Method of forming a point on a floating gate for electron injection

A method of forming a point on a floating gate for electron injection comprising the steps of:

• (a) providing a semiconductor substrate;
• (b) depositing a layer of a gate oxide material over said substrate;
• (c) depositing a layer of a gate silicon material over said gate oxide layer;
• (d) depositing a layer of silicon nitride over said gate silicon layer;
• (e) forming an opening in said silicon nitride layer to expose said gate silicon layer;
• (f) etching said gate silicon layer to form a trench having a bottom and a pair of sidewalls, each of said sidewalls defining a sharp angle at a top edge;
• (g) depositing a layer of an oxide in said trench and opening;
• (h) removing said silicon nitride layer wherein said oxide layer forms a plug over said gate silicon layer;
• and
• (i) removing said gate silicon layer using said oxide as a mask to form said floating gate wherein said sharp angle at said top edge of each of said sidewalls defines said point on said floating gate for electron injection.

A method of forming a charge injection region on a floating gate of a semiconductor structure comprising the steps of:

• providing said semiconductor structure, said semiconductor structure comprising,
• a first insulating layer over a semiconductor substrate;
• a first semiconductor layer over said first insulating layer;
• and
• a dielectric layer over said first semiconductor layer;
• defining a floating gate region in said semiconductor structure;
• forming said charge injection region along an edge of said floating gate region by a first etching process, said first etching process etching a trench in said first semiconductor layer, said trench having a bottom and a pair of sidewalls;
• and
• forming said floating gate on said semiconductor structure.