Semiconductor device

Abstract

A semiconductor switching device for an inverter includes a first conductivity type, low impurity concentration, semiconductor substrate having a band gap equal to or greater than 2.0 eV, a first conductivity type first region formed in a first plane of the substrate having a resistance lower than the substrate, a first electrode formed in another plane of the first region, a first conductivity type second region formed in a second plane of the substrate, and a second electrode formed on the second region. A trench is formed in the second plane, a control region is formed from a bottom of the trench into the substrate and a control electrode of a different conductivity type is formed on the control region. The second electrode is formed over the control electrode through an insulator film, and the control electrode is formed on the trench sidewalls so the control region contacts the second region.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to improvements for transistors such as junction FETs (JFETs) and static induction transistors (SITs). [0002] Silicon carbide (SiC) has about 10 times as high a dielectric breakdown field as silicon (Si), so that a drift region provided to maintain a blocking voltage can be made thin and highly concentrated, thus reducing losses. Power semiconductor devices using SiC include junction FETs (JFETs) and static induction transistors (SITs). [0003] An example of an SIT that takes advantage of the features of SiC is described in JP-A-2001-94120. The structure in this Japanese patent has an n+ drain region, an n− drift region, an n+ source region, a p-type gate region and a p+ contact region. It also has a drain electrode, a source electrode and a gate electrode. [0004] SIT are transistors that turns an electric current on or off by a depletion layer expanding from the gate into a channel. By narrowing the channel width, whic...

AI Technical Summary

Benefits of technology

This approach enhances the gate blocking effect while reducing on-state resistance, achieving a high blocking voltage with reduced process variability and lower energy ion implantation.

Problems solved by technology

Such a high energy ion implantation, however, requires a thick mask material for shielding, so that for a fine channel it is necessary to form a fine line with a large aspect ratio with a photolithography process, making the formation of fine channels more susceptible to process variations.

If we take process variations to be ±0.05 μm, the on-state voltage and the blocking voltage are both susceptible to the effect of the process variations, resulting in characteristic variations including a desired blocking voltage failing to be produced or a current failing to flow even during the on-state due to a too narrow channel.

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