WO2009155507A1

WO2009155507A1 - Titanium pyrrolyl-based organometallic precursors and use thereof for preparing dielectric thin films

Info

Publication number: WO2009155507A1
Application number: PCT/US2009/047940
Authority: WO
Inventors: Peter Nicholas Heys; Rajesh Odedra; Andrew Kingsley; Hywel Owen Davies
Original assignee: Sigma-Aldrich Co.
Priority date: 2008-06-20
Filing date: 2009-06-19
Publication date: 2009-12-23
Also published as: WO2009155520A1; TW201014925A; TW201014924A

Abstract

Titanium pyrrolyl-based organometallic precursors and methods of use thereof are provided to prepare metal-containing dielectric thin films by a vapor deposition process. The organometallic precursors correspond in structure to Formula I or dimers of Formula I: [(R)_nPy]Ti(L)₃(I) wherein: R is independently selected from the group consisting of alkyl, alkoxy and NR¹R²; R¹ and R² are each independently hydrogen or alkyl; n is zero, 1, 2, 3 or 4; Py is pyrrolyl; L is selected from the group consisting of alkyl, alkoxy and NR¹R².

Description

EPICHEM038/5

TITANIUM PYRROLYL-BASED ORGANOMETALLIC PRECURSORS AND USE THEREOF FOR PREPARING DIELECTRIC THIN FILMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent claims the benefit of U.S. provisional application Serial No. 61/074,363, filed on 20 June 2008, U.S. provisional application Serial No. 61/177,137, filed on 11 May 2009 and U.S. provisional application Serial No. 61/177,165, filed on 11 May 2009. The disclosure of each recited U.S. provisional application is incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to pyrrolyl-based organometallic precursors and methods of preparing dielectric thin films by chemical vapor deposition (CVD) and atomic layer deposition (ALD) using such precursors.

BACKGROUND OF THE INVENTION

[0003] Various organometallic precursors are used to form high-κ dielectric thin metal films. A variety of techniques have been used for the deposition of thin films. These include reactive sputtering, ion-assisted deposition, sol-gel deposition, CVD, and ALD, also known as atomic layer epitaxy. The CVD and ALD processes are being increasingly used as they have the advantages of good composition control, high film uniformity, good control of doping and, significantly, they give excellent conformal step coverage on highly non-planar microelectronics device geometries. [0004] CVD (also referred to as metalorganic CVD or MOCVD) is a chemical process whereby precursors are deposited on a substrate to form a solid thin film. In a typical CVD process, the precursors are passed over a substrate (wafer) within a low pressure or ambient pressure reaction chamber. The precursors react and/or decompose on the substrate surface creating a thin film of deposited material. Volatile by-products are removed by gas flow through the reaction chamber. The deposited film thickness can be difficult to control because it depends on coordination of many parameters such as temperature, pressure, gas flow volumes and uniformity, chemical depletion effects and time.

[0005] ALD is another method for the deposition of thin films. It is a self -limiting, sequential, unique film growth technique based on surface reactions that can provide EPICHEM038/5 atomic layer-forming control and deposit-conformal thin films of materials provided by precursors onto substrates of varying compositions. In ALD, the precursors are separated during the reaction. The first precursor is passed over the substrate producing a monolayer on the substrate. Any excess unreacted precursor is pumped out of the reaction chamber. A second precursor is then passed over the substrate and reacts with the first precursor, forming a second monolayer of film over the first-formed film on the substrate surface. This cycle is repeated to create a film of desired thickness. ALD film growth is self-limited and based on surface reactions, creating uniform depositions that can be controlled at the nanometer- thickness scale.

[0006] Dielectric thin films have a variety of important applications, such as nanotechnology and fabrication of semiconductor devices. Examples of such applications include high-refractive index optical coatings, corrosion-protection coatings, photocatalytic self-cleaning glass coatings, biocompatible coatings, dielectric capacitor layers and gate dielectric insulating films in FETS, capacitor electrodes, gate electrodes, adhesive diffusion barriers and integrated circuits. Dielectric thin films are also used in microelectronics applications, such as the high-*; dielectric oxide for dynamic random access memory (DRAM) applications and the ferroelectric perovskites used in infra-red detectors and non-volatile ferroelectric random access memories (NV-FeRAMs). The continual decrease in the size of microelectronics components has increased the need for the use of such dielectric thin films.

[0007] Tanski J. and Parkin G. report a series of structurally characterized zirconium- pyrrolyl complexes. Organometallics , 21:587-589, (2002).

[0008] Choukroun et al. report reactivity of the titanium-nitrogen bond in the mixed trisalkoxy dialkylamide derivative Ti(OR)₃(NEt₂). Synth. React. Inorg. Met.-Org. Chem. 8(2):137-147, (1978).

[0009] Dias et al. report the synthesis and characterization of the complex [Ti(NC₄Me₄)(NMe₂)_S] Collect. Czech. Chem. Commun. 63:182-186, (1998). [0010] Dias et al. report synthesis and characterization of titanium complexes containing 2,3,4,5-tetramethylpyrrolyl. J. Chem. Soc, Dalton Trans. 1055-1061, (1997). [0011] Bradley D. and Chivers K. report metallo-organic compounds such as Ti(NC₄H₂Me₂)(NEt₂)S. Inorg. Phys. Theor. 1967-1969, (1968). EPICHEM038/5

[0012] Current precursors for use in CVD and ALD do not provide the required performance to implement new processes for fabrication of next generation devices, such as semi-conductors. For example, improved thermal stability, higher volatility, increased deposition rates and a high permittivity are needed.

SUMMARY OF THE INVENTION

[0013] In one embodiment, a method of forming a metal-containing film by a vapor deposition process is provided. The method comprises delivering at least one precursor to a substrate, wherein the at least one precursor corresponds in structure to Formula I:

[(R)_nPy]Ti(L)₃

(Formula I) wherein:

R is independently selected from the group consisting of alkyl, alkoxy and NR¹R²; R¹ and R² are each independently hydrogen or alkyl; n is zero, 1, 2, 3 or 4; Py is pyrrolyl; and

L is selected from the group consisting of alkyl, alkoxy and NR¹R² [0014] In another embodiment an organometallic precursor is provided corresponding in structure to Formula II:

X:X

(Formula II) wherein: each X can be the same or different and corresponds in structure to [(R)_nPy]Ti(L)₃ wherein: R is independently selected from the group consisting of alkyl, alkoxy and

NR¹R²;

R¹ and R² are each independently hydrogen or alkyl; n is zero, 1, 2, 3 or 4;

Py is pyrrolyl; and

L is selected from the group consisting of alkyl, alkoxy and NR¹R² EPICHEM038/5

[0015] In another embodiment, a method of forming a metal-containing film by a vapor deposition process is provided. The method comprises delivering at least one precursor to a substrate, wherein the at least one precursor corresponds in structure to Formula II:

X:X

(Formula II) wherein: each X can be the same or different and corresponds in structure to [(R)_nPy]Ti(L)₃ wherein:

R is independently selected from the group consisting of alkyl, alkoxy and NR¹R²;

R¹ and R² are each independently hydrogen or alkyl; n is zero, 1, 2, 3 or 4;

Py is pyrrolyl; and

L is selected from the group consisting of alkyl, alkoxy and NR¹R² [0016] Other embodiments, including particular aspects of the embodiments summarized above, will be evident from the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS [0017] Fig. 1 is the molecular structure of (Me₂Py)Ti(NMe₂)_S. [0018] Fig. 2 is the molecular structure of [(Me₂Py)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂. [0019] Fig. 3 is the molecular structure of [(Py)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂. [0020] Fig. 4 is a graphical representation of TGA data demonstrating % weight loss vs. temperature of (Me₂Py) Ti(NMe₂)₃.

[0021] Fig. 5 is a graphical representation of TGA data demonstrating % weight loss vs. temperature for (Me₂Py)Ti(NMe₂)₃ (1), [(Me₂Py)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂ (2) and [(Py)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂ (3).

[0022] Fig. 6 is a graphical representation demonstrating variation of growth rate with substrate temperature for TiO₂ films grown by CVD using (Me₂Py)Ti(NMe₂)₃ (1) (T), [(Me₂Py)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂ (2) (O) and [(MeCp)Ti(NMe₂)₃] (•). [0023] Fig. 7 is a graphical representation demonstrating variation of growth rate with substrate temperature for TiO₂ films grown by ALD using (Me₂Py)Ti(NMe₂)₃ (1) EPICHEM038/5

(T), [(Me₂Py)Ti(μ2-O¹Pr)(O¹Pr)₂]2 (2) (O) and [(MeCp)Ti(NMe₂)₃] (•). DETAILED DESCRIPTION OF THE INVENTION

[0024] In various aspects of the invention, pyrrolyl-based organometallic precursors and methods of using such precursors to form thin metal-containing films, such as metal oxide films or metal nitride films, are provided.

[0025] The methods of the invention are used to create or grow metal-containing thin films which display high dielectric constants. A dielectric thin film as used herein refers to a thin film having a high permittivity.

A. Definitions

[0026] As used herein, the term "high-κ dielectric" refers to a material, such as a metal-containing film, with a higher dielectric constant (K) when compared to silicon dioxide (which has a dielectric constant of about 3.7). Typically, a high-κ dielectric film is used in semiconductor manufacturing processes to replace a silicon dioxide gate dielectric. A high-κ dielectric film may be referred to as having a "high-κ gate property" when the dielectric film is used as a gate material and has at least a higher dielectric constant than silicon dioxide.

[0027] As used herein, the term "relative permittivity" is synonymous with dielectric constant (K).

[0028] As used herein, the term "vapor deposition process" is used to refer to any type of vapor deposition technique such as CVD or ALD. In various embodiments of the invention, CVD may take the form of conventional CVD, liquid injection CVD or photo- assisted CVD. In other embodiments, ALD may take the form of conventional ALD, liquid injection ALD or photo-assisted ALD.

[0029] As used herein, the term "precursor" refers to an organometallic molecule, complex and/or compound which is deposited or delivered to a substrate to form a thin film by a vapor deposition process such as CVD or ALD.

[0030] In a particular embodiment, the precursor may be dissolved in an appropriate hydrocarbon or amine solvent. Appropriate hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons, such as hexane, heptane and nonane; aromatic hydrocarbons, such as toluene and xylene; aliphatic and cyclic ethers, such as diglyme, triglyme and tetraglyme. Examples of appropriate amine solvents include, without EPICHEM038/5 limitation, octylamine and N,N-dimethyldodecylamine. For example, the precursor may be dissolved in toluene to yield a 0.05 to IM solution.

[0031] As used herein, the term "Py" refers to a pyrrolyl ligand which is bound to a metal center.

[0032] The term "alkyl" (alone or in combination with another term(s)) refers to a saturated hydrocarbon chain of 1 to about 10 carbon atoms in length, such as, but not limited to, methyl, ethyl, propyl and butyl. The alkyl group may be straight-chain or branched-chain. For example, as used herein, propyl encompasses both w-propyl and iso- propyl; butyl encompasses w-butyl, sec-butyl, iso-butyl and tert-butyl. Further, as used herein, "Me" refers to methyl, "Et" refers to ethyl, "iPr" refers to iso-propy\ and "tBu" refers to tert-butyl.

[0033] The term "alkoxy" (alone or in combination with another term(s)) refers to a substituent, i.e., -O-alkyl. Examples of such a substituent include methoxy (-O-CH₃), ethoxy, etc. The alkyl portion may be straight-chain or branched-chain. For example, as used herein, propoxy encompasses both w-propoxy and iso-propoxy; butoxy encompasses w-butoxy, iso-butoxy, sec-butoxy, and tert-butoxy.

[0034] The term "amino" herein refers to an optionally substituted monovalent nitrogen atom (i.e., -NR¹R², where R¹ and R² can be the same or different). Examples of

amino groups encompassed by the invention include, but are not limited to, -I -N(Me)₂

4* -N(Et)₂ — <-N(Et)(Me) and s and *> . Further, the nitrogen atom of this amino group is covalently bonded to the metal center which together may be referred to as an "amide"

group (i.e.

This can be further referred to as an "ammono" group or

inorganic amide, for example

wherein R¹ and R² are independently hydrogen or alkyl.

B. Organometallic Precursors

[0035] In a first embodiment, an organometallic precursor is provided. The organometallic precursor corresponds in structure to Formula I: EPICHEM038/5

[(R)_nPy]Ti(L)₃

(Formula I) wherein:

L is selected from the group consisting of alkyl, alkoxy and NR¹R² [0036] The metal center of the precursor according to Formula I is comprised of a Group IVB metal, i.e. titanium.

[0037] In one embodiment, R is alkyl, such as methyl, ethyl, propyl, or butyl. [0038] In another embodiment, R is alkoxy, such as methoxy, ethoxy, propoxy or butoxy.

[0039] In yet another embodiment, R is NR¹R², wherein R¹ and R² are each independently hydrogen or alkyl. For example, in one embodiment, R is N(Me)₂ or NH(Me) or N(Et)₂ or NH(Et) or N(Me)(Et).

[0040] The variable n is the number of R groups substituted on the pyrrolyl ligand. There may be from zero to four R groups substituted on the pyrrolyl ligand. If more than one R group is present, the R groups may be the same or different. In a particular embodiment, n is 1, 2, 3, or 4. In another embodiment, n is 2, 3 or 4. In another embodiment, n is 2 or 3. In a further particular embodiment, n is 2. [0041] There are three L substituents bonded to the metal center. Each L substituent is the same. This can be referred to as a "piano stool" arrangement. [0042] In one embodiment, L is alkyl, such as methyl, ethyl, propyl, or butyl. [0043] In another embodiment, L is alkoxy, such as methoxy, ethoxy, propoxy or butoxy.

[0044] In yet another embodiment, L is NR¹R², wherein R¹ and R² are each independently hydrogen or alkyl. For example, in one embodiment, L is N(Me)₂ or NH(Me) or N(Et)₂ or NH(Et) or N(Me)(Et).

[0045] In one embodiment, the at least one precursor corresponds in structure to Formula I wherein: EPICHEM038/5

R is independently alkyl or alkoxy;

R¹ and R² are each independently hydrogen or alkyl; n is 1, 2, 3 or 4;

Py is pyrrolyl;

L is alkoxy or NR¹R²

[0046] In another embodiment, the at least one precursor corresponds in structure to

Formula I wherein:

R is independently methyl, ethyl, propyl or butyl; n is zero, 1, 2, 3, or 4; and

L is methoxy, ethoxy, propoxy, butoxy, N(Me)₂ or N(Me)(Et).

[0047] In another embodiment, the at least one precursor corresponds in structure to

Formula I wherein:

R is independently methyl, ethyl, propyl or butyl; n is 1, 2, 3, or 4; and

L is methoxy, ethoxy, propoxy, butoxy, N(Me)₂ or N(Me)(Et).

[0048] In a particular embodiment, the at least one precursor corresponding in structure to Formula I is:

(Py)Ti(NMe₂)₃;

(Me₂Py)Ti(NMe₂)₃;

[(tert-butyl)₂Py]Ti(NMe₂)₃;

(Py)Ti(O¹Pr)₃;

(Me₂Py)Ti(O¹Pr)₃; and

[(fert-butyl)₂Py]Ti(O¹Pr)₃.

[0049] The precursors described above can all be referred to as monomers. However, the monomers can also dimerize. Thus, in another embodiment dimers of the above disclosed monomers is also provided. These organometallic precursors correspond in structure to Formula II:

X:X

(Formula II) wherein: each X can be the same or different and corresponds in structure to [(R)_nPy]Ti(L)₃ EPICHEM038/5 wherein:

R¹ and R² are each independently hydrogen or alkyl; n is zero, 1, 2, 3 or 4;

Py is pyrrolyl;

L is selected from the group consisting of alkyl, alkoxy and NR¹R² [0050] Each of the embodiments recited above for Formula I precursors may be applied mutatis mutandis to the organometallic precursors of Formula II.

C. Methods of Use

[0051] In another embodiment a method of forming a metal-containing film by a vapor deposition process is provided.

[0052] In one embodiment, the vapor deposition process is chemical vapor deposition.

[0053] In another embodiment, the vapor deposition process is atomic layer deposition.

[0054] The method comprises delivering at least one precursor to a substrate, wherein the at least one precursor corresponds in structure to Formula I and/or II above. [0055] The ALD and CVD methods of the invention encompass various types of ALD and CVD processes such as, but not limited to, conventional processes, liquid injection processes and photo-assisted processes.

[0056] In one embodiment, conventional CVD is used to form a metal-containing thin film using at least one precursor according to Formula I and/or II. For conventional CVD processes, see for example Smith, Donald (1995). Thin-Film Deposition: Principles and Practice. McGraw-Hill.

[0057] In another embodiment, liquid injection CVD is used to form a metal- containing thin film using at least one precursor according to Formula I and/or II. [0058] Examples of liquid injection CVD growth conditions include, but are not limited to:

(1) Substrate temperature: 200-600⁰C on Si(IOO)

(2) Evaporator temperature: about 200⁰C EPICHEM038/5

(3) Reactor pressure: about 5mbar

(4) Solvent: toluene, or any solvent mentioned above

(5) Solution concentration: about 0.05 M

(6) Injection rate: about 30 Cm³IIr^"1

(7) Argon flow rate: about 200 cm³ min^"1

(8) Oxygen flow rate: about 100 cm³ min^"1

(9) Run time: 10 min

[0059] In another embodiment, photo-assisted CVD is used to form a metal- containing thin film using at least one precursor according to Formula I and/or II. [0060] In a further embodiment, conventional ALD is used to form a metal- containing thin film using at least one precursor according to Formula I and/or II. For conventional and/or pulsed injection ALD process see, for example, George S. M., et. al. J. Phys. Chem. 1996. 100:13121-13131.

[0061] In another embodiment, liquid injection ALD is used to form a metal- containing thin film using at least one precursor according to Formula I and/or II, wherein at least one liquid precursor is delivered to the reaction chamber by direct liquid injection as opposed to vapor draw by a bubbler. For liquid injection ALD process see, for example, Potter R. J., et. al. Chem. Vap. Deposition. 2005. 11(3): 159. [0062] Examples of liquid injection ALD growth conditions include, but are not limited to:

(1) Substrate temperature: 160-300⁰C on Si(IOO)

(2) Evaporator temperature: about 175⁰C

(3) Reactor pressure: about 5mbar

(4) Solvent: toluene, or any solvent mentioned above

(5) Solution concentration: about 0.05 M

(6) Injection rate: about 2.5μl pulse^"1 (4 pulses cycle^"1)

(7) Inert gas flow rate: about 200 cm³ min^"1

(8) Pulse sequence (sec.) (precursor/purge/H₂O/purge): will vary according to chamber size.

(9) Number of cycles: will vary according to desired film thickness.

[0063] In another embodiment, photo-assisted ALD is used to form a metal- EPICHEM038/5 containing thin film using at least one precursor according to Formula I and/or II. For photo-assisted ALD processes see, for example, U.S. Patent No. 4,581,249.

[0064] Thus, the organometallic precursors according to Formula I and/or II utilized in these methods may be liquid, solid, or gaseous. Particularly, the precursors are liquid at ambient temperatures with high vapor pressure allowing for consistent transport of the vapor to the process chamber.

[0065] In one embodiment, the precursors corresponding to Formula I and/or II are delivered to the substrate in pulses alternating with pulses of an oxygen source, such as a reactive oxygen species. Examples of such oxygen source include, without limitation,

H₂O, O₂ and/or ozone.

D. Mixed Metal Films

[0066] In another embodiment of the invention, the method further comprises delivering for deposition at least one co-precursor to form a "mixed" metal film. [0067] In a particular embodiment, the method further comprises delivering for deposition at least one co-precursor to form a mixed metal oxide film. As used herein, a mixed metal oxide film contains at least two different metals.

[0068] In one embodiment, two or more precursors corresponding in structure to Formula I and/or II may be used to form a mixed metal oxide film. For example, a titanium and zirconium precursor can be used to create a titanium- zirconium oxide film. [0069] In another embodiment, a titanium precursor corresponding in structure to Formula I and/or II may be used in CVD or ALD with at least one strontium, bismuth, barium or lanthanum precursor to form a mixed metal oxide film. Examples of such mixed metal oxide films formed include, without limitation, SrTiO₃, LaTiO₃, BaTiO₃ and BiTiO₃.

E. Co-Reactants

[0070] A dielectric film can also be formed by the at least one precursor corresponding in structure to Formula I and/or II, independently or in combination with a co-reactant. Examples of such co-reactants include, but are not limited to, hydrogen, hydrogen plasma, oxygen, air, water, H₂O₂, ammonia, hydrazine, alkylhydrazine, borane, silane, ozone or any combination thereof. EPICHEM038/5

F. Substrates

[0071] A variety of substrates can be used in the methods of the present invention. For example, the precursors according to Formula I and/or II may be delivered for deposition on substrates such as, but not limited to, silicon, silicon oxide, silicon nitride, tantalum, tantalum nitride, copper, ruthenium, titanium nitride, tungsten, and tungsten nitride.

G. Applications

[0072] In particular embodiments, the method of the invention is utilized for applications such as dynamic random access memory (DRAM) and complementary metal oxide semi-conductor (CMOS) for memory and logic applications on silicon chips. [0073] Fundamental differences exist between the thermally-driven CVD process and the reactivity-driven ALD process. The requirements for precursor properties to achieve optimum performance vary greatly. In CVD a clean thermal decomposition of the precursor to deposit the required species onto the substrate is critical. However, in ALD such a thermal decomposition is to be avoided at all costs. In ALD the reaction between the input reagents must be rapid and result in the target material formation on the substrate. However, in CVD any such reaction between species is detrimental due to their gas phase mixing before reaching the substrate to generate particles. In general a good CVD source will be a poor ALD source and vice versa and therefore it is surprising that the pyrrolyl-based molecules of this invention perform well in both ALD and CVD processes.

[0074] The pyrrolyl-based precursors offer access to different temperature windows for deposition processes when compared to conventional precursors. This makes matching of these pyrrolyl-based precursors with other metal sources open to more manipulation when attempting to deposit ternary or quaternary alloys in an optimized fashion.

EXAMPLES

[0075] The following examples are merely illustrative, and do not limit this disclosure in any way.

[0076] All manipulations were carried out under an atmosphere of dry nitrogen using standard Schlenk line or dry box techniques. Dry solvents and other starting materials EPICHEM038/5 were supplied by Sigma-Aldrich Ltd. and were purified where necessary. ¹H NMR spectroscopy were carried out on a Bruker Avance 400 NMR spectrometer (¹H 400.1

MHz). Thermogravimetic Analysis (TGA) was carried out on a Mettler Toledo thermogravimetric analyser in a nitrogen filled glove box.

[0077] Auger electron spectroscopy (AES) was carried out on a Varian scanning

Auger spectrometer. The atomic compositions quoted are from the bulk of the film

(typically 70 - 80 nm depth), free from surface contamination, and were obtained by combining AES with sequential argon ion bombardment until comparable compositions were obtained for consecutive data points. Compositions were based on a TiO₂ powder reference.

[0078] Example 1 - Preparation of Batch #1 of [(Me)?PylTi[N(Me)?^

[0079] Ti(N(Me)₂)₄ (56.32g, 0.25moles) was dissolved in toluene (200ml). Dimethylpyrrole (23.9g, 0.25 moles) was added as a neat liquid to the toluene-dissolved Ti(N(Me)₂)₄ and the mixture refluxed for 3 hours with stirring. The mixture was allowed to stand overnight and then the toluene stripped. The resultant liquid (dark red-brown) was distilled under vacuum 110°C/0.1 mm Hg. The product was a low melting solid (30- 32°C) which crystallized to yellow plates. NMR: 2.2 ppm (pyrrolyl), 2.9 ppm (N(Me)₂), 3.1 ppm (N(Me)₂), and 5.9 ppm (pyrrolyl).

[0080] Fig. 4 is a graphical representation of TGA data demonstrating % weight loss vs. temperature of (Me₂Py) Ti(NMe₂)₃. [0081] Example 2 - Preparation of Batch #2 of [(Me)₇PvITi[N(Me)?^

EPICHEM038/5

[0082] To a 2OmL toluene solution of [Ti(NMe₂)₄] (5.63g, 25 mmol) was added a toluene (1OmL) solution of dimethylpyrrole (2.39g, 25 mmol) over a period of 30 minutes. The solution was heated at 90⁰C for 3 hours and then allowed to stir overnight at room temperature. The toluene removed in vacuo and the dark brown liquid distilled. Distillation commenced with conditions starting at 70°C/0.1 mm Hg and rising to 110°C/0.1 mm Hg as the distillation progressed. The product was isolated as a dark yellow low melting solid (mpt ~20°C). ¹H NMR (d₆-benzene, δ ppm): 2.35 (CH₁ of pyrrole, singlet, 6H), 3.1 (NMe₂, singlet, 18H), 6.1 (H of pyrrole, singlet, 2Η). [0083] Example 3 - Preparation of [(Me₇C₄H₇N)Ti(U₇-O¹Pr)(O¹Pr)₇I₇ [0084] To a hexane suspension of lithium dimethylpyrrole (prepared at -30⁰C and used in situ by reacting 1OmL 1.6M ⁿBuLi with 1.5g dimethylpyrrole) was added [TiCl(O¹Pr)₃] (15.77 ml, IM hexane solution) dropwise via syringe. The mixture immediately turned dark orange and was stirred for 3 hours at room temperature. The mixture was allowed to settle overnight before removing the mother liquor by filtration. The LiCl by-product was washed with 2 x 10ml w-hexane and then the hexane was removed in vacuo until incipient crystallization. The product was obtained as large red crystals. ¹U NMR (d₆-benzene, δ ppm): 1.1 (CH₃ of O¹Pr, doublet, 18Η), 2.3 (CH₃ of pyrrole, s, 6H), 4.2 (CH of O¹Pr, septet, 3H), 6.0 (H of pyrrole, singlet, 2H). [0085] Fig. 5 is a graphical representation of TGA data demonstrating % weight loss vs. temperature for (Me₂Py)Ti(NMe₂)₃ (1), [(Me₂Py)Ti^₂-O¹Pr)(O¹Pr)₂] ₂ (2) and [(Py)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂ (3).

[0086] Example 4 - Preparation of [(C₄H₄N)Ti(U₇-O¹Pr)(O¹Pr)₇I₇ [0087] To a hexane suspension of lithium pyrrole (prepared at -30⁰C and used in situ by reacting 1OmL 1.6M ⁿBuLi with 1.05g pyrrole) was added [TiCl(O¹Pr)₃] (15.65 ml, IM hexane solution) dropwise via syringe. The mixture immediately turned dark orange and was stirred for 3 hours at room temperature. The mixture was allowed to settle for 24hrs before removing the mother liquor by filtration. The LiCl by-product was washed with 2 x 10ml w-hexane and then hexane was removed in vacuo until incipient crystallization. Storage at -20⁰C yielded the product as large yellow crystals. ¹H NMR (d₆-benzene, ppm): 1.1 (CH₃ of O¹Pr, doublet, 18Η), 4.4 (CH of O¹Pr, septet, 3H), 6.45 (H EPICHEM038/5 of pyrrole, singlet, 2H) and 7.25 (H of pyrrole, singlet, 2Η)

[0088] Fig. 5 is a graphical representation of TGA data demonstrating % weight loss vs. temperature for (Me₂Py)Ti(NMe₂)S (1), [(Me₂Py)Ti^₂-O¹Pr)(O¹Pr)₂] ₂ (2) and [(Py)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂ (3).

[0089] Example 5 - Single crystal X-ray diffraction

[0090] Crystallographic data for [(Me₂C₄H₂N)Ti(NMe₂)S] (1) and [(Me₂C₄H₂N)Ti^₂-O¹Pr)(O¹Pr)₂] ₂ (2) were obtained using a Bruker Smart APEX ccd diffractometer using graphite monochromated Mo-Ka radiation (λ = 0.71073 A, T = 150 K). The structure was solved by Direct Methods and refined by full-matrix least squares against F² using all data. Non-hydrogen atoms were refined anisotropically and H-atoms were fixed in geometrically ideal positions.

[0091] Crystallographic data for [(C₄H₄N)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂ (3) were obtained using a Bruker D8 diffractometer with an APEX CCD detector using graphite monochromated Mo-Ka radiation (λ = 0.71073 A, T = 100 K). The structure was solved by Direct Methods and refined by full-matrix least squares against F² using all data. Non- hydrogen atoms were refined anisotropically and H-atoms were fixed in geometrically ideal positions. Crystallographic data (excluding structure factors) for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre (CCDC) as supplementary publication numbers CCDC 704352 (1) and 704351 (2) and 710796(3). Table 1. Crystallographic Data for Complexes 1, 2 and 3

EPICHEM038/5

EPICHEM038/5

[0092] Fig. 1 is the molecular structure of (Me₂Py))Ti(NMe₂)S.

[0093] Fig. 2 is the molecular structure of [(Me₂Py)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂.

[0094] Fig. 3 is the molecular structure of [(Py)Ti(μ₂-O¹Pr)(O¹Pr)₂]₂.

[0095] Example 6 - CVD and ALD studies

[0096] Liquid injection CVD and ALD experiments were carried out on an Aixtron

AIX 200FE AVD reactor fitted with a modified liquid injection system. During the CVD experiments, oxygen was introduced at the inlet of the reactor. For the ALD experiments, the oxygen was replaced by ozone, which was controlled by a pneumatic valve. The substrate was rotated throughout the CVD experiments. Films of TiO₂ were deposited on

Si (100) substrates using 0.05M solutions of complexes (1), (2) and [(MeCp)Ti(NMe₂)₃] in toluene. Full CVD and ALD growth conditions are shown in Table 2.

Table 2. Growth conditions used for the deposition of TiO₂ films by liquid injection

CVD and ALD using [(Me₂C₄H₂N)Ti(NMe₂)₃] (1), [(Me₂C₄H₂N)Ti(μ₂-OiPr)(OⁱPr)₂]₂

(2) and [(MeCp)Ti(NMe₂)₃]

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[0097] Film thicknesses were calculated by weight gain assuming a density of 3.895 gem^"3 for TiO₂ and the values obtained are plotted in Figs. 6 (for CVD) and 7 (for ALD). As expected, the ALD process resulted in thinner films and as the temperature was increased the deposition rate also increased as a CVD element began to contribute significantly to the process. For CVD a maximum rate was obtained at 350-450⁰C. [0098] Fig. 6 is a graphical representation demonstrating variation of growth rate with substrate temperature for TiO₂ films grown by CVD using (1) (▼), (2) (O) and [(MeCp)Ti(NMe₂)₃] (•).

[0099] Fig. 7 is a graphical representation demonstrating variation of growth rate with substrate temperature for TiO₂ films grown by ALD using (1) (▼), (2) (O) and [(MeCp)Ti(NMe₂),] (•).

Table 3. Composition of TiO₂ films (at.%) deposited by CVD (T_g = 450⁰C) and ALD (Tg = 250⁰C) using [(Me₂C₄H₂N)Ti(NMe₂)₃] (1), [(Me₂C₄H₂N)Ti(μ₂-OiPr)(OⁱPr)₂]₂ (2) and [(MeCp)Ti(NMe₂)₃].

EPICHEM038/5

[00100] Thin films of TiO₂ have been successfully deposited by liquid injection MOCVD using the new 2,5-dimethylpyrrolyl Ti complexes [(Me₂C₄H₂N)Ti(NMe₂)₃] (1) and [(Me₂C₄H₂N)Ti(μ₂-OiPr)(O¹Pr)₂]₂ (2). The MOCVD growth data suggest that these complexes have higher thermal stabilities than the Ti-cyclopentadienyl complex [(MeCp)Ti(NMe₂)₃]. Higher levels of carbon (C = 12.7 at.%) were observed in TiO₂ films grown by MOCVD using (1), largely attributable to decomposition of the [2,5- dimethylpyrrolyl] ligand. However, the presence of the [OPr¹] group in (2) leads to a cleaner, more facile elimination of [2,5-dimethylpyrrolyl] via an intramolecular β- hydrogen abstraction and results in higher purity TiO₂ films (C = 6.1 at.%). [00101] TiO₂ films grown using (1) and (2) at 250⁰C by ALD showed lower carbon levels (C = 4.1 -and 5.9 at.%) than those in films grown by MOCVD. [00102] Further optimization of deposition parameters is expected to further reduce carbon incorporation levels in deposited films.

[00103] All patents and publications cited herein are incorporated by reference into this application in their entirety.

[00104] The words "comprise", "comprises", and "comprising" are to be interpreted inclusively rather than exclusively.

Claims

EPICHEM038/5WHAT IS CLAIMED IS:

1. A method of forming a metal-containing film by a vapor deposition process, the method comprising delivering at least one precursor to a substrate, wherein the at least one precursor corresponds in structure to Formula I:

[(R)_nPy]Ti(L)₃

(Formula I) wherein:

R is independently selected from the group consisting of alkyl, alkoxy and NR¹R²; R¹ and R² are each independently hydrogen or alkyl; n is zero, 1, 2, 3 or 4; Py is pyrrolyl; and L is selected from the group consisting of alkyl, alkoxy and NR¹R²

2. The method of Claim 1, wherein R is independently alkyl or alkoxy;

R¹ and R² are each independently hydrogen or alkyl; n is 1, 2, 3 or 4; Py is pyrrolyl; and L is alkoxy or NR¹R²

3. The method of Claim 1, wherein

L is methoxy, ethoxy, propoxy, butoxy, N(Me)₂ or N(Me)(Et).

4. The method of Claim 1, wherein

R is independently methyl, ethyl, propyl or butyl; n is 1, 2, 3, or 4; and

L is methoxy, ethoxy, propoxy, butoxy, N(Me)₂ or N(Me)(Et). EPICHEM038/5

5. The method of Claim 1, wherein the at least one precursor is selected from the group consisting of:

(Py)Ti(NMe₂)₃;

[(te/t-butyl)₂Py]Ti(NMe₂)₃;

(Py)Ti(O¹Pr)₃;

(Me₂Py)Ti(O¹Pr)₃; and

[(fer?-butyl)₂Py]Ti(O¹Pr)₃.

6. The method of Claim 1, wherein the vapor deposition process is chemical vapor deposition.

7. The method of Claim 6, wherein the chemical vapor deposition is liquid injection chemical vapor deposition.

8. The method of Claim 1, wherein the vapor deposition process is atomic layer deposition.

9. The method of Claim 8, wherein the atomic layer deposition is liquid injection atomic layer deposition.

10. The method of Claim 8, wherein the atomic layer deposition is pulsed injection atomic layer deposition.

11. The method of Claim 1 , wherein the at least one precursor is delivered to the substrate in pulses alternating with pulses of an oxygen source to form a metal oxide film.

12. The method of Claim 11, wherein the oxygen source is selected from H₂O, O₂ or ozone. EPICHEM038/5

13. The method of Claim 11, further comprising delivering at least one co-precursor to form a mixed metal oxide film.

14. The method of Claim 13, wherein the mixed metal oxide film is selected from the group consisting of SrTiO₃, SrZrO₃, SrHfO₃, LaTiO₃, LaZrO₃, LaHfO₃, BaTiO₃ and BiTiO₃.

15. The method of Claim 1, further comprising delivering at least one appropriate co- reactant selected from the group consisting of hydrogen, hydrogen plasma, oxygen, air, water, ammonia, hydrazine, alkylhydrazine, borane, silane, ozone and a combination thereof.

16. The method of Claim 1, wherein the substrate is selected from the group consisting of silicon, silicon oxide, silicon nitride, tantalum, tantalum nitride, copper, ruthenium, titanium nitride, tungsten, and tungsten nitride.

17. The method of Claim 1, wherein the method is used for a memory or logic application.

18. The method of Claim 17, wherein the method is used for a DRAM or CMOS application.

19. A method of forming a metal-containing film by a vapor deposition process, the method comprising delivering at least one precursor to a substrate, wherein the at least one precursor corresponds in structure to Formula II:

X:X

(Formula II) wherein: each X can be the same or different and corresponds in structure to [(R)_nPy]Ti(L)₃ wherein: EPICHEM038/5

R is independently selected from the group consisting of alkyl, alkoxy and

NR¹R²;

R¹ and R² are each independently hydrogen or alkyl; n is zero, 1, 2, 3 or 4;

Py is pyrrolyl; and

L is selected from the group consisting of alkyl, alkoxy and NR¹R²

20. The method of Claim 19, wherein R is independently alkyl or alkoxy;

21. The method of Claim 19, wherein

L is methoxy, ethoxy, propoxy, butoxy, N(Me)₂ or N(Me)(Et).

22. The method of Claim 19, wherein

R is independently methyl, ethyl, propyl or butyl; n is 1, 2, 3, or 4; and

L is methoxy, ethoxy, propoxy, butoxy, N(Me)₂ or N(Me)(Et).

23. The method of Claim 19, wherein the at least one precursor is selected from the group consisting of:

[(Py)Ti(NMe₂)₃]₂; [(Me₂Py)Ti(NMe₂)₃]₂; [((te/t-butyl)₂Py)Ti(NMe₂)₃]₂; [(Py)Ti(O¹Pr)₃],; [(Me₂Py)Ti(O¹Pr)S]₂; and EPICHEM038/5

[((fert-butyl)₂Py)Ti(O¹Pr)₃]2.

24. The method of Claim 19, wherein the vapor deposition process is chemical vapor deposition.

25. The method of Claim 24, wherein the chemical vapor deposition is liquid injection chemical vapor deposition.

26. The method of Claim 19, wherein the vapor deposition process is atomic layer deposition.

27. The method of Claim 26, wherein the atomic layer deposition is liquid injection atomic layer deposition.

28. The method of Claim 26, wherein the atomic layer deposition is pulsed injection atomic layer deposition.

29. The method of Claim 19, wherein the at least one precursor is delivered to the substrate in pulses alternating with pulses of an oxygen source to form a metal oxide film.

30. The method of Claim 29, wherein the oxygen source is selected from H₂O, O₂ or ozone.

31. The method of Claim 29, further comprising delivering at least one co-precursor to form a mixed metal oxide film.

32. The method of Claim 31, wherein the mixed metal oxide film is selected from the group consisting of SrTiO₃, LaTiO₃, BaTiO₃ and BiTiO₃.

33. The method of Claim 19, further comprising delivering at least one appropriate co- reactant selected from the group consisting of hydrogen, hydrogen plasma, oxygen, air, EPICHEM038/5 water, ammonia, hydrazine, alkylhydrazine, borane, silane, ozone and a combination thereof.

34. The method of Claim 19, wherein the substrate is selected from the group consisting of silicon, silicon oxide, silicon nitride, tantalum, tantalum nitride, copper, ruthenium, titanium nitride, tungsten, and tungsten nitride.

35. The method of Claim 19, wherein the method is used for a memory or logic application.

36. The method of Claim 35, wherein the method is used for a DRAM or CMOS application.

37. An organometallic precursor corresponding in structure to Formula II:

X:X

NR¹R²

R¹ and R² are each independently hydrogen or alkyl; n is zero, 1, 2, 3 or 4;

Py is pyrrolyl; and

L is selected from the group consisting of alkyl, alkoxy and NR¹R²