D. Vitali¹, A. Chillico¹, W. Samek^2,3, and O. Bengtsson¹

Published in:

IEEE Trans. Microwave Theory Tech., early access, doi:10.1109/TMTT.2025.3557081 (2025).

Abstract:

This article describes a novel method for on-wafer probing of high-frequency components based on optical recog- nition of probe skating and positions. The method enables a more accurate automatic probing of on-wafer structures and is developed to increase precision and accuracy in radio frequency (RF) measurements. The presented real-time optical recognition of the probe touchdown enables an estimated probe skating precision of ± 3 µm on the evaluated probe system. Optical identification of the probes’ position is used for verification of the measurement distance. Wafer mapping of S-parameters conducted on microstrip (MS) lines on a GaN wafer are evaluated with regard to accuracy and precision in the 0.5–50 GHz range using metrology software for S-parameter analysis. The developed probing method is verified by comparing it to a standard procedure with fixed Z-height probing and to a bow- compensated method, with all measurements conducted on the same setup and the same device. It is shown that the optically recognized probe skating and position detection can improve the accuracy of S-parameter measurements by up to 50% for devices positioned across a wafer, assuming a 0.5σ acceptance margin for the probe distance.

Index Terms:

HEMTs, intelligent automation, microwave measurement, on-wafer measurements, S-parameters.

© 2025 The Authors. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/

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