Wafer Probe Calibration Accuracy Measurements

Assessing the uncertainty of wafer probe measurements can be a difficult problem. Setting uncertainty values implies the ability to measure the error terms that contribute to the uncertainty. The major error terms for S-Parameter measurements are Directivity, Source Match and Load Match. This paper describes a technique for measuring these parameters. The only structure required is a relatively long section of transmission line in the medium of the substrate. Measurement examples are given using a broadband 40 MHz to 110 GHz wafer probe system.