NORMALLY ON HIGH VOLTAGE SWITCH

摘要

In some embodiments, a normally on high voltage switch device (“normally on switch device”) incorporates a trench gate terminal and buried doped gate region. In other embodiments, a surface gate controlled normally on high voltage switch device is formed with trench structures and incorporates a surface channel controlled by a surface gate electrode. The surface gate controlled normally on switch device may further incorporate a trench gate electrode and a buried doped gate region to deplete the conducting channel to aid in the turning off of the normally on switch device. The normally on switch devices thus constructed can be readily integrated with MOSFET devices and formed using existing high voltage MOSFET fabrication technologies.

主权项

1. A normally on high voltage switch device (“normally on switch device”), comprising:
a first semiconductor layer of a first conductivity type, the first semiconductor layer being heavily doped and forming a drain region of the normally on switch device; a second semiconductor layer of the first conductivity type formed on the first semiconductor layer; a trench formed in the second semiconductor layer, the trench being lined with an insulating layer and filled with a conductive material; a first doped region of a second conductivity type, opposite the first conductivity type, formed under the trench, the first doped region being electrically connected to the trench to form a gate terminal of the normally on switch device; and a second doped region of the first conductivity type formed on a first surface of the first semiconductor layer, the second doped region being heavily doped and forming a source region of the normally on switch device, wherein the normally on switch device comprises a channel formed in the second semiconductor layer between the source region and the drain region, and the channel is shut off when a reverse bias voltage is applied to the gate terminal relative to the source region.