Methods and systems for forming a layer comprising aluminum, titanium, and carbon
Disclosed are methods and systems for depositing layers comprising a titanium, aluminum, and carbon. The layers are formed onto a surface of a substrate. The deposition process comprises a cyclical deposition process. Exemplary structures in which the layers may be incorporated include field effect transistors, VNAND cells, metal-insulator-metal (MIM) structures, and DRAM capacitors.
1. A method for forming a layer on a substrate, the method comprising:
providing the substrate in a reaction chamber;
executing a plurality of deposition cycles;
wherein a deposition cycle comprises
an aluminum precursor pulse, the aluminum precursor pulse comprising exposing the substrate to an aluminum precursor, the aluminum precursor comprising aluminum, a first alkyl ligand, and a second alkyl ligand, the first alkyl ligand and the second alkyl ligand being different; and,
a transition metal precursor pulse, the transition metal precursor pulse comprising exposing the substrate to a transition metal precursor, the transition metal precursor comprising a transition metal;
thus forming the layer on the substrate, the layer comprising the transition metal, the aluminum, and carbon.
2. The method according to claim 1 wherein executing a plurality of deposition cycles is preceded by executing one or more priming steps, a priming step comprising exposing the substrate to the transition metal precursor.
3. The method according to claim 1 wherein the aluminum precursor comprises a chemical compound represented by the formula (L 1 ) n (L 2 ) n−1 Al, wherein L 1 is the first alkyl ligand, L 2 is the second alkyl ligand, and n is an integer that equals 1 or 2.
4. The method according to claim 3 wherein L 1 is 1,1-dimethylethyl.
5. The method according to claim 3 wherein L 2 is methyl.
6. The method according to claim 1 wherein the first alkyl ligand is a C1 to C5 alkyl.
7. The method according to claim 1 wherein the second alkyl ligand is a C1 to C5 alkyl.
8. The method according to claim 1 wherein the aluminum precursor comprises bis(1,1-dimethylethyl)methylaluminum.
9. The method according to claim 1 wherein the transition metal precursor comprises a halogen.
10. The method according to claim 9 wherein the halogen comprises chlorine.
11. The method according to claim 1 wherein the transition metal is selected from tantalum, hafnium, vanadium, zirconium, niobium, molybdenum, tungsten, and titanium.
12. The method according to claim 1 wherein subsequent deposition cycles are separated by an inter deposition cycle purge.
13. The method according to claim 2 wherein the aluminum precursor pulse and the transition metal precursor pulse are separated by an intra deposition cycle purge.
14. The method according to claim 1 wherein the deposition cycles are executed in absence of a plasma.
15. The method according to claim 1 wherein the method is carried out until a layer having a thickness of least 0.2 nm to at most 5 nm is formed on the substrate.
16. The method according to claim 1 wherein the substrate comprises a monocrystalline silicon wafer.
17. The method according to claim 1 further comprising a step of exposing the substrate to an oxygen containing gas, thereby at least partially oxidizing the layer comprising the transition metal, the aluminum, and carbon.