US Patent 11189702 Split gate semiconductor with non-uniform trench oxide

Split gate semiconductor with non-uniform trench oxide. A metal oxide semiconductor field effect transistor (MOSFET) comprises a plurality of parallel trenches. Each such trench comprises a first electrode coupled to a gate terminal of the MOSFET and a second electrode, physically and electrically isolated from the first electrode. The second electrode is beneath the first electrode in the trench. The second electrode includes at least two different widths at different depths below a primary surface of the MOSFET. The trenches may be formed in an epitaxial layer. The epitaxial layer may have a non-uniform doping profile with respect to depth below a primary surface of the MOSFET. The second electrode may be electrically coupled to a source terminal of the MOSFET.