DEMONSTRATION OF A DIRECTLY PHOTOPATTERNABLE SPIN-ON-GLASS BASED ON HYDROGEN SILSESQUIOXANE AND PHOTOBASE GENERATORS

A commercially available spin-on-glass material, hydrogen silsesquioxa ne, has been rendered photopatternable to micrometer dimensions by the introduction of a photobase generator at concentrations of < 5 wt %. The cure process proceeds via hydrolysis of the silyl hydride linkage by residual water in the film, as activated by a photogenerated base c atalyst. Subsequent reaction of the generated silanol with neighboring silyl hydride groups yields a thermally stable siloxane cross-link. T he photochemical cross-linking of hydrogen silsesquioxane shows high s ensitivity (< 40 mJ/cm(2)) and is not inhibited by molecular oxygen. T he resultant oxide films can be further cured at elevated temperature either under an inert atmosphere to minimize the dielectric constant o r heated in an air atmosphere to complete the conversion to silica gla ss. The oxidative nature of both the photo and thermal cure processes and the release of only traces of hydrogen as byproduct results in min imal weight loss in the film during processing.