Trench MOSFET with Integrated Schottky Barrier Diode

A semiconductor device comprising a field effect transistor and a Schottky diode, the semiconductor device comprising:

• a semiconductor substrate of a first conductivity type;
• a semiconductor layer of the first conductivity type formed on the semiconductor substrate;
• first and second trenches formed in the semiconductor layer, the first and second trenches being lined with a thin dielectric layer and being filled with a first trench conductor layer, the first trench conductor layer filling a portion of each of the first and second trenches, remaining portions of the first and second trenches being filled with a first dielectric layer;
• a Schottky metal layer formed on a top surface of the semiconductor layer between the first trench and the second trench;
• a third trench formed in the semiconductor layer, the third trench being lined with the thin dielectric layer and being filled with the first trench conductor layer and a second trench conductor layer, the first trench conductor layer being insulated from the second trench conductor layer by a inter-layer dielectric layer, the first trench conductor layer filling a portion of the third trench and the second trench conductor layer extending from the inter-layer dielectric to near a top surface of the third trench;
• a first well region of a second conductivity type formed in a top portion of the semiconductor layer adjacent the third trench, the first well region extending to a depth near a bottom edge of the second trench conductor layer formed in the third trench;
• and
• a heavily doped source region of the first conductivity type formed in the first well region adjacent to the sidewall of the third trench,
• wherein the Schottky diode is formed with the Schottky metal layer as the anode and the semiconductor layer between the first and second trenches as the cathode;
• wherein the field effect transistor is formed with the heavily doped N-type semiconductor substrate as a drain electrode, the second trench conductor layer in the third trench as the gate electrode, the first well region as the body region, the heavily doped source region as the source electrode, and the first trench conductor layer in the third trench as a gate shielding electrode;
• and
• wherein the first trench conductor layer in the third trench is electrically connected to the source electrode and the first trench conductor layer in each of the first and second trenches are electrically connected to the anode of the Schottky diode.