical experiments, the polymer films were sandwiched between two quartz slides, applying a silicon oil fluid in order to minimize light scaltering at the film surfaces. The remaining scattering effects were compensated in the absorption measurements by subtracting the spectra of pure UHMW-PE films of comparable draw ratio and thickness. Received

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Block and random copolymers were prepared using the monomers tert-butyl methacrylate and [3-(methacryloxy)propyl]pentamethyldisiloxane. The polymers have low absorption at 193 nm wavelength, making them attractive candidates for 193 nm wavelength imaging. The resists have a high resistance to oxygen reactive ion etching, making them suitable for the imagable layer of a bilevel resist system. After exposure, the block copolymers have better development behavior in aqueous base than that of the corresponding random copolymers even though they have a long hydrophobic siloxane block.

We present recent modeling work aimed at understanding the influence of structural changes in photoacid generators ͑PAGs͒ on acid generation efficiency, deprotection efficiency, and photoacid diffusion in 193 nm chemically amplified resists. An analytical model for the postexposure bake process is used to study the reaction and diffusion properties of the various acids generated by the PAGs. Fourier transfer infrared spectroscopy is used to monitor the generation of photoacid during exposure. Resist thickness loss after PEB as a function of exposure dose is related to the deprotection extent to extract the reaction rate parameters. The effects of the acid size and boiling point on process latitude, line end shortening, and line edge roughness are presented. Analytical model predictions of process latitude and line end shortening are also presented and compared to experimental data. In this study, the photogenerated acid with the smallest molar volume and highest boiling point temperature gave the best overall lithographic performance.