tailieunhanh - Engineering Materials and Processes phần 8

Sự thất bại electromigration Al (Cu) kết nối đã được điều tra bởi vì việc sử dụng ưu thế của Al (Cu) là dây dẫn trong các thiết bị vi điện tử trong nhiều thập kỷ. Gần đây, nghiên cứu electromigration Củ đã được tiến hành đáng kể và, 5 bạc Electromigration kháng (lưu lượng khối - khối lượng dòng chảy ra) | Integration Issues 89 14 13 12 E 11 I I I I I r Ag 200nm Al 30nm on SiO2 400oC 500oC - A 600oC _ - 10 ID Õ5 7 6 30 40 50 60 70 80 90 time1 2 s1 2 Figure . Al oxide thickness as a square root function of time for an Ag 200nm Al 30 nm bilayer system 8 Growth Kinetics of Oxide Surface Layer In order to investigate the growth kinetics the thickness of either aluminum or silver was changed. The influence of the initial Al thickness on the oxide growth kinetics was studied by considering the following two bilayers structures Ag 200 nm Al 20 nm and Ag 200 nm Al 30 nm . The AlxOy thickness x derived from the RBS data presented in the previous sections was plotted as a function of the square root of annealing time t1 2 for the range 15 to 120 minutes Figures and . Note the square root of annealing time is expressed in seconds in Figures and . The plots of thickness x versus square root of time are straight lines which imply that the oxide growth follows a parabolic growth behavior x2 t . In Figure the slopes of the 500 and 600 C are almost parallel compare to the 400 C anneal. For the thicker Al 30 nm the lines are almost all parallel to each other Figure . The diffusion coefficient D for the different bilayers Ag 200 nm Al 20 nm and Ag 200 nm Al 30 nm systems annealed at different temperatures were determined by taking the squares of the slopes of the plots in Figures and . The results of these diffusion coefficients are given in Table and reflect the behavior of the plots of thickness versus time1 2. The diffusion coefficient increases as a function of temperature and is the highest for the 600 C anneal. It was found that the growth rates are much higher in Ag 200 nm Al 20 nm than those in Ag 200 nm Al 30 nm bilayers. 90 Silver Metallization Table . Effect of temperature on the rate constants in the Ag Al bilayer system for annealing times greater than 15 minutes 8 Temperature C .