Group 2 metal-containing film-forming compositions and vapor-deposited films using the same

Abstract

A method of forming a Group 2 metal-containing film on a substrate comprising a) exposing the substrate to a vapor of a Group 2 metal-containing film forming composition containing an alkaline earth metal precursor having the formula: wherein M is Be, Mg, Ca, Sr, or Ba; R 1 ‑ R 6 each independently is a C1-C 10 alkyl, fluorine, alkylsilyl, germyl, alkylamide, or alkylsilylamide, b) depositing at least a portion of the alkaline earth metal precursor onto the substrate by a vapor deposition process to form a Group 2 metal-containing film; and c) repeating a) and b) until the Group 2 metal-containing film of a desired thickness is formed.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Patent Application No. 18 / 409,331, filed January 10, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention generally relates to film-forming compositions containing Group 2 metals and the deposition of films using them, and particularly to the formation of films containing Group 2 metals using alkaline earth metal precursors having the following formula:

[0004] Where M is Be, Mg, Ca, Sr, or Ba; R 1 - R 6 Each is independently C1-C 10 Alkyl, fluorinated, alkylsilyl, methylgermanyl, alkylamide or alkylsilylamide. Background Technology

[0005] As the design and manufacturing of semiconductor devices continue to evolve, the semiconductor industry is constantly seeking new and novel methods to deposit films onto substrates in order to give the resulting films certain desirable properties.

[0006] A challenge for DRAM manufacturers is maintaining sufficient storage capacitance per cell as cell size shrinks. To address this challenge, films using alkaline earth metal oxides such as SrO, BaO, and CaO are actively researched. Studies have also been conducted on perovskites (ABO3) such as SrTiO3 or BaSrTiO3 for ultra-high-k materials, ruthenium-based materials such as CaRuO3, SrRuO3, and BaRuO3 for electrode applications, and SrO for doping dielectrics. Various strontium complexes have been investigated for depositing thin films via MOCVD (Metal-Organic Chemical Vapor Deposition), ALD (Atomic Layer Deposition), or other vapor deposition methods. These complexes include the following.

[0007] Sr(Me5Cp)2 has been used to deposit strontium films. This precursor is not volatile and is sometimes thermally unstable. The vaporization temperature of Sr(Me5Cp)2 is above 300°C. Vaporization of the same precursor yields a 20% residue due to decomposition.

[0008] Cameron et al., in WO2008 / 069821, disclosed amidinates and guanidinates. Sr2(iPr-iPr-iPr-GUA)4 is an example of this type of precursor. The main disadvantages of these precursors are their thermal instability and lack of volatility. Amidinate and guanidinate precursors are solids at room temperature and typically have high melting points. Furthermore, they tend to form dimers.

[0009] β-diketonate ligands typically form solid, non-volatile complexes with Sr. Sr(thd)₂ is a well-known member of the β-diketonate family. At atmospheric pressure, this precursor has a melting point of approximately 210 °C and a boiling point above 350 °C. Deposition of SrO using Sr(thd)₂ with O₃ results in the formation of SrO along with Sr₂CO₃. No deposition was observed with Sr(thd)₂ and water. This precursor is inconvenient for deposition due to its difficult vaporization.

[0010] ILJINA et al. (Materials science & engineering. B, Solid-state materials for advanced technology 1993, 18, 234-236) disclosed Sr(pivalate)₂. This precursor is a solid and can sublimate from 370 °C. The vapor pressure at this temperature is only 1.33 Pa. Sublimation produces a residue of nearly 60%. This precursor cannot be used for deposited films.

[0011] All known commercially available Group 2 organometallic compounds are solids, making their application in the current semiconductor industry as CVD / ALD precursors undesirable. To our knowledge, there are no suitable liquid strontium organometallic compounds with the desired thermal behavior to enable the vapor deposition of strontium-containing films.

[0012] Therefore, there is a need to develop liquid precursors.

[0013] Overview

[0014] A method for forming a film containing a Group 2 metal on a substrate is disclosed, the method comprising:

[0015] a) Exposing the substrate to the vapor of a film-forming composition containing a Group 2 metal, the composition containing an alkaline earth metal precursor having the following formula:

[0016] Where M is Be, Mg, Ca, Sr, or Ba; R 1 - R 6 Each is independently C1-C 10 Alkyl, fluorogroup, alkylsilyl group, germyl group, alkylamide, or alkylsilylamide. b) Depositing at least a portion of the alkaline earth metal precursor onto the substrate using a vapor deposition process to form the film containing the Group 2 metal; and c) Repeat steps a) and b) until a film containing the Group 2 metal of the desired thickness is formed. The disclosed deposition method may include one or more of the following features: The vapor deposition method mentioned is metal-organic chemical vapor deposition (MOCVD). • The vapor deposition method mentioned is the ALD method; • The vapor deposition method is thermal ALD, spatial ALD, temporal ALD, or plasma ALD. • The vapor deposition method mentioned is the thermal ALD method; • The vapor deposition method mentioned is the spatial ALD method; • The vapor deposition method mentioned is the time-dependent ALD method; • The vapor deposition method described is not the plasma ALD method; • The vapor deposition method mentioned is the plasma ALD method; It further includes exposing the surface to the co-reactant; • The co-reactant is an oxidizing agent or a nitriding agent; • The co-reactant is an oxidizing agent; • The co-reactant is a nitriding agent; It further includes the step of purging excess vapors of the film-forming composition containing Group 2 metals and excess co-reactants separately with an inert gas to separate each exposure, wherein the inert gas is N2, Ar, Kr or Xe; The co-reactants are selected from O3, O2, H2O, H2O2, D2O, and ROH, where R = C1 – C 10 Linear or branched hydrocarbons, NH3, NO, N2O, hydrazine, amines or combinations thereof; The co-reactant is H2O; • The co-reactant is NH3; The inert gas is N2, Ar, Kr, or Xe; • Mix the alkaline earth metal precursor with a solvent; The solvent in the mixture is 0% to about 50%; The solvent is selected from substituted or unsubstituted hydrocarbons of alkanes, alkenes, and alkynes; alcohols selected from alkyl alcohols and amino alcohols; or amines selected from primary amines, secondary amines, and tertiary amines; tetrahydrofuran; dichloromethane; ethyl acetate; butyl acetate; acetonitrile; dimethylformamide; The hydrocarbons mentioned include octane, ethylbenzene, xylene, mesitylene, decalin, decane, and dodecane; The concentrations of the alkaline earth metal precursors in the solvent vary; The metal-containing film-forming composition comprises the alkaline earth metal precursor at a concentration between approximately 50% w / w and approximately 100.0% w / w; The concentration of the alkaline earth metal precursor in the solvent is between approximately 50% w / w and approximately 100.0% w / w; • Expose the substrate to the precursor at a temperature from room temperature to approximately 500°C; The alkaline earth metal precursor is bis(tris-sec-butylcyclopentadienyl)strontium(II), Sr(sBu3Cp)2; The alkaline earth metal precursor is bis(tris-sec-butylcyclopentadienyl)barium(II), Ba(sBu3Cp)2; The alkaline earth metal precursor is bis(tris-isopropylcyclopentadienyl)strontium(II),Sr(iPr3Cp)2; The alkaline earth metal precursor is bis(tri-tert-butylcyclopentadienyl)strontium(II), Sr(tBu3Cp)2; The alkaline earth metal precursor is bis(tris-isopropylcyclopentadienyl)barium(II), Ba(iPr3Cp)2; • The metal-containing film-forming composition contains impurities ranging from about 0.0% w / w to about 5.0% w / w; • The alkaline earth metal precursor is purified to a purity of approximately 95% by weight or w / w to approximately 100% w / w; • The alkaline earth metal precursor is purified to a purity of approximately 99% w / w to approximately 99.999% w / w; • The alkaline earth metal precursor was purified to a purity of approximately 99% w / w to approximately 100% w / w; • The film containing the Group 2 metal is an SrO film; and • The membrane containing Group 2 metals is a BaO membrane.

[0017] A method for depositing SrO films on a substrate is also disclosed, the method comprising the following steps: a) Expose the substrate to vapors of bis(tris-sec-butylcyclopentadienyl)strontium(II),Sr(sBu3Cp)2; b) Expose the substrate to the co-reactant H2O; c) Depositing at least a portion of the alkaline earth metal precursor onto the substrate by vapor deposition to form an SrO film; and d) Repeat steps a)-c) until a SrO film of the desired thickness is formed. The disclosed deposition method may include one or more of the following features: • The vapor deposition method mentioned is MOCVD. • The vapor deposition method mentioned is the ALD method; • The vapor deposition method is thermal ALD, spatial ALD, temporal ALD, or plasma ALD. • The vapor deposition method mentioned is the thermal ALD method; • The vapor deposition method mentioned is the spatial ALD method; • The vapor deposition method mentioned is the time-dependent ALD method; • The vapor deposition method described is not the plasma ALD method; • The vapor deposition method mentioned is the plasma ALD method; Its further includes Excess vapors and excess co-reactants of the film-forming composition containing Group 2 metals are purged separately using an inert gas, wherein the inert gas is N2, Ar, Kr, or Xe. • Mix Sr(sBu3Cp)2 with a solvent; The solvent in the mixture is 0% to about 50%; The solvent is selected from substituted or unsubstituted hydrocarbons of alkanes, alkenes, and alkynes; alcohols selected from alkyl alcohols and amino alcohols; or amines selected from primary amines, secondary amines, and tertiary amines; tetrahydrofuran; dichloromethane; ethyl acetate; butyl acetate; acetonitrile; dimethylformamide; The hydrocarbons mentioned include octane, ethylbenzene, xylene, mesitylene, decahydronaphthalene, decane, and dodecane; The concentration of Sr(sBu3Cp)2 varies in the solvent; • The concentration of Sr(sBu3Cp)2 in the solvent is between approximately 50% w / w and approximately 100.0% w / w; • Expose the substrate to the precursor at a temperature from room temperature to approximately 500°C; • Sr(sBu3Cp)2 contains impurities ranging from approximately 0.0% w / w to approximately 5.0% w / w; • Purify Sr(sBu3Cp)2 to approximately 95% by weight or w / w to approximately 100% w / w purity; • Purify Sr(sBu3Cp)2 to a purity of approximately 99% w / w to approximately 99.999% w / w; and • Purify Sr(sBu3Cp)2 to a purity of approximately 99% w / w to approximately 100% w / w.

[0018] A method for depositing a BaO film on a substrate is also disclosed, the method comprising the following steps: a) Expose the substrate to vapors of bis(tris-sec-butylcyclopentadienyl)barium(II), Ba(sBu3Cp)2; b) Expose the substrate to the co-reactant H2O; c) Depositing at least a portion of the alkaline earth metal precursor onto the substrate by vapor deposition to form a BaO film; and d) Repeat steps a)-c) until a BaO film of the desired thickness is formed. The disclosed deposition method may include one or more of the following features: • The vapor deposition method mentioned is MOCVD. • The vapor deposition method mentioned is the ALD method; • The vapor deposition method is thermal ALD, spatial ALD, temporal ALD, or plasma ALD. • The vapor deposition method mentioned is the thermal ALD method; • The vapor deposition method mentioned is the spatial ALD method; • The vapor deposition method mentioned is the time-dependent ALD method; • The vapor deposition method described is not the plasma ALD method; • The vapor deposition method mentioned is the plasma ALD method; It further includes using an inert gas to purge excess vapors of the film-forming composition containing the Group 2 metal and excess co-reactants separately for each exposure, wherein the inert gas is N2, Ar, Kr or Xe; • Mix Ba(sBu3Cp)2 with a solvent; The solvent in the mixture is 0% to about 50%; The solvent is selected from substituted or unsubstituted hydrocarbons of alkanes, alkenes, and alkynes; alcohols selected from alkyl alcohols and amino alcohols; or amines selected from primary amines, secondary amines, and tertiary amines; tetrahydrofuran; dichloromethane; ethyl acetate; butyl acetate; acetonitrile; dimethylformamide; The hydrocarbons mentioned include octane, ethylbenzene, xylene, mesitylene, decahydronaphthalene, decane, and dodecane; The concentration of Ba(sBu3Cp)2 varies in the solvent; The concentration of Ba(sBu3Cp)2 in the solvent is between approximately 50% w / w and approximately 100.0% w / w; • Expose the substrate to the precursor at a temperature from room temperature to approximately 500°C; • Ba(sBu3Cp)2 contains impurities ranging from approximately 0.0% w / w to approximately 5.0% w / w; • Purify Ba(sBu3Cp)2 to a purity of approximately 95% by weight or w / w to approximately 100% w / w; • Purify Ba(sBu3Cp)2 to a purity of approximately 99% w / w to approximately 99.999% w / w; and • Purify Ba(sBu3Cp)2 to a purity of approximately 99% w / w to approximately 100% w / w.

[0019] Symbols and nomenclature

[0020] The following detailed description and claims use many abbreviations, symbols, and terms well known in the art. Certain abbreviations, symbols, and terms are used throughout the following description and claims, and include: As used in this article, the indefinite articles “a” or “an” refer to one or more.

[0021] As used herein, “about” or “approximately” in this document or in the claims means ±10% of the specified value.

[0022] As used herein, “room temperature” in this document or in the claims means approximately 20°C to approximately 25°C.

[0023] The term "ambient temperature" refers to an ambient temperature of approximately 20°C to approximately 25°C.

[0024] Note in this document that when the precursor is gaseous at room temperature and ambient pressure, the terms "precursor," "deposited compound," and "deposited gas" are used interchangeably. It is to be understood that a precursor may correspond to or be related to a deposited compound or deposited gas, and a deposited compound or deposited gas may refer to a precursor.

[0025] Note in this document that the terms “deposition temperature” and “substrate temperature” are used interchangeably. It is to be understood that substrate temperature may correspond to or be related to deposition temperature, and deposition temperature may refer to substrate temperature.

[0026] Please note that throughout this specification and claims, deposited films or layers, such as silicon oxides or silicon nitrides, may be listed without mentioning their appropriate stoichiometry (i.e., SiO, SiO2, SiO3, Si3N4). These layers may include oxides (Si... n O m A layer or mixture thereof, wherein m and n are in the range of 1 to 6 (inclusive). For example, silicon oxide is Si n O m Where n is in the range of 0.5 to 1.5, and m is in the range of 1.5 to 3.5. More preferably, the silicon oxide layer is SiO or SiO2. The silicon oxide layer can be a silicon oxide-based dielectric material, such as an organic-based or silicon oxide-based low-k dielectric material, such as Applied Materials, Inc.'s Black Diamond II or III material, with the formula SiOCH. Alternatively, any mentioned silicon-containing layer can be pure silicon. The silicon-containing film may also include Si a O b C c N d H e Where a, b, c, d, and e are in the range of 0.1 to 6, and b, c, d, and e can each be 0 independently. Alternatively, any silicon-containing layer may also include dopants such as B, C, P, As, and / or Ge.

[0027] The term "substrate" refers to one or more materials on which processes are performed. A substrate can refer to a wafer having one or more materials on which processes are performed. A substrate can be any suitable wafer used in the manufacture of semiconductor, photovoltaic, flat panel, or LCD-TFT devices. A substrate can also have one or more layers of different materials deposited thereon by previous manufacturing steps. For example, a wafer can include silicon layers (e.g., crystalline, amorphous, porous, etc.), silicon-containing layers (e.g., SiO2, SiN, SiON, SiC, SiCN, SiOCN, SiCOH, etc.), metal-containing layers (e.g., copper, cobalt, ruthenium, tungsten, manganese, platinum, palladium, nickel, ruthenium, gold, etc.), or combinations thereof. Furthermore, a substrate can be planar or patterned. A substrate can be an organically patterned photoresist film. The substrate may include oxide layers (e.g., ZrO2-based materials, HfO2-based materials, TiO2-based materials, rare earth oxide-based materials, ternary oxide-based materials, etc.) used as dielectric materials in MEMS, 3D NAND, MIM, DRAM, or FeRam device applications, or nitride-based films (e.g., TaN, TiN, NbN) used as electrodes. Those skilled in the art will recognize that the terms "film" or "layer" as used herein refer to a material of a certain thickness laid or spread on a surface, and that surface may be a trench or a line. Throughout this specification and claims, the wafer and any associated layers thereon are referred to as the substrate.

[0028] In this document, it is noted that the terms “film” and “layer” are used interchangeably. It is to be understood that a film can correspond to or be associated with a layer, and a layer can refer to a film. Furthermore, those skilled in the art will recognize that, as used herein, the terms “film” or “layer” refer to a material of a certain thickness laid or spread on a surface, and that the surface can be as large as an entire wafer to as small as a trench or line.

[0029] The terms "wafer," "patterned wafer," or "workpiece" refer to a wafer having a stack of films on a substrate, wherein at least the topmost film has morphological features that have been progressively created prior to the deposition of an indium-containing film. A "wafer" or "patterned wafer" refers to a wafer having a stack of films on a substrate and a patterned hardmask layer formed on the stack of films for pattern etching.

[0030] As used herein, the term “processing” includes patterning, exposure, development, etching, deposition, cleaning, and / or removal of by-products required to form the structure described herein.

[0031] The term "mask" refers to an etch-resistant layer. A mask layer can be placed on top of the layer to be etched. A mask layer also refers to a hard mask layer.

[0032] The term "aspect ratio" refers to the ratio of the height of a groove (or aperture) to the width of the groove (or the diameter of the aperture).

[0033] The term "high aspect ratio (HAR)" refers to an aspect ratio of about 1:1 to about 500:1, preferably about 20:1 to about 400:1.

[0034] The term "high aspect ratio etching" refers to the formation of a hole pattern in a target film by plasma etching when the aspect ratio of the formed hole structure exceeds a value of 5.

[0035] Note in this document that the terms “aperture,” “via,” “hole,” “trench,” and “structure” are used interchangeably and generally refer to an opening formed in a semiconductor structure and / or in an interlayer insulator.

[0036] The terms "dope" or "doping" are used interchangeably for the process of incorporating one or more elements into a membrane by various methods, where the elements can be chemically or physically bonded, and for the intentional incorporation of atoms of different elements into a membrane composition. Elements can be used for interstitial doping or substitution doping within the membrane.

[0037] As used in this article, the abbreviation "NAND" refers to a "Negated AND" or "Not AND" gate; the abbreviation "2D" refers to a 2D gate structure on a planar substrate; and the abbreviation "3D" refers to a 3D or vertical gate structure in which gate structures are stacked in the vertical direction.

[0038] As used herein, the term "film forming composition" refers to a mixture of components used for deposition that may contain precursors, catalysts, surfactants, wetting agents, and other polymers, oligomers, or monomers, such as, but not limited to, polysilazane, polycarbosilane, polysilane, etc.

[0039] As used herein, the term "hydrocarbon" refers to a saturated or unsaturated functional group containing only carbon and hydrogen atoms. As used herein, the term "alkyl" refers to a saturated functional group containing only carbon and hydrogen atoms. An alkyl group is a type of hydrocarbon. Furthermore, the term "alkyl" refers to a linear, branched, or cyclic alkyl group. Examples of linear alkyl groups include, but are not limited to, methyl, ethyl, propyl, butyl, etc. Examples of branched alkyl groups include, but are not limited to, tert-butyl. Examples of cyclic alkyl groups include, but are not limited to, cyclopropyl, cyclopentyl, cyclohexyl, etc.

[0040] As used herein, the term "hydrofluorocarbon" refers to a saturated or unsaturated functional group containing only carbon, fluorine, and hydrogen atoms.

[0041] As used herein, the term "fluorocarbon" refers to a saturated or unsaturated functional group containing only fluorine and hydrogen atoms.

[0042] As used herein, the term "alkyl" refers to a saturated functional group containing only carbon and hydrogen atoms. An alkyl group is a type of hydrocarbon. Furthermore, the term "alkyl" refers to a linear, branched, or cyclic alkyl group. Examples of linear alkyl groups include, but are not limited to, methyl, ethyl, propyl, butyl, etc. Examples of branched alkyl groups include, but are not limited to, tert-butyl. Examples of cyclic alkyl groups include, but are not limited to, cyclopropyl, cyclopentyl, cyclohexyl, etc.

[0043] As used in this article, the abbreviation "Me" refers to methyl; the abbreviation "Et" refers to ethyl; the abbreviation "Pr" refers to any propyl group (i.e., n-propyl or isopropyl); the abbreviation "iPr" refers to isopropyl; the abbreviation "Bu" refers to any butyl group (n-butyl, isobutyl, tert-butyl, sec-butyl); the abbreviation "tBu" refers to tert-butyl; the abbreviation "sBu" refers to sec-butyl; the abbreviation "iBu" refers to isobutyl; the abbreviation "Ph" refers to phenyl; the abbreviation "Am" refers to any pentyl group (isopentyl, sec-pentyl, tert-pentyl); the abbreviation "Cy" refers to cyclic hydrocarbon groups (cyclobutyl, cyclopentyl, cyclohexyl, etc.); and the abbreviation "Ar" refers to aromatic hydrocarbon groups (phenyl, xylyl, mesitylene, etc.).

[0044] The standard abbreviations of the elements in the periodic table are used in this article. It should be understood that elements may be referred to by these abbreviations (for example, 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.).

[0045] When used in the context of describing an R group, the term "independently" should be understood to mean that the R group is chosen independently not only relative to other R groups with the same or different subscripts or superscripts, but also independently relative to any other class of the same R group. For example, in the formula MR 1 x (NR 2 R 3 ) (4-x) (Where M is an atom, and x is 2 or 3) two or three R 1 Groups can, but do not need to, be identical to each other or to R. 2 Or R 3 The same. Furthermore, it should be understood that, unless otherwise explicitly stated, the values ​​of the R group are independent of each other when used in different formulas.

[0046] A range may be expressed herein as from approximately one particular value and / or to approximately another particular value. When expressing such a range, it should be understood that another embodiment is from one particular value and / or to another particular value, and all combinations within said range. Any and all ranges listed herein include their endpoints (i.e., x = 1 to 4 or x range from 1 to 4 including x = 1, x = 4, and x = any number therebetween), regardless of whether the term "inclusively" is used.

[0047] Optional or alternative means that the event or situation described below may or may not occur. The description includes both scenarios in which the event or situation will occur and scenarios in which it will not occur.

[0048] The phrase "an embodiment" or "implementation" as used herein refers to a particular feature, structure, or characteristic described in connection with that embodiment that may be included in at least one embodiment of the invention. The appearance of the phrase "in an embodiment" throughout the specification does not necessarily refer to the same embodiment, and separate or alternative embodiments are not necessarily mutually exclusive. The same applies to the term "implementation."

[0049] As used herein, the word “exemplary” is used to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, the use of the word “exemplary” is intended to present the concept in a specific manner.

[0050] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clearly apparent from the context, "X uses A or B" is intended to mean any natural inclusive arrangement. That is, if X uses A; X uses B; or X uses both A and B, then "X uses A or B" is satisfied in any of the foregoing cases. Additionally, the articles "a" and "an" as used in this application and the appended claims should generally be interpreted as meaning "one or more", unless otherwise specified or clearly apparent from the context to the singular form.

[0051] The term “comprising” in the claims is an open-ended transitional term, meaning that the subsequently confirmed claim elements are a non-exclusive list (i.e., may include any other content and still be within the scope of “comprising”). “Comprising” is defined herein as necessarily encompassing the more restrictive transitional terms “substantially composed of” and “composed of”; “comprising” can therefore be replaced by “substantially composed of” and “composed of”, and still remain within the explicitly defined scope of “comprising”.

[0052] In the claims, "providing" is defined as furnishing, supplying, making available, or preparing something. In the absence of explicit language to the contrary in the claims, this step can be performed by any participant. Brief description of the attached diagram

[0054] To further understand the nature and purpose of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, wherein similar elements are given the same or similar reference numerals, and wherein: Figure 1Thermogravimetric analysis (TGA) plots are displayed, demonstrating the weight percentage of bis(tris-sec-butylcyclopentadienyl)strontium(II),Sr(sBu3Cp)2 as temperature increases; Figure 2 The differential thermal analysis (DTA) plot shows the melting point of bis(tris-sec-butylcyclopentadienyl)strontium(II),Sr(sBu3Cp)2; Figure 3 Differential scanning calorimetry (DSC) shows the difference between bis(tris-sec-butylcyclopentadienyl)strontium(II),Sr(sBu3Cp)2. Figure 4 The TGA graph shows the weight percentage of bis(tris-sec-butylcyclopentadienyl)barium(II), Ba(sBu3Cp)2 as the temperature increases; Figure 5 The DTA plot shows the melting point of bis(tris-sec-butylcyclopentadienyl)barium(II), Ba(sBu3Cp)2; Figure 6 The DTA plot shows the melting point of bis(tris-isopropylcyclopentadienyl)strontium(II),Sr(iPr3Cp)2; Figure 7 The DTA plot shows the melting point of bis(tri-tert-butylcyclopentadienyl)strontium(II),Sr(tBu3Cp)2; Figure 8 The DTA plot shows the melting point of bis(tris-isopropylcyclopentadienyl)barium(II), Ba(iPr3Cp)2; Figure 9 Show comparison table; and Figure 10 The ALD window displays bis(tri-sec-butylcyclopentadienyl)strontium(II),Sr(sBu3Cp)2.

[0055] Description of preferred implementation scheme

[0056] Film-forming compositions containing Group 2 metals and films deposited using the same are disclosed. More specifically, a new class of thermally stable liquid Group 2 organometallic compounds and their use in depositing Group 2 metal-containing films by ALD or MOCVD methods are disclosed.

[0057] Film-forming compositions containing Group 2 metals may contain stereometallocenes, such as trialkyl-substituted cyclopentadienyl Ca, Sr, or Ba compounds, which are among the most promising precursors for film deposition in superconductor and semiconductor manufacturing due to their high volatility, thermal stability, stable monomer structure, and relatively low melting point.

[0058] However, most space metallocenes are solids at room temperature. For example, the melting points of some exemplary space metallocenes are listed in the table: Table 1

[0059] In the solid state, spatial metallocenes typically exhibit strong intermolecular attraction and are tightly packed in a regular pattern. Therefore, if the molecular structure has asymmetric ligands or long, flexible alkyl chains, disorder may result in lattice packing, and the material tends to be liquid-like.

[0060] The disclosed film-forming compositions containing Group 2 metals include alkaline earth metal precursors. These alkaline earth metal precursors can be developed by introducing alkyl chains that are more flexible and linear than isopropyl or tert-butyl into cyclopentadienyl-alkaline earth metal compounds to increase the degrees of freedom in the molecule.

[0061] The disclosed alkaline earth metal precursors have the following general formula:

[0062] Where M = Be, Mg, Ca, Sr, or Ba; R 1 - R 6 Each is independently C1-C 10 Alkyl, fluorinated, alkylsilyl, methylgermanyl, alkylamide or alkylsilylamide.

[0063] Exemplary alkaline earth metal precursors include bis(tri-sec-butylcyclopentadienyl)strontium(II)Sr(sBu3Cp)2, bis(tri-sec-butylcyclopentadienyl)barium(II)Ba(sBu3Cp)2, bis(tri-isopropylcyclopentadienyl)strontium(II)Sr(iPr3Cp)2, bis(tri-tert-butylcyclopentadienyl)strontium(II)Sr(tBu3Cp)2, bis(tri-isopropylcyclopentadienyl)barium(II)Ba(iPr3Cp)2, etc.

[0064] The disclosed film-forming composition containing a Group 2 metal comprises the liquid alkaline earth metal precursor bis(tris-sec-butylcyclopentadienyl)strontium(II), Sr(sBu3Cp)2.

[0065] The disclosed film-forming composition containing a Group 2 metal comprises the liquid alkaline earth metal precursor bis(tris-sec-butylcyclopentadienyl)barium(II), Ba(sBu3Cp)2.

[0066] The disclosed film-forming composition containing a Group 2 metal comprises the liquid alkaline earth metal precursor bis(tri-isopropylcyclopentadienyl)strontium(II),Sr(iPr3Cp)2.

[0067] The disclosed film-forming composition containing a Group 2 metal comprises the liquid alkaline earth metal precursor bis(tri-tert-butylcyclopentadienyl)strontium(II), Sr(tBu3Cp)2.

[0068] The disclosed film-forming composition containing a Group 2 metal comprises the liquid alkaline earth metal precursor bis(tris-isopropylcyclopentadienyl)barium(II), Ba(iPr3Cp)2.

[0069] The disclosed alkaline earth metal precursors are liquid at atmospheric pressure and suitable for depositing metal-containing films, such as SrO or BaO films, via vapor deposition methods (e.g., ALD or MOCVD), and have the following advantages: Typically, compared to solid precursors, even in solution, the disclosed alkaline earth metal precursors generate fewer particles; for example, no particles are blown into the precursor delivery line and thus into the wafer processing within the chamber. Furthermore, the disclosed alkaline earth metal precursors reduce the frequency of chamber maintenance, resulting in a longer chamber lifespan than when using solid precursors. • Compared to solid precursors that accumulate over time during heating and exhibit variable particle surface areas to generate non-constant vapor pressures, liquid precursors have the advantage of producing very constant material delivery due to the constant surface area within the vessel.

[0070] Although the disclosed alkaline earth metal precursors are ideally liquid and vaporized in a bubbler or direct liquid injection system, it is also possible to use solid precursors for ALD precursor vaporization using existing sublimation equipment. Alternatively, the solid precursors can be mixed or dissolved in a solvent to achieve a melting point and viscosity usable by a direct liquid injection system. Alternatively, the liquid precursors can also be mixed with a solvent to reduce their viscosity.

[0071] The solvent can be a substituted or unsubstituted hydrocarbon, such as alkanes, alkenes, alkynes, etc.; alcohols, such as alkyl alcohols, amino alcohols, etc.; or amines, such as primary amines, secondary amines, tertiary amines; tetrahydrofuran; dichloromethane; ethyl acetate; butyl acetate; acetonitrile; dimethylformamide. Hydrocarbons may include octane, ethylbenzene, xylene, mesitylene, decahydronaphthalene, decane, dodecane, etc. The concentration of the alkaline earth metal precursor in the solvent varies; for example, the concentration of the alkaline earth metal precursor in the solvent can range from about 50% w / w to about 100.0% w / w. Preferably, the solvent content in the mixture of the liquid precursor and the solvent is in the range of 0% to about 50%.

[0072] The disclosed metal-containing film-forming composition may contain an alkaline earth metal precursor between about 50% w / w and about 100.0% w / w.

[0073] To ensure process reliability, the disclosed alkaline earth metal precursors can be purified to a purity of about 95% by weight or from about 100% by weight, preferably from about 99% by weight to about 99.999% by weight, and more preferably from about 99% by weight to about 100% by weight, by continuous or fractional distillation or sublimation before use.

[0074] The disclosed alkaline earth metal precursors may contain any of the following impurities: undesired congeneric species; solvents; metal chloride compounds; or other reaction products. In one alternative, the total amount of these impurities is less than 5.0% w / w, preferably less than 0.1% w / w.

[0075] Solvents such as hexane, pentane, dimethyl ether, or anisole can be used in the synthesis of the precursor. The solvent concentration in the disclosed metal-containing precursor can be from about 0% w / w to about 5% w / w, preferably from about 0% w / w to about 0.1% w / w. Separation of the solvent from the precursor can be difficult if both have similar boiling points. Cooling the mixture in a liquid solvent can produce a solid precursor, which can be separated by filtration. Vacuum distillation can also be used, provided that the precursor product is not heated above approximately its decomposition point.

[0076] In one alternative, the disclosed alkaline earth metal precursor contains less than 5% v / v, preferably less than 1% v / v, more preferably less than 0.1% v / v, and even more preferably less than 0.01% v / v of any undesirable similar substance, reactant, or other reaction product. This alternative provides better process reproducibility. This alternative can be produced by distillation of the disclosed alkaline earth metal precursor.

[0077] In another alternative, the disclosed alkaline earth metal precursor may contain one or more congeneric metal-containing precursors, reactants, or other reaction products at a concentration between 5% v / v and 50% v / v, particularly when the mixture provides improved process parameters or when the separation of the target compound is too difficult or expensive. For example, a mixture of two alkaline earth metal precursors may produce a stable liquid mixture suitable for vapor deposition.

[0078] In another alternative, the disclosed alkaline earth metal precursor may contain metal impurities ranging from about 0 ppbw to about 500 ppbw.

[0079] The concentrations of trace metals and metalloids in the disclosed alkaline earth metal precursors can each be in the range of about 0 ppb to about 100 ppb, more preferably from about 0 ppb to about 10 ppb.

[0080] In addition to the disclosed alkaline earth metal precursor, reactants or co-reactants can be introduced into the reaction chamber. Co-reactants can be oxygen-containing or nitrogen-containing gases used for metal oxide film deposition. Co-reactants include, but are not limited to, oxidants such as O3, O2, H2O, H2O2, D2O, and ROH (R = C1 – C2O). 10 Linear or branched hydrocarbons, etc.

[0081] ALD sequences can include sequential pulses of several compounds. For example, a surface can be exposed to O2 / O3, followed by H2O, to increase the density of hydroxyl groups on the surface.

[0082] Alternatively, the co-reactant can be a nitrogen-containing gas used for nitrogen-containing film deposition. Nitrogen-containing gases include, but are not limited to, NH3, NO, N2O, hydrazine, primary amines such as methylamine, ethylamine, and tert-butylamine; secondary amines such as dimethylamine, diethylamine, diisopropylamine, ethylmethylamine, and pyrrolidine; tertiary amines such as trimethylamine, triethylamine, and trimethylsilylamine; N2; N2 / H2 mixtures thereof; and preferably NH3. The co-reactant can be selected from NH3, NO, N2O, hydrazine, amines, or combinations thereof.

[0083] A method or process for forming a film containing a Group 2 metal on a substrate by vapor deposition is also disclosed. In one embodiment, the method for forming a film containing a Group 2 metal on a substrate includes the following steps: a) providing a substrate in a reaction chamber; b) exposing the substrate to a vapor containing a film-forming composition of the disclosed Group 2 metal, the composition containing the disclosed alkaline earth metal precursor; c) depositing at least a portion of the disclosed alkaline earth metal precursor onto the substrate by vapor deposition to form a film containing a Group 2 metal; and repeating b) and c) until a film containing a Group 2 metal of the desired thickness is formed.

[0084] The method further includes, after step b), exposing the substrate to a co-reactant, wherein the co-reactant is selected from O3, O2, H2O, H2O2, D2O, ROH (R = C1 – C2O). 10 (Linear or branched) hydrocarbons, NH3, NO, N2O, hydrazine, amines, or combinations thereof. For example, one or a combination of the above co-reactants can be used to deposit silicon oxynitride films by co-flow or sequential deposition of the co-reactants.

[0085] In an alternative embodiment, a method for forming a film containing a Group 2 metal on a substrate includes the steps of: a) providing a substrate in a reaction chamber, b) exposing the substrate to the vapor of a disclosed film-forming composition containing a Group 2 metal, the composition containing a disclosed alkaline earth metal precursor, such as bis(tri-sec-butylcyclopentadienyl)strontium(II)Sr(sBu3Cp)2, bis(tri-sec-butylcyclopentadienyl)barium(II)Ba(sBu3Cp)2, bis(tri-isopropylcyclopentadienyl)strontium(II)Sr(iPr3Cp)2, bis(tri-tert-butylcyclopentadienyl)strontium(II)Sr(tBu3Cp)2, bis(tri-isopropylcyclopentadienyl)barium(II)Ba(iPr3Cp)2, and c) depositing a film containing a Group 2 metal on the substrate in a vapor deposition process. The method further includes, after step b), exposing the substrate to a co-reactant, wherein the co-reactant is selected from O3, O2, H2O, H2O2, D2O, ROH (R = C1 – C2O). 10 (Linear or branched) hydrocarbons, NH3, NO, N2O, hydrazine, amines, or combinations thereof. The method further comprises the following steps: repeated exposure to the vapor of the film-forming composition containing the Group 2 metal and exposure to the co-reactant until a film containing the Group 2 metal of desired thickness is formed; and purging excess vapor of the film-forming composition containing the Group 2 metal and excess co-reactant separately with an inert gas, wherein the inert gas is N2, Ar, Kr, or Xe.

[0086] The disclosed methods using the disclosed alkaline earth metal precursors include ALD methods for depositing films containing Group 2 metals. Suitable ALD methods include thermal ALD, spatial ALD, and temporal ALD. Suitable ALD methods may also include plasma ALD methods. Preferably, suitable ALD methods do not use plasma because it is difficult to grow conformal films at high aspect ratios with this type of ALD. It should be understood that suitable ALD can operate under imperfect self-limiting growth conditions to allow some parasitic CVD to occur. This parasitic CVD may not be a problem as long as the deposited film meets the conformality requirements.

[0087] The disclosed methods using the disclosed alkaline earth metal precursors also include MOCVD for depositing films containing Group 2 metals.

[0088] The reaction chamber can be any enclosed space or room of the apparatus in which the deposition method is performed, such as, but not limited to, a parallel-plate type reaction chamber, a hot-wall type reaction chamber, a single-wafer reaction chamber, a multi-wafer reaction chamber, or other deposition systems of this type. All of these exemplary reaction chambers can serve as ALD reaction chambers.

[0089] The reaction chamber contains one or more substrates on which films will be deposited. A substrate is generally defined as the material on which the process is performed. The substrate is cleaned to remove native oxides and dried prior to deposition. The substrate can be any suitable substrate used in the manufacture of semiconductor, photovoltaic, flat panel, or LCD-TFT devices. Examples of suitable substrates include wafers, such as metals (e.g., W, Ge, etc.), silicon, SiGe, silicon dioxide, or glass. The substrate may also have surface regions of one or more different materials that have already been deposited thereon by previous manufacturing steps. For example, a wafer may include simultaneously exposed dielectric and conductive or electrode surfaces, such as metal surfaces, metal oxide surfaces, silicon surfaces, silicon layers (crystalline, amorphous, porous, etc.), silicon oxide layers / surfaces, silicon nitride layers / surfaces, silicon oxynitride layers / surfaces, carbon-doped silicon oxide (SiCOH) layers / surfaces, or combinations thereof. Additionally, a wafer may include copper, cobalt, ruthenium, tungsten, and / or other metal layers (e.g., platinum, palladium, nickel, ruthenium, or gold). The wafer may include barrier layers or electrodes, such as tantalum, tantalum nitride, etc. The wafer may be planar or patterned. The substrate may include an oxide layer having an exposed oxide surface and used as a dielectric material in 3D NAND, MIM, DRAM, or FeRam technologies (e.g., ZrO2-based materials, HfO2-based materials, TiO2-based materials, rare earth oxide-based materials, ternary oxide-based materials, etc.), or a nitride-based film (e.g., TaN, TiN, NbN) used as an electrode. The disclosed methods may deposit the metal-containing layer directly onto the wafer or directly onto one or more layers on top of the wafer (when a patterned layer forms the substrate). Furthermore, those skilled in the art will recognize that the terms "film" or "layer" as used herein refer to a material of a certain thickness laid or spread on a surface, and that surface may be trenches or lines. Throughout this specification and claims, the wafer and any associated layers / surfaces thereon are referred to as the substrate. The actual substrate used may also depend on the specific precursor embodiment used.

[0090] The disclosed method can be used on substrates having a temperature range from room temperature to about 500°C to use alkaline earth metal precursors.

[0091] The temperature of the reaction chamber can be controlled by controlling the temperature of the substrate support or by controlling the temperature of the reaction chamber walls. Devices for heating the substrate are known in the art. Heating the reaction chamber walls to a sufficient temperature allows for obtaining the desired membrane at a sufficient growth rate and with the desired physical state and composition. Non-limiting exemplary temperature ranges to which the reaction chamber walls can be heated include room temperature to approximately 500°C.

[0092] In the disclosed method using the disclosed precursor, the substrate exposure time in the reaction chamber can be from 1 millisecond to 5 minutes, preferably from 1 millisecond to 60 seconds. In the disclosed method, the co-reactant exposure time in the reaction chamber can be from 1 millisecond to 1 minute, preferably from 100 milliseconds to 30 seconds.

[0093] The pressure within the reaction chamber is maintained under conditions suitable for the reaction between the precursor and the substrate surface. For example, the pressure in the chamber can be maintained between about 0.1 millitors (mTorr) and about 1,000 torr, preferably between about 1 millitor and about 400 torr, more preferably between about 0.1 torr and about 100 torr, and even more preferably between about 0.5 torr and about 10 torr.

[0094] The disclosed methods or sequences typically include the removal of excess precursors and excess co-reactants from the deposition surface by providing a purging step, which involves purging the reaction chamber with an inert gas or passing the substrate through a high-vacuum section and / or a carrier gas curtain. The inert gas is N2, Ne, Ar, Kr, or Xe, preferably N2 or Ar.

[0095] The disclosed alkaline earth metal precursor and co-reactant can be sequentially introduced into the reaction chamber (ALD). The reaction chamber can be purged with an inert gas between and after the introduction of the precursor and co-reactant. Alternatively, the substrate can be moved from one precursor exposure zone to another co-reactant exposure zone (space ALD).

[0096] Depending on the specific process parameters, deposition can be carried out for varying durations. Typically, deposition can be allowed to continue for the desired or necessary duration to produce a film of the required thickness. Typical film thicknesses can range from atomic monolayers to hundreds of micrometers, depending on the specific deposition process, preferably between 0.1 and 100 nm, more preferably between 0.1 and 50 nm. The deposition process can also be performed multiple times as needed to obtain the desired film.

[0097] In a non-limiting exemplary ALD process, the gaseous phase of the disclosed alkaline earth metal precursor is introduced into a reaction chamber, where it is physically or chemically adsorbed onto a substrate. Excess composition can then be removed from the reaction chamber by purging and / or evacuating the chamber. A desired gas (e.g., an oxidant H₂O or O₃) is introduced into the reaction chamber, where it reacts with the physically or chemically adsorbed precursor in a self-limiting manner. Any excess oxidant gas is removed from the reaction chamber by purging and / or evacuating the chamber.

[0098] Example

[0099] The following non-limiting embodiments are provided to further illustrate implementations of the invention. However, these embodiments are not intended to be all-encompassing, nor are they intended to limit the scope of the invention described herein.

[0100] Example 1 Synthesis of bis(tris-sec-butylcyclopentadienyl)strontium(II),Sr(sBu3Cp)2

[0101] A solution of K(sBu3Cp) (3.3 g, 12.11 mmol) was added dropwise to a solution of SrI2 (1.88 g, 5.51 mmol) in 30 mL THF at -30 °C. The reaction mixture was slowly heated to room temperature with stirring overnight. After filtration, the solvent was removed under reduced pressure to obtain a brown liquid. This material was then purified by distillation at 130 °C @ 25 mTorr to give 1.2 g (40.0%) of yellow oil. The material was analyzed by NMR. 1 H (δ, ppm, C6D6) characterization: 5.62 (m, 4H), 2.57 (m, 6H), 1.52 (m, 12H), 1.34, 1.18 (m, 18H), 0.96, 0.88 (m, 18H).

[0102] The purified product left a 3.8% residual mass and did not exhibit a melting point during open-cup TGA / DTA analysis measured at a heating rate of 10 °C / min under an inert atmosphere with nitrogen flowing in at 200 mL / min. These results show... Figure 1 and Figure 2 The figure shows TGA and DTA plots illustrating weight (%) and heat flux at elevated temperatures. The decomposition onset temperature (430°C) of the product was measured by differential scanning calorimetry (DSC), and it is shown in the figure. Figure 3 middle.

[0103] Figure 10 The ALD window of bis(tris-sec-butylcyclopentadienyl)strontium(II),Sr(sBu3Cp)2 is shown. Pyrolysis tests show that the precursor Sr(sBu3Cp)2 is stable up to 450 °C and decomposes above 500 °C. This demonstrates the thermal stability of this novel Sr precursor, allowing it to be deposited as an SrO film using a high-temperature ozone process.

[0104] Example 2 Synthesis of bis(tris-sec-butylcyclopentadienyl)barium(II), Ba(sBu3Cp)2

[0105] A solution of K(sBu3Cp) (3.2 g, 11.76 mmol) was added dropwise to a solution of BaI2 (2 g, 5.1 mmol) in 30 mL THF at -30 °C. The reaction mixture was slowly heated to room temperature with stirring overnight. After filtration, the solvent was removed under reduced pressure to obtain a brown liquid. This material was then purified by distillation at 130 °C @ 25 mTorr to give 1.0 g (32.5%) of yellow oil. The material was analyzed by NMR. 1 H (δ, ppm, C6D6) characterization: 5.5 (m, 4H), 2.63 (m, 6H), 1.66, 1.54 (m, 12H), 1.27, 1.20 (m, 18H), 0.99 (m, 18H).

[0106] The purified product left a residual mass of 2.7% and did not exhibit a melting point during open-cup TGA / DTA analysis measured at a heating rate of 10 °C / min under an inert atmosphere with nitrogen flowing in at 200 mL / min. These results show... Figure 4 and Figure 5 The figure shows the TGA and DTA plots of weight (%) and heat flow as the temperature increases.

[0107] Comparative Example 1: Bis(tri-isopropylcyclopentadienyl)strontium(II), Sr(iPr3Cp)2

[0108] The melting point was 44 °C during open-cup DTA analysis measured in an inert atmosphere with nitrogen flowing in at a heating rate of 10 °C / min. These results show... Figure 6 The diagram shown is a DTA plot illustrating the heat flow as the temperature increases.

[0109] Comparative Example 2: Bis(tri-tert-butylcyclopentadienyl)strontium(II), Sr(tBu3Cp)2

[0110] The melting point was 143 °C during open-cup DTA analysis, measured at a heating rate of 10 °C / min in an inert atmosphere with nitrogen flowing in at 200 mL / min. These results show... Figure 7 The diagram shown is a DTA plot illustrating the heat flow as the temperature increases.

[0111] Comparative Example 3: Bis(tris-isopropylcyclopentadienyl)barium(II), Ba(iPr3Cp)2

[0112] The melting point was 92 °C during open-cup DTA analysis measured in an inert atmosphere with nitrogen flowing in at a heating rate of 10 °C / min. These results show... Figure 8 The diagram shown is a DTA plot illustrating the heat flow as the temperature increases.

[0113] Pyrolysis tests showed that the precursor was stable up to 450°C and decomposed above 500°C. This demonstrates that the novel Sr precursor is thermally stable, allowing for the deposition of SrO films using a high-temperature ozone process. Figure 9 Display a comparison table.

[0114] It should be understood that those skilled in the art can make many additional changes to the details, materials, steps, and arrangements of components that have been described and exemplified herein for the purpose of explaining the nature of the invention, within the principles and scope of the invention as set forth in the appended claims. Therefore, the invention is not intended to be limited to the specific embodiments given above and / or in the accompanying drawings.

[0115] Although embodiments of the invention have been shown and described, modifications can be made thereto by those skilled in the art without departing from the spirit or teachings of the invention. The embodiments described herein are exemplary only and not limiting. Many variations and modifications of the compositions and methods are possible and within the scope of the invention. Therefore, the scope of protection is not limited to the embodiments described herein, but is limited only by the following claims, the scope of which should include all equivalents of the subject matter of the claims.

Claims

1. A method for forming a film containing a Group 2 metal on a substrate, the method comprising: a) Exposing the substrate to the vapor of a film-forming composition containing a Group 2 metal, the composition containing an alkaline earth metal precursor having the following formula: Where M is Be, Mg, Ca, Sr, or Ba; R 1 R 6 Each is C1 independently C 10 Alkyl, fluorinated, alkylsilyl, methylgermanyl, alkylamide or alkylsilylamide; b) Deposit at least a portion of the alkaline earth metal precursor onto the substrate by vapor deposition to form the film containing the Group 2 metal; and c) Repeat a) and b) until the desired thickness of the film containing the Group 2 metal is formed.

2. The method of claim 1, further comprising: The substrate is exposed to a co-reactant selected from oxidizing agents or nitriding agents.

3. The method according to claim 2, wherein the co-reactant is selected from O3, O2, H2O, H2O2, D2O, and ROH, wherein R = C1 – C 10 Linear or branched hydrocarbons, or combinations thereof.

4. The method according to claim 2, wherein the co-reactant is selected from NH3, NO, N2O, hydrazine, amine or a combination thereof.

5. The method according to claim 2, wherein the co-reactant is H2O.

6. The method according to claim 1, wherein the alkaline earth metal precursor is a liquid.

7. The method of claim 1, wherein the alkaline earth metal precursor is mixed with a solvent.

8. The method according to claim 7, wherein the solvent is a substituted or unsubstituted hydrocarbon selected from alkanes, alkenes, alkynes; an alcohol selected from alkyl alcohols, amino alcohols; or an amine selected from primary amines, secondary amines, tertiary amines; tetrahydrofuran; dichloromethane; ethyl acetate; butyl acetate; acetonitrile; dimethylformamide.

9. The method according to any one of claims 1 to 8, wherein the substrate is exposed to the vapor of the film-forming composition containing the Group 2 metal at a temperature from room temperature to about 500°C.

10. The method according to any one of claims 1 to 8, wherein the alkaline earth metal precursor is selected from bis(tri-sec-butylcyclopentadienyl)strontium(II)Sr(sBu3Cp)2, bis(tri-sec-butylcyclopentadienyl)barium(II)Ba(sBu3Cp)2, bis(tri-isopropylcyclopentadienyl)strontium(II)Sr(iPr3Cp)2, bis(tri-tert-butylcyclopentadienyl)strontium(II)Sr(tBu3Cp)2, and bis(tri-isopropyl and cyclopentadienyl)barium(II)Ba(iPr3Cp)2.

11. The method according to any one of claims 1 to 8, wherein the alkaline earth metal precursor is bis(tris-sec-butylcyclopentadienyl)strontium(II), Sr(sBu3Cp)2.

12. The method according to any one of claims 1 to 8, wherein the alkaline earth metal precursor is bis(tris-sec-butylcyclopentadienyl)barium(II), Ba(sBu3Cp)2.

13. The method according to any one of claims 1 to 8, wherein the vapor deposition method is MOCVD or an ALD method selected from thermal ALD, spatial ALD, temporal ALD or plasma ALD.

14. A method for depositing a SrO film on a substrate, the method comprising the following steps: a) Expose the substrate to vapors of bis(tris-sec-butylcyclopentadienyl)strontium(II),Sr(sBu3Cp)2; b) Expose the substrate to the co-reactant H2O; c) Deposit at least a portion of the alkaline earth metal precursor onto the substrate by vapor deposition to form an SrO film; and d) Repeat steps a)-c) until a SrO film of the desired thickness is formed.

15. A method for depositing a BaO film on a substrate, the method comprising the following steps: a) Expose the substrate to vapors of bis(tris-sec-butylcyclopentadienyl)barium(II), Ba(sBu3Cp)2; b) Expose the substrate to the co-reactant H2O; c) Deposit at least a portion of the alkaline earth metal precursor onto the substrate by vapor deposition to form a BaO film; and d) Repeat steps a)-c) until a BaO film of the desired thickness is formed.

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