Structure and method for controlling copper diffusion and for utilizing low K materials for copper interconnects in integrated circuit structures

A method of forming a copper-based interconnect structure, the method comprising:

• forming a layer of intermetal dielectric material on an underlying layer of conductive material;
• forming a pattern of vias through the intermetal dielectric later to expose surface regions of the conductive material;
• forming an adhesion layer on exposed sidewalls of the vias and on an upper surface of the intermetal dielectric materials;
• filling the adhesion-layer-lined vias with a conductive material that includes copper;
• performing a planarizing step to planarize the copper-including conductive material and the upper surface of the intermetal dielectric material;
• removing the intermetal dielectric material to expose the adhesion-layer-lined copper-including conductive material;
• depositing a diffusion barrier material on exposed surfaces of the adhesion-layer-lined copper-including conductive material while allowing exposed surfaces of the underlying conductive material to remain exposed;
• depositing a layer of low k dielectric material on the exposed surfaces of the underlying conductive material and to cover the copper-including conductive material;
• and
• forming passivation material on the layer of low k dielectric material.