True Kelvin CMOS Test Structure to achieve Accurate and Repeatable DC Wafer-Level Measurements for Device Modelling Applications

A 6-pad True Kelvin Test Structure for advanced CMOS devices is proposed in this work. It allows test engineers to make very accurate and repeatable wafer-level measurements required for SPICE modelling applications. This design helps to overcome parasitic resistance of the probe holder and probe which is found to be dependent on test temperatures. It also mitigates increase in probe contact resistance due to oxidation of exposed underlying copper on aluminum capped test pads as a result of repeated probing at elevated temperatures. Most important of all, it enables accurate device measurements with minimal probe scrub, essential for 30 micrometers or less test pads, without the need for frequent probe tip cleaning.