Mobile Charge Induced Breakdown Instability in 700V LDMOSFET

One chip solution for SMPS (switch mode power supply) has been drawing great attention of the designers with its green mode standby power and high efficiency in the AC-DC adaptor and LED lighting applications. The UHV (ultra-high voltage) foundry process, which enables the integration solution for green compliance SMPS, is proposed in this paper. The technology integrated low voltage CMOS (5 V), medium voltage (40 V) and UHV (700 V) devices in one single process. The UHV technology provides a novel UHV device structure with RESURF (Reduce-SURface-Field) effect to sustain ultra-high breakdown voltage and not to affect the original low/medium voltage devices performance in the same time. Thus, the concept of this novel structure is easily to apply to the other technology nodes and extend its voltage-sustaining range by adjusting the drift length for the RESURF structure. In this research, the 700 V technology has realized the performance that the BVdss (breakdown voltage) is 800 V with Ronsp (on-resistance) of 270 mOhm-cm². In the same time, the process challenge to optimize 700 V device performance against un-balanced mobile charge issue was also discussed.