RF performance boosting for 40nm-node CMOS device by low-k/Cu dual damascene contact

To enhance RF performance, low-k/Cu dual-damascene (DD) contact is implemented into 40 nm-node CMOS devices for the first time. The Cu DD contact in reliable double-layered low-k films of silica-carbon composite (SCC, k=3.1) and SiOCH (k=3.1) boosts the cut-off frequency (f_T) and the maximum oscillation frequency (f_max) by 8.0 % and 10.5% referred to those of the conventional SiO₂/W-plug structure, respectively. The low-k/Cu-DD contact structure becomes effective to reduce the parasitic factors in the scaled-down 40 nm-node more than the 55 nm-node reported. The contact resistance and the parasitic capacitance (C_gs) are reduced by 80% (one-fifth) and 17% referred to those of the conventional SiO₂/W-plug structure, respectively. The low-k/Cu DD contact is essential to scaled-down CMOS devices for RF/ubiquitous applications.