50-GHz Interconnect Design in Standard Silicon Technology

Coplanar waveguides were fabricated in a process that emulates silicon CMOS technologies with 5 to 10 metal layers. The observed S21 loss of 0.3dB/mm at 50 GHz is among the lowest ever reported with standard Al interconnects on Si/SiO2. Optimum design parameters were counter-intuitive: in some frequency ranges, the lowest loss was achieved with relatively narrow lines over a low-resistivity substrate. This was exploited in the design of transmission lines that are fully compatible with a CMOS technology. The process emulation was calibrated with a commercial 4-layer Al/Cu CMOS technology.