Diluted drift layer with variable stripe widths for power transistors

Abstract

A multi-finger lateral high voltage transistors (MFLHVT) includes a substrate doped a first dopant type, a well doped a second dopant type, and a buried drift layer (BDL) doped first type having a diluted BDL portion (DBDL) including dilution stripes. A semiconductor surface doped the second type is on the BDL. Dielectric isolation regions have gaps defining a first active area in a first gap region (first MOAT) and a second active area in a second gap region (second MOAT). A drain includes drain fingers in the second MOAT interdigitated with source fingers in the first MOAT each doped second type. The DBDL is within a fingertip drift region associated drain fingertips and/or source fingertips between the first and second MOAT. A gate stack is on the semiconductor surface between source and drain. The dilution stripes have stripe widths that increase monotonically with a drift length at their respective positions.