Group 13 metal compounds for ALD applications

Abstract

The present invention relates to indium compounds and a method of using these compounds as precursors for deposition of indium-containing films, in particular by atomic layer deposition.

Description

[0001] Foreignfiling text P24-155. docx

[0002] - 1 -

[0003] Group 13 Metal Compounds for ALD Applications

[0004] Field

[0005] The present invention relates to indium compounds and a method of using these compounds as precursors for deposition of indium-containing films, in particular by

[0006] 5 atomic layer deposition (ALD).

[0007] Background Art

[0008] Metal-containing films are used in semiconductor and electronics applications. Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) have been applied as the

[0009] 10 main deposition techniques for producing thin films for semiconductor devices. These methods enable the achievement of conformal films (metal, metal oxide, metal nitride, metal silicide, and the like) through chemical reactions of metal-containing compounds (precursors). The chemical reactions occur on surfaces which may include metals, metal oxides, metal nitrides, metal silicides, and other surfaces. In CVD and ALD, the precursor molecule plays a critical role in achieving high quality films with high

[0010] 15 conformality and low impurities. The precursor needs to have an appropriate vapor pressure and sufficient thermal stability. Furthermore, it needs to be vaporizable in a stable supply amount for forming a thin film by CVD or ALD method. The temperature of the substrate in CVD and ALD processes is an important consideration in selecting a precursor molecule. The precursor molecules should preferably be stable at typical

[0011] 20 substrate temperatures, e.g. in the range of 150 to 600 °C. Furthermore, the preferred precursor is capable of being delivered to the reaction vessel in a liquid or gaseous phase. The liquid phase of precursors at volatilization temperature generally provides a more uniform delivery of the precursor to the reaction vessel than solid phase precursors. While it is sufficient that the precursor is a liquid at delivery temperature, it is

[0012] 25 preferable that the precursor is a liquid at room temperature. This has the advantage that condensation is less likely to occur if there is any cold spot in the precursor delivery system. Furthermore, the handling of a compound which is a liquid at room temperature is technically easier, e.g. the filling of the vessels from which the precursor is applied.

[0013] The ALD process deposits thin layers of solid materials using two or more different vapor

[0014] 30 phase precursors. The surface of a substrate onto which the film is to be deposited is exposed to a dose of vapor of a first precursor. Then any excess unreacted vapor from that precursor is pumped away, e.g. by inert gas purges. Next, a vapor dose of a second precursor is brought to the surface and allowed to react. This cycle of steps can be repeated to build up thicker films. One particularly important aspect of this process is that

[0015] 35 the ALD reactions are self-limiting in that only a certain maximum thickness can form in Foreignfiling text P24-155. docx

[0016] - 2 - each cycle, after which no further deposition occurs during that cycle, even if excess reactant is available. Because of this self-limiting character, ALD reactions produce coatings with highly uniform thicknesses not only on flat substrate surfaces, but also into narrow holes and trenches as well as other three-dimensional surfaces, which renders this technique indispensable for the semiconductor industry.

[0017] 5

[0018] Thin films containing indium have enormous technological significance. Such thin films can contain metallic indium or indium compounds, such as indium oxide, indium nitride, indium sulfide, etc.. In thin-film photovoltaics, mixed oxide-sulfides of indium act as electron-transport layers, and copper-indium-gallium-sulfide serves as an absorber layer.

[0019] 10 By far the most common use is in indium tin oxide (ITO), a transparent conducting oxide (TOO) widely used in flat-panel and touch-sensitive displays as well as thin-film solar cells. Furthermore, indium gallium zinc oxide (IGZO) from the group of TCOs is gaining more and more interest in the semiconductor industry. Due to increasing demand for highly conformal, very thin films containing indium as part of a multi-component composition, it would be advantageous to have highly volatile compounds with a low

[0020] 15 melting point having a low and wide ALD window as precursors for ALD of indium containing films.

[0021] Precursors for ALD of thin films comprising group 13 metals are widely dominated by alkyl precursors, such as trimethyl indium (TMI). These precursors have in common that

[0022] 20 they have a very high volatility and extreme reactivity enabling a large variety of ALD processes for a multitude of materials, such as for the respective metals, metal oxides, metal nitrides, metal sulfides and several inorganic-organic hybrid materials. However, the largest disadvantage is their high pyrophoricity which bears a high risk in handling these compounds and which necessitates strong safety regulations and renders them

[0023] 25 hazardous in case of accidents. Therefore, it is highly desirable to replace these compounds with compounds which do not show this disadvantage. Furthermore, the thermal stability is an issue in particular in the case of TMI which results in a non-existing or only very narrow ALD window and a maximum deposition temperature of 250 °C. Furthermore, TMI is solid at room temperature, thus resulting in fluctuating evaporation rates.

[0024] 30

[0025] Additionally, amidinate complexes, such as dialkyl indium amidinates, are known as precursors for ALD applications. WO 95 / 04063 discloses complexes of the formula MR2L for CVD applications wherein M = Al, Ga or In, R represents a Ci to Cs alkyl group, and L is an amidinate ligand. The only disclosed examples comprise either H or aromatic

[0026] 35 substituents on the N atoms of the amidinate ligand. All disclosed indium complexes are Foreignfiling text P24-155. docx

[0027] - 3 - solid at room temperature. Furthermore, for one of the indium complexes, the TGA curve has been measured showing a evaporation temperature of around 400 °C and a weight residue of more than 30 %. It can therefore be concluded that the compound is not stable during evaporation.

[0028] 5 WO 2006 / 012052 discloses precursors for CVD of the formula [R1NC(R2)NR3]xMLnwherein M is a main group or transition metal, R1, R2and R3are aliphatic or aromatic groups, and Lnis an ancillary ligand array. No indium complexes are disclosed.

[0029] KR 10-1221861 B1 discloses metal precursors of the formula [R3NC(X)N(R4)]lnR1R2

[0030] 10 wherein R1to R4are alkyl groups and X is an alkyl or dialkylamino group. No formamidinate complexes are disclosed.

[0031] WO 2021 / 200218 A1 discloses an ALD precursor of the formula LMR1R2wherein M is indium or gallium, R1and R2are H or alkyl, and L is a p-diketonate ligand or an amidinate ligand in which the substituents on the N atoms differ from each other. No

[0032] 15 formamidinate complexes are disclosed, and no TGA results are disclosed for the amidinate complex. The use of different substituents on the N atoms of the amidinate ligand has the technical disadvantage that it requires a considerably more complicated ligand synthesis.

[0033] 20 KR 2020-0083340 A discloses dimethylindium-bis(tert-butyl)acetamidinate as an ALD precursor, as well as dimethylindium-bis(iso-propyl)acetamidinate and further complexes with dialkylacetamidinate as comparative compounds. The evaporation properties of dimethylindium-bis(tert-butyl)acetamidinate and dimethylindium-bis(iso-propyl)- acetamidinate shown by TGA are very similar. However, there is still room for

[0034] 25 improvement with respect to the evaporation temperature.

[0035] In a method of forming a thin-film through the vaporization of a compound such as the CVD or ALD method, important properties that the compound to be used as a thin-film forming precursor (reactant) is required to have are as follows: its vapor pressure is high, i.e. its evaporation temperature is low; its melting point is low, and the compound is

[0036] 30 preferably a liquid at room temperature; its thermal stability is high; and the compound can produce a high-quality thin-film with high productivity, i.e. the reactivity towards the surface, the co-reactant and the deposited material is high and the reactions are clean, i.e. the reactions do essentially not produce any undesired byproducts on the surface. As discussed above, there is still room for improvement with respect to the amidinate

[0037] 35 compounds of the prior art. Accordingly, an object of the present invention is to provide Foreignfiling text P24-155. docx

[0038] - 4 - novel compounds, which have high vapor pressures, low melting points, and can each produce high-quality thin-films with high productivity when used as a thin-film forming raw material as compared to the related-art amidinate compounds. In particular, it is the object of the present invention to provide novel indium precursors which have a lower evaporation temperature. It is a particular advantage if the compound is a liquid at

[0039] 5 evaporation temperature, and in particular liquid at room temperature, as condensation is less likely to occur if there is any cold spot in the precursor delivery system. Furthermore, the handling of a compound which is a liquid at room temperature is technically easier, e.g. the filling of the vessels from which the precursor is applied.

[0040] 10 Surprisingly, it was found that modification of the amidinate ligand in dialkylindium amidinate complexes could significantly decrease the evaporation temperature and therefore increase the volatility of the resulting indium compounds compared to the indium compounds known in the prior art. These compounds, several of which are liquid at room temperature, furthermore have appropriate thermal stability and can be employed in a CVD or ALD method to form an indium-containing film. Such compounds are therefore the

[0041] 15 object of the present invention.

[0042] Summary

[0043] The disclosed and claimed subject matter is directed to a compound of the following formula (1):

[0044] 20

[0045] Formula (1) wherein the symbols used are as follows:

[0046] 30

[0047] R1, R2are on each occurrence, identically or differently, a tertiary alkyl group with 4, 5 or 6 carbon atoms;

[0048] R3, R4are on each occurrence, identically or differently, an alkyl group having 1 , 2 or 3 C atoms. Foreignfiling text P24-155. docx

[0049] - 5 -

[0050] The disclosed and claimed subject further includes compositions and formulations comprising the compound of formula (1) and methods of using the compound of formula (1) as precursor for deposition of indium-containing films.

[0051] Detailed description

[0052] 5 All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0053] 10 The use of the terms "a", "an", "the" and similar expressions in the context of describing the disclosed and claimed subject matter (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms ( / .e., meaning “including, but not limited to”) unless otherwise noted. Recitation of ranges of values herein are merely

[0054] 15 intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it was individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary

[0055] 20 language (e.g., “such as”) provided herein, is intended merely to better illuminate the disclosed and claimed subject matter and does not pose a limitation on the scope of the disclosed and claimed subject matter unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed and claimed subject matter. The use of the term “comprising” or

[0056] 25 “including” in the specification and the claims includes the narrower language of “consisting essentially of’ and “consisting of.”

[0057] Embodiments of the disclosed and claimed subject matter are described herein, including the best mode known to the inventors for carrying out the disclosed and claimed subject matter. Variations of those embodiments may become apparent to those of ordinary skill in

[0058] 30 the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the disclosed and claimed subject matter to be practiced otherwise than as specifically described herein. Accordingly, the disclosed and claimed subject matter includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by

[0059] 35 applicable law. Moreover, any combination of the above-described elements in all possible Foreignfiling text P24-155. docx

[0060] - 6 - variations thereof is encompassed by the disclosed and claimed subject matter unless otherwise indicated herein or otherwise clearly contradicted by context.

[0061] The group [R1N-CH-NR2]" in the compound of formula (1) is referred to as a “ligand”, "amidinate ligand” or “formamidinate ligand”.

[0062] 5

[0063] The compound according to the present invention is also referred to as “precursor” or “reactant” when the use of the compound in CVD or ALD deposition techniques is described.

[0064] 10 For ease of reference, “microelectronic device” or “semiconductor device” corresponds to semiconductor wafers having integrated circuits, memory, and other electronic structures fabricated thereon, and flat panel displays, phase change memory devices, solar panels and other products including solar substrates, photovoltaics, and microelectromechanical systems (MEMS), manufactured for use in microelectronic, integrated circuit, or computer chip applications. Solar substrates include, but are not

[0065] 15 limited to, silicon, amorphous silicon, polycrystalline silicon, monocrystalline silicon, CdTe, copper indium selenide, copper indium sulfide, and gallium arsenide on gallium. The solar substrates may be doped or undoped. It is to be understood that the term “microelectronic device” or “semiconductor device” is not meant to be limiting in any way and includes any substrate that will eventually become a microelectronic device or

[0066] 20 microelectronic assembly.

[0067] As defined herein, the term “barrier material” corresponds to any material used in the art to seal the metal lines, e.g., copper interconnects, to minimize the diffusion of said metal, e.g., copper, into the dielectric material. Preferred barrier layer materials include tantalum,

[0068] 25 titanium, ruthenium, hafnium, and other refractory metals and their nitrides and silicides.

[0069] Unless otherwise indicated, “alkyl” refers to hydrocarbon groups which can be linear (e.g. methyl, ethyl, n-propyl), branched (e.g., iso-propyl, tert-butyl) or cyclic (e.g., cyclopentyl). A tertiary alkyl groups is an alkyl group, which is bound via a tertiary carbon atom, i.e. via a C atom which is substituted by three C atoms (e.g., tert-butyl, tert-amyl =

[0070] 30 tert-pentyl, tert-hexyl).

[0071] “Substantially free” is defined herein as less than 0.001 wt.%. “Substantially free” also includes 0.000 wt.%. The term “free of’ means 0.000 wt.%. As used herein, "about" or “approximately” are intended to correspond to within ± 5% of the stated value. Foreignfiling text P24-155. docx

[0072] - 7 -

[0073] In all such compositions, wherein specific components of the composition are discussed in reference to weight percentage (or “weight %” or “wt.%”) ranges including a zero lower limit, it will be understood that such components may be present or absent in various specific embodiments of the composition, and that in instances where such components are present, they may be present at concentrations as low as 0.001 wt.%, based on the total weight of

[0074] 5 the composition in which such components are employed. All percentages of the components are weight percentages and are based on the total weight of the composition, / .e., 100%.

[0075] Moreover, when referring to the compositions described herein in terms of weight % or

[0076] 10 wt.%, it is understood that in no event shall the wt.% of all components, including non- essential components, such as impurities, add to more than 100 wt.%. In compositions “consisting essentially of’ recited components, such components may add up to 100 wt.% of the composition or may add up to less than 100 wt.%. Where the components add up to less than 100 wt.%, such composition may include some small amounts of a non-essential contaminants or impurities. For example, in one such embodiment, the formulation can

[0077] 15 contain 2 wt.% or less of impurities. In another embodiment, the formulation can contain 1 wt.% or less than of impurities. In a further embodiment, the formulation can contain 0.05 wt.% or less than of impurities. In other such embodiments, the constituents can form at least 90 wt.%, more preferably at least 95 wt.% , more preferably at least 99 wt.%, more preferably at least 99.5 wt.%, most preferably at least 99.9 wt.%, and can include other

[0078] 20 ingredients that do not or not significantly affect the deposition process. Otherwise, if no significant non-essential impurity component is present, it is understood that the composition of all essential constituent components will essentially add up to 100 wt.%.

[0079] Any reference to “one or more” or “at least one” includes “two or more” and “three or more”

[0080] 25 and so on.

[0081] The headings employed herein are not intended to be limiting; rather, they are included for organizational purposes only.

[0082] As described above, R1and R2are identically or differently at each instance a tertiary

[0083] 30 alkyl groups. Preferred groups R1are the same or different at each instance and are selected from the groups of the following structures R1-1 to R1-8, and preferred groups R2are selected from the groups of the following structures R2-1 to R2-8,

[0084] 35 Foreignfiling text P24-155. docx

[0085] 5

[0086] 10 wherein the dashed bond represents the bond to the N atom of the amidinate ligand. Preferred structures are tertiary alkyl groups having 4 or 5 C atoms, i.e. R1-1 / R2-1 , R1-2 I R2-2, R1-7 / R2-7 and R1-1 / R2-8. Particularly preferred are non-cyclic tertiary alkyl

[0087] 15 groups having 4 or 5 C atoms, i.e. R1-1 / R2-1 , R1-2 / R2-2, and most preferred, R1and R2are both tert-butyl.

[0088] In one embodiment of the invention, R1and R2are identical. In a further embodiment of the invention, R1and R2are different from each other. In a preferred embodiment of the

[0089] 20 invention, R1and R2are identical. This has the advantage of an easier ligand synthesis.

[0090] According to the invention, R3and R4are identically or differently at each instance an alkyl group having 1 to 3 C atoms, i.e. methyl, ethyl, n-propyl or iso-propyl. In a preferred embodiment of the invention, R3and R4are the same or different at each instance and

[0091] 25 are selected from methyl or ethyl, and particularly preferred, R3and R4are both methyl.

[0092] In one embodiment of the invention, R3and R4are identical. In a further embodiment of the invention, R3and R4are different from each other. In a preferred embodiment of the invention, R3and R4are identical. This has the advantage of an easier synthesis of the compound of formula (1).

[0093] 30

[0094] Suitable combinations of R1, R2, R3and R4are the compounds of Table 1.

[0095] 35 Foreignfiling text P24-155. docx

[0096] - 9 -

[0097] Table 1 :

[0098] 5

[0099] 10

[0100] 15

[0101] 20

[0102] A particularly preferred embodiment of the invention is the compound 1 in Table 1 , i.e. the following compound:

[0103] 25

[0104] 30 It is preferable that the compound of formula (1) or the preferred embodiments is essentially free of impurities. This refers in particular to metal impurities, organic byproducts and halogen impurities. The content of each of the impurity metal elements is preferably 10 ppm or less, more preferably 1 ppm or less, and the total content thereof is preferably 50 ppm or less, more preferably 10 ppm or less. The total content of the

[0105] 35 impurity halogens is preferably 100 ppm or less, more preferably 10 ppm or less, and most preferably 1 ppm or less. Foreignfiling text P24-155. docx

[0106] - 10 -

[0107] The compound of formula (1) and the preferred embodiments can be synthesized by reaction of an appropriate indium precursor lnR3R4X wherein R3and R4have the same meanings as defined above and X is a counteranion, such as halogen (F, Cl, Br, I, preferably Cl), triflate or tosylate, with the desired formamidinate salt, such as LiAMD,

[0108] 5 NaAMD or KAMD, preferably LiAMD, where AMD stands for the corresponding formamidinate ligand. This synthesis is shown in Scheme 1. The formamidinate salt can be prepared in situ from the corresponding formamidine by deprotonation in a solvent, wherein polar or non-polar aprotic solvents, such as THF, dioxane, diethylether, methyl- tert-butylether, dibutylether, hexane, pentane or toluene or mixtures thereof, are

[0109] 10 preferred. Suitable bases for the deprotonation of the formamidine are for example alkyllithium compounds, such as butyllithium, or alkali hydrides, such as LiH, NaH or KH.

[0110] 1) Base

[0111] 15 2) lnR3R4X

[0112] 20 An alternative synthesis method is the reaction of trialkylindium where the alkyl groups correspond to the alkyl groups R3and R4of the synthesized compound, such as trimethylindium for the synthesis of a compound with R3= R4= methyl, with a corresponding formamidine in a polar or non-polar aprotic solvent, such as THF, dioxane, diethylether, methyl-tert-butylether, dibutylether, hexane, pentane or toluene or mixtures thereof.

[0113] 25

[0114] The present invention is therefore further directed to a method of manufacturing a compound of formula (1) or the preferred embodiments wherein a compound lnR3R4X wherein R3, R4is same or different at each instance an alkyl group having 1 , 2 or 3 C atoms and X is a counterion, preferably F, Cl, Br, I, triflate or tosylate and particularly

[0115] 30 preferably Cl, is reacted with a formamidinate salt of the formula [cation]+[R1NCHNR2]" where R1and R2have the meanings as defined above and [cation]+is a suitable cation, preferably Li, Na or K and particularly preferably a Li or Na, or wherein a trialkylindium compound wherein alkyl corresponds to R3and R4as defined above is reacted with a formamidine of the formula R1HN-CH=NR2where R1and R2

[0116] 35 have the meanings as defined above. Foreignfiling text P24-155. docx

[0117] - 11 -

[0118] Method of Use

[0119] The disclosed compounds can be used as precursors (reactants) for the deposition of indium-containing films using any chemical vapor deposition process known to those of skill in the art. The precursor for forming a thin film, also referred to as “thin film forming

[0120] 5 precursor” comprises the compound according to the present invention and optionally further compounds, depending on the production process to which the precursor is applied. For example, when a thin film containing only indium as a metal is produced, the thin film forming precursor of the present invention is free of metal compounds other than the compound represented by the general formula (1). Meanwhile, when a thin film

[0121] 10 containing two or more kinds of metals is produced, the thin film forming precursor of the present invention may contain a compound containing a desired metal in addition to the compound represented by the general formula (1). The thin film forming precursor of the present invention may further contain an organic solvent. As described above, the physical properties of the compound represented by the general formula (1) are suitable for serving as the precursor for a CVD method, and hence the thin film forming precursor

[0122] 15 of the present invention is useful as a CVD precursor. In particular, the thin-film forming precursor of the present invention is particularly suitable for an ALD method because the compound represented by the general formula (1) has a self-limiting reaction behavior at the surface, i.e. is not reacting with the adsorbed surface precursor species.

[0123] 20 As used herein, the term “chemical vapor deposition process” (CVD) refers to any process wherein a substrate is exposed to one or more volatile precursors, which react and / or decompose on the substrate surface to produce the desired deposition. As used herein, the term “atomic layer deposition process” (ALD) refers to a self-limiting (e.g., the amount of film material deposited in each reaction cycle is constant), sequential surface chemistry

[0124] 25 that deposits films of materials onto substrates of varying compositions. Although the precursors, reagents and co-reagents used herein may be sometimes described as “gaseous,” it is understood that the precursors can be either liquid or solid at room temperature and / or at elevated temperature and are transported with or without an inert gas into the reactor via direct vaporization, bubbling or sublimation. In some cases, the vaporized precursors can pass through a plasma generator. The term “reactor” as used

[0125] 30 herein, includes without limitation the reaction chamber (reaction vessel, deposition chamber).

[0126] Chemical vapor deposition processes in which the disclosed and claimed compounds can be utilized as precursors include, but are not limited to, those used for the manufacture of

[0127] 35 semiconductor type microelectronic devices, such as ALD, CVD, pulsed CVD, plasma Foreignfiling text P24-155. docx

[0128] - 12 - enhanced ALD (PEALD) and / or plasma enhanced CVD (PECVD). Examples of suitable deposition processes for the method disclosed herein include, but are not limited to, cyclic CVD (CCVD), MOCVD (Metal Organic CVD), thermal chemical vapor deposition, plasma enhanced chemical vapor deposition (“PECVD”), high density PECVD, photon assisted CVD, plasma-photon assisted (“PPECVD”), cryogenic chemical vapor deposition, chemical

[0129] 5 assisted vapor deposition, hot-filament chemical vapor deposition, CVD of a liquid polymer precursor, deposition from supercritical fluids, low energy CVD (LECVD), roll-to-roll ALD, spatial ALD and atmospheric pressure ALD. In certain embodiments, the indium-containing films are deposited via atomic layer deposition (ALD), plasma enhanced ALD (PEALD) or plasma enhanced cyclic CVD (PECCVD) process.

[0130] 10

[0131] In one embodiment, the indium-containing film is deposited using an ALD process. In another embodiment, the indium-containing film is deposited using a CCVD process. In a further embodiment, the indium-containing film is deposited using a thermal CVD process.

[0132] Suitable substrates on which the disclosed and claimed precursors can be deposited are

[0133] 15 not particularly limited and vary depending on the intended final use. For example, the substrate may be chosen from oxides, such as HfC>2 based materials, TiC>2 based materials, ZrC>2 based materials, rare earth oxide-based materials, ternary oxide-based materials, etc., or from nitride-based materials. Other substrates may include solid substrates, such as metal substrates (e.g., Au, Pd, Rh, Ru, W, Al, Ni, Ti, Co, Pt), metal

[0134] 20 silicide containing substrates (e.g., TiSi2, CoSi2, and NiSi2), metal nitride containing substrates (e.g., TaN, TiN, WN, TaCN, TiCN, TaSiN, and TiSiN), semiconductor materials (e.g., Si, SiGe, GaAs, InP, diamond, GaN, and SiC), insulators (e.g., SiO2, SisN4, SiON, HfO2, Ta2Os, ZrO2, TiO2, AI2O3, and barium strontium titanate), and combinations thereof. Preferred substrates include TiN, Ru and Si type substrates.

[0135] 25

[0136] In such deposition methods and processes, usually a co-reactant is used, such as an oxidizing agent or a reducing agent. An “oxidizing agent” in the sense of this application is understood to mean a chemical compound which transfers oxygen to the indium- containing film. The oxidizing agent is typically introduced in gaseous form. Examples of suitable oxidizing agents include, but are not limited to, oxygen gas, water vapor, ozone,

[0137] 30 oxygen plasma, or mixtures thereof. Examples for suitable reducing agents are H2, H2 plasma, hydrazine or aminoboranes. Further possible co-reactants are nitrogencontaining co-reactants, such as hydrazine, NH3, N2 or N2 plasma, sulfur-containing coreactant, such as H2S or elemental sulfur, or peroxides, such as H2O2 or HOOtBu.

[0138] 35 Foreignfiling text P24-155. docx

[0139] - 13 -

[0140] The deposition methods and processes may also involve purge steps, which are usually done by using one or more purge gases. The purge gas, which is used to purge away unconsumed reactants and / or reaction byproducts, is an inert gas that does not react with the precursors and with the formed thin film. Exemplary purge gases include, but are not limited to, argon (Ar), nitrogen (N2), helium (He), neon (Ne), and mixtures thereof. For example, a

[0141] 5 purge gas, such as Ar, is supplied into the reactor at a flow rate ranging from about 10 to about 2000 seem for about 0.1 to 10000 seconds, thereby purging the unreacted material and any byproduct that may remain in the reactor.

[0142] The deposition methods and processes require that energy be applied to the at least one

[0143] 10 of the precursors according to the present invention, co-reactants or combination thereof to induce reaction and to form the indium-containing film or coating on the substrate. Such energy can be provided by, but not limited to, temperature (thermally induced), plasma, pulsed plasma, helicon plasma, high density plasma, inductively coupled plasma, X-ray, e-beam, photon, remote plasma methods, and combinations thereof. In some processes, a secondary RF frequency source can be used to modify the plasma

[0144] 15 characteristics at the substrate surface. When utilizing plasma, the plasma-generated process may include a direct plasma-generated process in which plasma is directly generated in the reactor, or alternatively a remote plasma-generated process in which plasma is generated outside of the reactor and supplied into the reactor.

[0145] 20 When utilized in such deposition methods and processes, suitable precursors, such as the compounds of the present invention, may be delivered to the reaction chamber, such as a CVD or ALD reactor, in a variety of ways. A preferred method of delivering the precursors to the reaction chamber is by vaporization of the precursor, e.g. either by vacuum driven thermal vaporization or by active vaporization using a carrier gas. In other

[0146] 25 instances, a liquid delivery system or a combined liquid delivery and flash vaporization process unit may be employed to enable low volatility materials to be volumetrically delivered, which leads to reproducible transport and deposition without thermal decomposition of the precursor. The precursor compositions described herein can be effectively used as reagents via direct liquid injection (DLI) or via vacuum driven vaporization to provide a vapor stream of these indium precursors into an ALD or CVD

[0147] 30 reactor. Vacuum driven vaporization is the preferred method of delivery for the precursors according to the present invention.

[0148] When used in these deposition methods and processes, the disclosed and claimed compounds may include hydrocarbon solvents which are particularly desirable due to

[0149] 35 their ability to be dried to sub-ppm levels of water. Exemplary hydrocarbon solvents that Foreignfiling text P24-155. docx

[0150] - 14 - can be used in the precursors include, but are not limited to, toluene, mesitylene, cumene (isopropylbenzene), p-cymene (4-isopropyl toluene), 1 ,3-diisopropylbenzene, octane, dodecane, 1 ,2,4-trimethylcyclohexane, n-butylcyclohexane, and decahydronaphthalene (decalin). The disclosed and claimed compounds can also be stored and used in stainless steel containers. In certain embodiments, the hydrocarbon solvent is a

[0151] 5 high boiling point solvent or has a boiling point of 100 °C or greater. The disclosed and claimed compounds can also be mixed with other suitable metal compounds, which can be utilized as precursors, and the mixture used to deliver both metals simultaneously for the growth of a binary metal-containing films.

[0152] 10 A flow of argon and / or other gas may be employed as a carrier gas to help deliver a vapor containing at least one of the disclosed and claimed precursors to the reaction chamber during the precursor pulsing. When delivering the precursors, the reaction chamber process pressure is between 1 and 50 torr, preferably between 5 and 20 torr.

[0153] Substrate temperature can be an important process variable in the deposition of high-

[0154] 15 quality metal-containing films. Typical substrate temperatures range from about 100 °C to about 550 °C. Higher temperatures can promote higher film growth rates, but might result in bulk CVD rather than ALD. Furthermore, there is the risk at higher substrate temperatures that the precursor desorbs from the substrate, thus resulting in lower growth rates. If the substrate temperature is not high enough, the temperature might be

[0155] 20 too low for a sufficient reaction of the precursor with the surface, which also results in lower growth rates, and / or the precursor might condense on the surface resulting in increasing growth rates.

[0156] In view of the forgoing, those skilled in the art will recognize that the disclosed and

[0157] 25 claimed subject matter further includes the use of the disclosed and claimed compounds as precursors in chemical vapor deposition (CVD) processes as follows.

[0158] In one embodiment, the disclosed and claimed subject matter includes a method for forming an indium-containing film on at least one surface of a substrate that includes the steps of:

[0159] (a) providing the at least one surface of the substrate in a reaction vessel; and

[0160] 30

[0161] (b) forming an indium-containing film on the at least one surface by a deposition process selected from a chemical vapor deposition (CVD) process and an atomic layer deposition (ALD) process using at least one compound of formula (1) or the preferred embodiments as precursor of an indium source compound for the deposition process.

[0162] 35 Foreignfiling text P24-155. docx

[0163] - 15 -

[0164] In a further aspect of this embodiment, the method includes introducing at least one coreactant into the reaction vessel. A co-reactant is a reactant which is used in addition to the precursor of the present invention for the deposition of the indium-containing film. In a further aspect of this embodiment, the method includes introducing at least one coreactant into the reaction vessel where the at least one co-reactant is selected from the

[0165] 5 group of water, oxygen (O2), oxygen plasma, ozone (O3), NO, N2O, NO2, CO, CO2 and combinations thereof. These co-reactants are typically used for forming a metal oxide thin film. In another aspect of this embodiment, the method includes introducing at least one co-reactant into the reaction vessel where the at least one co-reactant is selected from the group of ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, nitrogen,

[0166] 10 nitrogen / hydrogen, ammonia plasma, nitrogen plasma, nitrogen / hydrogen plasma, and combinations thereof. These co-reactants are typically used for forming a metal nitride thin film, but ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, ammonia plasma, and combinations thereof, might also be used for forming a metallic film, if the metal is indium. In another aspect of this embodiment, the method includes introducing at least one co-reactant into the reaction vessel where the at least one co-reactant is

[0167] 15 selected from the group of hydrogen, hydrogen plasma, a mixture of hydrogen and helium, a mixture of hydrogen and argon, hydrogen / helium plasma, hydrogen / argon plasma, boron-containing compounds, silicon-containing compounds and combinations thereof. These co-reactants are typically used for forming metallic film, i.e. formation of the elemental indium.

[0168] 20

[0169] In one embodiment, the disclosed and claimed subject matter includes a method of forming a indium-containing film via an atomic layer deposition (ALD) process or ALD- like process that includes the steps of:

[0170] (a) providing a substrate in a reaction vessel;

[0171] 25 (b) introducing into the reaction vessel one or more of the compounds of formula (1) or the preferred embodiments as precursor;

[0172] (c) a purging step, in particular purging the reaction vessel with a first purge gas;

[0173] (d) introducing into the reaction vessel a co-reactant;

[0174] (e) a purging step, in particular purging the reaction vessel with a second purge gas;

[0175] (f) sequentially repeating steps (b) through (e) until a desired thickness of the indium-

[0176] 30 containing film is obtained.

[0177] Depending on the desired composition of the produced indium-containing thin film, the steps (b), (c), (d) and (e) may also be repeated with a second co-reactant in step (d) and optionally a third or further co-reactant and a purging step with the third purge gas and

[0178] 35 optionally a fourth or further purge gases. Foreignfiling text P24-155. docx

[0179] - 16 -

[0180] Furthermore, it is possible in step (b) to introduce two or more precursors, wherein at least one precursor is a compound of formula (1) or the preferred embodiments. These two or more precursors may be introduced as a mixture from the same container or may be introduced from different containiers.

[0181] 5

[0182] Furthermore, it is possible in step (d) to introduce two or more co-reactants. These two or more co-reactants may be introduced as a mixture from the same source vessel or may be introduced from different containers.

[0183] 10 In a further aspect of this embodiment, the co-reactant is one or more of an oxygencontaining co-reactant selected from water, O2, oxygen plasma, O3, NO, N2O, NO2, CO, CO2 and combinations thereof. In another aspect of this embodiment, the co-reactant is one or more of a nitrogen-containing co-reactant selected from ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, nitrogen, nitrogen / hydrogen, ammonia plasma, nitrogen plasma, nitrogen / hydrogen plasma and mixture thereof. In another aspect of this

[0184] 15 embodiment, the co-reactant is selected from hydrogen, hydrogen plasma, a mixture of hydrogen and helium, a mixture of hydrogen and argon, hydrogen / helium plasma, hydrogen / argon plasma, boron-containing compounds, silicon-containing compounds and combinations thereof. In a further aspect of this embodiment, the method the first and second purge gases are each independently selected one or more of argon, nitrogen,

[0185] 20 helium, neon, and combinations thereof. Additionally or alternatively, vacuum may be applied for one or more purging steps. In a further aspect of this embodiment, the method further includes applying energy to at least one of the precursor, the co-reactant, the substrate, and combinations thereof, wherein the energy is one or more of thermal, plasma, pulsed plasma, helicon plasma, high density plasma, inductively coupled plasma,

[0186] 25 capacitively coupled plasma, X-ray, e-beam, photon, remote plasma methods and combinations thereof. In a preferred aspect of this embodiment, step (b) of the method includes introducing into the reaction vessel the precursor using thermal energy and vacuum. In a further aspect of this embodiment, step (b) of the method further includes introducing into the reaction vessel the precursor using a stream of carrier gas to deliver a vapor of the precursor into the reaction vessel. In a further aspect of this embodiment, step

[0187] 30 (b) of the method further includes use of a solvent medium comprising one or more of toluene, mesitylene, isopropylbenzene, 4-isopropyl toluene, 1 ,3-diisopropylbenzene, octane, dodecane, 1,2,4-trimethylcyclohexane, n-butylcyclohexane, and decahydronaphthalene and combinations thereof.

[0188] 35 Foreignfiling text P24-155. docx

[0189] - 17 -

[0190] The shape of the substrate is not particularly limited and can be, for example, a plate shape, a spherical shape, a fibrous shape, or a scaly shape. The surface of the substrate may be planar, or may have a three-dimensional structure such as a trench structure.

[0191] 5 In addition, examples of the above-mentioned production conditions include a reaction temperature (substrate temperature), a reaction pressure, and a deposition rate. The reaction temperature is preferably from room temperature to 500 °C, more preferably from 100°C to 300°C. In addition, the reaction pressure is preferably from 10 Pa to an atmospheric pressure in the case of the thermal CVD or the optical CVD, and is

[0192] 10 preferably from 10 Pa to 2,000 Pa in the case of using plasma. For ALD, the pressure of a system (in the film formation chamber) when this step is performed is preferably from 1 Pa to 10,000 Pa, more preferably from 10 Pa to 1 ,000 Pa.

[0193] In addition, the deposition rate may be controlled by the supply conditions (vaporization temperature and vaporization pressure) of the precursor, the reaction temperature, and

[0194] 15 the reaction pressure. When the deposition rate is large, the characteristics of a thin-film to be obtained may deteriorate. When the deposition rate is small, a problem may occur in productivity. Accordingly, for CVD processes, the deposition rate is preferably from 0.01 nm / min to 100 nm / min, more preferably from 1 nm / min to 50 nm / min. In addition, in the case of the ALD method, the deposition rate is controlled by the number of cycles so

[0195] 20 that a desired film thickness may be obtained. In an ALD process, typical deposition rates are from 0.01 nm / cycle to 0.2 nm / cycle, more typically from 0.05 nm / cycle to 1.3 nm / cycle. Further, as the above-mentioned production conditions, there are given a temperature and a pressure when the thin-film forming precursor is vaporized to obtain a precursor gas. The step of vaporizing the thin-film forming precursor to obtain a

[0196] 25 precursor gas may be performed in the precursor vessel or in the vaporization chamber. In any case, it is preferred that the thin-film forming precursor of the present invention be evaporated at a temperature between 0 °C and 150 °C. In addition, when the thin-film forming precursor is vaporized to obtain a precursor gas in the precursor vessel or in the vaporization chamber, the pressure in the precursor vessel and the pressure in the vaporization chamber are each preferably from 1 Pa to 10,000 Pa.

[0197] 30

[0198] In addition, in the method of producing a thin-film of the present invention, after the thin- film deposition, annealing treatment may be performed under an inert atmosphere, an oxidizing atmosphere, or a reducing atmosphere in order to obtain more satisfactory electrical characteristics. The temperature for annealing is from 200 °C to 1 ,000 °C,

[0199] 35 preferably from 250 °C to 500 °C. Foreignfiling text P24-155. docx

[0200] - 18 -

[0201] Brief description of the drawings

[0202] Fig. 1 shows the TGA curves for an indium compound according to the invention as well as comparative indium compounds.

[0203] 5 Fig. 2 shows the thermal stability study for lnMe2(tBu2-fAMD) on Si(100) with native oxide (ALD-Example 1).

[0204] Fig. 3 shows the result of the saturation study of lnMe2(tBu2-fAMD) on Si(100) with native oxide at 300 °C (ALD-Example 2).

[0205] 10

[0206] Fig. 4 shows the temperature dependency of the lnMe2(tBu2-fAMD) / O3 process on Si(100) with native oxide (ALD-Example 3).

[0207] Fig. 5 shows the conformality within a Pillar Hall Step Coverage test vehicle of the I nMe2(tBu2-fAMD) / O3 process at 300 °C (ALD-Example 5).

[0208] 15

[0209] Examples

[0210] Reference will now be made to more specific embodiments of the present disclosure and experimental results that provide support for such embodiments. The examples are given below to more fully illustrate the disclosed subject matter and should not be

[0211] 20 construed as limiting the disclosed subject matter in any way. It will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed subject matter and specific examples provided herein without departing from the spirit or scope of the disclosed subject matter. Thus, it is intended that the disclosed subject matter, including the descriptions provided by the following examples, covers the modifications and

[0212] 25 variations of the disclosed subject matter that come within the scope of any claims and their equivalents.

[0213] Materials and Methods:

[0214] All solvents and starting materials were purchased from Sigma-Aldrich unless otherwise indicated. Bis(tert-butyl)formamidine and the other formamidine and acetamidine ligands

[0215] 30 can be synthesized by the process described in E. C. Taylor et al., J. Org. Chem. 1963, 28(4), 1108-1112.

[0216] General synthetic procedure:

[0217] In a Schlenk flask, the respective formamidine (fAMDH) (1 eq.) to prepare the below

[0218] 35 described complexes was dissolved in toluene (40 eq.) and cooled to -78 °C. n-Butyl- Foreignfiling text P24-155. docx

[0219] - 19 - lithium (nBuLi), 1.6 M in hexane (1 eq.), was added dropwise to the solution. The mixture was allowed to warm to room temperature and was stirred for 2 h. The mixture was cooled to 0 °C and was transferred slowly via a cannula into a 0 °C cold solution of dimethylindium chloride (lnMe2CI) (1 eq.) in toluene (40 eq.). After addition, the reaction mixture was stirred at room temperature overnight. The formed suspension was filtered,

[0220] 5 and solvent of the filtrate was removed under reduced pressure. The crude product was sublimed or distilled under vacuum to obtain spectroscopically pure complexes.

[0221] Example 1 : lnMe2(tBu2-fAMD)

[0222] Compound with R1, R2= tert-butyl, R3, R4= methyl.

[0223] 101H NMR (500 MHz, C6D6) 5 8.11 (s, 1 H), 1.04 (s, 18H), 0.16 (s, 6H).

[0224] TGA: Tso%= 122.9 °C, mresidue=0.4 %

[0225] DSC. Tmelting point—2 C, Tdecomposition—202 C

[0226] Vapor Pressure: lg(p[Pa]]) = -2610.2 (1 / T[K]) +10.455 1 Torr at 40.2 °C

[0227] Comparative Example 1 : lnMe2(Et2-fAMD)

[0228] 15

[0229] Compound with R1, R2= ethyl, R3, R4= methyl.

[0230] 1H NMR (500 MHz, C6D6) 6 7.28 (s, 1 H), 2.98 (q, J = 7.2 Hz, 4H), 1.02 (t, J = 7.2 Hz, 6H), 0.02 (s, 6H).

[0231] TGA: decomposition, mresidue (after first step) = 80%

[0232] DSC. Tmelting point—110 C, Tdecomposition—117 C

[0233] 20

[0234] Comparative Example 2: lnMe2(iPr2-fAMD)

[0235] Compound with R1, R2= iso-propyl, R3, R4= methyl.

[0236] 1H NMR (500 MHz, C6D6) 5 7.62 (s, 1 H), 3.24 (hept, J = 6.3 Hz, 2H), 0.95 (d, J = 6.3 Hz, 12H), 0.14 (s, 6H).

[0237] 25 TGA: Tso%=121.4°C, mresidue=24.6 %

[0238] DSC. Tmelting point—30 C, Tdecomposition—149 °C

[0239] Comparative example 3: lnMe2(tBu2-MeAMD)

[0240] Compound with bis(tert-butyl)acetamidinate ligand according to KR 2020-0083340 A.

[0241] 1H NMR (500 MHz, C6D6) 6 1.79 (s, 3H), 1.09 (s, 18H), 0.14 (s, 6H).

[0242] 30

[0243] TGA: Tso%=145.3 °C, mresidue=0.2 %

[0244] DSC. Tmelting point—1 1 C, Tdecomposition—251 °C

[0245] Analysis by TGA

[0246] 35 Foreignfiling text P24-155. docx

[0247] - 20 -

[0248] TGA curves were determined for the indium precursor of Example 1 and Comparative Examples 1 to 3. The sample mass of each compound was 10 mg for the TGA experiment. The TGA curves are shown in Figure 1.

[0249] Discussion of results

[0250] 5 The results show the significance of the use of a formamidinate ligand compared to an acetamidinate ligand (Example 1 and Comparative Example 3) and the use of tertiary alkyl groups as substituents on the formamidinate ligand compared to smaller linear or branched alkyl groups (Example 1 and Comparative Examples 1 and 2). As can be seen from the results, only the usage of a formamidinate which is substituted on the N atoms

[0251] 10 with tertiary alkyl groups results in a compound with a reduced evaporation temperature which is liquid at room temperature and which shows a sufficient thermal stability. The compounds of Comparative Examples 1 and 2 are solid at room temperature and show low thermal stability and can therefore not be evaporated without decomposition. Even though the compound of Comparative Example 3 is liquid at room temperature and shows sufficient thermal stability, it has a considerable higher evaporation temperature

[0252] 15 where Tso% is 22 K higher than for the compound of Example 1 , as shown by TGA experiments (see Fig. 1 and Table 1). The results show that a simple reduction of the molecular mass of the precursor, such as in Comparative Examples 1 and 2 compared to Comparative Example 3, is not sufficient to reduce the evaporation temperature, but it is obligatory to use a formamidinate ligand instead of an acetamidinate ligand to achieve

[0253] 20 the desired technical effect.

[0254] Table 1 : Comparison of the indium formamidinate compound of Example 1 with indium compounds from Comparative Examples 1 to 3 in terms of 50 % mass loss (Tso%), residue after evaporation, decomposition temperature and melting point.

[0255] 25

[0256] 30

[0257] ALD Experiments

[0258] Experimental:

[0259] 35 Foreignfiling text P24-155. docx

[0260] - 21 -

[0261] An Atomic Premium CN-1 200 mm reactor was employed to demonstrate atomic layer deposition of indium oxide films with the precursors of this invention. The precursor lnMe2(tBu2-fAMD) was delivered from SS316 ampoule (container) kept at 41 °C (ampoule wall temperature). 25 seem of argon carrier gas flow was used to deliver precursor vapor to the reactor chamber. For purging a flow of 1000 seem Ar was used.

[0262] 5 The co-reactant ozone was delivered with a concentration of 20% at 225 seem. Reactor chamber pressure was 1.2 -1.5 torr. Si with native oxide was used to deposit indium oxide films. Indium oxide film thickness was measured by X-ray fluorescence (XRF) calibrated using XRR of deposited indium oxide films.

[0263] 10 ALD-Example 1 : Thermal Stability of lnMe2(tBu2-fAMD)

[0264] In this experiment, lnMe2(tBu2-fAMD) precursor vapors were delivered to the deposition chamber in a pulsed mode separated by argon purge. Pulse sequence was: 6 s precursor pulse and 30 s of argon purge. The total number of precursor / Ar purge cycles was 50. No oxidant pulse was used in this experiment to demonstrate good thermal stability of the precursor in the absence of the oxidant. Good thermal stability (lack of

[0265] 15 deposition in the absence of oxidant) is an important precursor property for an atomic layer deposition process. Wafer temperature was varied from 150 to 350 °C. After the experiment, the indium layer density on the surface was measured by X-Ray fluorescence analysis and is shown in Fig. 2. No increase in indium concentration on the silicon with native oxide wafers was observed up to at least 350 °C suggesting very good

[0266] 20 thermal stability of this precursor in the vapor phase and its utility for vapor deposition applications.

[0267] ALD-Example 2: Saturation study of lnMe2(tBu2-fAMD)

[0268] In this experiment, indium oxide films were deposited by atomic layer deposition method

[0269] 25 comprising the following steps: a. providing Si substrate in a reaction vessel; b. introducing into the reaction vessel lnMe2(tBu2-fAMD) precursor; c. purging the reaction vessel with argon; d. introducing into the reaction vessel ozone; e. purging the reaction vessel with argon; and

[0270] 30 f. sequentially repeating steps b through e until a desired thickness of the transition metal-containing film is obtained.

[0271] A saturation study of lnMe2(tBu2-fAMD) was conducted at 300 °C. In the study, the precursor pulse time was varied between 2 s and 8 s, while the rest of the ALD cycle times were held constant to yield the following pulse / purge sequence: x s (precursor

[0272] 35 pulse) / 30 s (precursor purge) / 2 s (ozone pulse) / 30 s (ozone purge). Foreignfiling text P24-155. docx

[0273] - 22 -

[0274] At 300 °C, the precursor reached saturation with a 4 s pulse time, showing very little variation in the measured thicknesses at different pulse times. At a deposition temperature of 300 °C, the precursor saturated with a GPC of 0.63 A, thereby proving the ALD-like self-limiting behavior of lnMe2(tBu2-fAMD). The result of the saturation study is shown in Fig. 3.

[0275] 5

[0276] ALD-Example 3: Temperature Dependency of the lnMe2(tBu2-fAMD) / ozone process

[0277] In this experiment, indium oxide films were deposited by atomic layer deposition method comprising the following steps:

[0278] 10 a. providing Si substrate in a reaction vessel; b. introducing into the reaction vessel lnMe2(tBu2-fAMD) precursor; c. purging the reaction vessel with argon; d. introducing into the reaction vessel ozone; e. purging the reaction vessel with argon; and f. sequentially repeating steps b through e until a desired thickness of the transition

[0279] 15 metal-containing film is obtained.

[0280] To demonstrate the temperature dependency of the lnMe2(tBu2-fAMD) / C>3 process, the deposition temperature was varied between 150 °C and 350 °C using a 4 s precursor pulse followed by a 30 s purge, while ozone was pulsed for 2 s followed by a 30 s purge. A weak temperature dependency was observed, as the GPC consistently, slowly

[0281] 20 increased with higher deposition temperatures from 0.39 A cycle-1at 150 °C to 1.04 A cycle-1at 350 °C. The result of the temperature dependency experiment is shown in Fig. 4.

[0282] ALD-Example 4: Composition of the lnMe2(tBu2-fAMD) / ozone process

[0283] 25 In this experiment, indium oxide films were deposited by atomic layer deposition method comprising the following steps: a. providing Si substrate in a reaction vessel; b. introducing into the reaction vessel lnMe2(tBu2-fAMD) precursor; c. purging the reaction vessel with argon; d. introducing into the reaction vessel ozone;

[0284] 30 e. purging the reaction vessel with argon; and f. sequentially repeating steps b through e until a desired thickness of the transition metal-containing film is obtained.

[0285] To evaluate the composition of the ln2Oa film deposited by the lnMe2(tBu2-fAMD) / O3 process, a 250 A sample was prepared using the optimized conditions from ALD-

[0286] 35 Example 3 and measured using X-ray Photoelectron Spectroscopy (XPS), Rutherford Foreignfiling text P24-155. docx

[0287] - 23 -

[0288] Backscattering Spectrometry (RBS) and Hydrogen Forward Scattering Spectrometry (HFS). XPS results, after brief Ar sputtering to remove the adventitious carbon from the films, show non-detectable (<1%) levels of C in the film. Both XPS and RBS show the ratio of Indium to Oxygen is very close to stoichiometric 2:3. HFS results show reasonably low Hydrogen (-3.7%) remaining in the film after processing. Table 2 shows

[0289] 5 the XPS results and Table 3 shows the RBS / HFS results.

[0290] Table 2: Composition by XPS of 250 A of lnMe2(tBu2-fAMD) I O3 process on Si(100) with native oxide at 300 °C

[0291] 10

[0292] 15 nd = not detectable, <1%

[0293] Table 3: Composition by RBS / HFS of 250 A of lnMe2(tBu2-fAMD) I O3 process on

[0294] Si(100) with native oxide at 300 °C

[0295] 20

[0296] 25

[0297] ALD-Example 5: Conformality of the lnMe2(tBu2-fAMD) / ozone process

[0298] In this experiment, indium oxide films were deposited by atomic layer deposition method comprising the following steps: a. providing a Pillar Hall Step Coverage substrate in a reaction vessel;

[0299] 30 b. introducing into the reaction vessel lnMe2(tBu2-fAMD) precursor; c. purging the reaction vessel with argon; d. introducing into the reaction vessel ozone; e. purging the reaction vessel with argon; and f. sequentially repeating steps b through e until a desired thickness of the transition metal-containing film is obtained.

[0300] 35 Foreignfiling text P24-155. docx

[0301] - 24 - g. Following deposition, the top membrane of the Pillar Hall Test Coupon is removed and SEM / EDX is used to measure the depth the ln2Oa film deposited into the test vehicle. The depth is converted to effective aspect ratio based on the dimensions of the Pillar Hall structure.

[0302] To demonstrate the conformality of the lnMe2(tBu2-fAMD) / C>3 process, the deposition at

[0303] 5 300 °C was completed on a Pillar Hall Test Vehicle using a longer pulse / purge sequence of 60s precursor pulse, 60s purge, 2s ozone followed by a 30s Ar purge, 30s pump down purge and another 10s Ar purge, to allow molecules to diffuse into and off the high aspect ratio structures. Based on SEM / EDX measurements the I n2Os conformality shows close to >90% step coverage up to an aspect ratio of 50:1. The result of the conformality

[0304] 10 experiment is shown in Fig. 5.

[0305] 15

[0306] 20

[0307] 25

[0308] 30

[0309] 35

Claims

Foreignfiling text P24-155. docx- 25 -Claims1. Compound of formula (1):5Formula (1)10 wherein the symbols used are as follows:R1, R2are on each occurrence, identically or differently, a tertiary alkyl group with 4, 5 or 6 carbon atoms;15R3, R4are on each occurrence, identically or differently, an alkyl group having 1, 2 or 3 C atoms.

2. Compound according to Claim 1, characterized in that R1is selected from the20 groups R1-1 to R1-8 and R2is selected from the groups R2-1 to R2-8,35 wherein the dashed bond represents the bond to the N atom of the amidinate ligand.Foreignfiling text P24-155. docx- 26 -3. Compound according to claim 1 or 2, characterized in that R1and R2are identical.

4. Compound according to one or more of Claims 1 to 3, characterized in that R1and R2are each tert-butyl.

55. Compound according to one or more of Claims 1 to 4, characterized in that R3and R4are identical.

6. Compound according to one or more of Claims 1 to 5, characterized in that R3and10 R4are each methyl.

7. Compound according to one or more of Claims 1 to 6, characterized in that the compound is selected from the following compounds:15 (1) R1= R2= tert-butyl, R3= R4= methyl(2) R1= R2= tert-butyl, R3= R4= ethyl(3) R1= R2= tert-pentyl, R3= R4= methyl(4) R1= R2= tert-pentyl, R3= R4= ethyl(5) R1= R2= tert-hexyl, R3= R4= methyl(6) R1= R2= tert-hexyl, R3= R4= ethyl20(7) R1= R2= 3-methyl-3-pentyl, R3= R4= methyl(8) R1= R2= 3-methyl-3-pentyl, R3= R4= ethyl(9) R1= R2= 2,3-dimethyl-2-butyl, R3= R4= methyl(10) R1= R2= 2,3-dimethyl-2-butyl, R3= R4= ethyl(11) R1= R2= 1-methylcyclopentyl, R3= R4= methyl25 (12) R1= R2= 1-methylcyclopentyl, R3= R4= ethyl(13) R1= R2= 1-methylcyclobutyl, R3= R4= methyl(14) R1= R2= 1-methylcyclobutyl, R3= R4= ethyl(15) R1= R2= 1-methylcyclopropyl, R3= R4= methyl(16) R1= R2= 1-methylcyclopropyl, R3= R4= ethyl30 (17) R1= tert-butyl, R2= tert-pentyl, R3= R4= methyl(18) R1= tert-butyl, R2= tert-pentyl, R3= R4= ethyl.

8. Compound according to one or more of Claims 1 to 7, characterized in that the compound has the following structure:35Foreignfiling text P24-155. docx59. Method of manufacturing a compound according to one or more of claims 1 to 8, characterized in that a compound I nR3R4X wherein R3and R4have the same meanings as defined in claim 1 and X is a counterion, preferably F, Cl, Br, I, triflate10 or tosylate, is reacted with a formamidinate salt of the formula [cation]+[R1NCHNR2]" where R1and R2have the same meanings as defined in claim 1 and [cation]+is a cation, preferably Li, Na or K, or that trialkylindium where alkyl corresponds to R3and R4as defined in claim 1 is reacted with a formamidine of the formula R1HN-CH=NR2where R1and R2have the meanings as defined in claim 1.1510. Use of a compound according to one or more of claim 1 to 8 for the deposition of an indium-containing film.11 . Method for forming an indium-containing film on at least one surface of a substrate,20 comprising the steps:(a) providing at least one surface of the substrate in a reaction vessel; and(b) forming an indium-containing film on the at least one surface by a deposition process selected from a chemical vapor deposition (CVD) process and an atomic layer deposition (ALD) process using at least one compound according to one or25 more of claim 1 to 8 as precursor of an indium source compound for the deposition process.

12. Method according to claim 11 , further comprsing introducing into the reaction vessel at least one co-reactant.3013. Method according to claim 12, characterized in that the co-reactant is selected from the group of water, oxygen, oxygen plasma, ozone, NO, N2O, NO2, CO, CO2, ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, nitrogen, nitrogen / hydrogen, ammonia plasma, nitrogen plasma, nitrogen / hydrogen plasma, hydrogen, hydrogen plasma, a mixture of hydrogen and helium, a mixture ofForeignfiling text P24-155. docx- 28 - hydrogen and argon, hydrogen / helium plasma, hydrogen / argon plasma, boron- containing compounds, silicon-containing compounds and combinations thereof.

14. Method for forming an indium-containing film via an atomic layer deposition (ALD) process or ALD-like process, the method comprising the steps of:5 (a) providing a substrate in a reaction vessel;(b) introducing into the reaction vessel one or more compounds according to one or more of claims 1 to 8 as precursor;(c) a purging step, in particular purging the reaction vessel with a first purge gas;(d) introducing into the reaction vessel a co-reactant;10 (e) a purging step, in particular purging the reaction vessel with a second purge gas;(f) sequentially repeating steps (b) through (e) until a desired thickness of the indium-containing film is obtained.

15. Method according to claim 14, characterized in that at least one co-reactant in step (d)15 is selected from water, O2, O3, NO, N2O, NO2, CO, CO2, ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine, nitrogen, nitrogen / hydrogen, hydrogen, a mixture of hydrogen and helium, a mixture of hydrogen and argon, hydrogen / helium plasma, boron-containing compounds, silicon-containing compounds and combinations thereof or a plasma of these co-reactants.202530

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