PHOTOGENERATED ACID-CATALYZED FORMATION OF PHOSPHONIC PHOSPHORIC-ACIDS BY DEPROTECTION OF ESTERS IN POLYMER-FILMS

A new class of photodefinable polymers based on phosphonic acid esters has been developed. Photogenerated acid catalysts convert the esters to phosphonic acids in the exposed regions of films during postexposure bake. These phosphonic acids, in addition to-providing the base solubility necessary for positive-tone development, are also uniquely capable of binding metal ions and cations from solution. Preliminary lithographic evaluations indicate that these polymers generally show high contrast (similar to 10), good sensitivity, low volume loss (<15%), and the potential for submicron resolution. More importantly, the patterned deposition of refractory metal ions has also been demonstrated, which could be useful for circuit fabrication via at-the-surface imaging schemes.