Precursor compositions for atomic layer deposition and chemical vapor deposition of titanate, lanthanate, and tantalate dielectric films
View Patent ↗Barium, strontium, tantalum and lanthanum precursor compositions useful for atomic layer deposition (ALD) and chemical vapor deposition (CVD) of titanate thin films. The precursors have the formula M(Cp) 2 , wherein M is strontium, barium, tantalum or lanthanum, and Cp is cyclopentadienyl, of the formula wherein each of R 1 -R 5 is the same as or different from one another, with each being independently selected from among hydrogen, C 1 -C 12 alkyl, C 1 -C 12 amino, C 6 -C 10 aryl, C 1 -C 12 alkoxy, C 3 -C 6 alkylsilyl, C 2 -C 12 alkenyl, R 1 R 2 R 3 NNR 3 , wherein R 1 , R 2 and R 3 may be the same as or different from one another and each is independently selected from hydrogen and C 1 -C 6 alkyl, and pendant ligands including functional group(s) providing further coordination to the metal center M. The precursors of the above formula are useful to achieve uniform coating of high dielectric constant materials in the manufacture of flash memory and other microelectronic devices.
1. A method of forming a metal-containing material on a substrate, wherein the metal comprises at least one metal selected from among barium and strontium, said method comprising contacting the substrate with a vapor of a precursor composition, to deposit said metal on the substrate from said vapor, wherein the precursor composition includes a compound of the formula M(Cp) 2 , wherein M is strontium or barium, and wherein Cp is cyclopentadienyl of the formula
wherein each of R 1 -R 5 is the same as or different from one another, with each being independently selected from among hydrogen, C 1 -C 12 alkyl, C 1 -C 12 amino, C 6 -C 10 aryl, C 1 -C 12 alkoxy, C 3 -C 6 alkylsilyl, C 2 -C 12 alkenyl, R 1 R 2 R 3 NNR 3 , wherein R 1 , R 2 and R 3 may be the same as or different from one another and each is independently selected from hydrogen and C 1 -C 6 alkyl, and pendant ligands including functional group(s) providing further coordination to metal center M, wherein R 1 -R 5 are not simultaneously H, and wherein the precursor composition further includes a solvent medium selected from the group consisting of xylene and tetrahydronaphthalene, wherein R 1 -R 5 are not all simultaneously methyl when the solvent medium is xylene and the metal M is strontium, wherein three of R 1 -R 5 are not isopropyl when the remaining two are H, and wherein the compound is not complexed with adduct-forming groups.
2. The method of claim 1 , comprising atomic layer deposition of barium and/or strontium on the substrate.
3. The method of claim 2 , wherein said atomic layer deposition further comprises deposition of titanium on said substrate from a titanium precursor.
4. The method of claim 3 , wherein the titanium precursor comprises a precursor of the formula X 2 TiCp 2 , wherein Cp is cyclopentadienyl, of the formula
wherein each of R 1 -R 5 is the same as or different from one another, with each being independently selected from among hydrogen, C 1 -C 12 alkyl, C 1 -C 12 amino, C 6 -C 10 aryl, C 1 -C 12 alkoxy, C 3 -C 6 alkylsilyl, C 2 -C 12 alkenyl, R 1 R 2 R 3 NNR 3 , wherein R 1 , R 2 and R 3 may be the same as or different from one another and each is independently selected from hydrogen and C 1 -C 6 alkyl, and pendant ligands including functional group(s) providing further coordination to Ti, and each X is independently selected from among chlorine, bromine, iodine, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, dialkylamido and cyclic alkylamido.
5. The method of claim 4 , wherein X is selected from among dialkylamido of the formula R 1 R 2 N—, wherein R 1 and R 2 are independently selected from C 1 -C 4 alkyls, and cyclic alkylamido of the formula (CH 2 ) y N—, wherein y is an integer selected from among 2, 3, 4, 5 and 6.
6. The method of claim 3 , wherein the titanium precursor comprises a precursor selected from the group consisting of titanium alkoxides and titanium beta-diketonate alkoxides.
7. The method of claim 3 , wherein the titanium precursor comprises a titanium precursor selected from the group consisting of Ti(OPr-i) 4 , Ti(OBu-t) 4 , (Ti(thd) 2 (OPr-i) 2 and Ti(thd) 2 (OBu-t) 2 .
8. The method of claim 3 , wherein said substrate comprises hydroxyl functional groups thereon.
9. The method of claim 3 , wherein said substrate comprises a semiconductor substrate.
10. The method of claim 3 , wherein the metal-containing material on the substrate comprises barium and/or strontium titanate.
11. The method of claim 10 , wherein said barium and/or strontium titanate comprises a titanate selected from the group consisting of strontium titanate, barium titanate and barium strontium titanate.
12. The method of claim 10 , as conducted in a process of fabricating a semiconductor device.
13. The method of claim 12 , wherein said semiconductor device comprises a flash memory device.
14. An atomic layer deposition process for forming barium and/or strontium titanate on a substrate, comprising:
(a) contacting the substrate with a titanium source under conditions producing a coating of titanium on the substrate;
(b) contacting the titanium-coated substrate with an oxidant or water to form a hydroxylated surface;
(c) contacting the hydroxylated surface with a barium and/or strontium precursor composition, under conditions producing a coating of barium and/or strontium thereon, wherein the precursor composition comprises a precursor selected from among precursors having the formula M(Cp) 2 , wherein M is strontium or barium, and wherein Cp is cyclopentadienyl of the formula
wherein each of R 1 -R 5 is the same as or different from one another, with each being independently selected from among hydrogen, C 1 -C 12 alkyl, C 1 -C 12 amino, C 6 -C 10 aryl, C 1 -C 12 alkoxy, C 3 -C 6 alkylsilyl, C 2 -C 12 alkenyl, R 1 R 2 R 3 NNR 3 , wherein R 1 , R 2 , and R 3 may be the same as or different from one another and each is independently selected from hydrogen and C 1 -C 6 alkyl, and pendant ligands including functional group(s) providing further coordination to metal center M, wherein R 1 -R 5 are not simultaneously H, and wherein the composition further comprises a solvent medium selected from the group consisting of xylene and tetrahydronaphthalene, wherein R 1 -R 5 are not all simultaneously methyl when the solvent medium is xylene and the metal M is strontium, wherein three of the R 1 -R 5 are not isopropyl when the remaining two are H, and wherein the compound is not complexed with adduct-forming groups;
(d) contacting the barium and/or strontium-coated substrate with an oxidant or water to form a hydroxylated surface; and
(e) repeating steps (a) through (d) for a sufficient number of repetitions to produce a barium and/or strontium titanate film of predetermined thickness.
15. The process of claim 14 , wherein said predetermined thickness is in a range of from 5 nm to 500 nm.
16. The method of claim 3 , wherein the precursor is in a solid form.
17. The method of claim 3 , wherein the precursor is in a liquid form.
18. A chemical vapor deposition process, comprising contacting a substrate with vapor of a barium and/or strontium precursor, and with vapor of a titanium precursor, under vapor deposition conditions, to form a layer of barium and/or strontium titanate on the substrate, wherein said barium and/or strontium precursor composition comprises a compound of the formula M(Cp) 2 , wherein M is barium or strontium, and Cp is cyclopentadienyl, of the formula
wherein each of R 1 -R 5 is the same as or different from one another, with each being independently selected from among hydrogen, C 1 -C 12 alkyl, C 1 -C 12 amino, C 6 -C 10 aryl, C 1 -C 12 alkoxy, C 3 -C 6 alkylsilyl, C 2 -C 12 alkenyl, R 1 R 2 R 3 NNR 3 , wherein R 1 , R 2 and R 3 may be the same as or different from one another and each is independently selected from hydrogen and C 1 -C 6 alkyl, and pendant ligands including functional group(s) providing further coordination to metal center M, wherein R 1 -R 5 are not simultaneously H, and wherein the precursor composition further comprises a solvent medium selected from the group consisting of xylene and tetrahydronaphthalene, wherein R 1 -R 5 are not all simultaneously methyl when the solvent medium is xylene and the metal M is strontium, wherein three of R 1 -R 5 are not isopropyl when the remaining two are H, and wherein the compound is not complexed with adduct-forming groups.
19. The process of claim 14 , wherein the titanium source comprises a titanium precursor selected from the group consisting of Ti(OPr-i) 4 , Ti(OBu-t) 4 , (Ti(thd) 2 (OPr-i) 2 and Ti(thd) 2 (OBu-t) 2 .
20. The process of claim 18 , wherein the titanium precursor comprises a compound selected from the group consisting of Ti(OPr-i) 4 , Ti(OBu-t) 4 , (Ti(thd) 2 (OPr-i) 2 and Ti(thd) 2 (OBu-t) 2 .
21. The method of claim 1 , wherein M(Cp) 2 is selected from the group consisting of bis(pentamethylcyclopentadienyl)strontium and bis(tetramethyl-n-propylcyclopentadienyl)strontium.
22. The atomic layer deposition process of claim 14 , wherein M(Cp) 2 is selected from the group consisting of bis(pentamethylcyclopentadienyl)strontium and bis(tetramethyl-n-propylcyclopentadienyl)strontium.
23. The chemical vapor deposition process of claim 18 , wherein M(Cp) 2 is selected from the group consisting of bis(pentamethylcyclopentadienyl)strontium and bis(tetramethyl-n-propylcyclopentadienyl)strontium.