High-Frequency Characterization of On-Chip Digital Interconnects

On-chip inductance is becoming increasingly important as technology continues to scale. This paper describes a way to characterize inductive effects in interconnects. It uses realistic test structures that study the effect of mutual couplings to local interconnects, to random lines connected to on-chip drivers, and to typical power and ground grids. The use of parameters to characterize the inductance allows a large number of lines to be extracted while requiring only a small overhead measurement of dummy open pads to remove measurement parasitics. It also enables direct extraction of the frequency-dependent , , , parameters. The results are summarized with curve-fitted formulas of inductance and resistance over a wide range of line spacings and line widths. The significance of the frequency dependence is illustrated with transient analysis of a typical repeater circuit in a 0.25m technology. A model that captures the frequency dependency of the extracted parameters accurately predicts the performance of a new inductance-sensitive ring oscillator.