Time Dependent Dielectric Breakdown (TDDB) Evaluation of PE-ALD SiN gate dielectrics on AlGaN/GaN recessed gate D-mode MIS-HEMTs and E-mode MIS-FETs

This paper reports a comprehensive time dependent dielectric breakdown (TDDB) evaluation of recessed-gate devices with five different AlGaN barrier thicknesses with characteristics ranging from a D-mode MIS-HEMT to an E-mode MIS-FET. First, the fitted parameter beta (the slope of the Weibull distribution) was smaller for a deeper recessed gate and larger for a thicker gate dielectric. Secondly, the extrapolated V-G (criterium of 0.01% failures after 20 years) for the devices with Wg (gate width) = 10 mu m was lower when less AlGaN barrier remains under the gate. However, the extrapolated VG was increased when the AlGaN barrier was completely removed. Thirdly, a deeper recessed gate could result in a dominant percolation path due to a thinner gate dielectric on the sidewall of the gate recess edge. Fourthly, the Weibull distribution could scale with the gate width, indicating an intrinsic failure. Finally, the lifetime was extrapolated to 0.01% of failures for W-g=36mm at 150 degrees C after 20 years by fitting the data with a power law or an exponential law to gate voltages of 4.9V and 7.2V, respectively.