Trench MOSFETs integrated with clamped diodes having trench field plate termination to avoid breakdown voltage degradation

A semiconductor power device comprising:

• an epitaxial layer of a first conductivity type extending over a substrate;
• a plurality of first type trenches formed in said epitaxial layer in an active area, each of said first type trenches being filled with a first type shielded gate structure comprising a first poly-silicon in a lower portion to serve as a first shielded electrode and a second poly-silicon layer in an upper portion to serve as a gate electrode, wherein said first shielded electrode is insulated from said epitaxial layer by a first insulating film and said gate electrode is insulated from said epitaxial layer by a gate insulating film which has a thickness less than said first insulating film, wherein said first shielded electrode and said gate electrode are insulated from each other by a second insulating film;
• and
• a trench field plate termination area comprises at least a second type trench surrounding said active area, wherein each of said second type trench is filled with a second shielded electrode and connected with a source metal;
• a Gate-Drain(GD) clamp diode formed between a gate metal and a drain metal along a device periphery;
• and
• a Gate-Source(GS) clamp diode formed between said gate metal and said source metal.