Method of forming structures for threshold voltage control
Methods and systems for depositing rare earth metal carbide containing layers on a surface of a substrate and structures and devices formed using the methods are disclosed. An exemplary method includes using a cyclical deposition process such as an atomic layer deposition process for depositing a rare earth metal carbide containing layer onto a surface of the substrate.
1. A method for depositing a rare earth metal carbide containing layer on a substrate, the method comprising the steps of:
providing a substrate within a reaction chamber, the substrate comprising a surface layer;
depositing a rare earth metal carbide containing layer onto the surface layer by means of a cyclical deposition process, the cyclical deposition process comprising one or more cycles, a cycle comprising:
providing a rare earth metal precursor to the reaction chamber in a precursor pulse; and
providing a carbon reactant to the reaction chamber in a reactant pulse;
thus forming a rare earth metal carbide containing layer on the substrate;
wherein the rare earth metal carbide layer comprises cerium carbide, and wherein the rare earth metal precursor comprises a cerium precursor.
2. The method according to claim 1 wherein the cerium precursor comprises at least one of cerium in oxidation state +3 and cerium in oxidation state +4.
3. The method according to claim 1 wherein the rare earth metal precursor comprises a substituted or unsubstituted cyclopentadienyl ligand.
4. The method according to claim 3 wherein the rare earth metal precursor comprises Ce(iPrCp) 3 .
5. The method according to claim 1 wherein the carbon reactant comprises a halogenated C1 to C6 alkane or alkene.
6. The method according to claim 1 wherein the carbon reactant comprises iodine.
7. The method according to claim 1 wherein the precursor pulse precedes the reactant pulse.
8. The method according to claim 7 wherein the cyclical deposition process further comprises a first hydrogen pulse, and wherein the first hydrogen pulse comprises providing a first hydrogen containing gas to the reaction chamber.
9. The method according to claim 8 wherein the first hydrogen pulse occurs after the precursor pulse and before the reactant pulse.
10. The method according to claim 9 wherein the cyclical deposition process further comprises a second hydrogen pulse, wherein the second hydrogen pulse comprises providing a second hydrogen containing gas to the reaction chamber, and wherein the second hydrogen pulse occurs after the reactant pulse.
11. The method according to claim 1 wherein the cyclical deposition process comprises a further precursor pulse, wherein the further precursor pulse comprises providing a further precursor to the reaction chamber, and wherein the further precursor and the rare earth metal precursor are different.
12. The method according to claim 11 wherein the further precursor comprises at least one of a rare earth metal and a transition metal.
13. A system comprising:
one or more reaction chambers;
a precursor gas source comprising a precursor;
a reactant gas source comprising a reactant;
an exhaust source; and
a controller,
wherein the controller is configured to control gas flow into at least one of the one or more reaction chambers to carry out a method according to claim 1 .
14. A method for forming an electrode on a substrate, the method comprising the steps of:
providing a substrate within a reaction chamber the substrate comprising a gate dielectric;
depositing a first conductive layer on the gate dielectric;
depositing a rare earth metal carbide containing layer onto the first conductive layer by means of a cyclical deposition process, the cyclical deposition process comprising one or more cycles, a cycle comprising:
providing a rare earth metal precursor to the reaction chamber in a precursor pulse; and
providing a carbon reactant to the reaction chamber in a reactant pulse; and,
depositing a second conductive layer on the rare earth metal carbide layer;
thus forming an electrode on the substrate, the electrode comprising the first conductive layer, the rare earth metal carbide containing layer, and the second conductive layer;
wherein the rare earth metal carbide containing layer comprises cerium carbide, and wherein the rare earth metal precursor comprises a cerium precursor.
15. The method according to claim 14 wherein the first conductive layer comprises a first transition metal nitride.
16. The method according to claim 14 wherein the second conductive layer comprises a second transition metal nitride.
17. The method according to claim 14 wherein the first conductive layer comprises a first transition metal carbide.
18. The method according to claim 14 wherein the second conductive layer comprises a second transition metal carbide.