Vertical dmos transistor

A transistor, comprising:

• a semiconductor body;
• a trench formed in the semiconductor body, the trench being lined with a thin dielectric layer as a sidewall dielectric layer, the trench being filled with a bottom dielectric layer at a lower portion of the trench and a conductive layer above the bottom dielectric layer;
• a first body region and a second body region, both of a first conductivity type, formed in the semiconductor body on opposite sides of the trench;
• a first gate electrode formed partially overlapping the first body region and insulated from the semiconductor body by a gate dielectric layer, the first gate electrode having a first side formed adjacent and next to the trench and a second side opposite the first side;
• a second gate electrode formed partially overlapping the second body region and insulated from the semiconductor body by the gate dielectric layer, the second gate electrode having a first side formed adjacent and next to the trench and a second side opposite the first side;
• a first source region of a second conductivity type formed in the first body region on the second side of the first gate electrode;
• a second source region of the second conductivity type formed in the second body region on the second side of the second gate electrode;
• and
• a doped sidewall region of the second conductivity type formed in the semiconductor body along the sidewall of the trench outside of the trench, the doped sidewall region forming a vertical drain current path for the transistor, the drain current of the transistor flowing in the doped sidewall region in the semiconductor body outside of the trench, wherein the conductive layer inside the trench is electrically connected to the first and second gate electrodes or to the first and second source electrodes.