that is analyzed by dual-inlet isotope ratio mass spectrometry (IRMS). We describe a new laser spectroscopy instrument for highprecision 17 O measurements. The new instrument uses cavity ring-down spectroscopy (CRDS) with laser-currenttuned cavity resonance to achieve reduced measurement drift compared with previous-generation instruments. Liquid water and water-vapor samples can be analyzed with a better than 8 per meg precision for 17 O using integration times of less than 30 min. Calibration with respect to accepted water standards demonstrates that both the precision and the accuracy of 17 O are competitive with conventional IRMS methods. The new instrument also achieves simultaneous analysis of δ 18 O, δ 17 O and δD with precision of < 0.03 ‰, < 0.02 and < 0.2 ‰, respectively, based on repeated calibrated measurements.

Acid diffusion during postexposure baking is viewed to be a limiting factor in the extension of lithography using chemically amplified resists to formation of nanoscale features. Quantification of thermally activated reaction-diffusion kinetics in these materials is therefore an important step in understanding the extendability of this class of resist systems. Previous investigations have addressed this issue, however there is poor agreement among them, and too few data exist in the literature to allow the systematics of the effect of polymer, photoacid generator, added base or other resist components on the diffusion process to be understood. We describe in this article a combined experimental and modeling protocol that is designed to elucidate the chemistry and physics of the reaction-diffusion process. Because it is physically based, not phenomenological, it provides a means of developing a set of predictive, mutually comparable data that will allow new insights to be developed into the nanoscale behavior of chemically amplified resist materials. We apply the protocol to a p-t-butyloxycarbonyloxystyrene/bis͑t-butylphenyl͒iodonium perfluorobutanesulfonate positive-tone photoresist system. The resulting kinetics measurements show that diffusion is environment sensistive and describable with two limiting diffusion coefficients. The Arrhenius parameters for the coefficients in p-t-butyloxycarbonyloxystyrene are D 0 ϭ1.9ϫ10 8 cm 2 /s and E a ϭ36.5 kcal/mol; those for diffusion in the deprotected polymer product p-hydroxystyrene are D 0 ϭ9ϫ10 Ϫ3 cm 2 /s and E a ϭ22.1 kcal/mol. The coefficients are much smaller than previously reported, resulting in a very slow diffusion rate. The model indicates that the considerable image spreading observed during the postexposure bake process is attributable primarily to the efficiency of the catalytic chemistry. Our results suggest that numerical models currently used for prediction of imaging in chemically amplified resists may require refinement in order to be useful for feature sizes below 100 nm and for new classes of resist systems.

A system of two aspheric lenses is described, which efficiently converts a collimated Gaussian beam to a flattop beam. Departing from earlier designs, both aspheric surfaces were convex, simplifying their fabrication; the output beam was designed with a continuous roll-off, allowing control of the far-field diffraction pattern; and diffraction from the entrance and exit apertures was held to a negligible level. The design principles are discussed in detail, and the performance of the as-built optics is compared quantitatively with the theoretical design. Approximately 78% of the incident power is enclosed in a region with 5% rms power variation. The 8-mm-diameter beam propagates approximately 0.5 m without significant change in the intensity profile; when the beam is expanded to 32 mm in diameter, this range increases to several meters.

We present an overview of our research effort on volume holographic digital data storage. Innovations, developments, and new insights gained in the design and operation of working storage platforms, novel optical components and techniques, data coding and signal processing algorithms, systems tradeoffs, materials testing and tradeoffs, and photon-gated storage materials are summarized.

We describe a digital holographic storage system for the study of noise sources and the evaluation of modulation and error-correction codes. A precision zoom lens and Fourier transform optics provide pixel-to-pixel matching between any input spatial light modulator and output CCD array over magnifications from 0.8 to 3. Holograms are angle multiplexed in LiNbO(3):Fe by use of the 90 degrees geometry, and reconstructions are detected with a 60-frame/s CCD camera. Modulation codes developed on this platform permit image transmission down to signal levels of ~2000 photons per ON camera pixel, at raw bit-error rates (BER's) of better than 10(-5). Using an 8-12-pixel modulation code, we have stored and retrieved 1200 holograms (each with 45,600 user bits) without error, for a raw BER of <2x10(-8).