Stabilization of flatband voltages and threshold voltages in hafnium oxide based silicon transistors for CMOS
View Patent ↗The present invention provides a metal stack structure that stabilizes the flatband voltage and threshold voltages of material stacks that include a Si-containing conductor and a Hf-based dielectric. This present invention stabilizes the flatband voltages and the threshold voltages by introducing a rare earth metal-containing layer into the material stack that introduces, via electronegativity differences, a shift in the threshold voltage to the desired voltage. Specifically, the present invention provides a metal stack comprising a hafnium-based dielectric; a rare earth metal-containing layer located atop of, or within, said hafnium-based dielectric; an electrically conductive capping layer located above said hafnium-based dielectric; and a Si-containing conductor.
1. A material stack comprising:
a hafnium-based dielectric;
an electrically conductive capping layer comprising at least one of Ce, Y, Sm, Er and Tb and located above said hafnium-based dielectric; and
a Si-containing conductor located directly on said electrically conductive capping layer.
2. The material stack of claim 1 further comprising a chemox layer located beneath said Hf-based dielectric.
3. The material stack of claim 1 wherein said Hf-based dielectric comprises hafnium oxide, hafnium silicate, hafnium silicon oxynitride, a mixture of hafnium oxide and zirconium oxide or multilayers thereof.
4. The material stack of claim 3 wherein said Hf-based dielectric comprises hafnium oxide.
5. The material stack of claim 1 comprising n-doped Si as said Si-containing conductor.
6. A material stack comprising:
a hafnium-based dielectric containing a concentration gradient of a rare earth metal-containing layer located atop of said hafnium-based dielectric;
an electrically conductive capping layer comprising at least one of Ce, Y, Sm, Er and Tb and located above said hafnium-based dielectric; and
a Si-containing conductor located directly on said electrically conductive capping layer.
7. The material stack of claim 6 further comprising a chemox layer located beneath said Hf-based dielectric.
8. The material stack of claim 6 wherein said Hf-based dielectric comprises hafnium oxide, hafnium silicate, hafnium silicon oxynitride, a mixture of hafnium oxide and zirconium oxide or multilayers thereof.
9. The material stack of claim 8 wherein said Hf-based dielectric comprises hafnium oxide.
10. The material stack of claim 6 comprising n-doped Si as said Si-containing conductor.
11. A material stack comprising:
a hafnium-based dielectric containing foreign atoms having a valence and electronegativity different from hafnium;
an electrically conductive capping layer comprising at least one of Ce, Y, Sm, Er and Tb and located above said hafnium-based dielectric; and
a Si-containing conductor located directly on said electrically conductive capping layer.
12. The material stack of claim 11 wherein said Hf-based dielectric comprises hafnium oxide, hafnium silicate, hafnium silicon oxynitride, a mixture of hafnium oxide and zirconium oxide or multilayers thereof.
13. The material stack of claim 12 wherein said Hf-based dielectric comprises hafnium oxide.
14. A semiconductor structure comprising:
a patterned material stack located on a surface of a semiconductor substrate, said patterned material stack comprising a hafhium-based dielectric; an electrically conductive capping layer comprising at least one of Ce, Y, Sm, Er and Tb and located above said hafnium-based dielectric, wherein said electrically conductive capping layer is a rare earth metal-containing material; and a Si-containing conductor located directly on said electrically conductive capping layer.
15. A material stack comprising:
a dielectric material having a dielectric constant of greater than about 4.0 and comprising a hafnium-based dielectric;
an electrically conductive capping layer comprising at least one of Ce, Y, Sm, Er and Tb and located above said hafnium-based dielectric; and
a Si-containing conductor located directly on said electrically conductive capping layer.