Engineered metal gate electrode
AssigneeAdvanced Micro Devices, Inc.
InventorsJames N. Pan, Paul R. Besser, Christy Woo, Minh Van Ngo, Jinsong Yin
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Abstract
A metal gate electrode is formed with an intrinsic electric field to modify its work function and the threshold voltage of the transistor. Embodiments include forming an opening in a dielectric layer by removing a removable gate, depositing one or more layers of tantalum nitride such that the nitrogen content increases from the bottom of the layer adjacent the gate dielectric layer upwardly. Other embodiments include forming the intrinsic electric field to control the work function by doping one or more metal layers and forming metal alloys. Embodiments further include the use of barrier layers when forming metal gate electrodes.
Claims20
A semiconductor device comprising:
- a metal gate electrode, having top, bottom and side surfaces, over a substrate with a gate dielectric layer therebetween, wherein the metal gate electrode comprises:
- a layer of tantalum nitride forming the bottom and side surfaces of the metal gate electrode, the layer of tantalum nitride having a nitrogen content that increases from the gate dielectric layer toward the top surface.
A method of manufacturing a semiconductor device having a transistor with a metal gate electrode, the metal gate electrode having upper and lower surfaces, the method comprising:
- forming a removable gate over a substrate with a gate dielectric layer therebetween;
- forming a dielectric layer over the substrate and exposing an upper surface of the removable gate;
- removing the removable gate leaving an opening in the dielectric layer, the opening defined at its bottom by the gate dielectric layer and defined at its sides by exposed surfaces of the dielectric layer;
- deposing at least one conductive layer, having a work function, on the gate dielectric layer lining the opening;
- modifying the work function of the conductive layer by creating an intrinsic electric field therein;
- and
- depositing a metal on the conductive layer with the modified work function filling the opening.
Dependencies are inferred from the claim text.