Measurement of interconnect loss due to dummy fills

This paper reports measurement results of on-chip interconnects with CMP dummy fill. CMP dummy fill is a floating metal for metal density adjustment. In high frequency above 10 GHz, the eddy current induced in dummy fills affects the interconnect loss. We fabricated test structures of on-chip interconnect with dummy fills. From the measurement results, the effect of the dummy fills on the wire resistance is not negligible even if the ground wires are adjacent to the signal wire. The dummy fills in the upper/lower metal layer affect the wire resistance and the resistance increases by 20% at 50 GHz.