PMMA has been the primary resist used in synchrotron exposures for micro-machined parts fabricated by the LIGA process. Because development ofthis resist directly influences both tolerances and surface fmish ofcompleted LIGA structures, it is important to have a good quantitative understanding of PMMA development as a function ofthe absorbed dose, as well as both the exposure and development conditions. The various synchrotron sources used for LIGA fabrication vary widely in beam energy and flux, and these variations would be expected to influence development rates. Here we present a simple method to measure PMMA development rate over a moderate range of doses using only a single exposure at the synchrotron source. By employing several exposures, this method allows ready determination of development rates over a wide range ofexposure and development conditions. Results are presented for the kinetics ofPMMA development over a range of development temperatures, absorbed doses, dose rates and sample ages for exposures performed at three major x-ray sources in the United States

The region of glass formation in the new glass-forming system phosphorus-sulfurtellurium has been established, and the local structure investigated using 31P wide-line and magic-angle spinning (MAS) NMR as well as vibrational spectroscopies. The results are consistent with the absence of phosphorus-tellurium bonds, and a structure dominated by S=PSs/2 units. Characteristic chemical shift effects and changes in the vibrational frequencies of the P=S bond suggest that these units associate with tellurium in the glasses. In addition, the presence of tellurium tends to suppress the formation of molecular P4Sn species, which form at higher phosphorus concentrations in the binary system. All of these results indicate active participation of tellurium in the network consistent with compositional trends of the glass transition temperatures.

LIGA, an acronym from the German words for Lithography, Electroforming, and Molding, is being evaluated worldwide as a method to produce microparts from engineering materials. Much of the work to date in LIGA has focused on producing metal microparts, with nickel as the most common material of choice. There is a growing interest in producing plastic parts replicated from LIGA metal masters due largely to microanalytical instrumentation and medical applications. These plastic replicates are generally made by either hot embossing or injection molding. Ceramic replication, of particular interest fa high temperature applications or to produce piezoelectric or magnetic microparts, is also emerging as an area of interest. In this paper, a model of the LIGA exposure and development processes is presented along with the results of numerical optimization of mask design and process cost. The baseline processes for a cost-effective method to produce metal microparts are discussed, along with replication methods and results for plastics and ceramics.

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