Power MOSFET with metal filled deep source contact

A method of fabricating a planar gate power metal-oxide-semiconductor field effect transistor (power MOSFET), comprising:

• providing a planar gate power MOSFET die including a plurality of transistor cells (cells) including a first cell and at least a second cell formed on a substrate having a semiconductor surface doped a first conductivity type, said first cell having a first gate stack and said second cell having a second gate stack, each said gate stack including a gate electrode on a gate dielectric over a body region, a trench having an aspect ratio of at least 3 extending down from a top side of said semiconductor surface between said first and said second gate stack providing a source contact (SCT) from said substrate to a source doped a second conductivity type, a field plate (FP) over said gate stacks extending to provide a liner for said trench, said trench having a refractory or platinum-group metal (PGM) metal filler (metal filler) within, and a drain doped said second conductivity type in said semiconductor surface on a side of said gate stacks opposite said trench, wherein said trench is formed by an etching process using self-alignment provided by said gate stacks;
• first etching of said metal filler for removing said metal filler along a sidewall of said FP over said drain and removing a portion of said metal filler in said trench;
• depositing said metal filler including to fill said trench, and
• second etching of said metal filler.