Medium High Voltage MOSFET Device

A method, comprising:

• receiving a substrate having a horizontal surface;
• forming a drain drift region in the substrate;
• forming a body region aligned vertically with the drain drift region;
• forming a source region within the body region;
• forming a lightly doped drain (LDD) region aligned vertically with the drain drift region and abutting the body region;
• and
• forming a RESURF trench extending from the body region to the drain drift region, the RESURF trench having a conducting plate coupled to the source region and the body region, and a dielectric liner insulating the conducting plate from the drain drift region.

A method, comprising:

• receiving a substrate having a horizontal surface;
• forming a drain drift region positioned in the substrate;
• and
• forming transistor cells, each including:
• forming a body region aligned vertically with the drain drift region;
• forming a source region within the body region;
• forming a gate positioned above the horizontal surface, the gate free from overlapping any conductor positioned within the substrate;
• forming a first RESURF trench extending from the body region to the drain drift region, the first RESURF trench having a first conducting plate coupled to the source region and the body region, and a first dielectric liner insulating the first conducting plate from the drain drift region;
• and
• forming a second RESURF trench laterally surrounding the first RESURF trench, the body region and the source region, the second RESURF trench having a second conducting plate parallel to the first conducting plate, and a second dielectric liner insulating the second conducting plate from the drain drift region.