Semiconductor device and method for manufacturing the same

A method for manufacturing a semiconductor device comprising:

• a step of forming a plurality of MOSFETs each having a channel of a first conductivity type in a stripe on the first major surface of a wafer;
• a step of implanting an impurity of a first conductivity type into the second major surface of said wafer, and performing a laser annealing treatment, to form a buffer layer;
• a step of implanting an impurity of a second conductivity type into said second major surface, and performing a laser annealing treatment, to form a collector layer;
• a step of locally radiating charged particles onto a drift layer of a first conductivity type of said plurality of MOSFETs to form a lattice defect region of a stripe or a mesh, and
• a step of forming an emitter electrode on said first major surface, and forming a collector electrode on said second major surface.

A semiconductor device comprising:

• a plurality of MOSFETs each having a channel of a first conductivity type formed in a stripe on the first major surface of a wafer;
• a buffer layer of a first conductivity type formed on the second major surface of said wafer, wherein highly activated portions and lowly activated portions are alternately formed in a stripe;
• a collector layer of a second conductivity type formed on the second major surface side of said wafer than said buffer layer;
• an emitter electrode formed on the first major surface of said wafer;
• and
• a collector electrode formed on the second major surface of said wafer.

A semiconductor device comprising:

• a plurality of MOSFETs each having a channel of a first conductivity type formed in a stripe on the first major surface of a wafer;
• a buffer layer of a first conductivity type formed on the second major surface of said wafer;
• a collector layer of a second conductivity type formed on the second major surface side of said wafer than said buffer layer;
• an emitter electrode formed on the first major surface of said wafer;
• a collector electrode formed on the second major surface of said wafer;
• and
• a lattice defect region of a stripe or a mesh formed in a drift layer of a first conductivity type of said plurality of MOSFETs.