Abstract
Many high voltage complementary metal-oxide-semiconductor (HV-CMOS) processes are modified from a standard 5 V CMOS process by adding an N-type heavily doped layer under the P-well of a HV-PMOS drain terminal to isolate a high voltage P-well from a grounded P-substrate. The limitation of breakdown voltage is dominated by P-well concentration and junction depth. For designing a certain breakdown voltage (BV dss ) for a HV-PMOS, the original 5 V CMOS P-well concentration should be decreased, which could degrade 5 V CMOS characteristics, such as NMOS punch through and latchup immunity. In this study, we demonstrate a novel HV-PMOS based on a split N-type buried layer (NBL), which provides a high BV dss in a HV-CMOS process. The newly proposed device with NBL split under the P-well of a drain electrode increases BV dss without degrading specific on-resistance (R on,sp ) and any added process complexity. From this result, P-well concentration could be increased to improve both 5 V NMOS characteristics and HV-PMOS R on,sp . ©2007 The Japan Society of Applied Physics.