Low resistance dual damascene process by new Al reflow using Nb liner

This paper describes excellent Al filling characteristics and low resistance dual damascene interconnects obtained with a new Al reflow process using Nb liner. This novel process can fill vias of AR4 and can achieve 40-50% drop in resistance compared with current RIE-Al lines and reflow-Al lines with Ti liner. These properties are attributed to a slower reaction rate between Nb and Al. Excellent via electrical properties have been verified across 200 mm wafers using this process. This new process is a leading candidate for sub-0.25-0.15 um Al metallization.