A hybrid Cu-Al BEOL process for cost effective and efficient tool utilization

In this paper, we describe the implementation of a successful Cu-Al hybrid backend of line (BEOL) interconnect scheme for 0.13um process. Cu-Al hybrid process was used effectively to combine the advantages of both metals to lower cost of manufacturability and reduction in mask layers. A hybrid process also utilizes existing Aluminum tools efficiently for interconnects in wider via and top metal layer. Mask data preparation, suitable alignment structures and other details are also discussed. A reliable barrier process is employed to ensure a stable Cu-Al interface, which is critical for maintaining the integrity of the interconnects. SRAM Yield, Stress, electromigration lifetimes and MIM time dependent dielectric breakdown (TDDB) lifetimes were also tested. This study demonstrates a promising approach to achieving cost effective BEOL process for consumer applications.