In this paper we extract the characteristic impedance of
Back End Of Line (BEOL) interconnections from radio frequency (RF)
scattering parameter measurements. Quantification of the electric
interconnection performance on a broad frequency band requires a good
knowledge of the characteristic impedance Zc and the
propagation exponent γ. Propagation exponent is easily obtained by
measuring two interconnections with different lengths. However, because of
the complex test structure with mismatched ports where interconnections are
embedded, the extraction of Zc from scattering parameter
measurements remains challenging. To solve this problem, we propose an
approach based on the Winkel method without using simplified
assumptions. Limits of validity for our de-embedding procedure to extract
characteristic impedance are also analyzed.