Automated wafer-level measurement of LDMOS reverse recovery parameters

Accurate measurement of reverse recovery parameters (RRPs) in high-speed, high-power switches and rectifiers is a fundamental task in their test and characterization process. Performing such tests at a wafer-level in laterally diffused MOSFETs (LDMOS) presents several challenges with respect to their test in packaged devices. The handling of prober parasitic impedances, current injection constraints, and automated signal synchronization top the list of issues that need to be addressed. Moreover, making the tests amenable for automated execution just adds more constraints to the problem. This paper proposes a solution for automatic characterization of wafer-level LDMOS RRPs that include reverse recovery time (t_rr), reverse recovery current (I_rr), and storage charge (Q_rr). Its implementation has enabled accurate automated parametric wafer-level LDMOS tests at currents as high as 15A and ∂I/∂t´s of up to 173A/μs.