Trench Edge Termination Structure for Power Semiconductor Devices

A trench termination structure of a power semiconductor device, comprising:

• a heavily doped P-type substrate;
• a lightly doped P-type drift region on an upper surface of the heavily doped P-type substrate;
• a metal drain electrode on a lower surface of the heavily doped P-type substrate;
• and
• a field oxide layer on an upper surface of the lightly doped P-type drift region,
• wherein the lightly doped P-type drift region includes a trench and a heavily doped P-type region;
• the heavily doped P-type region is located in a top portion of the lightly doped P-type drift region and on a side away from an active region of the power semiconductor device;
• an upper surface of the heavily doped P-type region contacts a lower surface of the field oxide layer;
• the trench is filled with an insulating material whose upper surface contacts a lower surface of the field oxide layer;
• a polysilicon floating island that stores positive charges is located in the trench;
• a sidewall of the trench on a side near the active region contacts a N-type semiconductor main junction;
• an upper surface of the polysilicon floating island is lower than a lower surface of the N-type semiconductor main junction;
• a cross-sectional shape of the trench is an inverted trapezium;
• and
• an angle between the sidewall and a horizontal plane is in the range of 60 to 90 degrees.