Integrated strain sensor for micromachined terahertz on-wafer probe

This paper introduces an improved method for monitoring and controlling the contact condition of terahertz on-wafer probes. This method enables accurate contact force measurement without modification to the standard probe station. Repeatable probe contact force is crucial for RF measurement repeatability and can be achieved by properly monitoring and controlling the strain generated at designated positions on the terahertz probe due to probe deformation induced by contacting the test substrate. A WR-1.5 (500 GHz-750 GHz) probe with integrated strain sensor is developed and tested. Measurement results of the WR-1.5 probe using 11 mN contact force controlled separately by load cell and strain sensor are presented.