RF-performance of thick damascene Cu interconnect on silicon

The performance of 2 μm thick damascene Cu lines embedded in low K material are evaluated. The process is well control over a 200 mm wafer, provided that tiling is used. A minimum linewidth of 560 nm is achieved. The RF performance of substrate and metal lines in the 1 - 100 GHz frequency range is investigated with coplanar waveguides. Various substrates were used with resistivities ranging from 3-5 Ω-cm to 4-5kΩ-cm. With a properly treated substrate, RF losses are only determined by AC series resistance of the metal lines yielding very low losses of 1.7 dB/cm at 10 GHz.