Potential of 4H-SiC CMOS for high temperature applications using advanced lateral p-MOSFETs

In this work, the impact of the n-well doping concentration on the channel mobility and threshold voltage of p-MOSFETs and their applications in CMOS-devices is evaluated. For this purpose lateral p-channel MOSFETs with different channel lengths (L = 800 mm, 10 mm, 5 mm, and 3 mm) and doping concentrations (ND= 1015cm-3and 8·1015cm-3) were fabricated and the respective field-effect mobility was extracted from the transfer-characteristics. Comparable to n- MOSFETs the mobility of p-MOSFETs was found to be the highest for the lowest doping concentration in the channel and the absolute value of the threshold voltage increases with increasing doping concentration [3]. To investigate its suitability for CMOS applications, inverters with different doping concentrations for n- MOSFET (NA= 1015cm-3and 1017cm-3) und p- MOSFET (ND= 1015cm-3and 8·1015cm-3) were built. For logic levels of 0 V and 10 V, the voltage transfer characteristic with the highest input range was obtained for a low p-MOSFET and a high n- MOSFET doping concentration. The lowest propagation delay time could be achieved with a low p- MOSFET and a low n-MOSFET doping concentration. For temperatures up to 300 °C the drain current of p-MOSFETs with channel lengths below 3 mm is hampered by the series resistance of the source and drain region which limits the high-frequency performance of CMOS devices.