Abstract A conductivity-modulation MOSFET employs a substrate of an N type conductivity as its N base. A first source layer of a heavily-doped N type conductivity is formed in a P base layer formed in the N base. A source electrode electrically conducts the P base and the source. A first gate electrode insulatively covers a channel region defined by the N + source layer in the P base. A P drain layer is formed on an opposite substrate surface. An N + second source layer is formed in a P type drain layer by diffusion to define a second channel region. A second gate electrode insulatively covers the second channel region, thus providing a voltage-controlled turn-off controlling transistor. A drain electrode of the MOSFET conducts the P type drain and second source. When the turn-off controlling transistor is rendered conductive to turn off the MOSFET a "shorted anode structure" is temporarily formed wherein the N type base is short-circuited to the drain electrode, whereby case, the flow of carriers accumulated in the N type base into the drain electrode is facilitated to accelerate dispersion of carriers upon turn-off of the transistors.
A semiconductor device comprising: a semiconductive substrate; a conductivity-modulation field effect transistor formed on said substrate, said transistor having a first base region, a second base region, a source region formed in said second base region, a source electrode for electrically connecting said second base region and said source region, a drain region, a drain electrode formed in said drain region, and a gate electrode insulatively provided above said substrate to define a channel region in said second base region, said gate electrode being used to turn on and off said device; said substrate being used as said first base region; and a turn-off controlling field effect transistor, having a second source region formed in said drain region, a second gate electrode insulatively disposed above said drain region to define a channel region in said drain region, for rendering said conductivity-modulation transistor nonconductive by electrically connecting said first base region with aid drain thereby to accelerate dispersion of carriers accumulated in said conductivity-modulation transistor.
Claim 2
Dependent Claim
164 words
A semiconductor device comprising: a semiconductive substrate; a conductivity-modulation field effect transistor formed on said substrate, said transistor having a first base region, a second base region, a source region formed in said second base region, a source electrode for electrically connecting said second base region and said source region, a drain region, a drain electrode formed in said drain region, and a gate electrode insulatively provided above said substrate to define a channel region in said second base region, said gate electrode being used to turn on and off said device; said substrate being used as said first base region; and a turn-off controlling field effect transistor, having a second source region formed in said drain region, a second gate electrode insulatively disposed above said drain region to define a channel region in said drain region, for rendering said conductivity-modulation transistor nonconductive by electrically connecting said first base region with aid drain thereby to accelerate dispersion of carriers accumulated in said conductivity-modulation transistor.
Claim 3
Dependent Claim
42 words
The device according to claim 1, wherein said turn-off controlling transistor causes said first base region to be short-circuited to said drain electrode thereby to provide a "shorted anode" structure in said device only during a turn-off control mode of said device.
Claim 4
Dependent Claim
28 words
The device according to claim 1, wherein said turn-off controlling transistor electrically disconnects said first base region from said drain electrode when said conductivity-modulation transistor is rendered conductive.
Claim 5
Dependent Claim
33 words
The device according to claim 3, wherein said conductivity-modulation transistor includes a first metal oxide semiconductor field effect transistor, and said turn-off controlling transistor includes a second metal oxide semiconductor field effect transistor.
Claim 6
Dependent Claim
26 words
The device according to claim 4, wherein said first and second metal oxide semiconductor field effect transistors are respectively formed on opposite surfaces of said substrate.