US 7,923,767 B2 · Non-volatile storage with substrate cut-out and process of fabricating

Abstract

Shallow trench isolation regions are positioned between NAND strings (or other types of non-volatile storage). These isolation regions include sections that form concave cut-out shapes in the substrate for the NAND string (or other types of non-volatile storage). The floating gates (or other charge storage devices) of the NAND strings hang over the sections of the isolation region that form the concave cut-out shape in the substrate. To manufacture such a structure, a two step etching process is used to form the isolation regions. In the first step, isotropic etching is used to remove substrate material in multiple directions, including removing substrate material underneath the floating gates. In the second step, anisotropic etching is used to create the lower part of the isolation region.

Claims21

Dependent claims

A non-volatile storage device, comprising:

a first active area including a first substrate region and a first floating gate, said first floating gate includes a lowest surface;
a second active area including a second substrate region and a second floating gate, said second floating includes a lowest surface;
and
an isolation region between said first substrate region and said second substrate region, said isolation region includes a first section that forms a concave cut-out shape in said first substrate region, said isolation region includes a second section that forms a concave cut-out shape in said second substrate region, said lowest surface of said first floating gate hangs over said first section, said lowest surface of said second floating gate hangs over said second section.

1 more element

A non-volatile storage device, comprising:

a first substrate region having a first top surface;
a first lower dielectric layer on said first top surface;
a first floating gate on said first lower dielectric layer;
a first upper dielectric layer on said first floating gate;
a first control gate layer on said first upper dielectric layer;
a second substrate region having a second top surface;
a second lower dielectric layer on said second top surface;
a second floating gate on said second lower dielectric layer;
a second upper dielectric on said second floating gate;
a second control gate layer on said second upper dielectric layer;
and
an isolation region between said first substrate region and said second substrate region, a first portion of said isolation region forms a concave cut-out in said first substrate region, a second portion of said isolation region forms a concave cut-out in said second substrate region, said isolation region includes a third portion that includes all of said isolation region except said first portion and said second portion, said first floating gate overhangs said first portion of said isolation region without overhanging said third portion of said isolation region, said second floating gate overhangs said second portion of said isolation region without overhanging said third portion of said isolation region.

9 more elements

Dependencies are inferred from the claim text.

Non-volatile storage with substrate cut-out and process of fabricating

Life of this patent

Non-volatile storage with substrate cut-out and process of fabricating

Life of this patent

Abstract

Claims21