Gate resistance thermometry measurements on fully vertical AlGaN (2.5%) FinFETs

We have demonstrated gate resistance thermometry (GRT) measurements to determine the channel temperature in fully vertical AlGaN (2.5%) FinFETs with different fin widths (Wfin = 200, 300, and 400 nm). The experimental results are validated using a 3D thermal finite element method simulation, considering thermal conductivities for the various materials in the FinFET structure. A close agreement between the measured and modeled gate metal temperatures is observed in all devices. In a FET with Wfin = 300 nm at power density PD = 50 kW/cm2, the extracted gate metal temperature is 49.8 °C, while the actual channel temperature obtained from simulations is 67.3 °C, indicating the limitation of the GRT method in directly estimating the real device temperature. A modified gate contact design is proposed to improve measurement accuracy. These findings highlight that with careful device design optimization, the actual channel temperature can be extracted in these complex vertical power devices using a simple and fast thermometry method.