Method of forming self aligned contacts for a power MOSFET
First Claim
1. A method for providing self aligned contacts in a semiconductor device having an active area and a gate bus area comprising:
- forming an oxide layer on a substrate of said semiconductor device;
forming a hard mask of silicon nitride on said oxide layer;
etching said hard mask of silicon nitride to form trenches in said active area and said gate bus area in said substrate wherein said hard mask of silicon nitride is deposited on said oxide layer;
forming a gate oxide layer on walls of said trenches;
applying polysilicon to fill said trenches and to cover the surface of said hard mask of silicon nitride;
removing said polysilicon from the surface of said hard mask of silicon nitride;
forming and recessing polysilicon plugs in trenches that are located in said active area to form recesses above said polysilicon plugs while leaving the polysilicon coplanar with the hard mask of silicon nitride on the gate bus area; and
selectively etching said hard mask of silicon nitride and forming flat, wholly planar surfaced oxide buttons to cover said trenches that are located in said active area.
4 Assignments
0 Petitions
Accused Products
Abstract
A method for providing self aligned contacts for a trench power MOSFET is disclosed. The method includes, etching trenches in a substrate through a mask of silicon nitride deposited on an oxide layer, forming a gate oxide layer on the walls of the trenches, applying polysilicon to fill the trenches and to cover the surface of the mask of silicon nitride, removing the polysilicon from the surface of the mask of silicon nitride and applying a photoresist mask to cover a location of a gate bus. The method further includes recessing polysilicon plugs formed in trenches that are located in the active area to form recesses above the polysilicon plugs, filling recesses formed above the polysilicon plugs formed in trenches that are located in the active area with an insulator, applying a fourth photo resist mask to define contact windows that are opened in the nitride layer, and selectively etching the silicon nitride film and leaving flat surfaced oxide buttons covering the trenches that are located in the active area. Moreover, electric contact trenches are defined using self-aligned spacer operations, and a fifth photo resist mask is applied to pattern metal contacts that reach the semiconductor device active areas.
-
Citations
32 Claims
-
1. A method for providing self aligned contacts in a semiconductor device having an active area and a gate bus area comprising:
-
forming an oxide layer on a substrate of said semiconductor device; forming a hard mask of silicon nitride on said oxide layer; etching said hard mask of silicon nitride to form trenches in said active area and said gate bus area in said substrate wherein said hard mask of silicon nitride is deposited on said oxide layer; forming a gate oxide layer on walls of said trenches; applying polysilicon to fill said trenches and to cover the surface of said hard mask of silicon nitride; removing said polysilicon from the surface of said hard mask of silicon nitride; forming and recessing polysilicon plugs in trenches that are located in said active area to form recesses above said polysilicon plugs while leaving the polysilicon coplanar with the hard mask of silicon nitride on the gate bus area; and selectively etching said hard mask of silicon nitride and forming flat, wholly planar surfaced oxide buttons to cover said trenches that are located in said active area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method for providing self aligned contacts in a semiconductor device having an active area and a gate bus area comprising:
-
forming an oxide layer on a substrate of said semiconductor device; forming a hard mask of silicon nitride on said oxide layer; etching said hard mask of silicon nitride to form trenches in said active area and said gate bus area in said substrate wherein said hard mask of silicon nitride is deposited on said oxide layer; forming a gate oxide layer on walls of said trenches; applying polysilicon to fill said trenches and to cover the surface of said hard mask of silicon nitride; removing said polysilicon from the surface of said hard mask of silicon nitride; forming and recessing polysilicon plugs in trenches that are located in said active area to form recesses above the polysilicon plugs while leaving the polysilicon coplanar with the hard mask of silicon nitride on the gate bus area and filling recesses formed above said polysilicon plugs, that are formed in said trenches located in said active area, with an insulator; and etching said silicon nitride film and forming flat, wholly planar surfaced oxide buttons to cover the trenches that are located in said active area. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
-
-
25. A method for providing self aligned contacts in a semiconductor device having an active area and a gate bus area comprising:
-
forming an oxide layer on a substrate of said semiconductor device; forming a hard mask of silicon nitride on said oxide layer; etching said hard mask to form trenches in said active area and said gate bus area in said substrate; forming a gate oxide layer on walls of said trenches; applying polysilicon to fill said trenches; removing said polysilicon from the surface of said hard mask; forming and recessing polysilicon plugs in trenches that are located in said active area to form recesses above the polysilicon plugs while leaving the polysilicon coplanar with the hard mask of silicon nitride on the gate bus area and filling recesses formed above said polysilicon plugs, that are formed in said trenches located in said active area, with an insulator; and forming flat, wholly planar surfaced oxide buttons above the trenches that are located in said active area. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
-
Specification