Analysis of residual errors due to calibration transfer in on-wafer measurements at mm-wave frequencies

in this work we analyze, by means of 3D electromagnetic simulations, the accuracy limitations of mm-wave probe-level calibrations. The field coupling of the unshielded probe-wafer transition is the considered source of calibration inaccuracy when changing substrate between calibration and measurements. The problem of calibration transfer is first schematized in terms of error box analysis. After, EM simulations are used to assess the residual error associated to the calibration transfer. A method for error minimization is proposed, showing an improvement as high as 50% on measurement results (65% on simulations) when transferring the calibration from alumina (ε_r=3D9.6) to SiGe back-end-of-line (ε_r=3D4.1).