TWI879060B - Novel chelating and sterically encumbered ligands and their corresponding organometallic complexes for deposition of metal-containing films - Google Patents

Abstract

A ligand L capable of forming a coordinated complex with at least one metal atom, the ligand having a general formula: N(R ₁R ₂)-C(R ₃R ₄)-C(R ₅R ₆)-N(R ₇)-CH ₂-C(CR ₈R ₉R ₁₀)=O. The disclosure describes use of L to form liganded metallic complexes ML with a metal M. The disclosure describes use of ML for vapor deposition processes.

Description

Novel chelating and sterically hindered ligands and their corresponding organometallic complexes for the deposition of metal-containing films

Organometallic complexes used for depositing metal-containing films, especially for making semiconductors and battery electrodes.

Lithium-containing films are well known for their use as surface coatings for electrode materials in lithium-ion battery applications. Examples of lithium-containing films include lithium phosphate (LiPO), lithium phosphorus oxynitride (LiPON), lithium borate, lithium borophosphate, lithium fluoride, lithium metal fluoride, lithium metal oxides such as lithium niobate, lithium titanium oxide, lithium zirconium oxide, etc. The absence of silicon is preferred for the formation of some of these materials, especially lithium niobate, lithium titanium oxide, lithium zirconium oxide.

During the first few cycles of lithium-ion batteries, a solid electrolyte interface (SEI) is observed to form on the anode and/or cathode due to the decomposition of the electrolyte at the electrolyte/electrode interface. Due to the consumption of lithium, the capacity of the lithium-ion battery is lost. In addition, the SEI layer formed is uneven and unstable, cracks and dendrites may occur and lead to thermal runaway. In addition, these SEI layers also produce a backfill that makes embedding in the electrode more difficult.

Surface coating of electrodes by vapor deposition techniques such as ALD or CVD is the preferred method to form the desired solid electrolyte interface thin film, thus avoiding the formation of unstable layers. As a result, the decomposition of some components of the liquid electrolyte is greatly reduced, and the dissolution of transition elements from the cathode material such as manganese is also avoided. Vapor deposition techniques are suitable for depositing very thin and conformal films to have the above advantages without the disadvantage of reduced ionic and electronic conductivity. Lithium-containing thin films are very promising candidates as protective electrode coatings due to their good conductivity and high electrochemical stability.

Another important application of lithium-containing thin films is in the formation of solid electrolyte materials used in solid-state batteries. Solid-state batteries are solvent-free systems that have longer life, faster charging times and higher energy density than conventional lithium-ion batteries. Preventing the loss of solid electrolyte elements (especially sulfur) is crucial for their long-term performance. Solid electrolyte materials are very sensitive to air and moisture and require protective layers to improve their performance and scalability. Solid-state batteries are considered to be the next technological stage in battery development. In the same logic, solid microbatteries are being implemented in electronic circuits. Lithium-containing thin film solid electrolytes, such as lithium phosphate, lithium borate and lithium borophosphate, are deposited by ALD/CVD technology. Even uniform and conformal lithium-containing films can be obtained on complex architectures such as 3D batteries.

Vapor deposition of films/coatings containing metals (e.g., Li) requires sufficiently: a) thermally stable and b) volatile chemical precursors that are c) capable of depositing the metal via a deposition mechanism. The deposition mechanism can be thermal, chemical, surface catalytic, or other pathways. Deposition of alloy or combination films typically requires two or more chemical precursors that can be used together under compatible conditions. Co-reactants, such as oxidants or reductants, or significant improvements to the deposition process are also typically required. Identifying metal-containing chemical precursors that meet these and other process/application requirements is an ongoing challenge. Vapor deposition on semiconductor and electrode materials can have significantly different process constraints and criteria, such as temperature and aggregate heat exposure limits (“thermal budget”).

N,N,O-tridentate ligands of metals such as lithium have been characterized in the field of catalysts. See, for example, Lu, Wei-Yi, et al. "Synthesis, characterization, and catalytic activity of lithium complexes bearing NNO-tridentate Schiff base ligands toward ring-opening polymerization of L-lactide." Polymer 139 (2018): 1-10. These molecules are designed for catalytic reactions and are not suitable for vapor phase deposition.

US 20090136677 A1 describes a class of trihalogenated beta-ketoiminate molecules suitable for use as vapor phase deposition precursors. R4 is a C3-10 branched alkyl bridge having at least one chiral carbon atom. This ligand is limited to use with metals having a valence of 2 or more and is therefore not suitable for alkaline metals such as Na, K or Li.

Several lithium precursors are known and have been evaluated for their deposition properties. Hämäläinen, Jani, et al. “Lithium phosphate thin films grown by atomic layer deposition.” Journal of The Electrochemical Society 159.3 (2012): A259. https://iopscience.iop.org/article/10.1149/2.052203jes The two best characterized lithium precursors are lithium tertiary butoxide (LiO ^t Bu) and lithium hexamethyldisilazane [LiHMDS, also known as lithium bis(trimethylsilyl)amide]. LiO ^t Bu stops forming a good quality film at 200°C, and LiHMDS stops forming a good quality film at 250°C.

Even at the highest possible temperatures, LiO ^t Bu has a very low vapor pressure, and the optimal vapor pressure of ≥ 1 Torr is not possible. Sønsteby, Henrik H., et al. “Tert-butoxides as precursors for atomic layer deposition of alkali metal containing thin films.” Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 38.6 (2020): 060804.

https://iopscience.iop.org/article/10.1149/2.052203jes/meta

LiHMDS produces vapor-deposited materials with both silicon and carbon contamination well above 1%. Hämäläinen, Jani, et al. “Lithium phosphate thin films grown by atomic layer deposition.” Journal of The Electrochemical Society 159.3 (2012): A259.

In particular, there is a need for ligands that can form lithium precursors with improved volatility and vapor deposition temperatures below 200° C. Preferably, such lithium precursors can produce conformal, high quality vapor deposited films with good step coverage and low carbon and silicon content.

The present invention can be understood with reference to the following embodiments presented in the form of numbered sentences _{: 1.} A ligand L capable of forming a coordination complex with at least one metal atom, the ligand having the general formula: N( _{R1R2 )} -C( _R3R4 )-C( _R5R6 )-N _{( R7 )} -CH2 _- C( _CR8R9R10 )=O (Formula A) or N( _{R1R2 )} -C( _R3R4 )-C( _R5R6 )--C( _{R11R12 )} -N( _R7 )-CH2 _{- C} ( _CR8R9R10 )=O (Formula B) _and structurally represented by the following Formula _{A :} , having a SMILES formula: [R2]N(C([R3])([R4])C([R5])([R6])N(CC(C([R8])([R9])[R10])=O)[R7])[R1], and is structurally represented by the following formula B: , having a SMILES formula: [R2]N([R1])C([R4])(C([R6])(C([R11])([R12])N([R7])CC(C([R9])([R10])[R8])=0)[R5])[R3] wherein R ₁ -R ₁₂ are each independently selected from H, C ₁ to C ₄ alkyl (when C ₃ or C ₄ , it is straight chain or branched chain); or C ₁ -C ₄ alkylamino C _1-4 NR ₂ , wherein R are each independently selected from H, C ₁ to C ₄ alkyl (when C ₃ or C ₄ , it is straight chain or branched chain). 2. The ligand L as described in sentence 1, further comprising a coordinated metal atom M to form a metal-containing chemical ML, which is structurally represented by: (Formula A1) and has the SMILES formula: [R2][N@@]1([R1])C([R4])(C([R6])([N@]2([R7])C=C(O[M]12)C([R9])([R10])[R8])[R5])[R3], or is structurally represented by: (Formula B1) and has a SMILES formula: [R2][N@]1([R1])[C@]([R4])([C@@]([R6])([C@@]([R11])([R12])[N@]2([R7])CC(C([R9])([R10])[R8])=[O][M]12)[R5])[R3], wherein M is selected from Li, Na, or K. 3. The metal-containing chemical as described in Statement 2, wherein M is Li. 4. The ligand as described in Statement 1 or the metal-containing chemical as described in Statement 2, wherein R ₈ , R ₉ and R ₁₀ are each independently selected from methyl or ethyl. 5. The ligand as described in statement 1 or the metal-containing chemical as described in statement 2, wherein M is Li and wherein R ₈ , R ₉ and R ₁₀ are each independently selected from methyl or ethyl. 6. The metal-containing chemical as described in statement 5, wherein R ₈ , R ₉ and R ₁₀ are each methyl. 7. The ligand as described in statement 1 or the metal-containing chemical as described in statement 2, wherein R ₁ -R ₇ are each independently selected from H, methyl, or ethyl. 8. The metal-containing chemical as described in statement 7, wherein R ₁ -R ₇ are each independently selected from H or methyl. 9. The metal-containing chemical as described in statement 2, which is structurally represented by: and has a SMILES formula: CC(C)(C)C1=C[N@@]2(C)CC[N](C)(C)[M]2O1. 10. The metal-containing chemical as described in statement 9, wherein M is Li. 11. The metal-containing chemical as described in statement 2, wherein M is a polyvalent metal and two or more ligands L are coordinated with M. 12. The metal-containing chemical as described in statement 11, wherein M is selected from calcium, magnesium, strontium, and barium. 13. The metal-containing chemical as described in statement 2, wherein M is a polyvalent metal and two or more ligands are coordinated with M, wherein M has one or more ligands L and one or more additional different ligands D to form a heteroleptic molecule M ^x LyDz, x 2, y 1, and z 1. 14. A metal-containing chemical as described in sentence 13, wherein M is selected from niobium, tantalum, vanadium, zirconium, uranium, titanium, tungsten, molybdenum, chromium, cobalt, nickel, copper, manganese, and zinc. 15. A metal-containing chemical as described in sentence 13, wherein M is niobium. 16. A method for depositing a metal-containing film, comprising the following steps: a) contacting a substrate with a vapor phase of a metal-containing chemical as described in any of sentences 1-15, b) forming a deposition material on the substrate, the substrate comprising the metal from the metal-containing chemical. 17. The method of sentence 16, further comprising the step of exposing the substrate to a gas phase or vapor phase of one or more additional reactants. 18. The method of sentence 17, wherein M is Li, the deposition material is LiNbO _x , and the one or more additional reactants include an oxygen source reactant and a niobium source reactant. 19. The method of sentence 17, wherein M is Li, the deposition material is LiPO, and the one or more additional reactants include an oxygen source reactant and a phosphorus source reactant. 20. The method of sentence 17, wherein M is Li, the deposition material is LiPNO, and the one or more additional reactants include an oxygen source reactant, a nitrogen source reactant, and a phosphorus source reactant. 21. The method of claim 18, 19 or 20, wherein the oxygen source reactant is selected from ozone, hydrogen peroxide, oxygen, water, methanol, ethanol, isopropanol, nitric oxide, nitrogen dioxide, nitrous oxide, carbon monoxide, carbon dioxide and combinations thereof. 22. The method of claim 18, 19 or 20, wherein the oxygen source reactant is ozone. 23. The method of claim 18, wherein the niobium source reactant is a Group 5 transition metal-containing chemical having one of the following formulas: wherein M is Nb, and each of ^R1 , ^R2 , ^R3 , ^R4 , ^R5 and ^R6 is independently selected from H; C1-C5 linear, branched or cyclic alkyl; C1-C5 linear, branched or cyclic alkylsilyl; C1-C5 linear, branched or cyclic alkylamino; or C1-C5 linear, branched or cyclic fluoroalkyl. 24. The method of sentence 18, wherein the niobium source reactant comprises tert-butylimide bis(diethylamido)mono(tert-butylalkoxy)niobium(V), tert-butylimide mono(diethylamido)bis(tert-butylalkoxy)niobium(V) and combinations thereof. 25. The method of clause 18, wherein the niobium source reactant is selected from tertiary butylimidotris(diethylamido)niobium(V), tertiary butylimidotris(dimethylamido)niobium(V), tertiary butylimidotris(ethylmethylamido)niobium(V), or a member of the known class of Nb(RCp)(NR2) ₂ (=NR), such as tertiary butylimidobis(diethylamido)cyclopentadienylniobium(V), tertiary butylimidobis(dimethylamido)cyclopentadienylniobium(V), tertiary butylimidobis(dimethylamido)methylcyclopentadienylniobium(V), and combinations thereof. 26. The method of claim 19 or 20, wherein the phosphorus source reactant is selected from trimethyl phosphate (TMPO), diethyl phosphoramidate (DEPA), triethyl phosphate (TEPO), TMP, and combinations thereof. 27. The method of claim 19 or 20, wherein the phosphorus source reactant comprises TMPO. 28. The method of any one of claims 16-27, wherein step a) and/or step b) is performed at a temperature higher than the melting point of the metal-containing chemical and at or below 200°C. 29. The method of any one of claims 16-27, wherein step a) and/or step b) is performed at a temperature higher than the melting point of the metal-containing chemical and at or below 175°C. 30. The method of any one of clauses 16-27, wherein step a) and/or step b) is performed at a temperature above the melting point of the metal-containing chemical and at or below 150° C. 31. The method of any one of clauses 16-30, wherein a) the substrate has a surface structure with an aspect ratio of 6.25 or less, and b) the deposited material on the substrate comprising the metal from the metal-containing chemical has a step coverage of the surface structure of 50% or more, such as 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or > 99%. 32. The method of any of clauses 16-31, wherein the method comprises atomic layer deposition (ALD), wherein steps a) and b) are repeated in ALD cycles. 33. The method of claim 32, wherein the growth rate of the deposited material per ALD cycle is 0.2 angstroms or greater, such as 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.8 or greater, 0.9 or greater, 1.0 or greater, 1.1 or greater, or 1.2 or greater.

The inventors synthesized and tested a new tridentate N,N,O ligand for metals that form low melting point solids, which has good vaporization properties due to thermal stability and high volatility; making these ligands suitable for vapor phase deposition. The ligand structure in one embodiment is represented by the following formula _and structure representation: Formula A : _N ( _R1R2 )-C( _R3R4 )-C( _{R5R6 )} -N( _R7 ) _-CH2 - _C ( _CR8R9R10 )= _O , SMILES formula: [R2]N(C([R3])([R4])C([R5])([R6])N(CC(C([R8])([R9])[R10])=O)[R7])[R1] Formula B : N(R ₁ R ₂ )-C(R ₃ R ₄ )-C(R ₅ R ₆ )--C(R ₁₁ R ₁₂ )-N(R ₇ )-CH ₂ -C(CR ₈ R ₉ R ₁₀ )=O SMILES formula: [R2]N([R1])C([R4])(C([R6])(C([R11])([R12])N([R7])CC(C([R9])([R10])[R8])=0)[R5])[R3] R ₁ -R ₁₂ are each independently selected from H, C ₁ to C ₄ alkyl (when C ₃ or C ₄ , it is linear or branched); or C ₁ -C ₄ alkylaminoC _1-4 NR ₂ , wherein R is each independently selected from H, C ₁ to C ₄ alkyl (when C ₃ or C ₄ , it is linear or branched).

The new ligand species is capable of forming a tridentate chelate ligand ("L") with a metal ion. In a preferred embodiment, the metal ("M") is a monovalent metal ion, such as an alkaline metal (e.g., Na ⁺ and Li ⁺ ), which forms a chelate chemical ML. Formula A1 : SMILES formula: [R2][N@@]1([R1])C([R4])(C([R6])([N@]2([R7])C=C(O[M]12)C([R9])([R10])[R8])[R5])[R3] Formula B1 : (Formula B1) SMILES formula: [R2][N@]1([R1])[C@]([R4])([C@@]([R6])([C@@]([R11])([R12])[N@]2([R7])CC(C([R9])([R10])[R8])=[O][M]12)[R5])[R3], However, the tridentate ligand L can chelate a higher valent metal alone (M ^+x L _x ) or combine with other metal ligands (D) to produce a heteroleptic ligand metal (M ^+x L _y D _z ). For example, M can be chelated by two ligands L to form Ca ⁺² L ₂ (see Example X below) or chelated with different ligands to form D-Ca ⁺² -L Ca ⁺² .

The chemical (ML) formed from the monovalent metal and the ligand L generally has a melting point below 150°C and is therefore a low melting solid. Preferred materials have a melting point below 70°C. Liquid chemicals or low melting solids that form liquids upon heating are preferred as chemical precursors for the vapor deposition process. Sublimated solids are also used, but the handling and management of sublimated precursors is more complicated and is generally associated with higher losses of the chemical due to thermal degradation.

Also highly relevant to use in vapor deposition processes is the vapor pressure achievable with the chemical precursor. This parameter is related to the rate and quality of the deposited M-containing material. Vapor pressure is generally inversely proportional to thermal stability. It is important to avoid using chemical precursors that cannot achieve sufficient vapor pressure without using temperatures that would also cause significant thermal degradation of the chemical precursor. These compensatory parameters are typically evaluated using thermogravimetric analysis ("TGA"). See, for example, ASTM E2008-17(2021), Standard Test Method for Volatility by Thermogravimetric Analysis. TGA evaluation of vapor deposition precursors evaluates the temperature profile of the volatility curve to define the 50% point (" _T50 ") where half of the chemical has evaporated and the temperature of complete vaporization (" _Tto ") where further temperature increase does not reduce the weight of residual material. This is typically performed both at atmospheric pressure and in a vacuum (e.g., 15 Torr) to represent these two common vapor deposition process conditions. TGA also allows for a simple evaluation of thermal stability from the weight of residual material that does not evaporate further with increasing temperature. Finally, the resulting vapor pressure can be plotted against the temperature/weight curve to provide a working evaluation of the three parameters of volatility, _T50 , and thermal stability.

For vapor deposition processes, it is preferred to have as low a _T50 as possible, and as low a temperature as possible at which the chemical precursor vapor pressure reaches 1 Torr (" _{T1 Torr} "). In particular, the 1 Torr vapor pressure should be at a temperature where thermal degradation is minimized. (For sublimating solids, the balancing of parameters is more challenging.)

Chemicals (ML) formed from a monovalent metal and a ligand L typically have a _{T1 Torr} at or below 150°C and above the melting temperature. These same chemicals typically exhibit good evaporation with a) _T50 at or below 250 and above the melting temperature; and b) TGA residues less than 1% by weight.

Due to the above properties, the metal M complexed with the ligand L is particularly suitable for coating cathode electrode materials, which include catalyst carbon support structures, such as single-walled fullerenes (Ceo and C72), multi-walled fullerenes, single-walled or multi-walled nanotubes, nanohorns, and/or carbon support structures with a density of about 0.2 g/cm3 to about 1.9 g/cm3, such as specialty carbons such as VULCAN or Imerys' SUPER C65.

Due to the aforementioned properties, the chemistry formed by the monovalent metal and the ligand L (ML) is very suitable for use in vapor deposition processes that require low temperatures due to substrate limitations on temperature and/or co-reactant exposure. LiTHD and LiO ^t Bu have 1 Torr pressure at over 150°C, resulting in longer pulses and/or higher dep T, which is unfavorable for many electrode materials in terms of absolute temperature exposure and also the thermal budget of these materials. Cathode materials, for example, can experience lattice changes, oxygen losses, composition changes, etc. at temperatures of 200 degrees or higher. For deposited materials that are negatively affected by silicon contamination, the ligand L provides a silicon-free chemical precursor that can deposit Si-free M-containing films. This is an advantage over LiTMSO and LiHMDS, both of which produce silicon-contaminated deposits, which are particularly problematic at the lowest ALD temperatures available for these chemistries.

Metal M chelated or otherwise coordinated with the ligand L described herein can be used as an M source vapor phase precursor for vapor deposition of M-containing materials on a substrate. Vapor phase deposition such as chemical vapor deposition and atomic layer deposition are well known in the art. The deposition material may also contain other atoms from other co-reactants or vapor phase precursors. Common co-reactants are oxygen source reactants and phosphorus source reactants and nitrogen source reactants, which, depending on the vapor deposition process, can provide O, N, or P as dopants, or react with the ML vapor phase precursor to form materials such as oxides or nitrides of M, for example, MOx, MNx, MONx, MPO, MPON, etc. The specific examples herein are LiNbOx and LiPOx, but many other materials can be used with different combinations of precursors and co-reactants. One skilled in the art can choose from a variety of known oxygen source reactants, phosphorus source reactants, _and nitrogen source reactants to design a vapor deposition process. Oxygen source reactants include _O2 , _O3 , _H2O , _H2O2 , NO, _NO2 , carboxylic acids, alcohols, diols, free radicals thereof, and combinations thereof. Nitrogen source reactants include _N2 , _H2 , _NH3 , hydrazine (such as _N2H4 , _MeHNNH2 , _MeHNNHMe ), organic amines (such as NMeH2, _NEtH2 , _NMe2H , _NEt2H , _NMe3 , _NEt3 , ( _SiMe3 ) _2NH ), pyrazoline, pyridine, diamines ₍ such as ethylenediamine), free radicals thereof, and mixtures thereof. Phosphorus source reactants include trimethyl phosphate (TMPO), diethylpyrophosphamide (DEPA), triethyl phosphate (TEPO), TMP, and combinations thereof. Examples Example 1 - Synthesis O=C(tBu)CH2NMe(CH2)2NMe2 Li-OC(tBu)=CHNMe(CH2)2NMe2

O=C(tBu)CH2NMe(CH2)2NMe2 : Ligand synthesized by 1:1 reaction of O=C(tBu)CH2Cl and HNMe[(CH2)2NMe2 in THF/ACN with TEA, K2CO3, or NaHCO3 at 50oC - 60oC. 1H NMR (CDCl3, 400 MHz): 3.412 (2H, br s ), 2.488 (2H, t , 3J = 7.7 Hz), 2.327 (2H, t , 3J = 7.7 Hz), 2.247 (3H, br s ), 2.147 (6H, br s ), 1.060 (9H, br s )

The complex was prepared by reaction of O=C(tBu)CH2NMe[(CH2)2NMe2 with BuLi, LiNH2, or LiH in hexane, pentane, or MTBE. The crude material was purified by distillation to give a white solid with 85% yield. Melting point = 68°C.

1H NMR (C6D6, 400 MHz): 2.110 (6H, br s ), 1.871 (2H, q , 3J = 10.2 Hz), 1.625 (2H, q , 3J = 10.2 Hz), 2.811 (1H, t , 3J = 11.9 Hz), 2.460 (1H, t , 3J = 11.9 Hz), 2.345 (3H, s), 4.126 (1H, s ), 1.369 (9H, s ) 13C NMR (C6D6, 101 MHz): 57.1, 46.9, 36.2, 57.5, 102.6, 171.3, 30.3, 28.9.

TGA was performed under the following measurement conditions: 11.4 mg sample weight, closed cup under N2 at 1 atm (complete evaporation temperature at 305°C); 10.4 mg sample weight, open cup under N2 at 1 atm (complete evaporation temperature _Ttotal = 254°C); 30.1 mg sample weight, open cup under N2 at 15 Torr (complete evaporation temperature _Ttotal = 178°C). The temperature ramp rate was set to 10.0°C/min. 50% evaporation _T50 = 225°C of the open cup TGA method was used under N2 at 1 atm.

The results are presented graphically in Figure 1. As shown, at _Ttotal , the residues are negligible (less than 1% by weight). Example 2-5 - Additional Synthesis

The same synthesis was performed with the following variants of Example 1: ●  Example 2: Changing positions R1, R2, and R7 to ethyl ●  Example 3: Changing position R7 to n-butyl ●  Example 3: Changing position R7 to ethyl ●  Example 5: M is Na

The synthesis of ML was carried out in the same manner as in Example 1, wherein L had a different alkyl group as described above. For M = Na, Na was provided as NaNH2 for the formation of ML. Similar results were obtained in terms of yield and purity. Example 6 - Synthesis of Exemplary M ^{+ 2} _L2 ( M = Ca )

Synthesis: Na{OC(tBu)=CHN(Me)(CH ₂ CH ₂ NMe ₂ )} was added to 0.5 eq. of CaI ₂ in THF and stirred for 16 h. Filtration and sublimation (120° C./0.1 torr) 1H NMR (C 6 D 6 , 400 MHz): 3.812 (2H, br s), 2.488 (4H, br dt), 2.327 (4H, br dt), 2.147 (6H, br s), 2.032 (12H, br s), 1.000 (19H, br s).

TGA measurements were performed under the following measurement conditions: 6.2 mg sample weight, open cup under N2 at 1 atm (complete evaporation temperature at 280°C) with a temperature ramp rate set to 10.0°C/min. 50% evaporation using the open cup TGA method under N2 at 1 atm; _T50 = 230°C, as shown in Figure 2. Example 7 - LiPOx deposition on substrates

Li-OC(tBu)=CHNMe(CH2)2NMe2 from Example 1 was used as the Li source for atomic layer deposition (ALD) of LiPOx films on blank silicon wafers as test substrates. Trimethyl phosphate (TMPO) is a prior art standard phosphate source used with prior art Li precursors. Hence, we chose TMPO as co-reactant. Preliminary characterizations: ● Li-OC(tBu)=CHNMe(CH2)2NMe2 thermally decomposes at 250°C. Hence, a baseline design for experimental parameter evaluation was performed at 200°C to avoid parasitic CVD. ● Under the test conditions (ozone as co-reactant), the pulse time dose ramping of both precursors showed self-limiting growth at 0.9 Å/cycle. This confirms that 200 degree deposition is an ALD process. ● An oxygen source is required to form LiPOx. ALD does not occur in the absence of ozone.

The effect of temperature on ALD of LiPOx was then evaluated using a design of experimental parameters from preliminary tests at 200°C. Experimental conditions: Reactor temperature: X°C Reactor pressure: 1 Torr Carrier gas _N2 : 80 sccm Tank T: 110°C Tank P: 30 Torr _N2 bubbled in Li FR: 30 sccm TMPO Tank T: 80°C TMPO Tank P: 15 Torr _N2 bubbled in P FR: 30 sccm Substrate: Si (1% HF) Cycle number: 150 Pulse conditions: Li-OC(tBu)=CHNMe(CH2)2NMe2 (0.64 sccm): 30 s Purge: 120 s TMPO (30 sccm): 15 s Purge: 30 s _O3 : 5 s Purge: 30 s

As shown in Figures 3-5, the temperatures tested were 125°C, 150°C, 175°C, and 200°C. LiPOx was deposited as a uniform continuous film over this temperature range.

From Figure 3, the main difference (as one would expect) is the deposition rate, where the maximum deposition rate is at 200°C. However, even at 125°C, each cycle of ALD results in a 0.36 angstrom thick deposit, which is a commercially viable deposition rate. This is in contrast to the prior art molecules discussed above where deposition stops at or above 200°C.

Figure 4 shows that the refractive index of the deposited material remains stable over the entire temperature range and its value is close to that of Li ₃ PO ₄ (RI 1.59).

Figure 5 shows the atomic percentages, where silicon, N, and C are all below the detection limit (which is less than 1%). Consistent with the RI measurements, the deposited material has a composition of Li _2.8 PO _3.8 , very close to Li ₃ PO ₄ . This combination of low temperature ALD, GPC rate, and composition is an important advance that will enable the deposition of LiPOx on a variety of temperature/thermal budget-limited substrates, especially for materials used in Li-ion battery electrodes.

Good step coverage of non-uniform substrate surfaces is important for good electrode/cathode performance, since 1) thicker sites will inhibit Li ion transport, and 2) thinner sites will lead to TM loss (e.g. Mn migration out of the cathode) and/or dendrite formation. To evaluate the suitability of the ALD process for non-uniform surfaces, a test Si wafer with trenches was used as substrate. At an aspect ratio of 6.25, the step coverage is 87%. The maximum aspect ratio tested is 18. Even at this critical aspect ratio, the ALD layer is continuous. The step coverage at this size is 65%, indicating that the ALD deposition process decays on very distant surfaces. Nevertheless, the minimum thickness achieved at the bottom of the trench is 14.9 nm, which is sufficient for many applications. In many applications such as battery electrode materials, step coverages of less than 100% are acceptable. We expect that with further parameter optimization, these results will be improved compared to these preliminary experiments. Example 8 - LiNbOx Deposition on Substrate

As a diversified material deposition example, we chose the binary deposition of _LiNbO3 . Li-OC(tBu)=CHNMe(CH2)2NMe2 from Example 1 was used as the Li source precursor. For niobium, we chose the source precursor tert-butylimide bis(diethylamido)mono(tert-butylalkoxy)niobium(V) described in US 10106887 B2. One reason for choosing tert-butylimide bis(diethylamido)mono(tert-butylalkoxy)niobium(V) is that its ALD temperature window for NbOx deposition extends at least as low as 150°C. A temperature of 175°C was chosen to balance the ALD windows and GPC of the Li and Nb source precursors. Once again, a blank silicon wafer was used as a substrate for initial evaluation. The process conditions tested were: T [°C] (setting, actual) 175 P _reactor 1 T _tank [°C], VP _precursor [Torque] 115 1 P _tank [tray] 30 Carrier gas [sccm] 15 N ₂ FR [sccm], PP [torr] 0.64 Co-reactant O ₃ FR [sccm], PP [torr] 50 Dil FR [sccm] 200 N ₂

ALD cycle parameters are: Pulse[s] #loop 300 Li Xianji 40 Blow 90 O ₃ Pulse 10 Blow 15 Nb precursor 30 Blow 60 O ₃ Pulse 10 Blow 15

The Nb-ozone subcycle forms a layer of NbOx. The lithium precursor reacts with the NbOx to form the LiNbOx material. The total deposition growth rate of LiNbOx is 0.68 angstroms. Pulsed dosage experiments confirm that the LiNbOx formation is a self-limiting ALD reaction. The stoichiometry of the deposited material is approximately LiNbO ₂ . This is consistent with the RI of 1.9 for the deposited material compared to 2.2 for LiNbO _3. The deposition was further tested on silicon wafers with trenches. Even at an aspect ratio of 15, the step coverage is > 99%. The deposited layers are continuous and there are no gaps or visible defects in the slices scanned by SEM. It is expected that, with further optimization of parameters (such as ozone dosage), the atomic composition of the deposited material will be very close to LiNbO ₃ , similar to the final result obtained for LiPOx. Example 9 - Synthesis of Exemplary M ^x LyDz ^t BuN=Nb(OEt) ₂ {OC( ^t Bu)=CHN(Me)(CH ₂ CH ₂ NMe ₂ )}

Synthesis: ^tBuN =NbCl ₃ was added to 2 equivalents of NaOEt and 1 equivalent of Li{OC( ^tBu )=CHN(Me)(CH ₂ CH ₂ NMe ₂ )} in THF and stirred over 16 hours. Filtered and purified by distillation (110°C/0.1 torr) ¹ H NMR (C ₆ D ₆ , 400 MHz): 4.561 ppm (4H, tm), 4.002 ppm (1H, s), 2.610 ppm (1H, t, 3J = 11.6 Hz), 2.334 ppm (1H, d, 2J = 14.7 Hz), 2.382 ppm (3H, s), 2.108 ppm (3H, s), 1.975 ppm (3H, s), 1.323 ppm (1H, d, 3J = 14.7 Hz), 1.239 ppm (1H, t, 3J = 11.6 Hz), 1.163 ppm (6H, m), 1.108 ppm (9H, s), 1.006 ppm (9H, s). Example 9 : Synthesis of Li-OC( ^t Bu)=CHN[(CH ₂ ) ₂ OMe] ₂ O=C(tBu)CH2N[(CH2)3NMe2]2 (left); Li-OC(tBu)=CHN[(CH2)3NMe2]2 (right)

O=C(tBu)CH2N[(CH2)3NMe2]2: Ligand synthesized by the 1:1 reaction of O=C(tBu)CH2Cl and HN[(CH2)3NMe2]2 in THF/ACN with TEA, K2CO3, or NaHCO3 at 50°C - 60°C.

¹ H NMR (CDCl3, 400 MHz): 2.144 ppm (12H, s), 2.193 ppm (4H, t, 3J = 7.2 Hz), 1.541 ppm (1H, p, 3J = 7.2 Hz), 2.475 ppm (4H, t, 3J = 7.2 Hz), 3.465 ppm (2H, s), 1.075 ppm (9H, s) The complex was prepared by reaction of O=C(tBu)CH2N[(CH2)3NMe2]2 with BuLi, LiNH2, or LiH in hexane, pentane, or MTBE. The crude material was purified by sublimation to give a yellow solid in yield (45%). 1H NMR (C6D6, 400 MHz): 4.155 ppm (1H, br s), 2.495 ppm (4H, br s), 2.188 ppm (12H, br s), 2.1 - 2.3 ppm (4H, br m), 2.320 ppm (2H, br d, 3J = 11.1 Hz), 1.400 ppm (9H, br s)

¹³ C NMR (C6D6, 101 MHz): 173.6, 98.8, 70.6, 58.4, 57.9, 36.4, 29.3. Example 10 - Synthesis of Li-OC( ^t Bu)=CHN[(CH ₂ ) ₂ OMe] ₂ O=C( ^t Bu)CH ₂ N[(CH ₂ ) ₃ NMe ₂ ] ₂ (left); Li-OC( ^t Bu)=CHN[(CH2) ₃ NMe ₂ ] ₂ (right)

O=C( ^t Bu)CH ₂ N[(CH ₂ ) ₃ NMe ₂ ] ₂ : Ligand synthesized by 1:1 reaction of O=C( ^t Bu)CH ₂ Cl and HN[(CH ₂ ) ₃ NMe ₂ ] ₂ at 50°C - 60°C in THF/ACN with TEA, K ₂ CO ₃ , or NaHCO ₃ .

¹ H NMR (CDCl3, 400 MHz): 2.144 ppm (12H, s), 2.193 ppm (4H, t, 3J = 7.2 Hz), 1.541 ppm (1H, p, 3J = 7.2 Hz), 2.475 ppm (4H, t, 3J = 7.2 Hz), 3.465 ppm (2H, s), 1.075 ppm (9H, s) The complex was prepared by reaction of O=C( _t Bu)CH ₂ N[(CH ₂ ) ₃ NMe ₂ ] ₂ with BuLi, LiNH ₂ , or LiH in hexane, pentane, or MTBE. The crude material was purified by sublimation to give a yellow solid in yield (45%).

¹ H NMR (C6D6, 400 MHz): 4.155 ppm (1H, br s), 2.495 ppm (4H, br s), 2.188 ppm (12H, br s), 2.1 - 2.3 ppm (4H, br m), 2.320 ppm (2H, br d, 3J = 11.1 Hz), 1.400 ppm (9H, br s).

¹³ C NMR (C6D6, 101 MHz): 173.6, 98.8, 70.6, 58.4, 57.9, 36.4, 29.3. Industrial Applicability

The present invention is at least industrially applicable to chemical precursors suitable for depositing semiconductor manufacturing materials or battery electrodes.

Although the present invention has been described in conjunction with specific embodiments of the present invention, it is apparent that, in view of the foregoing description, many alternatives, modifications and variations will be clear to those skilled in the art. Therefore, it is intended to include all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. The present invention may suitably include, consist of, or consist essentially of the disclosed elements, and may be implemented in the absence of undisclosed elements. In addition, if there is language referring to order, such as first and second, it should be understood in an exemplary sense, rather than in a restrictive sense. For example, those skilled in the art may recognize that certain steps may be combined into a single step.

All references identified herein are each hereby incorporated by reference into this application in their entirety, and each reference is cited for the specific information for which it is intended. Legal Definitions and Principles of Interpretation

The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

The term "comprising" in the claims is an open transition term, which means that the subsequently identified claim elements are a non-exclusive list (i.e., anything else may be additionally included and remain within the scope of "comprising"). Unless otherwise indicated herein, "comprising" as used herein may be replaced by the more restrictive transition terms "consisting essentially of" and "consisting of."

"Provide" in the claims is defined to mean to supply, furnish, make available, or prepare something. The step may instead be performed by any actor in the absence of express language in the claims.

Optionally or optionally means that the subsequently described event or circumstance may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

Ranges may be expressed herein as from about one specific value and/or to about another specific value. When such a range is expressed, it should be understood that another embodiment is from the one specific value and/or to the other specific value, as well as all combinations within the range.

References to "one embodiment" or "an embodiment" herein mean that a particular feature, structure, or characteristic described in relation to that embodiment may be included in at least one embodiment of the invention. The phrase "in one embodiment" appearing in different places in the specification does not necessarily all refer to the same embodiment, nor do separate or alternative embodiments necessarily exclude other embodiments. The above also applies to the term "implementation".

As used herein, "about" or "around or approximately" in the text or patent application means ±10% of the stated value. Technical Definition

As used herein, "room temperature" in the text or patent application means from about 20°C to about 25°C.

The term "ambient conditions" refers to an ambient temperature (i.e., surrounding temperature) of about 20°C to about 25°C and an ambient pressure (ambient temperature) of about 1 atm or 1 bar.

The term "substrate" refers to the material or materials on which the manufacturing process is performed. A substrate may also have one or more layers of different materials already deposited on it from previous manufacturing steps.

Those skilled in the art will recognize that the term "film" or "layer" as used herein refers to a certain thickness of a material that is laid or spread on a surface and that the surface may be a groove or line.

Standard abbreviations for the elements from the Periodic Table of the Elements are used herein. It should be understood that the elements may be referred to by such abbreviations (e.g., Si refers to silicon, N refers to nitrogen, O refers to oxygen, C refers to carbon, H refers to hydrogen, F refers to fluorine, etc.).

Unique CAS Registry Numbers (i.e., "CAS") assigned by Chemical Abstracts Services are provided to help better identify disclosed molecules.

The aspect ratio of a geometric shape is the ratio of its dimensions in different dimensions. The aspect ratio is most often expressed as two integers separated by a colon (x:y). The values x and y do not represent the actual width and height, but rather the ratio of the width to the height. As examples, 8:5, 16:10, and 1.6:1 are all ways of expressing the same aspect ratio. In objects with more than two dimensions, such as hyperrectangles, the aspect ratio can still be defined as the ratio of the longest side to the shortest side.

Both conformality and step coverage refer to the degree of variation in the thickness of a film over a surface, especially over topologically different regions of the surface. This is particularly relevant to surfaces with microstructures having various aspect ratios. Complete (100%) conformality for the above example means that there is zero cusping and that the top surface, the trench sidewalls, and, when applicable, the trench bottom have all the same thickness. If a single conformality percentage is given, it is the minimum conformality measurement corresponding to the maximum deviation in the relative thickness of the overall film at two selected points on the surface. These two points can correspond to the highest aspect ratio point, or, for example, a point with a specific aspect ratio such as 6: 1 or less. The thickness of the film is evaluated by a variety of methods, such as scanning electron microscopy of a slice substrate. A film is generally "conformal" if it is at least 20% conformal, preferably at least 50% conformal.

without

To further understand the nature and purpose of the present invention, the following detailed description should be referenced in conjunction with the accompanying drawings, in which similar elements are given the same or similar figure labels, and in the accompanying drawings: [Figure 1] shows the TGA results of Example 1; [Figure 2] shows the TGA results of Example 6; [Figure 3] shows the effect of temperature on the deposition rate of Example 7; [Figure 4] shows the effect of temperature on the refractive index of the deposited material of Example 7; and [Figure 5] shows the effect of temperature on the atomic composition of the deposited material of Example 7.

without

Claims (21)

A ligand L capable of forming a coordination complex with at least one metal atom, the ligand having the general formula: N(R ₁ R ₂ )-C(R ₃ R ₄ )-C(R ₅ R ₆ )-N(R ₇ )-CH ₂ -C(CR ₈ R ₉ R ₁₀ )=O (Formula A), which is structurally represented by:

or N(R ₁ R ₂ )-C(R ₃ R ₄ )-C(R ₅ R ₆ )--C(R ₁₁ R ₁₂ )-N(R ₇ )-CH ₂ -C(CR ₈ R ₉ R ₁₀ )=O (Formula B), which is structurally represented by:

wherein R ₁ -R ₁₂ are each independently selected from H, C ₁ to C ₄ alkyl (when C ₃ or C ₄ , linear or branched); or C ₁ -C ₄ alkylamino C _1-4 NR ₂ , wherein R are each independently selected from H, C 1 to C 4 alkyl (when C ₃ or C ₄ , linear or branched). A metal-containing chemical, comprising a ligand L as described in claim 1, wherein the ligand has a general formula: N(R ₁ R ₂ )-C(R ₃ R ₄ )-C(R ₅ R ₆ )-N(R ₇ )-CH ₂ -C(CR ₈ R ₉ R ₁₀ )=O (Formula A), which is structurally represented by:

or

wherein M is selected from Li, Na, or K. A metal-containing chemical as described in claim 2, wherein M is Li. The metal-containing chemical as described in claim 2, wherein R ₈ , R ₉ and R ₁₀ are each independently selected from methyl or ethyl. The metal-containing chemical as described in claim 2, wherein M is Li, and wherein R ₈ , R ₉ and R ₁₀ are each independently selected from methyl or ethyl. The metal-containing chemical as described in claim 5, wherein R ₈ , R ₉ and R ₁₀ are each methyl. The metal-containing chemical as described in claim 2, wherein R ₁ -R ₇ are each independently selected from H, methyl, or ethyl. The metal-containing chemical as described in claim 7, wherein R ₁ -R ₇ are each independently selected from H or methyl. The metal-containing chemical as described in claim 2 is structurally represented by:

A metal-containing chemical as described in claim 9, wherein M is Li. A metal-containing chemical as described in claim 2, wherein M is a polyvalent metal and two or more ligands L coordinate with M. The metal-containing chemical as described in claim 2, wherein M is a polyvalent metal and two or more ligands are combined with M, wherein M has one or more ligands L and one or more other different ligands D to form a heteroleptic molecule M ^x LyDz, x≧2, y≧1, and z≧1. A method for depositing a metal-containing film comprising the steps of: a) contacting a substrate with a vapor phase of a metal-containing chemical as described in any one of claims 2-12, b) forming a deposited material on the substrate, the substrate comprising the metal from the metal-containing chemical. The method as described in claim 13 further comprises the step of exposing the substrate to a gas phase or vapor phase of one or more additional reactants. The method of claim 14, wherein M is Li, the deposited material is LiNbO _x , and the additional reactants include an oxygen source reactant and a niobium source reactant. The method as described in claim 14, wherein M is Li, the deposition material is LiPO or LiPON, and the additional reactant comprises an oxygen source reactant and a phosphorus source reactant, and for LiPON, the additional reactant further comprises a nitrogen source reactant. The method as described in claim 15 or 16, wherein the oxygen source reactant is ozone. The method of claim 15, wherein the niobium source reactant comprises a Group 5 transition metal-containing chemical having one of the following formulae:

wherein M is Nb, and each of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is independently selected from H; C1-C5 straight chain, branched chain, or cyclic alkyl; C1-C5 straight chain, branched chain, or cyclic alkylsilyl; C1-C5 straight chain, branched chain, or cyclic alkylamino; or C1-C5 straight chain, branched chain, or cyclic fluoroalkyl; or Nb(RCp)(NR2)2(=NR) (Formula III); or selected from tertiary butylimide tris(diethylamido)nitrogen (V), tertiary butylimide tris(dimethylamido)nitrogen (V) and tertiary butylimide tris(ethylmethylamido)nitrogen (V); and combinations thereof. The method as described in claim 16, wherein the phosphorus source reactant is trimethyl phosphate (TMPO), diethyl pyrophosphamide (DEPA), triethyl phosphate (TEPO), TMP and a combination thereof. A method as described in any one of claims 13-16 and 18-19, wherein step a) and/or step b) is carried out at a temperature higher than the melting point of the metal-containing chemical and at or below 200°C. A method as described in any one of claim 17, wherein step a) and/or step b) is carried out at a temperature higher than the melting point of the metal-containing chemical and at or below 200°C.