Preparation of group iii and lanthanide element containing precursors and their application to vapor depositions

Abstract

Chemicals suitable as gas-phase precursors for the formation of Y₂O₃, Sc₂O₃, and other materials have been disclosed. These chemicals share a common structure: R₁ and R₃ are hydrogen atoms, R₂ is the same and selected from C₁ to C₃ alkyl groups, and M is yttrium or scandium.

Description

[Technical Field]

[0001] Technical Field: Volatile lanthanide chemical substances suitable as precursors for vapor deposition. [Previous Technology]

[0002] In the prior art, various organometallic coordination ligands such as cyclopentadienyl and amidine, formamidinyl and guanidine are commonly used. Sengupta, D., A. Gómez-Torres and S. Fortier. "Guanidinate, Amidinate, and Formamidinate Ligands." Comprehensive Coordination Chemistry 3 (2021): 366-405.

[0003] The lanthanides (Ln) are no exception. Ln metals coordinated with heterocoordinates have been documented in detail, including those coordinated with heterocoordinates of cyclopentadienyl and amidine, formamidinium and guanidine. For example, US 20090302434 A1 broadly describes this genus in

[0055] : • Ln(R1Cp)m(R2-NC(R4)=N-R2)n, • where Ln represents a lanthanide group, including Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; R1 is selected from H or a C1-C5 alkyl chain; R2 is selected from H or a C1-C5 alkyl chain; R4 is selected from H, a C1-C5 alkyl chain, and NR′R″, wherein R′ and R″ are independently selected from a C1-C5 alkyl chain; m is selected from 1 or 2; and n is selected from 1 or 2.

[0004] Within this large class of hetero-coordinated Ln metals, many subgenus and species have been synthesized and their suitability as vapor deposition precursors for LnO3 materials in semiconductors and other applications has been evaluated.

[0005] WO 2022250400 A1 reveals the cyclopentadienylguanidinoyttrium molecule:

[0006] In the most extensive embodiment, WO 2022250400 A1 comprises an unsubstituted cyclopentadienyl group. However, preferred genera and all identified species include alkyl groups on the cyclopentadienyl group (R1 and R2 are C2-C5). And of course, the genera is limited to molecules containing guanidine groups. Another preferred element is the asymmetry of the coordinating group, which is why an alkyl group is preferred on the cyclopentadienyl group. "The metal precursor compounds of the present invention, due to their structural features including asymmetric cyclopentadienyl and guanidine coordinating groups, can remain liquid at room temperature and satisfy sufficient volatility and excellent chemical-thermal stability."

[0007] US 20220325411 A1 discloses a cyclopentadienylamidine yttrium molecule: • Chemical Formula I: • (R1Cp)2M[(CH3)2CH-NC(CH2CH3)=N-CH(CH3)2]; [Chemical Formula I] • Wherein, in the above Chemical Formula I, M is selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, • R1 is n-propyl (nPr) or isopropyl (iPr), and Cp is cyclopentadienyl.

[0008] Similarly, the cyclopentadienyl coordination group is replaced by an alkyl group.

[0009] US 20230040334 A1 discloses a cyclopentadienylamidinyl or formamidinyl yttrium molecule [general formula (I)]: • Wherein, R1 is a C1-C5 straight-chain or branched alkyl group, R2 and R3 are each a C1-C8 straight-chain or branched alkyl group, R2 has a structure different from R3, R4 is a hydrogen atom or a C1-C5 straight-chain or branched alkyl group, and n is an integer from 0 to 5. • In embodiments, in general formula (I), n may be appropriately selected according to the purpose of applying the compound represented by general formula (I). In the manufacturing process of the film, the process includes the vaporization of the compound represented by general formula (I), and compounds with relatively high vapor pressure and relatively low melting point may be used. To help ensure that the compound represented by general formula (I) exhibits a lower melting point and higher vapor pressure, R1 may be, for example, a C1-C3 alkyl group. In embodiments, R1 may be, for example, methyl or ethyl.

[0010] US 20230040334 A1 describes both amidine and formamidinyl embodiments, as well as embodiments having substituted or unsubstituted cyclopentadienyl groups (e.g., formulas 1, 2, 4, and 5). However, the preferred embodiments "to help ensure that the compounds represented by general formula (I) exhibit lower melting points and higher vapor pressures" are those having C1-C3 alkyl groups on the cyclopentadienyl group. This is experimentally demonstrated by the comparison of the chemicals of formulas 13-14 (solids) with those of formulas 16-17 (liquids) in Table 1. Similarly, coordinating asymmetry is used to lower the melting point and enhance volatility: "R2 and R3 are each C1-C8 straight-chain or branched alkyl groups, and R2 has a structure different from that of R3."

[0011] Even the very extensive US 20090302434 A1, for the same reasons stated in claim 4 and in all experimental examples, reveals a clear preference for the asymmetric cyclopentadienyl group.

[0056] -

[0057] :

[0056] Lanthanide-containing precursors offer unique physical and chemical properties compared to their corresponding homocoordinate compounds. Independently fine-tuning the substituents on the ligands increases volatility and thermal stability and lowers the melting point to produce liquids or low-melting-point solids (with melting points below about 105°C).

[0057] In order to synthesize stable lanthanide-containing precursors with properties suitable for vapor deposition processes (i.e., volatile, thermally stable liquids or low-melting-point solids (with melting points below about 105°C)), a direct correlation was observed between the properties of the central metal ion (coordination number, ionic radius) and the ligands (steric effect, ratio of two heterocoordinate ligands). Preferably, the R1 series consists of a C1-C3 alkyl chain; the R2 series consists of a C3-C4 alkyl chain; and the R4 series consists of H or Me. Preferably, the lanthanide-containing precursor has a melting point below about 105°C, more preferably below about 80°C, more preferably below about 70°C, and even more preferably below about 40°C. Preferred lanthanide-containing precursors include Ln(R1Cp)2(NZ-fmd), Ln(R1Cp)2(NZ-amd), Ln(R1Cp)(NZ-fmd)2, and Ln(R1Cp)(NZ-amd)2, wherein Ln is Y, Gd, Dy, Er, or Yb; R1 is Me, Et, or iPr; and Z is iPr or tBu.

[0012] In accordance with the above-described directions in the art, a number of candidate vapor precursors have been identified that are: a) liquid at 50°C or lower, b) sufficiently volatile to vaporize 50% of the starting mass at 240°C or lower (in TGA analysis), ideally also producing a partial vapor pressure of 1 Torr at 200°C or lower, and c) thermally stable at the vaporization temperature based on the residual mass after complete vaporization (in TGA analysis).

[0013] The following is a representative list of reference homocoordinating molecules from the art: molecular Melting point (C) 1 VP (C) ½ of the vaporization temperature (C) in TGA Quotation Cp3Y 293.2 182.3 Eur. J. Inorg. Chem. [European Journal of Inorganic Chemistry] 2020, 3587-3596 (MeCp)3Y 124 155 >270 Coatings, 2021, 11(5), 497 (EtCp)3Y 60 200 >270 Coatings, 2021, 11(5), 497 Y(iPr2amd)3 220 ? Approximately 260 Chem. Mater. [Materials Chemistry] 2005, 17, 19, 4808-4814

[0014] The reference molecules are solid at temperatures above 50°C, have a 50% TGA vaporization temperature above 240°C, have a 1 Torr vapor pressure temperature above 150°C, or two or more of the foregoing.

[0015] A representative list of prior art heterocoordinating molecules used for comparison with the present invention is as follows: molecular Melting point (C) ½ of the vaporization temperature (C) in TGA Quotation 29 239 US 20230040334 A1 34 256 US 20230040334 A1 liquid 245 US 20230040334 A1

[0016] These examples reflect the general view in the art that the asymmetry of alkyl groups lowers the melting point and increases volatility, as do C3+ alkyl groups. US 7557229,

[0059] . "Alkyl groups having more than one stereoisomer (such as secondary butyl) also result in a lower melting point." Ibid. The effects of these design strategies are reflected in the datasheet above from US 20230040334 A1.

[0017] Prior art still requires lanthanide chemicals (referred to in the art as "precursors") that are liquid, highly volatile, thermally stable and capable of vapor deposition of lanthanide-containing films and other coatings at commercially viable deposition rates and with a small amount of contaminating atoms (e.g., Y2O3 with less than 1% carbon). [Summary of the Invention]

[0018] As defined in US 20090302434 A1, the prior art includes a chemical structure cloud or genus broadly defined as: • Ln(R1Cp)m(R2-NC(R4)=N-R2)n, • where Ln represents a lanthanide group, including Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; R1 is selected from H or a C1-C5 alkyl chain; R2 is selected from H or a C1-C5 alkyl chain; R4 is selected from H, a C1-C5 alkyl chain, and NR′R″, wherein R′ and R″ are independently selected from a C1-C5 alkyl chain; m is selected from 1 or 2; and n is selected from 1 or 2.

[0019] However, prior art generally refers to a cloud having one or more of the structural features defined above, namely: • Structural asymmetry on the cyclopentadienyl (Cp) caused by asymmetric alkyl substitution (usually a single alkyl group). • Asymmetric alkyl groups bridging the nitrogen, preferably three or more carbon alkyl groups, wherein isomeric alkyl groups such as secondary butyl are preferably used for one of such alkyl groups (e.g., isopropyl and secondary butyl). • Alkyl groups bridging the carbon (i.e., amidine) or alkylated guanidine groups.

[0020] All of these features, along with species lacking one or more of these features, exist together in general structural clouds. Based on the aforementioned extensively empirically validated molecular design rules, those skilled in the art cannot anticipate that molecules lacking all of these features are viable candidates for vapor deposition precursors.

[0021] Applying the above design rules requires more complex synthetic schemes, especially using asymmetric alkyl groups in bridging nitrogen. Nevertheless, this characteristic has been recognized in the art as one of the main means of making such chemicals liquid and volatile. Therefore, it has been unexpectedly found that some species lacking any of the above characteristics are feasible and even superior to many proven species in the prior art for vapor deposition precursors.

[0022] In one embodiment, the novel molecule can be used for chemical vapor deposition, and more specifically for high-temperature epitaxy of alloys such as scandium aluminum nitride (ScAlN) and yttrium aluminum nitride (YAlN) films. ScAlN CVD processes using conventional non-scalable precursors such as ScCp3 and Sc(MeCp)3 have been reported, and these processes are limited by low growth rates due to the amount of Sc precursor delivered to the CVD chamber, which is directly determined by the vapor pressure of the Sc precursor. ScAlN or YAlN can be deposited by reacting the novel molecule disclosed herein with vapors of other molecules such as trimethylaluminum (TMA) and ammonia (NH3) at temperatures ranging from 400°C to 700°C, preferably 500°C to 600°C. The resulting film system is expected to be crystalline and have low carbon contamination. Disclosure of the Invention

[0023] A subgenus defined by the following: • R1 series hydrogen (i.e., Cp series unsubstituted) • R2 series identical (i.e. symmetrical) and selected from C1 to C3 alkyl, preferably C2 or C3. • R3 series hydrogen (i.e., formamidinyl).

[0024] The best members of this small subgenus are Cp2Sc[EtNC(H)NEt]; Cp2Y[EtNC(H)NEt]; and Cp2Sc[iPrNC(H)N iPr]:

[0025] As shown below, these molecules exhibit a surprisingly optimal combination of properties compared to the closest members in a larger chemical cloud with one or more superior structural features. Figure 1 is a table of baseline values ​​for the aforementioned chemicals. Some close chemical analogs in this genus are shown for comparison. The initial standard is a melting point below 50°C. Volatility can be assessed by two standard criteria in the art: • The temperature required to produce one Torr of chemical vapor pressure. • The temperature at which half the mass of the chemical evaporates in a thermogravimetric analysis.

[0026] Thermal stability can also be assessed by two standard criteria in the art: • The weight percentage of non-volatile residues of the chemical after complete evaporation in thermogravimetric analysis. • The decomposition temperature measured by differential scanning calorimetry (DSC).

[0027] The data in Figure 1 demonstrate the high variability and unpredictability of various properties. Within this subgenus of the larger chemical cloud, consistent structure function correlations are not strong. In particular, melting point and volatility are not consistently correlated as one might expect. For precursors with melting points in the preferred range below 35°C, the most volatile chemical series Cp2Y[EtNC(H)NEt], ScCp2(iPr-fmd), and ScCp2(Et-fmd) do not possess any of the characteristics recognized in the art for increasing volatility. Regarding Cp2Y[EtNC(H)NEt], this anomalous volatility persists despite the lower melting point of the closest comparable molecule. Cp2Y[EtNC(H)NEt] is particularly unique in its combination of low melting point and unexpectedly high volatility.

[0028] While melting point and volatility are important, these are merely screening criteria. The chemicals must still function effectively in vapor deposition to produce films of acceptable quality for the target application. Ideally, precursor chemicals can be manipulated in atomic layer deposition (ALD).

[0029] Figure 2 shows the results of wafer-based ALD of Cp2Y[EtNC(H)NEt] compared to (EtCp)2Y[iPrNC(CH3)NiPr] and the commercial precursor (EtCp)3Y. As shown, Cp2Y[EtNC(H)NEt] performs well in ALD, exhibiting a wide ALD "window" or temperature range over which ALD occurs (200°C–450°C). The lower end of the ALD window is significantly lower than that of the comparison molecule, partly due to the unexpectedly higher volatility of Cp2Y[EtNC(H)NEt]. Similarly, ScCp2(iPr-fmd) has an ALD window extending to 200°C due to its extremely high volatility.

[0030] Ideal ALD produces highly uniform films. As shown in Figure 3, Cp2Y[EtNC(H)NEt] exhibits excellent uniformity and ideal ALD behavior over a substrate temperature range of 200°C to 350°C. This is substantially superior to the two precursors used for comparison. ScCp2(iPr-fmd) ALD films exhibit similar uniformity from 225°C to 475°C.

[0031] XPS etching analysis was performed on an ALD film deposited at 350°C using wafer co-reactants and Cp2Y[EtNC(H)NEt]. The film contained undetectable (less than 0.5% atomic) levels of carbon, silicon, and nitrogen. Yttrium and oxygen contents were 40% and 60%, respectively, corresponding to Y2O3. ScCp2(iPr-fmd) for ALD with ozone as a co-reactant at 325°C produced Sc2O3 films with 40% / 60% atomic composition and undetectable (less than 0.5% atomic) levels of carbon, silicon, and nitrogen.

[0032] Consistent with the ALD film, the Y2O3 film formed with wafer co-reactants exhibits a highly uniform film thickness with 98% step coverage on a blank test silicon wafer with trenches (the thickness in the trenches ranges from 35.7 nm to 35.0 nm, as assessed by SEM images of the cross-sectional wafer). Similarly, the Sc2O3 film is uniformly 26.9 nm thick (i.e., 100% step coverage).

[0033] ALD results demonstrate the superior performance and results of Cp2Y[EtNC(H)NEt] in the formation of Y2O3 and ScCp2(iPr-fmd) in the formation of Sc2O3.

Implementation Method

[0037] The synthesis of the chemicals described herein may be carried out according to any method described in the prior art, including those in the background section of the references and further including US 8012536 B2.

[0038] MP, TGA, and VP thermogravimetric analyses (TGA) were performed on a METTLER TOLEDO® Thermal Analysis System TGA / DSC 3+ instrument with sample volumes of approximately 20 mg to approximately 40 mg, under a constant N2 inert gas flow of 100 mL / min, and at a heating rate of 10°C / min. The TGA instrument was placed in a glove box with < 0.5 ppm oxygen and moisture.

[0039] Vapor pressure (VP) measurements were performed on a METTLER TOLEDO® thermal analysis system TGA / DSC 3+ using a stepped isothermal TGA method in 10°C increments within the range of 100°C–260°C, with sample volumes ranging from approximately 25 mg to approximately 45 mg, under a constant N2 inert nitrogen flow rate of 200 mL / min. These steps were held at the respective temperatures for 10 minutes to allow the evaporation rate to reach equilibrium. Immediately after sample measurement, standard analytical grade anthracene was run using the same VP method as the sample under study. VP measurements were performed using standards from each point on the DIPPR [https: / / dippr.aiche.org / ] to calibrate the VP measurements.

[0040] Melting point (MP) measurements were performed on a METTLER TOLEDO® thermal analysis system DSC 3+ instrument with a sample volume of approximately 5 mg to approximately 15 mg and a heating rate of 10°C / min.

[0041] The ALD thin film is prepared in a showerhead-type ALD reactor. The precursor is placed in a container and the gas delivery line is heated to 20°C above the container temperature. A carrier gas is supplied to the reactor and the precursor line via a mass flow controller. High-purity argon is used both as a carrier gas to transfer the precursor and as a purge gas to remove byproducts and excess gas from the reactor. Typically, the reactor is operated at 0.5–2 Torr, which is achieved by throttling the argon flow using a flow control valve.

[0042] XPS: Analysis of film composition and impurities using X-ray photoelectron spectroscopy.

[0043] The uniformity of the film thickness was measured using an ellipsometry. Thickness was measured at 25 points on a 6-inch wafer, excluding the 7 mm edge. Non-uniformity was calculated using the Min-Max method: (MAX - MIN) / (2 * average) * 100%. Industrial Applicability

[0044] The present invention is at least industrially applicable to the formation of coatings and films for semiconductors.

[0045] Although the invention has been described in conjunction with specific embodiments thereof, it will be apparent to those skilled in the art that many alternatives, modifications, and variations will be apparent from the foregoing description. Therefore, it is intended to encompass all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims. The invention may suitably include, consist of, or be substantially composed of the disclosed elements, and may be practiced without any undisclosed elements. Furthermore, any language relating to sequence, such as "first" and "second," should be understood in an exemplary sense rather than a restrictive one. For example, those skilled in the art will recognize that certain steps may be combined into a single step.

[0046] All references herein are hereby incorporated in their entirety by reference, and are cited individually for the purpose of obtaining specific information. Notation and Nomenclature

[0047] The following detailed description and claims utilize many abbreviations, symbols, and terms commonly known in the art, and include: • The singular forms “a / an” and “the” include plural indicators unless the context clearly indicates otherwise. • “Comprising” in the claims is an open transitional term meaning that the subsequently identified claim elements are a non-exclusive list (i.e., anything else may be additionally included and remain within the scope of “comprising”). Unless otherwise stated herein, “comprising” as used herein may be replaced by the more restrictive transitional terms “consistently consisting of” and “consisting of”. • “Providing” in the claims is defined as meaning supplying, providing, making available, or preparing something. This step may, conversely, be performed by any actor in the absence of explicit language in the claims. • “As needed” or “as needed” means that the event or circumstance described below may or may not occur. The description includes examples in which the event or circumstance occurs and examples in which the event or circumstance does not occur. • The scope herein may be expressed as from about one specific value and / or about another specific value. When such ranges are described, it should be understood that another embodiment refers to a specific value and / or to that specific value, together with all combinations within the range. • As used herein, "about" or "around / approximately" in the text or claims means ±10% of the value. • As used herein, "room temperature" in the text or claims means approximately 20°C to approximately 25°C. • The term "ambient temperature" refers to an ambient temperature of approximately 20°C to approximately 25°C. • 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 different material layers deposited thereon from previous manufacturing steps. For example, the wafer may include a silicon layer (e.g., crystalline, amorphous, porous, etc.), a silicon-containing layer (e.g., SiO2, SiN, SiON, SiCOH, etc.), a metal-containing layer (e.g., copper, cobalt, ruthenium, tungsten, platinum, palladium, nickel, ruthenium, gold, etc.), or a combination thereof. Furthermore, the substrate may be planar or patterned. The substrate may be an organically patterned photoresist film. The substrate may include an oxide layer used as a dielectric material in MEMS, 3D NAND, MIM, DRAM, or FeRam device applications (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.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 surface may be a trench or a line. Throughout this specification and the scope of the claims, the wafer and any associated layers thereon are referred to as a substrate. • It should be noted herein that the terms "film" and "layer" are used interchangeably. It should be understood that a film may correspond to or be associated with a layer, and a layer may 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 surface may range from as large as the entire wafer to as small as a trench or line. • Standard abbreviations for elements of the periodic table are used herein. It should be understood that elements may be referred to by these abbreviations (e.g., Si refers to silicon, N to nitrogen, O to oxygen, C to carbon, H to hydrogen, F to fluorine, etc.). • A unique CAS registry number (i.e., "CAS") assigned by the Chemical Abstracts Service is provided to identify the specific molecule disclosed. • As used herein, the term "alkyl group" refers to a saturated or unsaturated functional group containing only carbon and hydrogen atoms. As used herein, the term "alkyl group" refers to a saturated functional group containing only carbon and hydrogen atoms; alkyl is a type of hydrocarbon. Additionally, the term "alkyl" refers to a straight-chain, branched, or cyclic alkyl group. Examples of straight-chain 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. • As used herein, the abbreviation "Me" refers to methyl; the abbreviation "Et" refers to ethyl; the abbreviation "Pr" refers to any propyl (i.e., n-propyl or isopropyl); the abbreviation "iPr" refers to isopropyl; the abbreviation "Bu" refers to any butyl (n-butyl, isobutyl, tert-butyl, tert-butyl); the abbreviation "tBu" refers to tert-butyl; the abbreviation "sBu" refers to tert-butyl; the abbreviation "iBu" refers to isobutyl; the abbreviation "Ph" refers to phenyl; the abbreviation "Am" refers to any pentyl (isopentyl, tert-pentyl, tert-pentyl); the abbreviation "Cy" refers to cycloalkyl (cyclobutyl, cyclopentyl, cyclohexyl, etc.); the abbreviation "amd" refers to ZNC(CH3)=NZ, where Z is an alkyl group as defined by the Z series, such as iPr or tBu; the abbreviation "fmd" refers to ZNC(H)=NZ, where Z is an alkyl group as defined by the Z series, such as iPr or tBu. • Please note that silicon-containing films, such as Si, SiN, SiO, SiOC, SiON, and SiCON, are listed throughout this specification and the claims without mentioning their appropriate stoichiometry. Silicon-containing films may also include dopants such as B, P, As, Ga, and / or Ge. The fact that the films contain some residual hydrogen is also omitted in the description of the film composition. For example, a SiOC film may contain residual H. • Scopes herein may be expressed as from about one specific value and / or about another specific value.When such a range is expressed, it should be understood that another embodiment is from that specific value and / or to that other specific value, together with all combinations within the range. Any and all ranges listed herein include their endpoints (i.e., x = 1 to 4, or x ranges from 1 to 4, including x = 1, x = 4, and x = any number in between), regardless of whether the term "inclusively" is used. • References to "one embodiment" or "implementation" herein mean that a particular feature, structure, or characteristic described with respect to that embodiment may be included in at least one embodiment of the invention. The phrase "in one embodiment" appearing in different places in the specification does not necessarily all refer to the same embodiment, and a single or alternative embodiment is not necessarily mutually exclusive with other embodiments. The above also applies to the term "implementation". • As used herein, when used in the context of describing an R group, the term "independently" should be understood to mean that the subject 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 additional kind of the same R group. For example, in the formula MR1 x (NR2R3)(4-x) (where x is 2 or 3), the two or three R1 groups may (but not necessarily) be identical to each other or identical to R2 or R3. Furthermore, it should be understood that, unless otherwise explicitly stated, the values ​​of the R groups are independent of each other when used in different formulas. • As used herein, the term "exemplary" is used to mean serving as an example, illustration, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as superior to or advantageous to other aspects or designs. Rather, the use of the term "exemplary" is intended to present concepts in a concrete manner. • Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless otherwise stated or clear from the context, "X adopts A or B" is intended to mean any natural inclusive arrangement. That is, if X adopts A; X adopts B; or X adopts both A and B, then "X adopts A or B" is satisfied in any of the foregoing cases. Furthermore, the article “a / an” used in this application and the appended claims should generally be interpreted as “one or more” unless otherwise stated or clearly indicated from the context to be in the singular form. [Simplified Explanation of the Diagram]

[0034] [Figure 1] shows a table of relevant properties of the chemicals presented herein and several comparative chemicals;

[0035] [Figure 2] shows the results of ALD deposition using Cp2Y[EtNC(H)NEt] and wafers at several temperatures;

[0036] [Figure 3] shows the degree of non-uniformity of the deposited film. [Biomaterial Storage]

[0049] None

Claims

1. A chemical substance defined by the following formula: , and selected from the group consisting of: , or.

2. The chemicals as described in claim 1, wherein, This chemical is...

3. The chemicals as described in claim 1, wherein, This chemical is...

4. The chemicals as described in claim 1, wherein, This chemical is...

5. A composition comprising the chemicals described in any one of claims 1-4, wherein, The composition is a liquid at 50°C.

6. A gaseous composition comprising any one of the chemicals described in claims 1-4.

7. The gaseous composition as described in claim 6, further comprising additional gaseous or chemical vapors.

8. The gaseous composition as described in claim 7, wherein, The additional gas system carrier gas is selected from nitrogen, hydrogen, helium, or argon.

9. A method for depositing a material on a surface, the method comprising the steps of: a) firstly, exposing the surface to vapors of a chemical as described in any one of claims 1-4, or a gaseous composition as described in claim 6, and b) secondly, exposing the surface to a co-reactant, thereby forming a deposit of a yttrium- or scandium-containing material on the surface.

10. The method as described in claim 9, wherein, The co-reactant is an oxidizing agent.

11. The method as described in claim 9 or 10, wherein, This method includes atomic layer deposition.

12. The method as described in claim 9 or 10, wherein, The surface temperature is maintained between 200°C and 475°C.

13. As in request item 12, wherein, The surface temperature is maintained between 200°C and less than 225°C.

14. The method as described in claim 9, wherein, The co-reactants include an aluminum source and a nitrogen source.

15. The method as described in claim 14, wherein, The aluminum source is trimethylaluminum (TMA) and the nitrogen source is ammonia (NH3).

16. The method as described in claim 14 or 15, wherein, The temperature range for steps a) and / or b) is 500°C to 600°C.

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