Vertical trench IGBT and method for manufacturing the same
A method for manufacturing a vertical trench IGBT includes: forming a body layer of a second conductivity type on a semiconductor substrate of a first conductivity type; forming a trench passing through the body layer; forming a trench gate in the trench via a gate insulating film; forming a polysilicon film containing an impurity of a first conductivity type on the body layer; diffusing the impurity from the polysilicon film into the body layer to form an emitter layer of a first conductivity type on the body layer; and forming a collector layer of a second conductivity type on a lower surface of the semiconductor substrate.
1. A method for manufacturing a vertical trench IGBT comprising:
forming a body layer of a second conductivity type on a semiconductor substrate of a first conductivity type;
forming a trench passing through the body layer;
forming a trench gate in the trench via a gate insulating film;
forming a substantially planar polysilicon film containing an impurity of a first conductivity type on the body layer;
diffusing the impurity from the polysilicon film into the body layer to form an emitter layer of a first conductivity type on the body layer; and
forming a collector layer of a second conductivity type on a lower surface of the semiconductor substrate, wherein
the emitter layer includes a true emitter layer formed in the vicinity of the trench gate, and an exterior emitter layer for extruding the true emitter layer.
2. The method for manufacturing a vertical trench IGBT according to claim 1 , further comprising:
forming a resist film on the polysilicon film in a region whereon the emitter layer is formed;
etching the polysilicon film using the resist film as a mask;
after etching the polysilicon film, injecting an impurity of a second conductivity type into the body layer using the resist film as a mask; and
performing a heat treatment to form a diffusion layer of a second conductivity type on a region of the body layer wherein the impurity of a second conductivity type is implanted.
3. The method for manufacturing a vertical trench IGBT according to claim 1 , wherein a natural oxide film is formed between the body layer and the polysilicon film.
4. The method for manufacturing a vertical trench IGBT according to claim 1 , wherein the polysilicon film is simultaneously formed together with a polysilicon which constitutes the trench gate.
5. The method for manufacturing a vertical trench IGBT according to claim 1 , wherein the polysilicon film is simultaneously formed together with a polysilicon which constitutes an electrode of a capacitor.
6. The method for manufacturing a vertical trench IGBT according to claim 1 , wherein the polysilicon film is simultaneously formed together with a polysilicon resistor.
7. A method for manufacturing a vertical trench IGBT comprising:
forming a body layer of a second conductivity type on a semiconductor substrate of a first conductivity type;
forming a trench passing through the body layer;
forming a trench gate in the trench via a gate insulating film;
forming a polysilicon film containing an impurity of a first conductivity type on the body layer;
diffusing the impurity from the polysilicon film into the body layer to form an emitter layer of a first conductivity type on the body layer; and
forming a collector layer of a second conductivity type on a lower surface of the semiconductor substrate,
wherein a grain size of the polysilicon film is smaller than a width of the emitter layer.