Patent ID: 8829641

Claim:
A method of forming a field effect transistor, comprising: forming a well region in a semiconductor region of a first conductivity type, the well region being of a second conductivity type and having an upper surface and a lower surface; forming a gate trench extending into the semiconductor region to a depth below a depth of the lower surface of the well region; forming a stripe trench extending through the well region and into the semiconductor region to a depth below the depth of the gate trench; forming a contiguous source region of the first conductivity type in the well region; and filling the stripe trench, at least partially, with a semiconductor material of the second conductivity type such that the semiconductor material of the second conductivity type forms a PN junction with a portion of the semiconductor region, the source region being in direct contact with the semiconductor material of the second conductivity type, the source region being in contact with the gate trench and being in contact with a first sidewall of the stripe trench, the semiconductor material of the second conductivity type being contiguous between the first sidewall of the stripe trench and a second sidewall of the stripe trench.