PLASMA-DEVELOPED IMAGES IN A POLYAMIC ACID DIAZOQUINONE PHOTORESIST

High-contrast, positive tone images were achieved in a resist consisting of a polyamic acid resin, a diazoquinone sensitizer, and a suitable casting solvent mixture, together with a simple processing scheme: spin-coat, bake, expose, silylate in a solution of hexamethylcyclotrisilazane/xylene, develop by reactive ion etching in oxygen. The resist is sensitive to deep-, mid-, and near-UV radiation. The thermal stability of the resulting images is discussed. An imaging mechanism is proposed involving leaching of unexposed sensitizer into the silylation bath. Studies indicate that the etch resistance imparted to the unexposed areas by the silylation step is largely due to the presence of the unreacted silylating agent in the top surface of the resist film.