A model set of 1,4-polybutadiene-l,2-polybutadiene diblock copolymers has been prepared and molecularly characterized. Physical characterization by differential scanning calorimetry (DSC) and qualitative identification of the flow behavior (liquidvs. solid-like) over a period of several days have established die critical degree of polymerization for this system as Nc = 1.20 (± 0.14) X 103. Below the microphase separation transition the polymers exhibit a single broad glass transition, as measured by DSC, which has been attributed to local segment density fluctuations. This effect was found to be dependent on the degree of polymerization, as predicted from theory.

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Oxygen~based plasmas commonly used in resist stripping and multilayer resist patterning are contrasted to highlight the differences involved in these applications. Mechanisms for polymer etching are reviewed, with particular emphasis on silicon~containing resists proposed for bilayer lithography. While silicon-containing materials offer a simpler process than trilayer schemes for improving lithographic resolution, considerable differences in etch behavior among these materials have been observed. Further characterization and fundamental understanding are required before widespread acceptance of silicon-containing resists is achieved..

This paper introduces new high-resolution amorphous Silicon (a-Si) image sensors specifically configured for demonstrating film-quality medical x-ray imaging capabilities. The device utilizes an x-ray phosphor screen coupled to an array of a-Si photodiodes for detecting visible light, and a-Si thin-film transistors (TFTs) for connecting the photodiodes to external readout electronics. We have developed imagers based on a pixel size of 127 tm x 127 xm with an approximately page-size imaging area of244nirn x 195mm, and array size of 1,536 data lines by 1,920 gate lines, for a total of2.95 million pixels.' More recently, we have developed a much larger imager based on the same pixel pattern, which covers an area of approximately 406mm x 293mm, with 2,304 data lines by 3,200 gate lines, for a total ofnearly 7.4 million pixels.2 This is very likely to be the largest image sensor array and highest pixel count detector fabricated on a single substrate. Both imagers connect to a standard PC and are capable oftaking an image in a few seconds.Through design rule optimization we have achieved a light sensitive area of 57% and optimized quantum efficiency for x-ray phosphor output in the green part ofthe spectrum, yielding an average quantum efficiency between 500 and 600 nm of -7O%. At the same time, we have managed to reduce extraneous leakage currents on these devices to a few fA per pixel, which allows for very high dynamic range to be achieved. We have characterized leakage currents as a function of photodiode bias, time and temperature to demonstrate high stability over these large sized arrays.At the electronics level, we have adopted a new generation of low noise, charge-sensitive amplifiers coupled to 12-bit AID converters. Considerable attention was given to reducing electronic noise in order to demonstrate a large dynamic range (over 4,000: 1) for medical imaging applications. Through a combination oflow data lines capacitance, readout amplifier design, optimized timing, and noise cancellation techniques, we achieve l,000e to 2,000e ofnoise for the page size and large size arrays, respectively. This allows for true 1 2-bit performance and quantum limited images over a wide range of x-ray exposures. Various approaches to reducing line correlated noise have been implemented and will be discussed. Images documenting the improved performance will be presented. Avenues for improvement are under development, including higher resolution 97 jim pixel imagers,3 further improvements in detective quantum efficiency, and characterization of dynamic behavior.

193 nm radiation causes direct photocrosslinking of polymer films which is sufficient to generate silylation selectivity under appropriate conditions. A variety of phenolic based polymers and blends with photoactive compounds were studied for their suitability as resists in a 193 nm, positive-tone, silylation process. Meta-cresol novolac resists and polyvinylphenol resists show the best sensitivity for this process. The threshold dose required to restrict diffusion of the silylating agent depends strongly on the composition of the resist. Sensitivities range from 12 mJ/cm2 to over 100 mJ/cm2 for various novolac and polyvinylphenol materials. Wide variations in sensitivity have been found between different synthetic methods for the same resin, different molecular weight characteristics, and different functional modifications.