Reverse pillar process: I. New approaches to interconnections in VLSI.

A new concept in multilevel interconnection, called the reverse pillar process, is reviewed. Instead of etching interconnections in the metal layer the reverse pillar process etches trenches in the dielectric using the reverse tone metal mask. A window contact is also etched and can be made self-aligned to the trench. The contacts and trenches are simultaneously filled by selective or blanket (+etchback) metal schemes. In this memorandum various approaches to the reverse pillar process are discussed. The approaches all benefit from the planarizing nature of the reverse pillar process.