Silicon carbide switching device with rectifying-gate

A three terminal gate controlled semiconductor switching device, comprising:

• an insulated-gate field effect transistor having an insulated gate electrode, a first source region and a first drain region;
• a rectifying-gate field effect transistor having a gate electrode, a second source region and a second drain region, wherein said gate electrode and said second source region are electrically connected to said first source region and said first drain region, respectively;
• a drain contact electrically connected to said second drain region;
• a source contact electrically connected to said first source region;
• and
• wherein said rectifying-gate field effect transistor comprises a MESFET.

A three terminal gate controlled semiconductor switching device, comprising:

• an insulated-gate field effect transistor having an insulated gate electrode, a first source region and a first drain region;
• a rectifying-gate field effect transistor having a gate electrode, a second source region and a second drain region, wherein said gate electrode and said second source region are electrically connected to said first source region and said first drain region, respectively, wherein said first source region and said first drain region comprise silicon and wherein said second source region and said second drain region comprise silicon carbide;
• a drain contact electrically connected to said second drain region;
• and
• a source contact electrically connected to said first source region.

A semiconductor switching device comprising:

• a semiconductor substrate having first and second opposing faces;
• a drift region of first conductivity type in said semiconductor substrate;
• a source region of said first. conductivity type in said semiconductor substrate, extending to the first face;
• a drain region of said first conductivity type in said semiconductor substrate, between said drift region and the second face, said drain region having a first conductivity type dopant concentration greater than said drift region;
• insulated-gate transistor means having an active region in said substrate, between said source region at the first face and said drift region, for electrically connecting said source region to said drift region in response to a turn-on bias signal;
• and
• rectifying-gate transistor means in said substrate, including a rectifying-gate adjacent said drift region, for controlling the conductivity of said drift region, said rectifying-gate electrically connected to said source region.

A semiconductor switching device, comprising:

• a semiconductor substrate;
• a drift region of first conductivity type in said semiconductor substrate;
• a source region of said first conductivity type in said semiconductor substrate, extending to a face thereof;
• insulated-gate transistor means having an active region in said substrate, between said source region and said drift region, for electrically connecting said source region to said drift region in response to a turn-on bias signal;
• rectifying-gate transistor means in said substrate, including a rectifying-gate adjacent said drift region, for controlling the conductivity of said drift region, said rectifying-gate electrically connected to said source region;
• and
• a trench in said semiconductor substrate at said face, said trench having a sidewall extending between said source region and said drift region and a bottom adjacent said drift region,
• wherein said insulated-gate transistor means includes an insulated-gate electrode which extends adjacent said sidewall and wherein said rectifying-gate extends adjacent said sidewall, between said insulated-gate electrode and said trench bottom.

A semiconductor switching device, comprising:

• a semiconductor substrate;
• a drift region of first conductivity type in said semiconductor substrate;
• a source region of said first conductivity type in said semiconductor substrate, extending to a face thereof;
• insulated-gate transistor means having an active region in said substrate, between said source region and said drift region, for electrically connecting said source region to said drift region in response to a turn-on bias signal;
• rectifying-gate transistor means in said substrate, including a rectifying-gate adjacent said drift region, for controlling the conductivity of said drift region, said rectifying-gate electrically connected to said source region;
• and
• wherein said insulated-gate transistor means comprises an N-channel enhancement-mode silicon MOSFET and wherein said rectifying-gate transistor means comprises a field effect transistor selected from the group consisting of silicon carbide MESFETs and silicon carbide JFETs.

A semiconductor switching device comprising:

• a semiconductor substrate having first and second opposing faces;
• a source contact on said first face;
• a drain contact on said second face;
• a field effect transistor in said semiconductor substrate having a first source region in said substrate, a gate electrically connected to said source contact and a first drain region electrically connected to said drain contact;
• and
• an insulated-gate field effect transistor having an insulated-gate electrode, a second source region electrically connected to said source contact and a second drain region electrically connected to said first source region, said insulated-gate field effect transistor being responsive to the application of a turn-on bias signal to said insulated-gate electrode for electrically connecting said second source region to said first source region and allowing majority carrier conduction therebetween when said drain contact is biased to a first polarity with respect to said source contact.

A silicon carbide switching device, comprising:

• a silicon carbide substrate having first and second opposing faces;
• a source region of first conductivity type in said substrate, extending to said first face;
• a drain region of first conductivity type in said substrate, extending to said second face;
• a drift region of first conductivity type in said substrate, extending between said source region and said drain region, said drift region having a first conductivity type doping concentration below the doping concentration of said source region and said drain region;
• first and second adjacent trenches in said substrate extending to said first face and defining a mesa including said source region therebetween, said mesa having first and second sidewalls extending between said drift region and said source region and said first trench having a bottom;
• and
• a conductive layer at the bottom, electrically connected to said source region.

A three terminal semiconductor switching device, comprising:

• a semiconductor substrate;
• a silicon carbide field effect transistor in said substrate selected from the group consisting of silicon carbide JFETs and silicon carbide MESFETs, said silicon carbide field effect transistor having a first drain region, a first source region and a first gate;
• a silicon insulated-gate field effect transistor in said substrate having a second drain region electrically connected to said first source region, a second source and a second gate;
• drain contact electrically connected to said first drain;
• and
• a source contact electrically connected to said first gate and said second source,
• wherein the application of a turn-on bias signal to said second gate electrically connects said source contact to said drain contact when said first drain is biased to a first polarity with respect to said second source.