Simplified Cu/Polyimide Damascene Approach Based on Imprint Process of Soluble Block Copolymer Polyimide

In this study, a Cu/polyimide damascene approach based on an imprint technique was demonstrated aiming at developing a low-cost fabrication process for high-density interconnections in polyimide. First, a UV-assisted thermal imprint process that utilizes the high formability and low shrinkage of a soluble block copolymer polyimide was proposed as a high precision patterning process for polyimide. As a result, fine patterns (line widths ranging from 3 to 50 µm) with rectangular cross sections and clear line edges were fabricated in soluble block copolymer polyimide films by UV-assisted thermal imprinting followed by curing. Additionally, Cu damascene structures with a minimum line width of 3 µm were fabricated in the polyimide by performing subsequent Cu electroplating and chemical mechanical polishing (CMP), and the feasibility of the process was verified.