Microwave characterisation of microstrip lines and spiral inductors in MCM-D technology

Abstract

MCM-D (multichip module-D) technology comprising a four-level metallization, aluminum-polyimide structure defined on a silicon substrate is considered. A dedicated microwave characterization layout was designed and implemented, which included a series of microstrip lines, spiral inductors, microstrip coupling structures, ring resonators, and microwave calibration structures. Analog measurements of these structures were then carried out using RF-on-wafer methods at frequencies from 0.5 to 20 GHz. Equivalent circuit models were derived which gave a close fit to the experimental measurements, and a range of transmission line and spiral inductor components was characterized. Useful analog transmission line behavior was indicated for 10-mm line lengths to 10 GHz, while inductors were measured with primary inductances approaching 10 nH with useful Q values in the 1 -3-GHz region. Layout rules for low crosstalk were also devised. The lower metallization resistance and increased dielectric separation from the silicon substrate resulted in improved performance for these MCM-D inductors in comparison with on-chip inductors of comparable inductance.<>