Replacement gate approach based on a reverse offset spacer applied prior to work function metal deposition
In a replacement gate approach, a spacer may be formed in the gate opening after the removal of the placeholder material, thereby providing a superior cross-sectional shape upon forming any electrode metals in the gate opening. Moreover, the spacer may be used for reducing the gate length, while not requiring more complex gate patterning strategies.
1. A method, comprising:
forming an opening in a gate electrode structure of a transistor by removing a placeholder electrode material of said gate electrode structure;
forming a spacer along exposed sidewalls of said opening;
after forming said spacer, forming a high-k dielectric material layer at least at a bottom of said opening so as to form a gate dielectric layer; and
forming a conductive electrode material in said opening.
2. The method of claim 1 , wherein forming a conductive electrode material in said opening comprises forming a material layer on said spacers and above a bottom of said opening, wherein said material layer comprises a work function metal species.
3. The method of claim 1 , further comprising forming said gate electrode structure so as to comprise a first dielectric material layer and said placeholder electrode material above said first dielectric material layer.
4. The method of claim 3 , wherein said high-k dielectric material is formed above said first dielectric material layer.
5. The method of claim 3 , wherein forming said spacer comprises forming said spacer from a layer of a conductive material.
6. The method of claim 1 , further comprising forming drain and source regions of said transistor prior to forming said opening.
7. The method of claim 6 , further comprising forming a dielectric material laterally adjacent to said gate electrode structure prior to forming said opening.
8. The method of claim 6 , wherein forming said drain and source regions comprises forming drain and source extension regions so as to define a gate length that is less than a gate length defined by said conductive electrode material.
9. The method of claim 8 , wherein said gate length defined by said spacer is 40 nm or less.
10. The method of claim 1 , wherein forming said spacer comprises forming a layer of spacer material in said opening and performing an etch process, said etch process exposing a bottom of said opening.
11. A method, comprising:
forming a gate electrode structure of a transistor on a semiconductor region, said gate electrode structure comprising a placeholder material having a first gate length;
forming drain and source regions in said semiconductor region based on a second gate length that is less than said first gate length;
forming an opening in said gate electrode structure by removing at least said placeholder material;
forming a spacer in said opening so as to reduce lateral dimensions of said opening;
after forming said spacer, forming a high-k dielectric material layer at least at a bottom of said opening so as to form a gate dielectric layer; and
forming a conductive electrode material in said opening, said conductive electrode material having said second gate length.
12. The method of claim 11 , wherein forming a high-k dielectric material in said opening is performed prior to forming said conductive electrode material.
13. The method of claim 12 , wherein said high-k dielectric material and said spacer define said second gate length.
14. The method of claim 11 , wherein forming said conductive electrode material comprises forming a work function metal in said opening.
15. The method of claim 11 , wherein forming said gate electrode structure comprises forming a first dielectric material layer and forming a layer said placeholder material of said first dielectric material layer.
16. The method of claim 15 , wherein forming said spacer comprises performing an etch process and removing a portion of said first dielectric material layer during said etch process.
17. The method of claim 11 , wherein said second gate length is 40 nm or less.
18. A method, comprising:
forming a gate electrode structure of a transistor element above an active region of a semiconductor device, said gate electrode structure comprising a dielectric material layer and a placeholder electrode material formed above said dielectric material layer;
forming an opening in said gate electrode structure by performing an etch process to selectively remove said placeholder electrode material from said gate electrode structure while using said dielectric material layer as an etch stop;
forming a layer of spacer material in said opening;
performing an etch process to form a reverse spacer from said layer of spacer material, said reverse spacer being formed adjacent to exposed sidewalls of said opening;
forming a layer of high-k dielectric material along exposed surfaces of said reverse spacer and above a bottom surface of said opening; and
forming a conductive electrode material above said layer of high-k dielectric material.
19. The method of claim 18 , wherein forming said reverse spacer comprises reducing lateral dimensions of said opening.
20. The method of claim 18 , wherein said layer of high-k dielectric material is formed above said dielectric material layer so as to form a gate insulation layer of said transistor element.