Semiconductor device and control method thereof

A semiconductor device comprising:

• a base layer of the first conductivity type;
• an emitter layer of the second conductivity type, formed on a surface of said base layer of the first conductivity type;
• a collector electrode, formed on a surface of said emitter layer of the second conductivity type;
• a base layer of the second conductivity type, formed in a surface of said base layer of the first conductivity type which is opposite to said emitter layer of the second conductivity type;
• a source layer of the first conductivity type, formed in a surface of said base layer of the second conductivity type;
• an emitter electrode, formed on said source layer of the first conductivity type and said base layer of the second conductivity type;
• a gate electrode, buried inside a first trench with a gate insulating film interposed therebetween, said first trench being provided extending from a surface of said source layer of the first conductivity type, through said base layer of the second conductivity type, to a depth within said base layer of the first conductivity type;
• and
• a buried electrode, buried inside a second trench with a gate insulating film interposed therebetween, said second trench being provided extending from a surface of said base layer of the second conductivity type to a depth within said base layer of the first conductivity type;
• wherein
• said buried electrode and said emitter electrode are electrically connected and substantially have a same potential.

A semiconductor device comprising:

• a base layer of the first conductivity type;
• an emitter layer of the second conductivity type, formed on a surface of said base layer of the first conductivity type;
• a collector electrode, formed on a surface of said emitter layer of the second conductivity type;
• a base layer of the second conductivity type, formed in a surface of said base layer of the first conductivity type which is opposite to said emitter layer of the second conductivity type;
• a source layer of the first conductivity type, formed in a surface of said base layer of the second conductivity type;
• an emitter electrode, formed on said source layer of the first conductivity type and said base layer of the second conductivity type;
• a gate electrode, buried inside a first trench with a gate insulating film interposed therebetween, said first trench being provided extending from a surface of said source layer of the first conductivity type, through said base layer of the second conductivity type, to a depth within said base layer of the first conductivity type;
• and
• a buried electrode, buried inside a second trench with a gate insulating film interposed therebetween, said second trench being provided extending from a surface of said base layer of the second conductivity type to a depth within said base layer of the first conductivity type;
• wherein
• said buried electrode has a fixed potential which is lower than a potential of said emitter electrode.