Aluminum-refractory metal interconnect with anodized periphery

Claim 1

An improved planar multilevel electrical interconnect structure for employment with semiconductor devices which are integrated on the surface of a semiconductor substrate; said interconnect structure being of the type which includes a first insulating layer overlying said surface; a first plurality of spaced-apart aluminum connectors to said devices lying on said first insulating layer; a second insulating layer overlying said first plurality of spaced-apart aluminum connectors; a second plurality of connectors to said devices lying on said second insulating layer and crossing over said first plurality of spaced-apart aluminum connectors at various locations with said second insulating layer lying therebetween; wherein the improvement comprises: a patterned anodized aluminum oxide layer between said first and second insulating layers filling the spaces between and forming a planar structure with said first plurality of spaced-apart aluminum connectors; a refractory metal selected from the group of tantalum, titanium, tungsten, and hafnium overlying said first plurality of connectors at said locations where said first and second plurality of connectors cross over each other and abutting said patterned anodized aluminum oxide layer; and the sides of said refractory metal abutting said patterned anodized aluminum oxide layer being anodized and operating as an insoluble barrier to anodizing solutions and the remainder of said refractory metal being unanodized.