US 12,342,569 B2
Trench MOSFET
Steven Peake, Nijmegen (NL); and Phil Rutter, Nijmegen (NL)
Assigned to Nexperia B.V., Nijmegen (NL)
Filed by NEXPERIA B.V., Nijmegen (NL)
Filed on May 18, 2022, as Appl. No. 17/747,381.
Claims priority of application No. 21175166 (EP), filed on May 21, 2021.
Prior Publication US 2022/0376108 A1, Nov. 24, 2022
Int. Cl. H10D 30/66 (2025.01); H10D 30/01 (2025.01)
CPC H10D 30/665 (2025.01) [H10D 30/0297 (2025.01); H10D 30/668 (2025.01)] 15 Claims
OG exemplary drawing
 
1. A trench metal-oxide-semiconductor field-effect transistor, trench MOSFET, comprising:
a semiconductor substrate;
an epitaxial layer of a first charge type arranged on the semiconductor substrate, in which the epitaxial layer is formed;
a first trench covered on an inside thereof with a gate oxide and filled with a first polysilicon body;
a pair of second trenches arranged on opposite sides of the first trench;
wherein the second trenches are deeper than the first trench;
wherein each second trench is covered on an inside thereof with a liner oxide and is filled with a second polysilicon body;
a source region of a first charge type; and
a body region of a second charge type;
wherein the epitaxial layer comprises a drift region of the first charge type arranged in between the body region and the substrate;
wherein the source region and body region are each formed in between the first trench and each of the second trenches;
wherein the body region is arranged in between the source region and the drift region; and
wherein the trench MOSFET further comprises an ion implantation region of the first charge type formed in the drift region, extending below the second trenches, and being vertically aligned with a base of the second trenches;
wherein the ion implantation region has an average net dopant concentration that is lower than in a remaining part of the drift region; and
wherein the ion implantation region also extends between the second trenches near the base of the second trenches.