A New Calibration Technique of Electromagnetic Simulators for Accurate Analyses of Microwave Components on Epitaxial Wafers

This article describes an innovative methodology to calibrate EM simulators, oriented to monolithic microwave integrated circuit design, in order to achieve the highest level of accuracy achievable in electromagnetic simulation. In particular, a two-stage measurement technique based on two types of network analyzer calibrations is adopted as a practical and accurate process for on-wafer S-parameter measurements of suitable test structures on semiconductor epitaxial wafers. Thus, a substrate parameter set for the electromagnetic simulator is appropriately identified by an optimization process that combines measurements of dedicated simple test structures and the corresponding models in the circuit simulator. The proposed approach allows one to accurately estimate the substrate characteristics without realizing expensive on-wafer structures that require a large substrate area. We will demonstrate, through several comparisons between measurements and electromagnetic simulations of different passive structures, how higher accuracy can be achieved, describing and quantifying the limitations that arise from commonly adopted calibration procedures for electromagnetic simulators.