Characterization of Silicon Nitride Capping Dielectrics on AlGaN/GaN/Silicon Substrate HEMT Structures with a Mercury Probe

The characterization of High Electron Mobility Transistor (HEMT) structures is important for predicting device behavior, monitoring and developing processes and improving performance. This also includes measuring the quality of the top dielectric capping layer. The top capping dielectric and its' associated charges both in the dielectric and at the interface can induce shifts and instabilities in the HEMT device pinch-off voltage. In this paper, a highly repeatable and accurate, small area mercury gate is used to measure critical HEMT parameters earlier in the process and prior to final device formation.