IGBT, control circuit, and protection circuit on same substrate

A semiconductor device in which an insulated gate bipolar transistor and a circuit region or circuit element for control use are formed on a same semiconductor substrate, comprising:

• a first diffused layer formed in said semiconductor substrate so as to be located near a surface of said semiconductor substrate, said first diffused layer having a conduction type different from that of said semiconductor substrate;
• a second diffused layer formed in said semiconductor substrate so as to be located near the surface of said semiconductor substrate, said second diffused layer being located within said first diffused layer, and said second diffused layer having a conduction type different from that of said first diffused layer;
• a first region formed on said second diffused layer, said first region being formed by removing a portion of an insulating film;
• a first metal wiring layer formed in said first region;
• a third diffused layer located in said second diffused layer or located so as to intersect with said second diffused layer, said third diffused layer having a conduction type identical to that of said second diffused layer;
• a second region formed on said third diffused layer, said second region being formed by removing another portion of the insulating film;
• a second metal wiring layer formed in said second region;
• and
• a protection circuit formed by combining a Schottky barrier diode using said first and second metal wiring layers as electrodes and a Zener diode formed by depositing polycrystalline silicon on the insulating film on said semiconductor substrate, said protection circuit being connected to at least one of input terminals of the semiconductor device, wherein
• said circuit region or circuit element is connected to said input terminal through said protection circuit and to a gate of said insulated gate bipolar transistor.