Transition metal alloys for use as a gate electrode and devices incorporating these alloys
View Patent ↗Embodiments of a transition metal alloy having an n-type or p-type work function that does not significantly shift at elevated temperature. The disclosed transition metal alloys may be used as, or form a part of, the gate electrode in a transistor. Methods of forming a gate electrode using these transition metal alloys are also disclosed.
1. A device comprising:
a substrate having a source region and a drain region formed therein:
an insulating layer disposed on the substrate and extending between the source and drain regions; and
a gate electrode overlying the insulating layer, the gate electrode formed of an alloy including
approximately 20 to 50 atomic percent of a transition metal, the transition metal selected from a group consisting of titanium, zirconium, tantalum, and hafnium,
approximately 30 to 60 atomic percent of carbon, and
up to approximately 20 atomic percent of aluminum.
2. The device of claim 1 , wherein the alloy has a work function in a range of approximately 3.8 eV to 4.4 eV.
3. The device of claim 2 , wherein the work function does not significantly shift at a temperature up to approximately 900° Celsius.
4. The device of claim 2 , wherein the source and drain regions comprise n-type regions and the substrate includes a p-type region underlying the source and drain regions.
5. The device of claim 1 , wherein the gate electrode alloy does not react substantially with the insulating layer at a temperature up to approximately 900° Celsius.
6. The device of claim 1 , wherein the insulating layer comprises a material having a high dielectric constant.
7. The device of claim 1 , wherein the high dielectric constant material comprises one of ZrO 2 , HfO 2 , and Al 2 O 3 .
8. The device of claim 1 , further comprising up to 5 atomic percent of a residual material, the residual material comprising at least one of oxygen, nitrogen, and chloride.