Patent ID: 9496357
Filing Date: 2016-11-15
CPC Classification: H01L

Claim Text:
1. A trench MOSFET comprising: an epitaxial layer; a body region on the epitaxial layer, the body region and the epitaxial layer forming a first interface; a trench; a trench bottom oxide in the trench; and polysilicon in the trench, the trench bottom oxide and the polysilicon forming a second interface; wherein the first and second interfaces are substantially aligned or are at substantially the same level, such that an overlap between the body region and the trench bottom oxide is less than about 25 nm; wherein a surface of the trench bottom oxide which is in contact with polysilicon is convex; wherein the trench bottom oxide comprises a first trench bottom oxide portion occupying substantially the entire width of the trench, and a second trench bottom oxide portion directly on the first trench bottom oxide portion, the second trench bottom oxide portion occupying substantially less than the entire width of the trench; wherein the second trench bottom oxide portion occupies a central portion of the trench with respect to the width of the trench; and wherein the second trench bottom oxide portion extends to the top of the trench.