Evaluation of the influence of process factors on plasma developed X‐ray resist properties

UV spectroscopy, gel permeation chromatography (GPC) and liquid chromatography (LC) have been used to analyze process factors that influence the properties of PDXR‐2 plasma developed X‐ray resist comprised of 92.5 wt percent poly(2,3‐dichloro‐1‐propyl acrylate) and 7.5 wt percent bis‐acryloxybutyltetramethyldisiloxane (BABTDS). The GPC‐LC method is particularly useful in optimizing fixing conditions, determining monomer concentration in the film, and studying molecular processes caused by absorbed X‐rays and thermal effects during fixing. Evidence for a synergistic sensitivity enhancement resulting from fixing and exposure is presented. Optimally processed O2 reactive‐ion etch developed patterns exhibit a microgranular texture in both exposed and unexposed regions of <500 Å size. Unexposed region texture consists of SiO2 resulting from the BABTDS monomer. It is completely removed by reactive ion etching with CHF3 for short times at low power. The exposed area texture is not removed and affords an edge roughness per line edge of <500 Å. Resolution appears mask limited while granular size is dependent on exposure time. A 20 sec exposure optimizes resolution, pattern uniformity, and granularity. 0.5 μm line and space resolution can be obtained with the X‐ray machine and masks currently in use.