Split-gate trench power mosfet with protected shield oxide

A semiconductor device, comprising:

• a plurality of gate trenches formed into a semiconductor substrate in an active cell region, each gate trench having a portion of a first conductive material in lower portions of the gate trench and a portion of a second conductive material in upper portions of the gate trench;
• and
• one or more transitional trenches formed into the semiconductor substrate in a pickup region, each transitional trench having a portion of the first conductive material in lower portions of the transitional trench and a portion of the second conductive material in upper portion of the transitional trench, wherein the transitional trenches are provided between the plurality of gate trenches and one or more pickup trenches formed into the semiconductor substrate in a pickup region, wherein the portion of the first conductive material in the lower portions of the transitional trenches in a U shape,
• wherein the portions of the first conductive material in each gate trench and each transitional trench are separated from the semiconductor substrate by a first insulating layer, and wherein the portions of the second conductive material in each gate trench and each transitional trench are separated from the semiconductor substrate by a second insulating layer and separated from the portions of the first conductive material in each gate trench and each transitional trench by a third insulating layer.