Accuracy and repeatability of automated non-contact probes for on-wafer characterization

We present significant performance improvements of non-contact probes for the mmW and sub-mmW device characterization. Repeatability and accuracy of the measurement setup is studied using an automated non-contact probe system and compared with conventional contact-probes. Owing to the planar, non-contact nature of the new setup, only 2-axis automated positioning is required, as compared to typical 3-axis manipulators, including precise contact-force control used in commercially available systems. We demonstrate repeatability studies for the 140-220 GHz band using a precision servo system, which can be fully automated using a software-controlled aligner for wafer-scale measurements. This fully-automated system also allows for periodic re-calibrations that are typically required for reliable sub-mmW measurements.