High resolution mask programmable via selected by low resolution photomasking

Abstract

A photoresist (18) is exposed through a design-independent high resolution reticle (20), producing a high resolution image of exposed resist (18A). Photoresist (18) is exposed for the second time through a design-specific low-resolution reticle (24), exposing selected portions (18D) of previously unexposed resist. The remaining portions (18B) of previously unexposed resist form a design-dependent high resolution image. After development of photoresist (18), its unexposed portions (18B) are removed, producing openings (26) in photoresist (18), that can be transferred to underlying material (36), for example by etching openings in that underlying material (36), thereby transferring the design-dependent high-resolution image to it. Since the design-independent high resolution reticle (20) can be prefabricated ahead of time and used to produce many designs with different functions, the above double-exposure method is suitable for fabricating design-specific high resolution features, e.g., contacts (vias) between conducting layers, within time and at the approximate cost required to fabricate and process a low resolution image. Several variants of the basic method are possible.

Dependencies are inferred from the claim text.