Fabrication based on radiation sensitive resists and related products

Abstract

A phase compatibile polymer blend serves as a radiation sensitive lithographic resist in the fabrication of circuits and circuit elements. Radiation sensitivity is due to inclusion of a 'modifier'. Resist properties, notably stability to agents and ambients to be masked are attributed largely to a second component, the 'matrix polymer'. In an exemplary embodiment in which the blend is positive acting, fabrication including dry processing is dependent upon use of a resist blend of a vapor developing polysulfone and a novolac. The novolac, inherently soluble in alkaline media is rendered insoluble in the blend. Radiation initiated depolymerization results in volatilization of the modifier to render the irradiated portions of the resist soluble in alkaline developers. Modifier may function in other manner; for example, it may undergo radiation initiated polymerization so as to insolubilize the blend in irradiated regions, so resulting in a negative acting resist. Effective isolation of lithographic from masking functions permits design of blends with high lithographic sensitivity, as well as good processing stability. The latter is sufficient to permit use in many dry processing procedures as practiced in direct writing, as well as in mask fabrication of large scale integrated silicon circuits.