No abstract

We have succeeded in observing the longitudinal microstructure of very narrow Cu interconnects for the first time. We found that the average grain sizes along the longitudinal direction of Cu interconnect trenches increased with increasing line width, and they were 278 nm for 80 nm, 303 nm for 100 nm, and 346 nm for 180 nm wide interconnects. Ratios of the average grain size to line width were 3.5 for 80 nm, 3.03 for 100 nm, and 1.9 for 180 nm line widths.

Grain size distributions and average grain sizes in the longitudinal direction of the Cu interconnect in 50-, 70-and 80-nm-wide Cu interconnects were evaluated and compared with the resistivities of each interconnect. After annealing, the standard deviation of grain sizes for 50-nm Cu interconnect increased to 27.5, and the average grain size microstructure grew to larger than that of as-deposited 50-nm Cu interconnects. The value of standard deviation of grain sizes in the normal distribution histogram for a 50-nm wire was found to be much smaller than those for 70-and 80-nm Cu wires after annealing. This implies that adequate grain growth should not be expected in the very narrow Cu interconnects (less than 50-nm) of the future if they are made with the conventional annealing process.

An elevator group supervisory control system is used to supervise multiple elevators, ensuring that they are operated efficiently. A conventional system aims at reducing average waiting time, although recently requests by elevator users have focused not only o n reducing average waiting time, but also o n reducing the riding time, the number of passengers, etc. Therefore the authors developed a new elevator group super-visory control system which improves plural control objects according to users' requests. The system effectiveness is confirmed by simulations.