Method of fabricating trench MIS device with graduated gate oxide layer
First Claim
1. A method of fabricating an MIS device comprising:
- providing a semiconductor substrate;
forming a trench in said substrate;
depositing a nitride layer in said trench;
etching said nitride layer to form an exposed area at a bottom of said trench; and
heating the substrate and thereby growing an oxide layer in said exposed area.
6 Assignments
0 Petitions
Accused Products
Abstract
A process for manufacturing a trench MIS device includes depositing a conformal nitride layer in the trench; etching the nitride layer to create an exposed area at the bottom of the trench; and heating the substrate and thereby growing an oxide layer in the exposed area. This process causes the mask layer to “lift off”, creating a “bird'"'"'s beak” structure. This becomes a “transition region”, where the thickness of the oxide layer decreases gradually in a direction away from the exposed area. The method further includes diffusing a dopant into the substrate, the dopant forming a PN junction with a remaining portion of said substrate, and controlling the diffusion such that the PN junction intersects the trench in the transition region. Because the thickness of the oxide layer decreases gradually, the PN junction does not need to be located at a particular point, i.e., there is a margin of error. This improves the manufacturability of the device and enhances its breakdown characteristics.
26 Citations
11 Claims
-
1. A method of fabricating an MIS device comprising:
-
providing a semiconductor substrate;
forming a trench in said substrate;
depositing a nitride layer in said trench;
etching said nitride layer to form an exposed area at a bottom of said trench; and
heating the substrate and thereby growing an oxide layer in said exposed area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
Specification