Semiconductor device and its manufacturing method

A semiconductor device comprising:

• a semiconductor substrate having a first surface and a second surface facing each other;
• a first dopant region of a first conductivity type as a cathode region arranged over the first surface of the semiconductor substrate;
• a second dopant region of a second conductivity type as an anode region arranged over the second surface of the semiconductor substrate;
• and
• a drift region of the first conductivity type that is arranged between the first dopant region and the second dopant region within the semiconductor substrate and has a lower dopant concentration of the first conductivity type than the first dopant region,
• wherein the semiconductor substrate includes a trench extending from the second surface into the drift region,
• a first field plate electrode that is arranged within the trench to be electrically insulated from the first dopant region and insulated from the drift region oppositely;
• and
• a first Zener diode that is electrically coupled between the second, dopant region and the first field plate electrode,
• the first Zener diode being coupled in a forward direction from the second dopant region to the first field plate electrode.

A manufacturing method of a semiconductor device comprising the following steps of:

• forming a first dopant region of a first conductivity type as a drain region over a first surface of a semiconductor substrate having the first surface and a second surface facing each other;
• forming a drift region of the first conductivity type having a lower dopant concentration of the first conductivity type than the first dopant region, over the first dopant region at a side of the second surface within the semiconductor substrate;
• forming a trench extending from the second surface into the drift region, in the semiconductor substrate;
• forming a first field plate electrode within the trench, to be electrically insulated from the first dopant region and insulated froth the drift region oppositely;
• forming a second dopant region of the first conductivity type as a source region over the second surface of the semiconductor substrate, to sandwich the drift region with the first dopant region;
• and
• forming a Zener diode that is electrically coupled between the second dopant region and the first field plate electrode;
• wherein the Zener diode is coupled in a forward direction from the second dopant region to the first field plate electrode.