Varying mesa dimensions in high cell density trench MOSFET

A trench-gate power MOSFET device comprising:

• a first trench gate;
• a second trench gate displaced from the first trench gate by a first distance;
• a third trench gate displaced from the second trench gate by a second distance;
• a first body region comprising a first well and located between the first trench gate and the second trench gate;
• and
• a second body region comprising a second well and located between the second trench gate and the third trench gate;
• wherein the first body region is processed to have a lower pinched-base resistance and a lower drain-to-bulk breakdown voltage than the second body region, and
• wherein the first distance is larger than the second distance.

A method of manufacturing a trench-gate power MOSFET device comprising:

• using a drain-to-bulk breakdown specification to determine a width of a wide cell;
• using the drain-to-bulk breakdown specification to determine a first width of a trench-gate for a wide cell;
• using a avalanche current specification to determine a first number of wide cells;
• using design rule limitations to determine a width of a narrow cell;
• and
• using an on resistance specification to determine a second number of narrow cells.

A method of designing a trench-gate power MOSFET comprising:

• determining a first physical parameter for a first cell type such that a first electrical characteristic for the first cell type meets a first requirement;
• determining a second physical parameter for a second cell type such that the first electrical characteristic for the second cell type exceeds the first electrical characteristic for the first cell type;
• determining a first number of the first cell type that are needed to meet a second requirement;
• and
• determining a second number of the second cell type that are needed to meet a third requirement.