US 9,812,564 B1
Split-gate MOSFET
Chih-Cheng Liu, Hsinchu County (TW); Jiong-Guang Su, Hsinchu County (TW); and Hung-Wen Chou, Hsinchu County (TW)
Assigned to Silicongear Corporation, Hsinchu County (TW)
Filed by Silicongear Corporation, Hsinchu County (TW)
Filed on Nov. 2, 2016, as Appl. No. 15/340,997.
Claims priority of application No. 105127204 A (TW), filed on Aug. 25, 2016.
Int. Cl. H01L 29/78 (2006.01); H01L 29/06 (2006.01); H01L 29/66 (2006.01); H01L 29/423 (2006.01)
CPC H01L 29/7813 (2013.01) [H01L 29/0642 (2013.01); H01L 29/4236 (2013.01); H01L 29/4238 (2013.01); H01L 29/66734 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A split-gate MOSFET at least having a terminal region and a cell region, comprising:
a substrate;
a first epitaxial layer formed on the substrate, wherein the first epitaxial layer has a first doping concentration;
a second epitaxial layer formed on the first epitaxial layer, wherein the second epitaxial layer has a second doping concentration greater than the first doping concentration, a plurality of trenches is in the first epitaxial layer and the second epitaxial layer, and the plurality of trenches pass through the second epitaxial layer and is extended into the first epitaxial layer;
a plurality of first gates respectively located within the plurality of trenches in the cell region;
a plurality of second gates respectively located within the plurality of trenches on the first gate in the cell region;
a plurality of third gates respectively located in the plurality of trenches in the terminal region, wherein the third gate closest to the cell region is grounded, and the rest of the plurality of third gates are floating gates;
a gate oxide layer located between the first gate and the second gate and located between the second gate and the second epitaxial layer;
a trench oxide layer located between the first gate and the first epitaxial layer and located between a surface of the plurality of trenches and the third gate in the terminal region; and
a trench implantation region located in the first epitaxial layer at a bottom of each of the plurality of trenches in the terminal region and the cell region, wherein the trench implantation region has a third doping concentration less than the first doping concentration.