Before revision: At this point, the capacitive RC coupling of interconnects became the speed(frequency)-limiting factor.Haumesser, 2016, 10.1016/b978-1-78548-092-8.50004-5 The process of reducing both R and C started in the late 1990’s, when Al was replaced with Cu for lower R, and SiO2 was replaced with low-k dielectrics for lower C. Cu was selected as the replacement for Al, because it has the lowest electronic resistance among low-cost materials at room temperature, and because Cu shows a slower electromigration than Al.
After revision: (aluminium)(copper)At this point, the capacitive RC coupling of interconnects became the speed(frequency)-limiting factor.Haumesser, 2016, 10.1016/b978-1-78548-092-8.50004-5 The process of reducing both R and C started in the late 1990’s, when Al was replaced with Cu for lower R, and SiO2 was replaced with low-k dielectrics for lower C. Cu was selected as the replacement for Al, because it has the lowest electronic resistance among low-cost materials at room temperature, and because Cu shows a slower electromigration than Al.