Long-term stability test on on-wafer measurement system in NMIJ

The paper reports investigation result of long-term stability for on-wafer measurement system adopting an automatic probing system developed by NMIJ-AIST. To RF probe coordinates in X-, Y-, Z-directions and tilt angle, their origins can automatically be adjusted by using actual measured S-parameter in the measurement system. The measurements were continued for 3 months to investigate on the stability by using same calibration and verification devices. A matched transmission line was used as the verification device. A standard deviation of measured refection coefficient achieved to approximately -50 dB, and that of measured transmission coefficient reached to approximately -60 dB. These deviation values are comparable to the short-term repeatability in measurement presented by other laboratory, even if the measurements are proceeded for long period, i.e. 3 months.