Proposal of 0.13um new structure LDMOS for automotive PMIC

Summary form only given. In this paper we studied 90V high-side LDMOS and 50V fully isolated LDMOS with double epi structure and also found the method of increasing thermal stability to meet requirements above mentioned. The 90V high-side LDMOS used normally in buck-boost circuit need high BVdss over 110V. This high BV dss can obtain by thicker Epi scheme but increasing Epi thickness should cause the difficulty of electrical connecting drain node to n+ buried layer (NBL-l) by implantation. So, this is the major reason to introduce the double Epi scheme instead of the conventional single Epi scheme. And we modified PBL doping concentration by slicing PBL structure to obtain maximized RESURF effect to more get high BVdss without changing doping concentration ofPBL (p+ buried layer). And we also increased BVdss by putting floated poly on STI oxide that can induce the voltage coupling of drain bias, which gradually reduce electric field concentrated under STI.