A high density, low on-resistance, trench lateral power MOSFET with a trench bottom source contact

This thesis deals with the design and implementation of lateral power MOSFETs which are used in a variety of applications such as disc drives, power supplies and automotive applications. Power MOSFETs are popular because of their high switching speed, high input impedance and wide safe operating area.; In this thesis, a novel Trench Lateral Power MOSFET with a trench bottom source contact (imbedded in the silicon substrate and referred to as the TLPM/S) is proposed. The device fabrication process is presented. The TLPM/S is implemented along the sidewall of trenches in order to increase packing density of the MOSFET. The process utilizes a self-aligned technique to form the gate electrode and trench bottom contact holes to the source to achieve minimum pitch and very low on-resistance compared to conventional lateral power MOSFETs. In addition, the TLPM/S features a small Miller capacitance and improved switching performance. Integration of the TLPM/S in a low voltage BiCMOS process is also proposed. Only the trench mask is added to integrate the TLPM/S devices in conventional low voltage BiCMOS process.; A 70 V class TLPM/S device with a device pitch of 3.0 μm, implemented in a 0.6 μm BiCMOS compatible process, exhibits a breakdown voltage of 73 V and a specific on-resistance of 60 mΩ-mm2. These values represent the best reported values to date and are very close to the silicon limit for this class of devices.