Semiconductor device with parasitic bipolar transistor

A semiconductor die comprising:

• a semiconductor substrate of a first conductive type;
• a first semiconductor layer of a second conductive type disposed on a front surface of the semiconductor substrate;
• a second semiconductor layer of the first conductive type disposed on the first semiconductor layer;
• a first electrode and a second electrode that are in contact with the second semiconductor layer so that a current runs between the two electrodes through the second semiconductor layer under a normal input current condition;
• a third semiconductor layer of the first conductivity type disposed on the front surface of the semiconductor substrate and adjacent the first semiconductor layer, and a third electrode that is in contact with the third semiconductor layer so as to connect the third semiconductor layer to a ground;
• and
• a metal film disposed on a back surface of the semiconductor substrate so as to be in a direct physical contact with the back surface, wherein the semiconductor die is bonded to an island of a lead frame by a conductive paste so that the metal film is attached to the island through the conductive paste, and the semiconductor substrate and the first and second semiconductor layers are configured to operate as a parasitic bipolar transistor so as to release an input current to the island when the parasitic bipolar transistor breaks down under a surge event.

A semiconductor device comprising:

• a lead frame comprising a first island, a second island and a lead, the lead receiving a power voltage;
• a semiconductor die disposed on the first island so as to be electrically connected to the first island;
• a conductive paste disposed on the first island so as to be electrically connected to the first island;
• a conductive paste disposed between the semiconductor die and the first island;
• and
• a switching element disposed on the second island;
• wherein the semiconductor die comprises;
• a semiconductor substrate of a first conductivity type;
• a first semiconductor layer of a second conductivity type disposed on a front surface of the semiconductor substrate;
• a second semiconductor layer of the first conductivity type disposed on the first semiconductor layer;
• a first electrode and a second electrode that are in contact with the second semiconductor layer so that a current runs between the two electrodes through the second semiconductor layer under a normal input current condition, the first electrode being connected to the lead;
• and
• a metal film disposed on a back surface of the semiconductor substrate so as to be in contact with the back surface;
• and
• wherein the semiconductor substrate and the first and second semiconductor layers are configured to operate as a parasitic bipolar transistor so as to release an input current to the first island when the parasitic bipolar transistor breaks down under a surge event.