Study of Ultra High Voltage 500V NLDMOS with Aggressive Design of Drift Region

Ultra high voltage BCD process technology is increasingly used in AC/DC circuit design. The ultra-high voltage LDMOS is the key device of this process and the breakdown voltage of this device is extremely important. The length of the drift region is a key factor in determining the breakdown voltage and conduction characteristics of the device. This article reports a 500V NLDMOS which has an aggressive short drift region length. In order to make the breakdown voltage of the device meet the requirements of 500V application, firstly the effects of drift region doping distribution and structure design on breakdown voltage were studied. The function of metal field plate in this device was discussed. Finally, the 500V NLDMOS device was obtained which has the smallest drift region in industry.