Factors Affecting the Interconnection Resistance and Yield in Multilayer Polyimide/Copper Structures

Abstract

This paper describes the use of a lift-off technique to fabricate a high density structure consisting of multiple layers of metal/polyimide thin film structures on a silicon substrate. To achieve better performance and high yield, we evaluated the process design, processing parameters, and the thickness of the Cr/Cu/Cr metallurgy, along with the use of suitable polyimide dielectrics. The plasma processing conditions, the types of passivation metals on Cu, and the use of a siloxane-polyimide as the gap-fill/etch-stop material were all shown to play a very critical role in affecting the interconnection resistance and yield of the multilayer thin film structures. By optimizing these parameters the feasibility of fabricating high density thin film wiring layers with good yield is demonstrated. © 1993 IEEE