Effect of Dummy Fills on High-Frequency Characteristics of On-Chip Interconnects

This paper discusses the effect of dummy fills on on-chip interconnect characteristics. The effect of dummy fills has been discussed from the viewpoint of the capacitance. However in high frequency, the magnetic coupling between the signal current and the eddy current in the dummy fills is not negligible. We evaluate the characteristics of on-chip interconnects with dummy fills by a 3D field solver. The size and the location of dummy fills are varied. We also evaluate the effect of dummy fills in the other interconnect layers. Experimental results shows that the impact of the dummy fills on the resistance and the attenuation is not negligible in high frequency such as 50 GHz, and the dummy fills in the other layers have strong effect to the interconnect characteristics. The increase of the attenuation constant due to the dummy fills becomes 20% in maximum