Enhanced drift in RF-power LDMOS transistors under pulsed stress conditions

This paper presents an experimental evaluation of the reliability of LDMOS transistors with possible use in radio base station PA or for pulsed S-band Radar applications. Alternative device layouts have been investigated in a stress-test measurement system capable of generating pulses in the nanosecond range. The investigation shows that pulsed operation accelerate device drift. For the most sensitive parameter R_ON, pulsed operation at low supply voltage increase the drift with a factor 3 compared to constant operation. The investigation indicates that the stress is affecting the overlap or the field region but not the channel region. RESURF designed devices with decreased field in this region therefore show less R_ON drift.