Low specific on-resistance power MOSFET with a surface improved super-junction layer

Abstract

A novel low specific on-resistance (Ron,sp) integrable power metal-oxide-semiconductor field-effect transistor (MOSFET) with a surface improved super-junction (SISJ) layer is proposed. A super-junction layer is implemented at the surface of the drift region and the P pillar in super-junction layer is split into two parts with different doping concentrations. Firstly, the super-junction layer causes the multiple-direction depletion effect. The drift region doping concentration of the SISJ LDMOS is therefore increased significantly. Secondly, the super-junction layer provides a surface low on-resistance path. Thirdly, the new electric field peak introduced by the variation in the doping concentration of the P pillar modulates the surface electric field distribution, resulting in an improved breakdown voltage (BV). It reduces the device pitch for a specific BV capacity. All of them decrease Ron,sp sharply. The SISJ LDMOS exhibits a Ron,sp of 10.2mΩcm2 for BV=230V and decreases Ron,sp by 37% compared with a conventional lateral double-diffused MOSFET (LDMOS) at the same BV. Finally, because of the shallow depth of the SISJ layer, the proposed structure can be compatible with CMOS technology. Consequently, the SISJ LDMOS must be a competitive power device for power integrated circuit applications.