Semiconductor device
AssigneesMitsubishi Denki Kabushiki Kaisha, Ryoden Semiconductor System Engineering Corporation
InventorsKazunari Hatade, Kazutoyo Takano
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Abstract
The object of the invention is to improve a characteristic under a reverse bias. A P base layer (6) is provided as a plurality of band-shaped portions parallel with each other. A P+ base layer to be a downward protrusion having a high impurity concentration is not formed in a bottom portion of the P base layer (6). The P base layer (6) is formed more shallowly than an N layer (17), and furthermore, the band-shaped portions forming the P base layer (6) are coupled to each other at ends thereof. Moreover, an N source layer (5) is ladder-shaped and is connected to a source electrode (16) through only a crosspiece portion thereof.
Claims12
A semiconductor device comprising a semiconductor substrate having an upper main surface and a lower main surface, said semiconductor substrate including:
- a first semiconductor layer of a first conductivity type;
- a second semiconductor layer of the first conductivity type which is formed on said first semiconductor layer to be exposed to said upper main surface and has a higher impurity concentration than said first semiconductor layer;
- a third semiconductor layer of a second conductivity type which is selectively formed in said upper main surface more shallowly than said second semiconductor layer, is divided into and provided as a plurality of band-shaped portions parallel with each other, and is not provided with a downward protrusion having a higher impurity concentration in a bottom portion than a periphery;
- a fourth semiconductor layer of the first conductivity type which is selectively formed in said upper main surface and is divided into and provided as a plurality of ladder-shaped portions parallel with each other, each of said ladder-shaped portions being formed to be extended more shallowly in and along any of at least a part of said band-shaped portions individually corresponding thereto;
- and
- a fifth semiconductor layer of the second conductivity type which is selectively formed in said upper main surface and couples said band-shaped portions to each other,
- said semiconductor device further comprising:
- an insulating film formed on a region interposed between adjacent sets of said ladder-shaped portions in said upper main surface;
- a gate electrode formed on said insulating film and opposed to said region;
- a first main electrode connected to each of said band-shaped portions and connected to each of said ladder-shaped portions through at least a crosspiece portion thereof;
- and
- a second main electrode connected to said lower main surface.
Dependencies are inferred from the claim text.