Conductivity modulation type misfet and a control circuit thereof

Claim 2

A control circuit for a conductivity modulation type MISFET, the MISFET comprising: a first conductive type conductivity modulation layer, a fist conductive type MIS part, the MIS part comprising a gate electrode over its obverse surface, a second conductive type channel diffusion layer on the obverse surface of the first conductive type conductivity modulation layer, an insulation film interposed between the gate electrode and the second conductive type channel diffusion layer, a first conductive type source area formed adjacent to the surface of the second conductive type channel diffusion layer; a first conductive type source area provided with a source electrode on the obverse surface of the second conductive type channel diffusion layer of said MIS part; a second conductive type drain area provided with a drain electrode which is conductively connected to said conductivity modulation layer in an area isolated from said MIS part; a parasitic transistor control electrode is conductively connected to said channel diffusion layer; and wherein said parasitic transistor control electrode and said source electrode are controlled to be brought into a short-circuited state or an open state by an external MISFET connected to these electrodes.

Claim 3

A control circuit for a conductivity modulation type MISFET, the MISFET comprising: a first conductive type conductivity modulation layer, a first conductive type MIS part, the MIS part comprising a gate electrode over its obverse surface, a second conductive type channel diffusion layer on the obverse surface of the first conductive type conductivity modulation layer, an insulation film interposed between the gate electrode and the second conductive type channel diffusion layer, a first conductive type source area formed adjacent to the surface of the second conductive type channel diffusion layer; `a first conductive type source area provided with a source electrode on the obverse surface of the second conductive type channel diffusion layer of said MIS part; a second conductive type drain area provided with a drain electrode which is conductively connected to said conductivity modulation layer in an area isolated from said MIS part; a parasitic transistor control electrode is conductively connected to said channel diffusion layer; wherein said channel diffusion layer has a high density second conductive type contact area formed on the obverse surface of said channel diffusion layer to be isolated from said source area and said parasitic transistor control electrode is conductively connected to said channel diffusion layer through said contact area; and wherein said parasitic transistor control electrode and said source electrode are controlled to be brought into a short-circuited state or an open state by an external MISFET connected to these electrodes.

Claim 4

A control circuit for a conductivity modulation type MISFET, the MISFET comprising: a first conductive type conductivity modulation layer, a first conductive type MIS part, the MIS part comprising a gate electrode over its obverse surface, a second conductive type channel diffusion layer on the obverse surface of the first conductive type conductivity modulation layer, an insulation film interposed between the gate electrode and the second conductive type channel diffusion layer, a first conductive type source area formed adjacent to the surface of the second conductive type channel diffusion layer; `a first conductive type source area provided with a source electrode on the obverse surface of the second conductive type channel diffusion layer of said MIS part; a second conductive type drain area provided with a drain electrode which is conductively connected to said conductivity modulation layer in an area isolated from said MIS part; a parasitic transistor control electrode is conductively connected to said channel diffusion layer; wherein said channel diffusion layer has a high density second conductive type contact area formed on the obverse surface of said channel diffusion layer to be isolated from said source area and said parasitic transistor control electrode is conductively connected to said channel diffusion layer through said contact area; and wherein said parasitic transistor control electrode and said source electrode are controlled to be brought into a short-circuited state or an open state by an external MISFET connected to these electrodes.

Claim 5

A control circuit according to claim 1 or 2 wherein, on a semiconductor substrate on which said conductivity modulation type MISFET is formed, said parasitic transistor control electrode and said source electrode are conductively connected in an area isolated from said conductivity modulation type MISFET and a switching element for switching over a circuit between said control and source electrodes to a short-circuited state or an open state.

Claim 6

A control circuit according to claim 3, wherein said switching element is a MISFET provided with a source area and a drain area to which said parasitic transistor control electrode and said source electrode are conductively connected.