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Title:
PYRROLYL COMPLEXES OF COPPER FOR COPPER METAL DEPOSITION
Document Type and Number:
WIPO Patent Application WO/2004/015164
Kind Code:
A1
Abstract:
The present invention relates to a process for the preparation of ligands and copper complexes useful in the deposition of copper via Atomic Layer Deposition (ALD) and Chemical Vapor Deposition (CVD), and the use of the copper complexes in ALD and CVD processes.

Inventors:
Grushin, Vladimir (533 Runnymeade Road, Hockessin, DE, 19707, US)
Application Number:
PCT/US2003/024117
Publication Date:
February 19, 2004
Filing Date:
July 31, 2003
Export Citation:
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Assignee:
E.I. DU PONT DE NEMOURS AND COMPANY (1007 Market Street, Wilmington, DE, 19898, US)
Grushin, Vladimir (533 Runnymeade Road, Hockessin, DE, 19707, US)
International Classes:
C07D207/30; C07D207/333; C07D207/335; C07F1/08; C23C16/18; C23C16/455; C07D207/32; C23C16/44; (IPC1-7): C23C16/00; C07D207/32
Foreign References:
EP1170308A2
US5464666A
US3594216A
Other References:
HISASHI TANAKA AND OSAMU YAMAUCHI: "]ber die Synthese und Chelatkomplexe von 2-Pyrrolylmethyleniminen. II." CHEMICAL & PHARMACEUTICAL BULLETIN, vol. 10, no. 6, 1962, pages 435-439, XP008025701
B EMMERT ET AL: "]ber innere Komplexsalze einiger Pyrrol-Derivate" CHEMISCHE BERICHTE, vol. 62, 1929, pages 1733-1738, XP008025676 cited in the application
YEH K-N ET AL: "SYNTHESIS AND PROPERTIES OF SOME METAL CHELATES OF 2-PYRROLEALDIMINES" INORGANIC CHEMISTRY, AMERICAN CHEMICAL SOCIETY. EASTON, US, vol. 6, no. 4, 1967, pages 830-833, XP000915350 ISSN: 0020-1669 cited in the application
HISASHI TANAKA AND OSAMU YAMAUCHI: "]ber die Synthese und die Chelatkomplexe von N-2-Pyrrolylmethylenaminen. I." CHEMICAL & PHARMACEUTICAL BULLETIN, vol. 9, 1961, pages 588-592, XP008025628
DATABASE CAPLUS [Online] CHEMICAL ABSTRACTS SERVICE, COLUMBUS, OHIO, US; KROWCZYNSKI, ADAM ET AL: "Metal complexes of pyrrole derivatives and method of their preparation" retrieved from STN Database accession no. 129:349117 XP002265131 -& PL 173 979 B (UNIWERSYTET WARSZAWSKI, POL.) 29 May 1998 (1998-05-29)
DATABASE CAPLUS [Online] CHEMICAL ABSTRACTS SERVICE, COLUMBUS, OHIO, US; HONDA, KENJI ET AL: "Polymeric pyrrole derivatives. 9. Reactions between copper complexes containing pyrrole Schiff bases and 2,2-diphenyl-1-picrylhydrazyl" retrieved from STN Database accession no. 81:106212 XP002265132 & NIPPON KAGAKU KAISHI (1974), (5), 972-6 ,
DATABASE CAPLUS [Online] CHEMICAL ABSTRACTS SERVICE, COLUMBUS, OHIO, US; TOMONO, TSUGIKAZU ET AL: "Synthesis and polymerization of copper(II) and cobalt(III) complexes containing 3-(2-pyrrolylmethylenimino)prop-1-ene or p-(2-pyrrolylmethylenimino)styrene" retrieved from STN Database accession no. 81:50107 XP002265133 & NIPPON KAGAKU KAISHI (1974), (3), 593-7 ,
GORDON L EGGLETON ET AL: " Oxygen-17 and Carbon-13 Nuclear Magnetic Resonance Spectra of Thiophene- and Pyrrole-2-carboxaldehyde. Condensation Products Prepared From Ephedrine Derivatives" JOURNAL OF HETEROCYCLIC CHEMISTRY, vol. 27, no. 1853, 1990, pages 1853-1855, XP002265130
Attorney, Agent or Firm:
Siegell, Barbara C. (E.I. Dupont de Nemours and Company, Legal Patent Records Center 4417 Lancaster Pik, Wilmington DE, 19805, US)
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Claims:
CLAIMS What is claimed is:
1. A process for preparing pyrrolealdimines, comprising the steps of: a) reacting 2formylpyrrole with a primary amine, RNH2, in an aqueous solution, wherein R is C1 to C10 alkyl or substituted alkyl, or C6 to C12 aryl or substituted aryl ; b) adding a waterimmiscible organic compound to form an aqueous phase and an organic phase; and c) isolating the organic phase.
2. The process of Claim 1 wherein R is methyl or phenyl.
3. The process of Claim 1 wherein the waterimmiscible organic compound is selected from the group consisting of alkanes, chlorinated alkanes, cycloalkanes, and aromatic solvents.
4. The process of Claim 3 wherein the waterimmiscible compound is selected from the group consisting of pentane, hexanes, heptanes, chloroform, dichloromethane, carbon tetrachloride, cylcopentane, cyclohexane, benzene, and toluene.
5. The process of Claim 1, wherein the molar ratio of 2 formylpyrrole to primary amine is between about 1: 2 and about 2: 1.
6. The process of Claim 1, wherein the temperature is between about 0 °C and about 100°C.
7. An aqueous process for preparing Cu (II) complexes of 2pyrrole ligands comprising reacting an aqueous mixture of 2formylpyrrole, a primary amine, R1NH2, and a source off ())), wherein Ri is selected from the group consisting of C1C10 alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl ; NHR3; and NR4R5; and R3, R4, and R5 are independently selected from the group of ClC6 alkyl or substituted alkyl, and C6 to C12 aryl or substituted aryl.
8. The process of Claim 7, wherein the primary amine is selected from the group consisting of methylamine, ethylamine, propylamine, isopropylamine, nbutylamine, tbutylamine, isobutylamine, 2 ethylhexylamine, aniline, 3trifluoromethylaniline, ßalanine isopropyl ester, pa) anine ethy ! ester and benzylamine.
9. The process of Claim 7, wherein the molar ratio of 2 formylpyrrole to primary amine is from about 1: 1 to about 1: 10 and the molar ratio of copper to 2formylpyrrole is from about 10: 1 to about 1: 10.
10. The process of Claim 7, wherein the temperature is from about 0 °C to about 100 °C.
11. An aqueous process for preparing Cu (II) complexes of 2pyrrole ligands comprising a. reacting 2formylpyrrole and a primary amine in water; and b. adding a source of copper (II) and allowing the mixture to react to form the copper (II) complex.
12. The process of Claim 7, wherein the source of copper (ll) is selected from the group consisting of copper hydroxide, copper (II) chloride, copper nitrate, copper sulfate, copper (li) salts of carboxylic acids, and copper alkoxide.
13. The process of Claim 11, wherein the source of copper (ii) is copper acetate.
14. The process of Claim 12, wherein the source of copper (li) is copper acetate.
15. The process of Claim 7, wherein the reaction is conducted in the presence of a waterimmiscible organic compound.
16. An aqueous process for preparing Cu (II) complexes of a 2 acylpyrrole comprising the steps of a. contacting an aqueous mixture of a source of Cu (II) with a 2acylpyrrole, where R8 is C1 to C10 alkyl ; and b. further reacting the aqueous mixture with a base.
17. The process of Claim 16, wherein the 2acylpyrrole is 2 acetylpyrrole.
18. The process of Claim 17, wherein the molar ratio of 2 acylpyrrole to primary amine is from about 1: 1 to about 1: 10 and the molar ratio of copper to 2acylpyrrole is from about 10: 1 to about 1: 10.
19. The process of Claim 16, wherein the temperature is from about 0 °C to about 100 °C.
20. A Cu (i I) complex comprising: a) a copper atom; and b) two pyrrole ligands bound to said copper atom, wherein said pyrrole ligands are independently selected from the group consisting of 2pyrrolealdnpropylimino, 2 pyrrolealdibutylimino, 2pyrrolealdnbutylimino, 2 pyrroleald2ethylhexylimino, 2pyrrolealdm trifluoromethylphenylimino, 2pyrrolylald (2 isopropoxycarbonylethyl) imino, 2pyrrolylald (2 ethoxycarbonylethyl) imino and 2pyrrolealdbenzylimino ligands.
21. A Cu (II) complex selected from the group consisting of bis (2 pyrrolylaldnpropylimino) copper (II), bis (2pyrrolylaldn butylimino) copper (II), bis (2pyrrolylaldisobutylimino) copper (il), bis (2 pyrrolylald (2ethylhexyl) imino) copper (li), bis (2pyrrolylald (m trifluoromethylphenyl) imino) copper (il), bis (2 pyrrolylaldbenzylimino) copper (II), bis (2pyrrolylald (2 ethoxycarbonylethyl) imino) copper (il), bis (2pyrrolylald (2 isopropoxycarbonylethyl) imino) copper (II), and bis (2 acetylpyrrolyl) copper (il).
22. A process for depositing copper on a substrate comprising: a) adsorbing onto a substrate at least one Cu (II) complex of structure 1, structure 1 = wherein: X is O, and R8 is ClClo alkyl or substituted alkyl, or C6 to C12 aryl or substituted aryl ; or X is NRI and R8 is H; RI is selected from the group consisting of ClClo alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl ; NHR3; and NR4R5; and R3, R4, and R5 are independently selected from the group of C1C6 alkyl or substituted alkyl, and C6 to C12 aryl or substituted aryl ; and b) exposing said absorbed complex to a reducing agent to form copper metal.
23. The process of Claim 22, wherein the Cu (II) complex is selected from the group consisting of bis (2pyrrolealdmethylimino) copper (II), bis (2 pyrrolealdethylimino) copper (il), bis (2pyrrolealdisopropylimino) copper (II), bis (2pyrrolealdtbutylimino) copper (II), bis (2 pyrrolealdphenylimino) copper (II), bis (2pyrrolylaldn propylimino) copper (li), bis (2pyrrolylaldnbutylimino) copper (II), bis (2 pyrrolylaldisobutylimino) copper (l 1), bis (2pyrrolylald (m trifluoromethylphenyl) imino) copper (II), bis (2 pyrrolylaldbenzylimino) copper (li), and bis (2acetylpyrrolyl) copper (II).
24. The process of Claim 22, wherein the substrate is selected from the group consisting of glass, metals and ceramics, and silicon wafers coated with a barrier layer.
25. The process of Claim 22, wherein the reducing agent is selected from the group consisting of ammonia, ammonia/hydrogen mixtures, hydrazine, CO/hydrogen mixtures, 9BBN, borane, dihydrobenzofuran, pyrazoline, diethylsilane, dimethylsilane, ethylsilane, phenylsilane, and silane.
26. The process of Claim 25, wherein the adsorbed copper complex is exposed to a reducing agent at a pressure of about 10 to about 760 millitorr, and the substrate is held at a temperature of about 100 °C to about 300 °C during the reduction.
27. A process for depositing copper on a substrate comprising heating a reducing agent and at least one Cu (II) complex of structure 1, structure 1 = in the presence of a substrate, wherein: X is O, and R8 is ClClo alkyl or substituted alkyl, or C6 to C12 aryl or substituted aryl ; or X is NRl and R8 is H; Rl is selected from the group consisting of C1C10 alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl; NHR3 ; and NR4R5; and R3, R4, and R5 are independently selected from ClC6 alkyl or substituted alkyl, and C6 to C12 aryl or substituted aryl.
28. An article comprising a substrate with a Cu (II) complex of structure 1 adsorbed on the surface or in or on porosity in the substrate, structure 1 = wherein: X is O, and R8 is C1C10 alkyl or substituted alkyl, or C6 to C12 aryl or substituted aryl ; or X is NRI and R8 is H; RI is selected from the group consisting of ClClo alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl ; NHR3; and NR4R5; and R3, R4, and R5 are independently selected from ClC6 alkyl or substituted alkyl, and C6 to C12 aryl or substituted aryl.
29. An article of Claim 28, wherein the substrate is selected from the group consisting of glass, metals and ceramics, and silicon wafers coated with a barrier layer.
30. ,.
31. The process of Claim 24, wherein the barrier layer is selected from the group consisting of titanium nitride and tantalum/tantalum nitride.
32. The article of Claim 29, wherein the barrier layer is selected from the group consisting of titanium nitride and tantalum/tantalum nitride.
33. A process for preparing aryl pyrrolealdimines, comprising reacting an aqueous solution of 2formylpyrrole with a waterimmiscible primary amine, R'NH2, wherein R'is C6 to C12 aryl or substituted aryl.
Description:
TITLE PYRROLYL COMPLEXES OF COPPER FOR COPPER METAL DEPOSITION FIELD OF THE INVENTION The present invention relates to a process for the preparation of ligands and copper complexes useful in the deposition of copper via Atomic Layer Deposition or Chemical Vapor Deposition.

TECHNICAL BACKGROUND Atomic Layer Deposition (ALD) and Chemical Vapor Deposition (CVD) processes are useful in the deposition of metals on substrates.

In the ALD process, a substrate on which the metal is to be deposited is placed in a vacuum chamber. A volatile metal complex is then admitted into the vacuum chamber and allowed to adsorb onto a substrate. The excess, unadsorbed vapor of the metal complex is then pumped or purged from the vacuum chamber. The adsorbed metal complex is then exposed to a second reagent, which causes the complex to react to produce metal. In the preparation of a copper film from a copper (il) complex, the second reagent is a reducing agent. Suitable copper precursor complexes for this process must be volatile enough to sublime and thermally stable in the temperature range of the process. The ligands themselves should preferably leave as the free ligand.

In a CVD process, a heated substrate is exposed to a vapor of the volatile metal complex, optionally in the presence of another reactant (a co-reactant) in the gas phase. In this process, the complex decomposes to metal on contact with the substrate, or reacts with the co-reactant (s) in the vicinity of the substrate, to produce a deposited metal film. The ligand can evolve either as volatile free ligand or be decomposed into volatile by- products. Thus, for CVD, the metal complex must be volatile and stable enough to form a vapor phase, but unlike for ALD, must decompose on contact with the heated substrate in the absence or presence of a co- reactant under the conditions of the CVD process to give the desired film.

Copper films formed via ALD or CVD processes are useful in many applications, including the production of electronic devices, catalytic surfaces and decorative effects.

K. Yeh and R. H. Parker, Inorganic Chemistry, 6,830-833 (1967), disclose the synthesis of 2-pyrrolealdimines and the corresponding copper chelate. B. Emmert, et al., Berichte, 62, 1733-1738 (1929), disclose the synthesis of 2-pyrrolealdmethylimine and of its copper complex.

SUMMARY OF THE INVENTION The present invention relates to processes for the preparation of ligands and the corresponding copper complexes, and the use of such complexes to deposit copper onto substrates.

A first embodiment of this invention relates to a process for preparing pyrrolealdimines, comprising the steps of: a) reacting 2-formylpyrrole with a primary amine, RNH2, in an aqueous solution, wherein R is C1 to C10 alkyl or substituted alkyl, or C6 to C12 aryl or substituted aryl ; b) adding a water-immiscible organic compound to form an aqueous phase and an organic phase; and c) isolating the organic phase.

A second embodiment of this invention is an aqueous process for preparing Cu (II) complexes of 2-pyrrolyl imino ligands comprising reacting an aqueous mixture of 2-formylpyrrole and a source of Cu (II) with a primary amine, R1 NH2, wherein R1 is selected from the group consisting of Cl-Clo alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl ; NHR3; and NR4R5; and R3, R4, and R5 are independently selected from Cl-C6 alkyl or substituted alkyl and C6 to C12 aryl or substituted aryl.

A third embodiment of this invention is a process for preparing Cu (ll) complexes of a 2-acylpyrrole comprising: a) combining a source of Cu (ii), water, and a 2-acylpyrrole, where R8 is C1 to C10 alkyl, to form an aqueous mixture; and b) adding a base to the aqueous mixture.

A fourth embodiment of this invention provides Cu (II) complexes comprising: a) a copper atom; and b) two pyrrole ligands bound to said copper atom, wherein said pyrrole ligands are independently selected from the group consisting of 2-pyrroleald-n-propylimino, 2-pyrroleald-i-butyl-

imino, 2-pyrroleald-n-butyl-imino, 2-pyrroleald-2-ethylhexyl- imino, 2-pyrroleald-m-trifluoromethylphenyl-imino, 2- pyrrolylald (2-isopropoxycarbonylethyl) imino, 2-pyrrolylald (2- ethoxycarbonylethyl) imino and 2-pyrroleald-benzyl-imino ligands.

A fifth embodiment of this invention is a process for depositing copper on a substrate comprising: a) adsorbing onto a substrate at least one Cu (ll) complex of structure 1 structure 1 = wherein: X is O, and R8 is Cl-Clo alkyl or substituted alkyl, or C6 to C12 aryl or substituted aryl ; or X is NRI and R8 is H; Ri is selected from the group comprising C1-C10 alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl; NHR3; and NR4R5; and R3, R4, and R5 are independently selected from Cl-C6 alkyl or substituted alkyl, and C6 to C12 aryl or substituted aryl ; and b) exposing the absorbed complex to a reducing agent to form copper metal.

A sixth embodiment of this invention provides a process for depositing copper on a substrate, comprising heating in the presence of a substrate a reducing agent and at least one Cu (II) complex of structure 1, structure 1 =

wherein: X is O, and R8 is Cl-Clo alkyl or substituted alkyl, or C6 to C12 aryl or substituted aryl ; or X is NRl and R8 is H ; R1 is selected from the group consisting of Cl-Clo alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl ; NHR3; and NR4R5; and R3, R4, and Rs are independently chosen from Cl-C6 alkyl or substituted alkyl, and C6 to C12 aryl or substituted aryl.

A seventh embodiment of this invention is an article comprising a substrate with a Cu (II) complex of structure 1 adsorbed on the surface or in or on porosity in the substrate, structure 1 = wherein: X is O, and R8 is C1-C10 alkyl or substituted alkyl, or C6 to C12 aryl or substituted aryl ; or X is NRl and R8 is H; RI is selected from the group consisting of C1-C10 alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl ; NHR3, and NR4R5; and R3, R4, and R5 are independently selected from C1-C6 alkyl or substituted alkyl, and C6 to C12 aryl or substituted aryl.

DETAILED DESCRIPTION It has been found that pyrrolealdimino and pyrroleketo complexes of copper are especially useful as volatile copper precursors for ALD and/or CVD processes. These complexes are air-and moisture-stable, thermally stable and volatile under ALD and/or CVD process conditions. These complexes can be decomposed in the presence of appropriate reducing agents to form copper metal.

The pyrrolealdimino and pyrroleketo copper (it) complexes are easily prepared in good yield in aqueous media from readily available

reagents. For example, the pyrrolealdimine ligands can be isolated from the reaction of 2-formylpyrrole with the appropriate primary amine, and then reacted with a source of copper (II) to give the desired copper (II) complex. Alternatively, the pyrrolealdimine ligand can be made in situ, such that the pyrrolealdimino copper complex is isolated directly from the aqueous reaction mixture of 2-formylpyrrole, the primary amine and a source of copper (II).

A preferred method for preparing the pyrrolealdimine ligands is to react 2-formylpyrrole with a primary amine in water, and then add a water- immiscible organic compound to form a two-phase system in which the pyrrolealdimine ligand is extracted into the organic phase. Preferred primary amines, RNH2, are those for which R is C1 to C10 alkyl or substituted alkyl, or C6 to C12 aryl or substituted aryl. The preferred molar ratio of 2-formylpyrrole to primary amine is between about 1: 2 and 2: 1.

Preferred temperatures are about 0 °C to about 100 °C. Preferred water- immiscible compounds are organic solvents such as alkanes, chlorinated alkanes, cycloalkanes, and aromatic solvents. Especially preferred solvents include pentane, hexanes, heptanes, chloroform, dichloromethane, carbon tetrachloride, cylcopentane, cyclohexane, benzene, and toluene. The pyrrolealdimine ligand can be isolated from the organic solvent by conventional means and further purified, if necessary, by crystallization, sublimation or other common methods. Alternatively, the water-immiscible organic compound is a water-immiscible liquid primary amine which functions as both the reagent and the organic phase.

The desired copper (II) complexes can also be obtained by reacting 2-formylpyrrole, a primary amine, R1NH2, and a source of copper (li) in water. Suitable primary amines are of the form, R1 NH2, where Rl is selected from the group comprising Cl-Clo alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl ; NHR3; and NR4R5, wherein R3, R4, and R5 are independently selected from Cl-C6 alkyl or substituted alkyl, and C6 to C12 aryl or substituted aryl.

Suitable substituent groups on the substituted alkyls and substituted aryls include F, Cl, perfluoroalkyls, alkyl esters, methoxy and ethoxy groups. For some electronic applications, complexes containing only Cu, C, H, and N are preferred.

The preferred molar ratio of 2-formylpyrrole to primary amine is between about 1: 1 and about 1: 10. The preferred molar ratio of copper to 2-formylpyrrole is from about 10 to 1 to about 1 to 10, more preferably

from about 1.2 to 2. Preferred temperatures are about 0 °C to about 100 °C, more preferably between about 20 °C and about 80 °C. If the product is a solid, it may be isolated and purified by standard methods (e. g., <BR> <BR> filtration, recrystallization, sublimation, etc. ). If the product is an oil, it may be isolated by decanting off the aqueous phase, and then purified by standard methods (e. g. , chromatography or distillation).

Alternatively, 2-formylpyrrole and a primary amine are reacted in water, and then a source of copper (II) is added and the resulting mixture is allowed to react to form the copper (II) complex. Isolation of the complex is carried out as described above.

Alternatively, the synthesis of the copper pyrrolylaldimino complexes may be performed under biphasic conditions, i. e. , in the presence of an organic solvent that is immiscible with water, yet capable of dissolving the desired Cu complex product. In this process, the Cu complex product will be extracted, fully or partially, into the organic phase as it forms. The biphasic technique may be beneficial due to more efficient agitation of the reaction mixture and higher conversions after shorter reaction times. After the reaction, the desired Cu complex product can be isolated from the organic phase via conventional filtration, evaporation, and recrystallization (if necessary). Solvents suitable for this technique include dichloromethane, toluene, benzene, ether, alkanes, and cycloalkanes, as long as the particular complex product exhibits sufficient solubility in such media.

The products of the reactions of 2-formylpyrrole, a primary amine, R1NH2 and a source of copper (II) are bis (2-pyrrolealdimino) copper (II) complexes in which the imino nitrogen is substituted with RI selected from the group consisting of Cl-Clo alkyl or substituted alkyl ; C6 to C12 aryl or substituted aryl ; allyl ; benzyl ; NHR3; and NR4R5; where R3, R4, and R5 are independently selected from Cl-C6 alkyl or substituted alkyl, and C6 to C12 aryl or substituted aryl.

Bis (acylpyrrolyl) copper (lI) complexes can be prepared by reacting an acylpyrrole and a source of copper (ii) in water, followed by addition of a base. Suitable 2-acylpyrroles include acetylpyrrole. Suitable bases include NaOH, KOH, and calcium hydroxide. Freshly precipitated copper (II) hydroxide may be used in the absence of extra base. The 2- acylpyrroles useful in this process are readily synthesized using known procedures.

Suitable sources of copper (II) include copper hydroxide, copper (il) chloride, copper nitrate, copper sulfate, copper (II) salts of carboxylic acids <BR> <BR> (e. g. , copper acetate and copper benzoate), and copper alkoxide (e. g., copper methoxide). Either the hydrated or the anhydrous form of these copper (II) salts may be used. If a copper (ll) salt of a strong acid is used (such as nitrate, sulfate, chloride, and bromide) the acid which is released during the synthesis may be neutralized by addition of a base such as alkali (NaOH, KOH, Ba (OH) 2) or Ca (OH) 2, or any base that can scavenge the acid while not interfering with Cu complex formation This invention includes compositions comprising a copper atom coordinated to two bidentate pyrrole ligands. The pyrrole ligand has either an acyl or aldimine group in the 2-position of the pyrrole ring. The ligands are chosen to form a copper (II) complex that is volatile in an appropriate temperature range (typically 20 °C to 250 °C) but does not decompose in this temperature range; however, the complex decomposes to metal on addition of a suitable reducing agent. The ligand is further chosen so that the ligand and or products of its transformations will desorb upon exposure to a reducing agent during the atomic layer deposition process.

The copper (II) complexes of this invention are suitable for use in ALD and CVD processes for creation of copper films for use as seed layers in formation of copper interconnects on integrated circuits or as decorative or catalytic applications.

In an ALD process of this invention, a substrate on which copper is to be deposited is placed in a vacuum chamber. At least one copper (II) complex (I) is then admitted into the vacuum chamber and allowed to adsorb onto the substrate. The copper complex will be added to a reactor at a temperature, time and pressure to attain a suitable fluence of complex to the surface. One of skill in the art will appreciate that the selection of these variables will depend on individual chamber and system design and the desired process rate. The excess, unadsorbed vapor of the copper complex is then pumped or purged from the vacuum chamber. The adsorbed metal complex is then exposed to a reducing reagent at a pressure of approximately 10 to 760 millitorr, which causes the complex to decompose to copper and free ligand. The substrate is held at a temperature between approximately 50 °C to 300 °C during reduction.

Reducing agent exposure times may be from about a second to several hours. Finally, the ligand and/or the products of its transformation are removed by evacuation of the chamber.

In a CVD process, the copper film is produced when the vapor of a volatile copper (l I) complex decomposes on contact with a heated substrate. A gas-phase reducing agent can be added with the volatile copper complex to facilitate the clean decomposition of the complex. In a CVD process, the substrate is heated to approximately 100 °C to 300 °C.

The ligand and/or the products of its decomposition are removed by evacuation of the chamber or an inert gas sweep.

Suitable substrates for the ALD and CVD processes include glass, metals and ceramics, preferably silicon wafers coated with a barrier layer such as titanium nitride or tantalum/tantalum nitride.

Suitable reducing reagents for the ALD and CVD processes of this invention include ammonia and ammonia/hydrogen mixtures, hydrazine, CO/hydrogen mixtures, 9-BBN, borane, dihydrobenzofuran, pyrazoline, diethylsilane, dimethylsilane, ethylsilane, phenylsilane, and silane.

Ammonia/hydrogen mixtures and diethylsilane are preferred.

Preferred copper (II) complexes for use in the ALD and CVD processes of this invention include bis (2-pyrrolylaldmethylimino) copper (il), bis (2-pyrrolylaldethylimino) copper (II), bis (2-pyrrolylald-n- propylimino) copper (II), bis (2-pyrrolylaldisopropylimino) copper (II), bis (2- pyrrolylald-n-butylimino) copper (II), bis (2-pyrrolylald-t-butylimino) copper (II), bis (2-pyrrolylaldisobutylimino) copper (il), bis (2- pyrrolylaldphenylimino) copper (II), bis (2-pyrrolylald (m- trifluoromethylphenyl) imino) copper (II), bis (2- pyrrolylaldbenzylimino) copper (II), and bis (2-acetylpyrrolyl) copper (II).

EXAMPLES Unless otherwise specified, all temperatures are in degrees Celsius, all mass measurements are in grams, and all solution percentages are weight percentages.

Preparation of Ligands Example 1 2-Pyrrolealdmethvlimine. Aqueous methylamine (40%; 4 mL) was added, with stirring, to 2-formylpyrrole (2.00 g). After stirring for 1 min at room temperature, a white solid formed. Water (25 mL) and hexanes (150 mL) were added with stirring to produce a solids-free liquid-liquid biphasic mixture. After 15 min of stirring the organic layer was separated and filtered through a short column filled with anhydrous sodium sulfate. The clear, colorless filtrate was reduced in volume to about 20 mL and kept at +5 °C overnight. The white crystals were collected, dried with a nitrogen

flow (the compound is very volatile), and sublimed under vacuum to give 1.80 g (79%) of white 2-pyrrolealdmethylimine (identical with an authentic sample).

Example 2 2-Pyrrolealdphenvlimine. A mixture of 2-formylpyrrole (5.00 g), aniline (5 mL), and water (50 mL) was vigorously stirred at room temperature in air for 3 days. The resulting solid was filtered, washed with water, and dried under vacuum to give 8.45 g (94%) of spectroscopically pure (1 H NMR) 2-pyrrolealdphenylimine (identical with an authentic sample).

Example 3 2-Pyrroleald (t-butvl) imine. t-Butylamine (2.35 g) was added to 2- formylpyrrole (2.00 g). After the latter had all dissolved upon gentle swirling, water (20 mL) and hexanes (50 mL) were added. The mixture was stirred until two clear, non-cloudy liquid layers were formed (ca.

30 min). The organic layer was separated, filtered through a short anhydrous Na2SO4 plug, and evaporated to leave a viscous colorless oil.

The oil crystallized after 2 h at +5 °C and the solid stayed crystalline after warming up to room temperature. The yield was 2.98 g (94%). The compound was identified by its H NMR spectrum indistinguishable from that reported in Inorg. Chim. Acta, 1984, vol. 89, p. 79.

Preparation of Complexes Example 4 Bis (2-pvrrolvlaldmethvlimino) copper (l). A mixture of 2-formylpyrrole (1.07 g), water (25 mL), and 40% aqueous methylamine (2 mL) was stirred for 1-2 min to produce a milky reaction mixture which quickly turned into a biphasic emulsion. Copper (II) acetate (1.20 g) was added, and the mixture was stirred at room temperature in air for 1 day. The resulting brown solid was filtered, washed with water, air-dried on the filter, and dissolved in dichloromethane. The solution was filtered, reduced in volume to 3-5 mL (dark crystals began to form), and treated with hexanes (25 mL). After 1.5 h at +5 °C, the dark crystals were collected, washed with hexanes (3 x 5 mL), and dried under vacuum. The yield was 1.18 g (75%), m. p. 168-169 OC.

Example 5 Bis (2-pyrrolylaldethvlimino) copper (lI This complex (m. p. 131-132 °C) was prepared similarly, using commercially available 70% aqueous EtNH2 (1.75 mL), 2-formylpyrrole (1.50 g), and Cu (II) acetate (1.72 g) in water (50 mL).

Example 6 Bis (2-pyrrolylald-n-propylimino) copper (li). Propylamine (2.3 mL) was added, with stirring, to a mixture of 2-formylpyrrole (1.23 g) and water (25 mL). After 1-2 min, when all aldehyde dissolved and a liquid-liquid biphasic system formed, Cu (OAc) 2 (1.40 g) was added. After 20 min of agitation, water (25 mL) was added and the mixture was vigorously stirred at room temperature in air for 4 h. The resulting brown solid was filtered, washed with water, air-dried, and dissolved in dichloromethane. The solution was filtered, reduced in volume to 1-2 mL, and treated with hexanes (10 mL). After keeping the mixture for 1.5 h at +5 °C, the black crystals were collected, washed quickly with cold hexanes (2 x 2 mL), and dried under vacuum. The yield was 1.96 g (91 %), m. p. 118-120 °C. Anal.

Calcd. for C16H22CuN4, %: C, 57.6 ; H, 6.6 ; N, 16.8. Found, %: C, 57.6 ; H, 6.5 ; N, 16.7. The structure was confirmed by single-crystal X-ray diffraction.

Example 7 Bis (2-pvrrolvlaldisopropylimino) copper IIL Isopropylamine (2.0 mL) was added, with stirring, to a mixture of 2-formylpyrrole (1.06 g) and water (10 mL). After 2 min, Cu (OAc) 2 (1.20 g) was added. The mixture was stirred at room temperature in air for 1.5 h, then water (50 mL) was added and the stirring continued for 2 more hours. The resulting brown solid was filtered, washed with water, air-dried, and dissolved in dichloromethane.

The dark-green solution was filtered and evaporated to leave well-shaped black crystals. The product was recrystallized by dissolving in boiling heptane and then cooling the solution to +5 °C. The large black crystals were washed quickly with hexanes (3 x 3 mL), and dried under vacuum.

The yield was 1.71 g (92%), m. p. 124-125 °C.

Example 8 Bis (2-pvrrolylald-n-butvlimino) copper (li). n-Butylamine (3.0 mL) was added, with stirring, to a mixture of 2-formylpyrrole (1.38 g) and water (25 mL). After 5 min, Cu (OAc) 2 (1.60 g) was added. The mixture was stirred at room temperature in air for 3.5 h, then water (25 mL) was added and the stirring continued for 3 more hours. The brown solid was filtered, washed with water, air-dried, and dissolved in dichloromethane. The solution was filtered and evaporated to dryness. Methanol (10 mL) was added to the residue and the dark solution was kept at about 5 °C for 4 hours. The well-shaped black crystals were separated, quickly washed with cold methanol, and dried under vacuum. The yield was 2.32 g (88%),

m. p. 93-95 °C. Anal. Calcd. for C18H26CuN4, %: C, 59.7 ; H, 7.2 ; N, 15.5.

Found, %: C, 59.8 ; H, 7.1 ; N, 15.5.

Example 9 Bis (2-pyrrolvlald-t-butylimino ! copper (ll !. t-Butylamine (2.0 mL) was added, with stirring, to a mixture of 2-formylpyrrole (1.00 g) and water (25 mL).

After 5 min, Cu (OAc) 2 (1.20 g) was added. The mixture was stirred at room temperature in air for 1 h, then water (25 mL) was added and the stirring continued overnight. The resulting green solid was filtered, washed with water, air-dried, and dissolved in dichloromethane. The solution was filtered and evaporated to dryness. Hexanes (10 mL) were added to the residue and the mixture was kept at ca. 5 °C overnight. The black-green crystals were separated, quickly washed with cold hexanes, dried under vacuum. The yield was 0.88 g (46%), m. p. 153-156 °C. The structure was confirmed by single-crystal X-ray diffraction.

Example 10 Bis (2-pyrrolylaldisobutvlimino) copper (II). i-Butylamine (2.7 mL) was added, with stirring, to a mixture of 2-formylpyrrole (1.30 g) and water (15 mL).

After 2 min, Cu (OAc) 2 (1.50 g) was added. The mixture was stirred at room temperature in air for 2.5 h, then water (35 mL) was added and the stirring continued for 3 more hours. The resulting solid was filtered, washed with water, air-dried, and dissolved in dichloromethane. The solution was filtered, evaporated to about 3-5 mL, and treated with hexanes (20 mL). After 3 hours at about 5 °C, the black crystals were separated, washed with hexanes (3 x 5 mL), and dried under vacuum.

The yield was 2.07 g (84%), m. p. 194-197 °C. Anal. Calcd. for C18H26CuN4, %: C, 59.7 ; H, 7.2 ; N, 15.5. Found, %: C, 59.9 ; H, 7.2 ; N, 15.5.

Example 11 Bis (2-pyrrolylald (2-ethvlhexvl) imino) copper (II). A mixture of 2- ethylhexylamine (3.3 g), 2-formylpyrrole (2.20 g), water (50 mL), and Cu (OAc) 2 (2. 50 g) was stirred at room temperature in air for 3 days. The aqueous phase was decanted off of the dark viscous oil which was then thoroughly washed with water, dissolved in dichloromethane, and filtered through a short silica gel plug. The filtrate was evaporated to leave a dark oil which was dried under vacuum overnight. The yield was 3.65 g (66%).

Attempts to obtain a crystalline sample of the product from hexanes or methanol were unsuccessful. Anal. Calcd. for C26H42CuN4, %: C, 65.9 ; H, 8.9 ; N, 11.8. Found, %: C, 65.7 ; H, 8.9 ; N, 11.8.

Example 12 Bis (2-pyrrolylaldphenylimino) copper (ii). A mixture of 2-formylpyrrole (3.00 g), water (50 mL), and aniline (3.00 mL) was stirred for 1-2 min.

Copper (II) acetate (3.00 g) was added, and the mixture was stirred at room temperature in air overnight. The resulting brown solid was filtered, washed with water, air-dried on the filter, and dissolved in dichloromethane. The solution was filtered through a short silica gel plug, reduced in volume to 3-5 mL, and treated with hexanes (50 mL). After 12 h at +5 °C, the dark crystals were collected, washed with hexanes (3 x 5 mL), and dried under vacuum. The yield was 4.58 g (72%), m. p.

186-187 °C. The structure was confirmed by single-crystal X-ray diffraction.

Example 13 Bis (2-pvrrolylald (m-trifluoromethylphenYl) imino) copper (ll !. A mixture of 2- formylpyrrole (1.00 g), water (25 mL), 3-trifluoromethylaniline (1.85 g), and copper (II) acetate (1.00 g) was vigorously stirred for 3 days. The solid was filtered, washed with water, air-dried on the filter, and dissolved in dichloromethane. The solution was filtered through a short silica gel plug and evaporated to dryness. The oily residue was re-dissolved in MeOH (10 mL). After 1.5 h at +5 °C, the dark-brown crystals were collected, washed with cold MeOH, and dried. Hexanes (10 mL) was added. After 1 h at +5 °C, the crystals were separated and dried under vacuum. The yield was 1.55 g (55%). Anal. Calcd. for C24H16CuF6N4, %: C, 53.6 ; H, 3.0 ; N, 10.4. Found, %: C, 53.7 ; H, 3.0 ; N, 10.4. The structure was confirmed by single-crystal X-ray diffraction.

Example 14 Bis (2-pvrrolylaldbenzylimino) copper (II). A mixture of 2-formylpyrrole (2.08 g), water (20 mL), and benzylamine (2.60 g) was stirred for 10 min.

Copper (II) acetate (2. 20 g) was added, and the mixture was stirred for 0.5 h. Water (20 mL) was added, and the stirring continued for 1.5 h. The resulting solid was filtered, washed with water, air-dried on the filter, and dissolved in dichloromethane. The solution was filtered through a short silica gel plug and evaporated to leave a dark viscous oil. Hexanes (50 mL) were added to the residue and the mixture was kept at +5 °C for 2 h. The dark crystals were collected, washed with hexanes, and dried under vacuum. The yield was 2.80 g (60%). Anal. Calcd. for C24H22CuN4, %: C, 67.0 ; H, 5.2 ; N, 13.0. Found, %: C, 67.0 ; H, 5.2 ; N, 13.0.

Example 15 Bis (2-pvrrolylald (2-ethoxycarbonylet) imino) copper (l l). A mixture of 2- formylpyrrole (0.62 g), water (15 mL), a-alanine ethyl ester hydrochloride (1.50 g), and copper (II) acetate (0.65 g) was stirred for 5 min. A solution of NaOH (0.6 g) in water (5 mL) was added and the mixture was stirred for 3 hours to produce brown oil. Hexanes (30 mL) was added and agitation resumed for 30 min. After evaporation of hexanes the mixture was extracted with dichloromethane (4 x 10 mL). The combined dichloromethane extracts were filtered through a short silica gel plug and evaporated. The dark oily residue was stirred with hexanes (20 mL), after which the volatiles were evaporated under vacuum to produce brown oil.

The latter crystallized upon standing. Yield : 0. 80 g (54%). Anal. Calcd. for C2oH26CUN404, %: C, 53. 4; H, 5.8 ; N, 12.4. Found, %: C, 53.1 ; H, 5.4 ; N, 12.3.

Example 16 Bisf2-pvrroiviaid (2-isooropoxvcarbonv) ethv)) imino) copper (ii). A mixture of 2-formylpyrrole (1.65 g), water (30 mL), (3-alanine isopropyl ester hydrochloride (3. 80 g; prepared as described in Inorg. Chem., 1986, vol. 25, p. 1956), and copper (II) acetate (1.90 g) was stirred for 10 min. A solution of NaOH (1.60 g) in water (10 mL) and hexanes (40 mL) were added, and the mixture was stirred for 1.5 hours. The upper hexane layer was separated by a pipette and disposed of. The mixture was extracted with dichloromethane (2 x 40 mL, then 4 x 10 mL). The combined extracts were filtered through a short silica gel plug and evaporated. The residue was dissolved in ca. 3 mL of dichloromethane and hexanes (50 mL) added. After 5 hours at +5 °C the product precipitated in the form of well- shaped brown crystals which were separated, washed with hexanes, and dried under vacuum. The yield was 2.85 g (69%). Anal. Calcd. for C22H30CuN404, %: C, 55.3 ; H, 6.3 ; N, 11.7. Found, %: C, 55.3 ; H, 6.1 ; N, 11.9.

Example 17 Bis (2-acetvlpvrrolyl) copper (ll !. A mixture of acetylpyrrole (2.04 g), copper (II) acetate (2.04 g), and water (75 mL) was stirred at room temperature in air for 1 h. A solution of NaOH (0.83 g) in water (10 mL) was added and the stirring was continued for 2 more hours. The resulting solid was filtered, washed with water, dried, and dissolved in dichloromethane. After filtration, the solid-free dark green solution was reduced in volume to ca.

10 mL and treated with hexanes (100 mL). The mixture was kept at about

+5 °C overnight. The resulting green crystals were separated by decantation, washed with hexanes, and dried under vacuum. The yield was 1.74 g (67%), m. p. 205 °C : The structure was confirmed by single- crystal X-ray diffraction.

Example 18 Bis (2-pyrrolylaldmethylimino) copper (li). Two batches of the crude complex were prepared separately. In the first batch, to a vigorously stirring mixture of 2-formylpyrrole (20.0 g), CuCI2 2H2O (19.7 g; 10% excess), and water (200 mL), was added 40% aqueous methylamine (20 mL) and after ca. 1 minute a solution of NaOH (10.6 g) in water (100 mL). A black-brown precipitate formed quickly. After the mixture was stirred for 2 hours, the product was separated by filtration, washed with water, and dried in air. The 2nd batch was prepared similarly, using 2- formylpyrrole (25.0 g), CuC12-2H20 (24.6 g) in water (200 mL), 40% aqueous methylamine (25 mL), and a solution of NaOH (16.6 g) in water (150 mL). The two crude products were combined and purified by Soxhlet extraction with simultaneous filtration through silica gel in a double thimble setup. The product was placed in the inner thimble which was centered inside a larger thimble. The space in between the two thimbles was filled with silica gel. After the extraction was complete (extracts colorless) the mixture in the receiver was reduced in volume to ca. 150 mL, treated with hexanes (500 mL), and kept in an ice bath for 2 h. The black-brown crystals were separated, washed with hexanes (3 x 50 mL), and dried under vacuum to give 50.5 g of the pure product. Evaporation of the combined mother liquor and washings, followed by recrystallization of the residue from dichloromethane-hexanes afforded additional 6.4 g of the pure complex. Total yield : 56.9 g (86%). Anal. Calcd. for C12H14CuN4, %: C, 51.9 ; H, 5.1 ; N, 20.2. Found, %: C, 51.9 ; H, 4.9 ; N, 20.2.

Example 19 Bis (2-pvrrolylaldethvlimino) copper . To a vigorously stirring mixture of 2- formylpyrrole (45.4 g), CuCi 20 (44.7 g), and water (450 mL), was added 70% aqueous methylamine (50 mL) and then a solution of NaOH (24.0 g) in water (100 mL). After the mixture was stirred for 3 hours, the black-brown product was separated by filtration, washed with water, and dried. The crude product was dissolved in dichloromethane (500 mL), and the solution was filtered through a short silica gel plug which was then washed with dichloromethane. The combined filtrate and washings were evaporated to a thick paste of the complex in a small amount of

dichloromethane, and treated with hexanes (300 mL). After 2 h at +5 °C the black crystals were separated, washed with hexanes (3 x 50 mL), and dried under vacuum. The yield of the analytically pure complex was 68.0 g (94%). Anal. Calcd. for C14H18CuN4, %: C, 55.0 ; H, 5.9 ; N, 18.3. Found, %: C, 55.1 ; H, 5.9 ; N, 18.2.

Volatilitv of the Copper Complexes All solid Cu (II) complexes described above sublime under vacuum without decomposition. Bis (2-pyrrolylald (2-ethylhexyl) imino) copper (li), which is an oil at ambient temperature, can be distilled under reduced pressure. Conditions for vacuum deposition of the compounds vary depending on the nature of the substituent on the ligand. For example, in the pressure range of 0.02-1 torr, bis (2-pyrrolylaldalkylimino) copper (II) complexes (alkyl = Me, Et, i-Pr, Pr, Bu) sublime cleanly at 85-120 °C.

Bis (2-pyrrolylaldphenylimino) copper (II) sublimes at ca. 150-160 °C/ 0.02-0. 1 torr.

Deposition of Copper Metal Films Example 20 Diethvlsilane as the Reducing Agent. Bis (2- pyrrolylaldphenylimino) copper (li) (10 mg) and diethylsilane (0.2 mL) were placed in a glass tube under nitrogen. The tube was sealed and then gradually heated to 210 °C. At 160-170 °C and above, copper metal formation (thin film) was noticed on the inner walls of the tube.

Example 21 Ammonia-Hydrogen as the Reducing Agent. A bis (2- pyrrolylaldalkylimino) copper (ii) complex (3-10 mg) was placed in a glass tube. The tube was heated under a mixture of NH3 and H2 (ca. 1: 1) with the temperature gradually being raised from 120 °C to 220 °C. At 180 °C and above, the formation of copper metal occurred, in the form of a thin film on the inner wall of the tube. Bis (2-pyrrolylaldmethylimino) copper (I 1) and bis (2-pyrrolylaldethylimino) copper (ll) gave the best films. For copper metal deposition, ammonia-hydrogen mixtures were superior to either pure component. Bis (2-acetylpyrrolyl) copper (II) underwent reduction to copper metal with ammonia-hydrogen at a slightly lower temperature, around 160 OC.