Antifuse element and method of manufacture
View Patent ↗An antifuse element ( 102, 152, 252, 302, 352, 402, 602, 652, 702 ) and method of fabricating the antifuse element, including a substrate material ( 101 ) having an active area ( 106 ) formed in an upper surface, a gate electrode ( 104 ) having at least a portion positioned above the active area ( 106 ), and a gate oxide layer ( 110 ) disposed between the gate electrode ( 104 ) and the active area ( 106 ). The gate oxide layer ( 110 ) including the fabrication of one of a gate oxide dip ( 128 ) or a gate oxide undercut ( 614 ). During operation a voltage applied between the gate electrode ( 104 ) and the active area ( 106 ) creates a current path through the gate oxide layer ( 110 ) and a rupture of the gate oxide layer ( 110 ) in a rupture region ( 130 ). The rupture region ( 130 ) defined by the oxide structure and the gate oxide dip ( 128 ) or the gate oxide undercut ( 614 ).
1. A method of fabricating an antifuse element, the method comprising:
providing a substrate material having an upper surface;
implanting an active area in the upper surface of the substrate material;
forming a gate electrode having at least a portion positioned above the active area;
forming a gate oxide layer including a thin oxide portion and a thick oxide portion, the gate oxide layer disposed between the gate electrode and the active area; and
forming a gate oxide dip including a thickness T 1 less than the thin oxide portion and the thick oxide portion along an interface between the thin oxide portion and the thick oxide portion.
2. The method of fabricating an antifuse element as claimed in claim 1 wherein the step of forming the gate oxide layer includes forming the thick oxide portion with a thickness T 2 and forming the thin oxide portion with a thickness T 3 ,wherein T 3 is less than T 2 .
3. The method of fabricating an antifuse element as claimed in claim 2 wherein the step of forming the gate oxide layer includes forming the thick oxide portion and the thin oxide portion of the gate oxide layer using a double gate oxide mask.
4. The method of fabricating an antifuse element as claimed in claim 3 wherein the step of forming the gate oxide layer includes depositing a first insulating layer over the substrate material, etching away a portion of the first insulating layer to expose a portion of the substrate material, and depositing a second insulating layer, wherein a portion of the second insulating layer is deposited over the first insulating layer and a portion is deposited over the exposed portion of the substrate material, thereby defining the gate oxide layer structure including the gate oxide dip.
5. The method of fabricating an antifuse element as claimed in claim 1 wherein the step of forming the gate oxide layer includes undercutting the gate oxide layer about a perimeter of the gate electrode.
6. The method of fabricating an antifuse element as claimed in claim 1 wherein the step of forming the gate oxide layer includes masking at least a portion of the gate electrode and exposing the gate oxide layer to an undercut etch about at least a portion of a perimeter of the gate electrode.
7. A method of fabricating an antifuse element, the method comprising:
providing a substrate material having an upper surface;
implanting a plurality of active areas in an upper surface of the substrate material thereby forming a source region and a drain region;
forming a gate electrode having at least a portion positioned above at least one active area of the plurality of active areas;
forming a gate oxide layer including a thick portion and a thin portion; and
forming a gate oxide dip in a transition area between the thick portion and the thin portion of the gate oxide layer, the gate oxide layer disposed between the gate electrode and the active area and including a thickness less than the thick portion and the thin portion.
8. The method of fabricating an antifuse element as claimed in claim 7 wherein the step of forming the gate oxide layer comprises:
depositing a first insulating layer over the substrate material;
etching away a portion of the first insulating layer to expose a portion of the substrate material; and
depositing a second insulating layer, wherein a portion of the second insulating layer is deposited over the first insulating layer and a portion is deposited over the exposed portion of the substrate material, thereby defining a gate oxide structure including the gate oxide dip.
9. The method of fabricating an antifuse element as claimed in claim 8 wherein the step of forming the gate electrode includes depositing a conductive material over the gate oxide structure, wherein a plurality of sidewalls of the gate electrode overlap at least a portion of the active area.
10. The method of claim 2 , wherein the step of forming the gate oxide dip comprises the step of forming the gate oxide dip with about 70% of the thickness of T 3 .
11. The method of claim 1 , wherein the step of forming the gate oxide layer comprises the step of growing the thin oxide portion at a slower speed than the thick oxide portion.
12. The method of claim 11 , wherein the step of forming the gate oxide dip comprises the steps of blocking, via the thick oxide portion, a supply of oxygen from reaching the interface between the thick oxide portion and the thin oxide portion during growth of the thick oxide portion and the thin oxide portion.
13. The method of claim 7 , wherein the step of forming the gate oxide dip comprises the step of forming the gate oxide dip with about 70% of the thickness of the thin portion.