Intrinsic ferroelectric Hf-Zr containing films

Abstract

The disclosed and claimed invention relates to crystalline ferroelectric materials comprising mixtures of hafnium oxide and zirconium oxide that have a substantial proportion (i.e., greater than about 40%) or a predominant proportion of the material in the ferroelectric phase in the as-deposited state (i.e., without the need for further processing such as subsequent capping or annealing), and methods for making and depositing these materials.

Description

[Technical Field]

[0001] The disclosed and claimed invention relates generally to ferroelectric materials deposited using vapor deposition techniques, including atomic layer deposition (ALD). More specifically, the disclosed and claimed invention relates to thin film crystalline ferroelectric materials, and methods for making and depositing these materials, comprising mixtures of hafnium oxide and zirconium oxide having a substantial proportion (i.e., greater than about 40%) of the material in the ferroelectric phase. Importantly, these materials exhibit ferroelectric properties without the need for further processing, such as subsequent capping or annealing. [Background technology]

[0002] Hafnium and zirconium oxide-based ferroelectric materials enable a variety of computing devices, including nonvolatile memory and power-saving logic devices, due to their strong nonlinear capacitance and remanent polarization. These materials may also be useful for a variety of other thermal and magnetic applications. Hafnium oxide- and zirconium oxide-containing materials are highly desirable for these applications due to their compatibility with many CMOS fabrication processes and materials. They are also desirable due to their ability to be deposited as thin films from the gas phase, including ALD processes involving the stepwise introduction and removal of precursors and subsequent introduction and removal of reactant gases, as well as other known processes (e.g., chemical vapor deposition (CVD) or pulsed CVD). Hafnium oxide- and zirconium oxide-based materials are polymorphic. Therefore, their atoms can be arranged in several crystalline structures (i.e., various regular atomic configurations). It is well known that the most stable bulk structure of hafnium oxide- and zirconium oxide-based materials is the monoclinic phase (Figure 7A); however, this phase does not support ferroelectricity. Other polymorphs (e.g., some orthorhombic phases (FIG. 7B) and rhombohedral phases (FIG. 7C)) have the necessary symmetry to support ferroelectric switching behavior, while other phases (e.g., the tetragonal phase common in zirconium oxide thin films (FIG. 7D)) can be antiferroelectric-like. The accompanying list of related art is intended as a reference for more detailed descriptions of the general features and aspects of this technology.

[0003] In many vapor-phase and atomic layer deposition processes for mixed hafnium oxide and zirconium oxide, these materials are amorphous in the as-deposited state. For example, in Figure 1, section A shows alternating atomic layer Hf deposited from an amide-based precursor and ozone at 285 °C. 0.45 Zr 0.55 Grazing incidence x-ray diffraction (GIXRD) pattern of a 7 nm film material composed of O2. The GIXRD pattern does not show strong crystalline peaks for the as-deposited material.

[0004] Even with thermal treatment, crystallization to a monoclinic or other non-ferroelectric phase is common, thereby reducing the fraction of material capable of ferroelectric behavior. For example, in Figure 1, section B shows the same material shown in section A after thermal annealing at 500°C for 10 minutes in nitrogen. This material has a predominantly monoclinic phase (evidenced by the peak areas between 27° and 30° 2θ) mixed with other phases that may be ferroelectric or antiferroelectric (evidenced by the peak areas between 30° and 32° 2θ).

[0005] Several techniques have been developed to suppress the monoclinic phase in favor of phases capable of supporting ferroelectricity. For example, the introduction of other elements into the material, either sequentially or simultaneously through the vapor phase introduction of precursors for other elements (such as, but not limited to, Si, Al, Gd, La, and Y), has been reported as a means of suppressing the monoclinic phase. Furthermore, heat treatment in the presence of a capping layer has been shown to be effective. For example, in Figure 1, section C shows the same material shown in section A after capping with a 5 nm thick PVD titanium nitride layer and subsequent heat treatment at 500 °C for 10 minutes in nitrogen. Unlike the uncapped film shown in section B, the capped film in section C shows nearly complete suppression of the monoclinic phase (evidenced by the peak area between 27° and 30° 2θ).

[0006] One study has shown that thick films (approximately 30 nm) of hafnium oxide and zirconium oxide can exhibit weak ferroelectricity from a ferroelectric phase. See Y. Li et al., “A Ferroelectric Thin Film Transistor Based on Annealing-Free HfZrO Film,” IEEE Journal of the Electron Devices Society, vol. 5, no. 5, pp. 378–383, September 2017, doi: 10.1109 / JEDS.2017.2732166. This behavior is likely the result of lower surface energy effects compared to thinner films and the prolonged thermal exposure required to produce films of such thickness, which serves as a functionally equivalent means to annealing. However, this study acknowledges what is generally known in the art: thin films (approximately 20 nm or less) do not exhibit ferroelectric behavior without elevated temperature annealing (alone or in combination with doping) and the capping methods described above.

[0007] Therefore, obtaining the desired ferroelectric phase in the prior art depends on a complex combination of (i) the deposition conditions of the material itself, (ii) the choice of dopant, interface, and importantly, top interface, and (iii) post-deposition heat treatment. As can be easily understood, this combination of factors imposes significant limitations on the usefulness of such materials in terms of possible substrates, interlayers, electrodes, compositions, and processes. In fact, the thermal profile in devices implementing such ferroelectric materials may not be compatible with all of the necessary or desirable applications for which the ferroelectric material may be useful. For example, it has been observed that specific electrodes may be required to modulate the electron work function, interfaces may be required to form barrier layers against chemical reactions and atomic diffusion, and heat treatment conditions may be limited by stresses induced in other layers in the multilayer stack. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US$8,568,530 [Non-patent literature]

[0009] [Non-Patent Document 1] Y. Li et al., “A Ferroelectric Thin Film Transistor Based on Annealing-Free HfZrO Film”, IEEE Journal of the Electron Devices Society, vol. 5, no. 5, pp. 378-383, September 2017, doi: 10.1109 / JEDS.2017.2732166 [Non-patent document 2] George SM,et al.J.Phys.Chem.,1996,100,13121-13131 [Non-patent document 3] Chemical Vapor Deposition:Precursors,Processes,and Applications;Jones,AC;Hitchman,ML,Eds.,The Royal Society of Chemistry:Cambridge,2009;Chapter 1,pp.1-36 [Non-patent document 4] https: / / onlinelibrary.wiley.com / doi / full / 10.1002 / pssb.201900285 Summary of the Invention [Problem to be solved by the invention]

[0010] The intrinsic ferroelectric film materials described herein, and their methods of use, address the problems previously described. In doing so, the materials and methods described herein reduce processing times, making them particularly suited to the demands of current manufacturing procedures. Those skilled in the art can readily appreciate the potential for subsequent optimization of interfaces, electrodes, and thermal processing conditions following the deposition of these materials. [Means for solving the problem]

[0011] In one aspect, the disclosed invention relates to ferroelectric thin film materials derived from a mixture of hafnium oxide and zirconium oxide deposited from the vapor phase, which have a substantial volume fraction of the ferroelectric phase in the as-deposited state (i.e., without further annealing and / or capping) and as measured by phase determination techniques or electrical testing known to those skilled in the art (e.g., x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM), polarization voltage or polarization field testing, piezoelectric force microscopy, or a combination thereof). In yet another aspect, the ferroelectric material has a majority volume fraction of the ferroelectric phase in the as-deposited state. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 20 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 15 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 10 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 5 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 3 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 1 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 0.5 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 0.2 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 0.2 nm to approximately 20 nm. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 0.2 nm to approximately 15 nm. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 0.2 nm to approximately 10 nm. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 0.2 nm to approximately 5 nm. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 0.2 nm to approximately 3 nm. In another aspect, the material exhibits ferroelectric properties as a thin film between approximately 0.2 nm and approximately 1 nm. In another aspect, the material exhibits ferroelectric properties as a thin film between approximately 0.2 nm and approximately 0.5 nm.

[0012] In another aspect, the ferroelectric material has the formula I("(R 1 -Cp)(R 2 -Cp)-M-(OR 3 )(R 4 )") (Cp is a cyclopentadienyl group) and / or Formula II ("(R 5 -Cp)(R 6 -Cp)-M-(R 7 )(R 8 )"), where Cp is a cyclopentadienyl group.

[0013] [ka] wherein M is Zr or Hf; and R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from C1 to C6 linear alkyl, C1 to C6 branched alkyl, C1 to C6 halogenated linear alkyl, and C1 to C6 halogenated branched alkyl.

[0014] In another aspect, in Formula I, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably a C1-C6 linear alkyl. 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each preferably the same C1-C6 linear alkyl. In another aspect, in Formula I, R 1 , R 2 , R 3, R 4 , R 5 , R 6 , R 7 and R 8 is preferably a methyl group. 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably an ethyl group. In another aspect, in Formula I, R 1 , R 2 , R 5 and R 6 is preferably an ethyl group. In another aspect, in Formula I, R 3 , R 4 , R 7 and R 8 is preferably a methyl group. 1 , R 2 , R 5 and R 6 are each preferably an ethyl group, and R 3 , R 4 , R 7 and R 8 are each preferably a methyl group.

[0015] In another aspect, in Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably a C1-C6 linear alkyl. In yet another aspect, in Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8are each preferably the same C1-C6 linear alkyl. In another aspect, in Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each preferably a methyl group. In another aspect, in Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each preferably an ethyl group. In another aspect, in Formula II, R 1 , R 2 , R 5 and R 6 are each preferably an ethyl group. In another aspect, in Formula II, R 3 , R 4 , R 7 and R 8 are each preferably a methyl group. In another aspect, in Formula II, R 1 , R 2 , R 5 and R 6 are each preferably an ethyl group, and R 3 , R 4 , R 7 and R 8 are each preferably a methyl group.

[0016] In another aspect, the advanced metallocene precursor is one or more of (MeCp)Zr(OMe)Me, (MeCp)Hf(OMe)Me, (MeCp)Zr(Me)2, (MeCp)Hf(Me)2, (EtCp)Zr(OMe)Me, (EtCp)Hf(OMe)Me, (EtCp)Zr(Me)2, (EtCp)Hf(Me)2, and combinations thereof.

[0017] In another aspect, the advanced metallocene precursor is one or more of a mixture of (MeCp)Zr(OMe)Me and (MeCp)Hf(OMe)Me, a mixture of (MeCp)Hf(Me) and (MeCp)Hf(Me)2, a mixture of (EtCp)Zr(OMe)Me and (EtCp)Hf(OMe)Me, and a mixture of (EtCp)Hf(Me)2 and (EtCp)Hf(Me)2.

[0018] In another aspect, the advanced metallocene precursor is one or more of the precursors disclosed and / or claimed in U.S. Pat. No. 8,568,530, the contents of which are incorporated herein in their entirety.

[0019] In another aspect, the disclosed invention provides a method for fabricating and depositing the ferroelectric thin film material on a substrate using vapor deposition techniques. In yet another aspect, the ferroelectric material is deposited on a substrate by an ALD process and / or other known deposition processes (e.g., CVD, pulsed CVD). In yet another aspect, the method uses a reactant gas comprising one or more of oxygen (e.g., ozone, elemental oxygen, molecular oxygen / O), water, hydrogen peroxide, and nitrous oxide at a deposition temperature greater than approximately 200°C and less than approximately 570°C, more preferably between approximately 265°C and approximately 500°C. In yet another aspect, the deposition temperature is preferably less than approximately 340°C. In yet another aspect, the deposition temperature is preferably between approximately 280°C and approximately 300°C. In yet another aspect, ozone is a preferred reactant gas. In yet another aspect, water is a preferred reactant gas.

[0020] This summary section is not intended to identify every aspect and / or novel aspect of the disclosed and claimed invention. Instead, this summary provides only a preliminary description of various aspects and corresponding points of novelty over conventional and known techniques. For additional details and / or possible perspectives of the disclosed and claimed invention and aspects, reference is made to the detailed description of the invention and corresponding drawings, further described below.

[0021] The order in which the different steps described herein are presented is provided for purposes of clarity. In general, the steps disclosed herein may be performed in any suitable order. Additionally, although different features, techniques, arrangements, etc. described herein may each be described in different parts of the specification, it is intended that each of these concepts can be implemented independently of each other or in combination with each other, where appropriate. Thus, the disclosed and claimed invention can be embodied and considered in many different ways.

[0022] The accompanying drawings provide a further understanding of the disclosed invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosed invention, and together with the description, serve to explain the principles of the disclosed invention. [Brief explanation of the drawings]

[0023] [Figure 1] Figure 1 shows the grazing incidence x-ray diffraction pattern for a 7 nm thin film material composed of alternating atomic layer deposited Hf0.45Zr0.55O2 from amide-based precursors and ozone at 285 °C. [Figure 2] FIG. 2 illustrates one embodiment of a method for depositing an example of the intrinsic ferroelectric material disclosed herein onto a substrate. [Figure 3] FIG. 3 illustrates another embodiment of a method for depositing an example of the intrinsic ferroelectric material disclosed herein onto a substrate. [Figure 4]FIG. 4 shows the grazing incidence XRD pattern for the intrinsic ferroelectric material formed and deposited by the process shown in FIG. [Figure 5] FIG. 5 shows a polarization-electric field plot for the intrinsic ferroelectric material formed and deposited by the process shown in FIG. 3, measured using a Radiant Ferroelectric Tester. [Figure 6] FIG. 6 illustrates another embodiment of a method for depositing an exemplary intrinsic ferroelectric material disclosed herein onto a substrate. [Figure 7A] 7A-D show the known crystalline phases: monoclinic phase P21 / c (FIG. 7A); orthorhombic phase Pca21 (FIG. 7B); rhombohedral phase R3 (FIG. 7C); and tetragonal phase P42 / nmc (FIG. 7D). [Figure 7B] 7A-D show the known crystalline phases: monoclinic phase P21 / c (FIG. 7A); orthorhombic phase Pca21 (FIG. 7B); rhombohedral phase R3 (FIG. 7C); and tetragonal phase P42 / nmc (FIG. 7D). [Figure 7C] 7A-D show the known crystalline phases: monoclinic phase P21 / c (FIG. 7A); orthorhombic phase Pca21 (FIG. 7B); rhombohedral phase R3 (FIG. 7C); and tetragonal phase P42 / nmc (FIG. 7D). [Figure 7D] 7A-D show the known crystalline phases: monoclinic phase P21 / c (FIG. 7A); orthorhombic phase Pca21 (FIG. 7B); rhombohedral phase R3 (FIG. 7C); and tetragonal phase P42 / nmc (FIG. 7D).

[0024] definition Unless otherwise stated, the following terms used in the specification and claims have the following meanings in this application.

[0025] As used herein, the use of the singular includes the plural, and unless specifically stated otherwise, the singular means "at least one." Furthermore, the use of the term "comprises," as well as other verb forms such as "comprise," is not limiting. Also, the use of terms such as "element" or "component" includes both elements or components containing one unit and elements or components containing more than one unit, unless specifically stated otherwise. As used herein, the conjunction "and" is intended to be inclusive, and the conjunction "or" is not intended to be exclusive unless otherwise indicated. For example, the phrase "or instead" is intended to be exclusive. As used herein, the term "and / or" refers to any combination of the aforementioned elements, including the use of a single element.

[0026] The term "about" or "approximately," when used in connection with a measurable variable, refers to the stated value of the variable, as well as all values ​​of the variable that are within experimental error of the stated value (e.g., within a 95% confidence limit of the mean) or within a percentage of the stated value (e.g., within ±10%, within ±5%), whichever is greater.

[0027] For purposes of this invention and the claims thereto, the numbering convention for the Periodic Table Groups follows the IUPAC Periodic Table of the Elements.

[0028] As used herein, the term "and / or" as used in phrases such as "A and / or B" is intended to include "A and B," "A or B," or "A" and "B."

[0029] The terms "substituent," "residue," "group," and "moiety" may be used interchangeably.

[0030] As used herein, the terms "metal-containing complex" (or more simply, "complex") and "precursor" are used interchangeably and refer to a metal-containing molecule or compound that can be used to produce a metal-containing film by a deposition process such as, for example, ALD or CVD. The metal-containing complex can be deposited, adsorbed, decomposed, delivered, and / or distributed onto a substrate or surface thereof such that a metal-containing film is formed.

[0031] As used herein, the term "metal-containing film" includes not only elemental metal films, as defined in more detail below, but also films that contain one or more elements in addition to metal, such as metal nitride films, metal silicide films, metal carbide films, and similar films.

[0032] As used herein, the terms “elemental metal,” “elemental metal film,” and “pure metal film” are used interchangeably and refer to a film consisting of or consisting essentially of pure metal. For example, an elemental metal film may contain 100% pure metal, or an elemental metal film may contain at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.9%, or at least about 99.99% pure metal, along with one or more impurities. However, films containing elemental metal are distinguished from binary films containing a metal and a nonmetal (e.g., C, N, O) and ternary films containing a metal and two nonmetals (e.g., C, N, O), although films containing elemental metal may contain some amount of impurities. Unless the context indicates otherwise, the term “metal film” is intended to mean an elemental metal film.

[0033] As used herein, the terms "deposition process" and "thermal deposition" refer to any type of vapor deposition technique, including, but not limited to, CVD and ALD. In various embodiments, CVD can take the form of conventional (i.e., continuous flow) CVD, liquid injection CVD, plasma-enhanced CVD, or photo-assisted CVD. CVD can also take the form of a pulsed technique, i.e., pulsed CVD. ALD is used to form metal-containing films by evaporating and / or flowing at least one metal complex disclosed herein onto a substrate surface. For conventional ALD methods, see, for example, George S. M., et al., J. Phys. Chem., 1996, 100, 13121-13131. In other embodiments, ALD can take the form of conventional (i.e., pulsed injection) ALD, liquid injection ALD, photo-assisted ALD, plasma-assisted ALD, or plasma-enhanced ALD. The term "vapor deposition method" further includes various vapor deposition techniques described in Chemical Vapor Deposition: Precursors, Processes, and Applications; Jones, AC; Hitchman, ML, Eds., The Royal Society of Chemistry: Cambridge, 2009; Chapter 1, pp. 1-36 (Non-Patent Document 3).

[0034] Unless otherwise specified, "alkyl" refers to a hydrocarbon group that can be linear, branched (e.g., methyl, ethyl, propyl, isopropyl, tert-butyl, and the like), cyclic (e.g., cyclohexyl, cyclopropyl, cyclopentyl, and the like), or polycyclic (e.g., norbornyl, adamantyl, and the like). Suitable acyclic groups can be methyl, ethyl, n- or isopropyl, n-, iso-, or tert-butyl, linear or branched pentyl, hexyl, heptyl, octyl, decyl, dodecyl, tetradecyl, and hexadecyl. Unless otherwise specified, alkyl refers to a moiety of 1 to 10 carbon atoms. Cyclic alkyl groups can be monocyclic or polycyclic. Examples of monocyclic alkyl groups include substituted cyclopentyl, cyclohexyl, and cycloheptyl groups. The substituents can be any of the acyclic alkyl groups described herein. As described herein, cyclic alkyl groups can have any of the acyclic alkyl groups described above as substituents. These alkyl moieties may be substituted or unsubstituted.

[0035] "Halogenated alkyl" refers to a linear, cyclic, or branched saturated alkyl group, as defined above, in which one or more of the hydrogens have been replaced with a halogen (e.g., F, Cl, Br, and I). Thus, for example, a fluorinated alkyl (also known as a "fluoroalkyl") refers to a linear, cyclic, or branched saturated alkyl group, as defined above, in which one or more of the hydrogens have been replaced with a fluorine (e.g., trifluoromethyl, perfluoroethyl, 2,2,2-trifluoroethyl, perfluoroisopropyl, perfluorocyclohexyl, and the like). Such haloalkyl moieties (e.g., fluoroalkyl moieties), when not perhalogenated / multihalogenated, may be unsubstituted or further substituted.

[0036] The section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described. All references or portions thereof cited herein, including but not limited to patents, patent applications, papers, books, and treatises, are incorporated herein in their entirety for all purposes. In the event that the definitions of terms in any of the references and similar materials cited herein conflict with those herein, the definitions herein shall control. DETAILED DESCRIPTION OF THE INVENTION

[0037] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to be limiting with respect to the invention as claimed. The objects, features, advantages, and concepts of the disclosed invention will be apparent to those skilled in the art from the description set forth herein, and the disclosed invention can be readily implemented by those skilled in the art based on the description set forth herein. The description of "preferred embodiments" and / or examples indicating preferred modes for carrying out the disclosed invention are included for illustrative purposes and are not intended to limit the scope of the claims.

[0038] It will also be apparent to those skilled in the art that various modifications may be made in the practice of the disclosed invention based on the aspects described herein without departing from the spirit and scope of the invention disclosed herein.

[0039] I. Intrinsic ferroelectric materials As previously described, the disclosed and claimed invention relates to crystalline ferroelectric thin film materials, and methods for fabricating and depositing these materials, comprising a mixture of hafnium oxide and zirconium oxide having a substantial proportion (i.e., greater than about 40%) of the material in the ferroelectric phase. In yet another aspect, the ferroelectric materials have a majority volume fraction in the ferroelectric phase. Importantly, these materials exhibit ferroelectric properties without the need for further processing, such as a subsequent capping step (as shown in FIG. 1) or an annealing step. To be ferroelectric, the fabricated materials possess one or more of the following: (i) remnant polarization or (ii) a polarization field curve with hysteresis and loop opening.

[0040] To be ferroelectric, the material must have an atomic arrangement capable of supporting ferroelectricity in a fraction of the film. Preferably, a substantial portion of the film volume has an atomic arrangement capable of supporting ferroelectricity. It is recognized that for thin films, doped materials, and some layered materials, the phase distribution in the material may not be easily determined by X-ray diffraction. In this case, any other suitable technique for establishing the phase of the film, such as Raman spectroscopy, infrared spectroscopy, X-ray absorption spectroscopy, transmission electron microscopy, or a combination thereof, can be used to determine the phase distribution. For example, https: / / onlinelibrary.wiley.com / doi / full / 10.1002 / pssb.201900285 (Non-Patent Document 4) describes a technique for identifying the phase of a film within approximately 10%.

[0041] The material can be composed of hafnium oxide and zirconium oxide in any suitable molar ratio, with a ratio between 1:3 and 3:1 being preferred. The thickness of the ferroelectric material can be any thickness suitable for a given application; the material can be made thicker to increase remanent polarization or reduce leakage current through the thickness of the material, or thinner due to geometric constraints or to increase the capacitance of the film.

[0042] In the present invention, the preferred range of thickness is approximately 0.2 nm to approximately 20 nm, more preferably approximately 0.2 nm to 10 nm.It is also preferred that the material forms a film having a thickness of approximately 10 nm or less.In some embodiments, it is preferred that the material forms a film having a thickness of approximately 5 nm or less.

[0043] However, as noted above, preferred and / or desirable thicknesses will vary depending on the particular application. Thus, as further indicated, in some embodiments, the material exhibits ferroelectric properties as a thin film of approximately 20 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 15 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 10 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 5 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 3 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 1 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 0.5 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film of approximately 0.2 nm or less. In another aspect, the material exhibits ferroelectric properties as a thin film between approximately 0.2 nm and approximately 20 nm. In another aspect, the material exhibits ferroelectric properties as a thin film between approximately 0.2 nm and approximately 15 nm. In another aspect, the material exhibits ferroelectric properties as a thin film between approximately 0.2 nm and approximately 10 nm. In another aspect, the material exhibits ferroelectric properties as a thin film between approximately 0.2 nm and approximately 5 nm. In another aspect, the material exhibits ferroelectric properties as a thin film between approximately 0.2 nm and approximately 3 nm. In another aspect, the material exhibits ferroelectric properties as a thin film between approximately 0.2 nm and approximately 1 nm. In another aspect, the material exhibits ferroelectric properties as a thin film between approximately 0.2 nm and approximately 1 nm.

[0044] In the disclosed and claimed materials, a substantial portion of the crystalline material, comprising approximately 40% or more, is in the ferroelectric phase; therefore, the total non-ferroelectric atomic ordering components are less than approximately 60% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic ordering components are less than approximately 50% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic ordering components are less than approximately 40% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic ordering components are less than approximately 30% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic ordering components are less than approximately 25% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic ordering components are less than approximately 20% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic ordering components are less than approximately 15% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic ordering components are less than approximately 10% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic ordering components are less than approximately 5% of the total volume of the material.

[0045] Furthermore, in the disclosed and claimed materials, less than approximately 60% of the total volume of the material comprises the non-ferroelectric monoclinic phase. Thus, in one embodiment of the disclosed and claimed materials, the monoclinic phase component is less than approximately 50% of the total volume of the material. In another embodiment, the monoclinic phase component is less than approximately 40% of the total volume of the material. In another embodiment, the monoclinic phase component is less than approximately 30% of the total volume of the material. In another embodiment, the monoclinic phase component is less than approximately 25% of the total volume of the material. In another embodiment, the monoclinic phase component is less than approximately 20% of the total volume of the material. In another embodiment, the monoclinic phase component is less than approximately 15% of the total volume of the material. In another embodiment, the monoclinic phase component is less than approximately 10% of the total volume of the material. In another embodiment, the monoclinic phase component is less than approximately 5% of the total volume of the material. In yet another embodiment, more than 50% of the total volume of the crystalline material is in the ferroelectric phase, less than 50% of the total volume of the crystalline material comprises a non-ferroelectric phase component, and less than 25% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component.

[0046] In the disclosed and claimed invention, the preferred carbon content of the material is less than approximately 6 atomic percent, as measured by a suitable technique such as x-ray photoelectron spectroscopy. In yet another aspect, the carbon content is less than approximately 5 atomic percent. In yet another aspect, the carbon content is less than approximately 4 atomic percent. In yet another aspect, the carbon content is less than approximately 3 atomic percent. In yet another aspect, the carbon content is less than approximately 2 atomic percent. In yet another aspect, the carbon content is less than approximately 1 atomic percent. In yet another aspect, the carbon content is between approximately 1 atomic percent and approximately 6 atomic percent. In yet another aspect, the carbon content is between approximately 1 atomic percent and approximately 5 atomic percent. In yet another aspect, the carbon content is between approximately 1 atomic percent and approximately 4 atomic percent. In yet another aspect, the carbon content is between approximately 1 atomic percent and approximately 3 atomic percent. In yet another aspect, the carbon content is between about 1 atomic percent and about 2 atomic percent.

[0047] The intrinsic ferroelectric material has the formula I("(R 1 -Cp)(R 2 -Cp)-M-(OR 3 )(R 4 )" (Cp is a cyclopentadienyl group) and / or Formula II ("(R 5 -Cp)(R 6 -Cp)-M-(R 7 )(R 8 )" (Cp is a cyclopentadienyl group).

[0048] [ka] wherein M is Zr or Hf; and R 1 , R 2 , R 3 , R 4 , R 5, R 6 , R 7 and R 8 are each independently selected from C1 to C6 linear alkyl, C1 to C6 branched alkyl, C1 to C6 halogenated linear alkyl, and C1 to C6 halogenated branched alkyl.

[0049] In another aspect, in Formula I, R 1 , R 2 , R 3 and R 4 is preferably a C1-C6 linear alkyl. 1 , R 2 , R 3 and R 4 are each preferably the same C1-C6 linear alkyl. In yet another aspect, in Formula I, R 1 , R 2 , R 3 and R 4 is preferably a methyl group. 1 , R 2 , R 3 and R 4 In yet another aspect, in Formula I, R 1 and R 2 In yet another aspect, in Formula I, R 3 and R 4 is preferably a methyl group. In another aspect, in Formula I, R 1 and R 2 are each preferably an ethyl group, and R 3 and R 4 are each preferably a methyl group.

[0050] In another aspect, in Formula II, R 5 , R 6 , R 7 and R 8 is preferably a C1-C6 linear alkyl. In yet another aspect, in Formula II, R 5 , R6 , R 7 and R 8 are each preferably the same C1-C6 linear alkyl. In another aspect, in Formula II, R 5 , R 6 , R 7 and R 8 is preferably a methyl group. 5 , R 6 , R 7 and R 8 In yet another aspect, in Formula II, R 5 and R 6 In yet another aspect, in Formula II, R 7 and R 8 is preferably a methyl group. 5 and R 6 are each preferably an ethyl group, and R 7 and R 8 are each preferably a methyl group.

[0051] In another aspect, in Formula I and Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably each independently C1-C6 linear alkyl. In yet another aspect, in Formula I and Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each preferably the same C1-C6 linear alkyl. In yet another aspect, in Formula I and Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R6 , R 7 and R 8 In yet another aspect, in Formula I and Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 In yet another aspect, in Formula I and Formula II, R 1 , R 2 , R 5 and R 6 In yet another aspect, in Formula I and Formula II, R 3 , R 4 , R 7 and R 8 In yet another aspect, in Formula I and Formula II, R 1 , R 2 , R 5 and R 6 are each preferably an ethyl group, and R 3 , R 4 , R 7 and R 8 are each preferably a methyl group.

[0052] In another aspect, the advanced metallocene precursor is one or more of (MeCp)Zr(OMe)Me, (MeCp)Hf(OMe)Me, (MeCp)Zr(Me)2, (MeCp)Hf(Me)2, (EtCp)Zr(OMe)Me, (EtCp)Hf(OMe)Me, (EtCp)Zr(Me)2, (EtCp)Hf(Me)2, and combinations thereof.

[0053] In another aspect, the advanced metallocene precursor is one or more of a mixture of (MeCp)Zr(OMe)Me and (MeCp)Hf(OMe)Me, a mixture of (MeCp)Hf(Me) and (MeCp)Hf(Me)2, a mixture of (EtCp)Zr(OMe)Me and (EtCp)Hf(OMe)Me, and a mixture of (EtCp)Hf(Me)2 and (EtCp)Hf(Me)2.

[0054] In another aspect, the advanced metallocene precursor is one or more of the precursors disclosed and / or claimed in U.S. Pat. No. 8,568,530, the contents of which are incorporated herein in their entirety.

[0055] II. Fabrication and Deposition Methods of Intrinsic Ferroelectric Materials As previously indicated, in one of its other aspects, the disclosed and claimed invention relates to a method of making and / or depositing the intrinsic ferroelectric materials disclosed herein, wherein the disclosed and claimed intrinsic ferroelectric materials are made by repeated deposition and purging of (i) a metallocene precursor and (ii) a reactant.

[0056] A. Metallocene Precursors As indicated above, the ferroelectric material has the formula I("(R 1 -Cp)(R 2 -Cp)-M-(OR 3 )(R 4 )" (wherein Cp is a cyclopentadienyl group) and / or Formula II ("(R 5 -Cp)(R 6 -Cp)-M-(R 7 )(R 8 )" (where Cp is a cyclopentadienyl group).

[0057] [ka] wherein M is Zr or Hf; and R 1 , R 2 , R3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from C1 to C6 linear alkyl, C1 to C6 branched alkyl, C1 to C6 halogenated linear alkyl, and C1 to C6 halogenated branched alkyl.

[0058] In another aspect, in Formula I, R 1 , R 2 , R 3 and R 4 is preferably a C1-C6 linear alkyl. 1 , R 2 , R 3 and R 4 are each preferably the same C1-C6 linear alkyl. In another aspect, in Formula I, R 1 , R 2 , R 3 and R 4 and each are preferably a methyl group. 1 , R 2 , R 3 and R 4 In yet another aspect, in Formula I, R 1 and R 2 In yet another aspect, in Formula I, R 3 and R 4 is preferably a methyl group. In another aspect, in Formula I, R 1 and R 2 are each preferably an ethyl group, and R 3 and R 4 are each preferably a methyl group.

[0059] In another aspect, in Formula II, R 5 , R 6 , R 7 and R 8is preferably a C1-C6 linear alkyl. In yet another aspect, in Formula II, R 5 , R 6 , R 7 and R 8 are each preferably the same C1-C6 linear alkyl. In another aspect, in Formula II, R 5 , R 6 , R 7 and R 8 are each preferably a methyl group. In another aspect, in Formula II, R 5 , R 6 , R 7 and R 8 In yet another aspect, in Formula II, R 5 and R 6 In yet another aspect, in Formula II, R 7 and R 8 is preferably a methyl group. 5 and R 6 are each preferably an ethyl group, and R 7 and R 8 are each preferably a methyl group.

[0060] In another aspect, in Formula I and Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably each independently C1-C6 linear alkyl. In yet another aspect, in Formula I and Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each preferably the same C1-C6 linear alkyl. In yet another aspect, in Formula I and Formula II, R 1 , R2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 In yet another aspect, in Formula I and Formula II, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 In yet another aspect, in Formula I and Formula II, R 1 , R 2 , R 5 and R 6 In yet another aspect, in Formula I and Formula II, R 3 , R 4 , R 7 and R 8 In yet another aspect, in Formula I and Formula II, R 1 , R 2 , R 5 and R 6 are each preferably an ethyl group, and R 3 , R 4 , R 7 and R 8 are each preferably a methyl group.

[0061] In another aspect, the advanced metallocene precursor is one or more of (MeCp)Zr(OMe)Me, (MeCp)Hf(OMe)Me, (MeCp)Zr(Me)2, (MeCp)Hf(Me)2, (EtCp)Zr(OMe)Me, (EtCp)Hf(OMe)Me, (EtCp)Zr(Me)2, (EtCp)Hf(Me)2, and combinations thereof.

[0062] In another aspect, the advanced metallocene precursor is one or more of a mixture of (MeCp)Zr(OMe)Me and (MeCp)Hf(OMe)Me, a mixture of (MeCp)Hf(Me) and (MeCp)Hf(Me)2, a mixture of (EtCp)Zr(OMe)Me and (EtCp)Hf(OMe)Me, and a mixture of (EtCp)Hf(Me)2 and (EtCp)Hf(Me)2.

[0063] In another aspect, the advanced metallocene precursor is one or more of the precursors disclosed and / or claimed in U.S. Pat. No. 8,568,530, the contents of which are incorporated herein in their entirety.

[0064] In general, suitable precursors for producing intrinsic ferroelectric materials can be deposited at or near the crystallization temperature of the desired ferroelectric material, typically between approximately 200°C and approximately 570°C, depending on the material's composition, substrate, and reactor design, among other factors. A preferred temperature is approximately 300°C (or generally between approximately 280°C and approximately 300°C), and the preferred temperature range is less than approximately 450°C, more preferably less than approximately 340°C. However, those skilled in the art will recognize that other temperatures may be possible depending on the particular precursor used, and that such precursors are within the scope of the disclosed and claimed invention. Furthermore, it should be noted that when using certain precursors other than those described herein, decomposition of the precursor may occur within the aforementioned temperature range. Decomposition products, particularly carbon and organic species, may be introduced into the deposited hafnium oxide or zirconium oxide material. While this carbon introduction may help stabilize the ferroelectric phase, it may be undesirable for reasons of material purity. Therefore, as noted above, the preferred carbon content of the material is less than approximately 6 atomic percent.

[0065] B. Reactants The reactants are reactive gases including one or more of oxygen (e.g., ozone, elemental oxygen, molecular oxygen / O), water, hydrogen peroxide, and nitrous oxide. In one embodiment, ozone is the preferred reactant gas. In another embodiment, water is the preferred reactant gas.

[0066] C. Process Steps Another aspect of the disclosed and claimed invention is (i) providing a substrate at a deposition temperature; (ii) exposing the substrate to a first precursor that does not decompose at deposition temperatures; (iii) exposing the substrate to a first reactive gas; (iv) exposing the substrate to a second precursor that does not decompose at the deposition temperature; and (v) exposing the substrate to a second reactive gas; This includes: In some embodiments, the method further comprises at least one purging step.

[0067] In one embodiment, the first and second reactive gases are each independently a gas containing one or more of oxygen, water, hydrogen peroxide, and nitrous oxide. In another embodiment, the first and second reactive gases are each independently an oxygen-containing gas. In another embodiment, the first and second reactive gases are each independently an ozone-containing gas. In another embodiment, the first and second reactive gases are each independently a water-containing gas. In another embodiment, the first and second reactive gases are the same gas. In another embodiment, the first and second reactive gases are different gases.

[0068] In one embodiment, the first precursor and second precursor are each independently a precursor having Formula I or Formula II, as described above.

[0069] In one embodiment, the method comprises an ALD process. In one embodiment, the method comprises a CVD process.

[0070] In one embodiment, the crystalline material deposited by the method of the present invention has a thickness between approximately 0.2 nm and approximately 20 nm.

[0071] In one embodiment, the crystalline material deposited by the disclosed and claimed method exhibits remnant polarization without additional heat treatment. In another embodiment, the crystalline material deposited by the disclosed and claimed method exhibits remnant polarization of 8 μC / cm 2 Remanent polarization (Pr) of more than 16 μC / cm 2 In one aspect, the crystalline materials deposited by the disclosed and claimed methods have hysteresis and remanent polarization in polarization-electric field measurements.

[0072] FIG. 2 illustrates an embodiment of a method for fabricating and depositing the intrinsic ferroelectric material described herein. As shown in FIG. 2, substrate 202 undergoes an ALD cycle 204 in which substrate 202 is exposed to vapor 201 to form and deposit the intrinsic ferroelectric material as a thin film layer 200. Layer 200 was formed without further thermal treatment or capping and exhibited ferroelectric properties in situ (i.e., as-deposited). Of course, those skilled in the art will recognize that layer 200 may then be annealed and / or capped, if desired, but doing so was not necessary to observe the ferroelectric behavior of the as-deposited layer. For example, the material can then be subjected to energy via, but not limited to, thermal, plasma, pulsed plasma, helicon plasma, high-density plasma, inductively coupled plasma, x-ray, e-beam, photon, remote plasma methods, and combinations thereof.

[0073] The composition of vapor 201 is changed during ALD cycle 204. In particular, substrate 202 is alternately exposed to metallocene precursor 205, followed by a purge, then reactant 206, followed by another purge. This process continues until the desired thickness for layer 200 is achieved. While ALD is the preferred vapor deposition technique, any suitable vapor phase deposition technique can be used, such as CVD or pulsed CVD. For example, in FIG. 2, ALD cycle 204 can be replaced by a CVD process, in which case metallocene precursor 205 and reactant 206 are provided as a mixture in vapor 201 and simultaneously provided to substrate 202.

[0074] The appropriate molar ratio of hafnium oxide to zirconium oxide can be adjusted in several ways, including introducing a hafnium-containing precursor during some of these cycles and a zirconium-containing precursor in other cycles. These cycles can be alternated, grouped together, or arranged in any other suitable permutation that results in a desired overall molar ratio, as both intimately blended and nanolaminated materials have been found to have desirable ferroelectric properties. It should also be noted that other elements can be added to the hafnium oxide-zirconium oxide material by adding appropriate precursors along with the hafnium and zirconium precursors or in separate cycles.

[0075] The substrate, e.g., substrate 202, upon which the intrinsic ferroelectric material is formed, e.g., as layer 200, can include any suitable material, such as semiconductor materials such as silicon, germanium, Group III through V materials, transition metal dichalcogenides, and mixtures thereof, metals and conductive ceramics such as titanium nitride, titanium, tantalum, tantalum nitride, tungsten, platinum, rhodium, molybdenum, cobalt, ruthenium, palladium, or mixtures thereof, or dielectrics such as silicon oxide, silicon nitride, aluminum oxide, titanium oxide, compositions of other ferroelectric materials, e.g., hafnium oxide and zirconium oxide materials, magnetic materials, and mixtures or stacks thereof.

[0076] Optionally, the substrate 202 can be patterned or textured with any suitable topography, such as a flat surface, trenches, vias, or a nanostructured surface, if desired. While this list illustrates typical substrates that may be useful in ferroelectric applications, it should not be considered limiting, as many other suitable compositions and surface patterns will be apparent to those skilled in the art. In this regard, the substrate may have some influence on the atomic arrangement and phase of the film formed thereon, for example, affecting the film's crystalline orientation and crystallization temperature. However, regardless of the particular substrate and the extent of these influences, the intrinsic ferroelectric materials described herein deposited on such substrates will have a substantial fraction of their volume in the ferroelectric phase as deposited.

[0077] FIG. 3 illustrates another embodiment of the method for fabricating and depositing the intrinsic ferroelectric materials described herein.

[0078] In this embodiment, a mixed hafnium oxide and zirconium oxide intrinsic ferroelectric material is fabricated and deposited as a layer 301 having a thickness of approximately 8.4 nm on a stack substrate 302 of PVD TiN (in direct contact with the ferroelectric material), a thermally grown SiO layer, and a Si wafer. Layer 301 was formed without any other heat treatments or capping. In this embodiment, the molar ratio of hafnium oxide to zirconium oxide is approximately 1:1 with an approximate 10% tolerance. The dielectric material is produced and deposited as a layer 301 from a vapor by ALD by alternating a first cycle 303 (which includes the steps of (i) pulsing (MeCp)Zr(OMe)Me 304, (ii) purging, (iii) pulsing ozone 305, and (iv) purging) and a second cycle 306 (which includes the steps of (i) pulsing (MeCp)Hf(OMe)Me 307, (ii) purging, (iii) pulsing ozone 308, and (iv) purging).

[0079] Those skilled in the art will appreciate that other precursors, such as (MeCp)2HfMe2 and (MeCp)2ZrMe2, and other reactants, such as water, hydrogen peroxide, or oxygen plasma, can additionally or alternatively be used. Furthermore, those skilled in the art will appreciate that the pulsing and purging times, respectively, can vary depending on the equipment. In one embodiment, the pulse lasts from approximately 2 seconds to approximately 3 seconds, followed by a purge of approximately 10 seconds. In one embodiment, the pulse lasts from approximately 10 seconds to approximately 15 seconds, followed by a purge of approximately 30 seconds to approximately 60 seconds. In another embodiment, the order in which the precursors are deposited can be reversed.

[0080] Figure 4 shows the grazing incidence XRD pattern of the intrinsic ferroelectric material fabricated and deposited as layer 301 in Figure 3 without further heat treatment or capping. As shown in Figure 4, the crystalline peaks of the material comprising layer 301 exhibit a monoclinic component 401 and a non-monoclinic component 402. By fitting the peaks and using the peak areas with the technique disclosed by McBriarty et al. (https: / / onlinelibrary.wiley.com / doi / full / 10.1002 / pssb.201900285) (Non-Patent Document 4), the calculated monoclinic component of the volume of the material comprising layer 301 is less than 25%, which is the preferred maximum volume fraction of monoclinic non-ferroelectric material.

[0081] Figure 5 shows a polarization-electric field plot for an intrinsic ferroelectric material formed and deposited by the process shown in Figure 3, measured using a Radiant Ferroelectric Tester. A top electrode contact was formed on the top surface of the ferroelectric material by applying PVD TiN through a shadow mask 501. The first curve 502 is measured using a triangular bipolar waveform from -3 V to 3 V in 25 V steps, using a frequency of 250 Hz and a period of 8 ms. The first curve 502 shows a clear opening, demonstrating remnant (non-zero) polarization at 0 V and therefore ferroelectric behavior. The second curve 503 shows a larger remnant polarization from the same device after applying a square bipolar waveform from -3 V to 3 V for 1000 cycles, using a period of 1 ms and a frequency of 1 kHz. This behavior is common to ferroelectric materials, including hafnium oxide and zirconium oxide. Polarization-electric field curves are not necessary for all applications; other techniques, such as piezoelectric force microscopy or optical experiments, can also establish ferroelectricity.

[0082] 6 illustrates another embodiment of a method for fabricating and depositing the intrinsic ferroelectric materials described herein using ALD. The method includes several steps that can be augmented with additional and / or optional steps. Step 1 involves providing a substrate at a deposition temperature between approximately 265°C and approximately 500°C, but preferably at or around approximately 300°C (e.g., above approximately 285°C and below approximately 300°C) and below 340°C. Step 2 involves (i) exposing the substrate to a first precursor that includes either hafnium or zirconium, or both hafnium and zirconium, and that does not decompose at the deposition temperature, and (ii) purging. Step 3 involves (i) exposing the substrate to a reactive gas that includes oxygen, and (ii) purging. Step 4 involves (i) exposing the substrate to a second precursor that includes either zirconium or hafnium, or both hafnium and zirconium, and that does not decompose at the deposition temperature, and (ii) purging. Step 5 involves exposing the substrate to a reactive gas comprising oxygen. Optional step 6 involves repeating steps 2-5 until a film of desired thickness of hafnium oxide and zirconium oxide is formed in a molar ratio between approximately 1:3 and approximately 3:1.

[0083] In the process of Figure 6, the intrinsic ferroelectric material is formed and deposited as a film having a substantial volume fraction of the ferroelectric phase as determined in the as-deposited state (i.e., without further annealing and / or capping) and by phase determination techniques or electrical testing known to those skilled in the art (e.g., XRD, XAS, TEM, polarization-voltage testing, piezoelectric force microscopy, or a combination thereof). Metallocene precursors that may be utilized and / or employed in the process of Figure 6 include all of those described above, and in particular, (MeCp)Zr(OMe)Me, (MeCp)Hf(OMe)Me, (MeCp)Zr(Me) and (MeCp)Hf(Me). The oxygen-containing reactant gas in Step 3 and / or Step 5 is preferably ozone. Those skilled in the art will recognize that other reactant gases, including those specifically described above (e.g., water, hydrogen peroxide), can be used.

[0084] Another aspect of the disclosed and claimed invention is a thin film, such as the thin film crystalline materials described above. In one embodiment, the film has a thickness of from about 0.2 nm to about 10 nm. In another embodiment, the film has a thickness of from about 0.2 nm to about 5 nm. In another embodiment, the film has a thickness of from about 0.2 nm to about 1 nm. In another embodiment, the film has a thickness of from about 0.2 nm to about 0.5 nm. In another embodiment, the film has a thickness of about 15 nm or less. In another embodiment, the film has a thickness of about 10 nm or less. In another embodiment, the film has a thickness of about 5 nm or less. In another embodiment, the film has a thickness of about 3 nm or less. In another embodiment, the film has a thickness of about 1 nm or less. In some embodiments, the film has a conductivity of 8 μC / cm 2 Remanent polarization (Pr) of more than 16 μC / cm 2 It has a total loop opening of over 1000 Hz.

[0085] Another aspect of the disclosed and claimed invention is the use of the thin film crystalline materials described above to form thin films that exhibit ferroelectric behavior.

[0086] Another aspect of the disclosed and claimed invention is the use of the above-described thin films as ferroelectric materials in computing devices. [Example]

[0087] More specific embodiments of the present disclosure and experimental results supporting such embodiments are described below. These examples are provided below to more fully explain the disclosed invention, and should not be construed as limiting the disclosed invention in any way.

[0088] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed invention and the specific examples provided herein without departing from the spirit or scope of the disclosed invention. Thus, the disclosed invention, including the description provided by way of example below, is intended to cover modifications and variations of the disclosed invention that come within the scope of any claims and their equivalents.

[0089] Materials and Methods: The metallocene precursors were prepared or can be prepared according to US Pat. No. 8,568,530, the contents of which are incorporated herein in their entirety.

[0090] This material was deposited in a Cambridge Nanotech Savannah 200 mm cross-flow ALD reactor using a substrate temperature of 300 °C and a paddle wheel temperature of 290 °C. The substrate consisted of a 45 mm × 45 mm p-type Si wafer covered with 1000 Å of thermally grown silicon oxide and a 5 nm PVD TiN layer sputtered at 250 °C in an Applied Materials 200 mm Endura PVD tool. To deposit 8.4 nm of mixed ZrO and HfO, 95 ALD cycles of (MeCp)Zr(OMe)Me and ozone and 95 ALD cycles of (MeCp)Hf(OMe)Me and ozone were used, alternating between these two types of cycles. Ozone was used at 200 g / m 3Ozone was provided using an InUSA ozone generator, model AC-2025, set at 0.25 psi. The oxygen flow rate into the ozone generator was approximately 300 sccm. A needle valve was located between the ozone supply and the reactor chamber to regulate the ozone flow rate. The ampoule temperature was 125°C, the precursor dose was 3 seconds, the reactant dose was 2 seconds, and the purge time was 10 seconds. The base pressure was maintained at an average pressure between 0.37 and 0.42 Torr during the purge step, between 0.42 and 0.48 Torr during the precursor pulse, and between 1 and 1.5 Torr during the reactant pulse. The process can use higher pressures intermittently or consistently. For example, in one embodiment, a maximum instantaneous pressure of 6 Torr was used during the first few pulses of ozone.

[0091] After deposition, the films were characterized by grazing incidence XRD on a Bruker D8 Discover diffractometer using a monochromatic Cu X-ray tube (CuKα, λ = 1.5418 Å). The incident beam angle was fixed at 0.7°, and XRD patterns were collected over the range 2θ 20° to 40° in steps of 0.05° using a position sensor. For ferroelectric testing, TiN top contacts (100 nm thick) were deposited by PVD on an Applied Materials Endura PVD tool at 250°C (i.e., at a non-annealed temperature below the temperature for ALD growth). Circular contacts (0.305 mm diameter; 0.073 mm 2 The area (area) was defined by a shadow mask. Polarization curves were collected using a Radian Precision II ferroelectric tester and a cascade probe station. Polarization field data were collected with a bipolar triangular waveform (0.25 kHz, -3 V to 3 V in 0.25 V steps) before and after a 1 s wake-up stress of ±3 V at 1 kHz. As shown in Figure 5, the as-deposited layer exhibited a polarization of 8 μC / cm when measured with a bipolar triangular waveform at a maximum applied field of approximately 3.8 MV / cm. 2 Remanent polarization (Pr) of more than 16 μC / cm 2 It has a total loop opening of over 1000 Hz.

[0092] Although the present invention has been described and illustrated with a certain degree of detail, it will be understood that this disclosure is made by way of example only, and that numerous variations in the conditions and order of the steps can be employed by those skilled in the art without departing from the spirit and scope of the invention. While this application is directed to the invention set forth in the claims, the disclosure of this application also includes: 1. A thin film crystalline material comprising hafnium oxide and zirconium oxide, which exhibits ferroelectric behavior in the as-deposited state. 2. (i) greater than 40% of the total volume of the crystalline material is in the ferroelectric phase; and (ii) less than 60% of the total volume of the crystalline material comprises a non-ferroelectric phase component; The crystalline material described in 1 above. 3. The crystalline material according to claim 1, wherein less than 50% of the total volume of the crystalline material is made up of non-ferroelectric phase components. 4. The crystalline material according to claim 1, wherein less than 40% of the total volume of the crystalline material is made up of non-ferroelectric phase components. 5. The crystalline material according to claim 1, wherein less than 30% of the total volume of the crystalline material is made up of non-ferroelectric phase components. 6. The crystalline material according to 1 above, wherein less than 25% of the total volume of the crystalline material is made up of non-ferroelectric phase components. 7. The crystalline material according to claim 1, wherein less than 20% of the total volume of the crystalline material is made up of non-ferroelectric phase components. 8. The crystalline material according to claim 1, wherein less than 15% of the total volume of the crystalline material is made up of non-ferroelectric phase components. 9. The crystalline material according to claim 1, wherein less than 10% of the total volume of the crystalline material is made up of non-ferroelectric phase components. 10. The crystalline material according to claim 1, wherein less than 5% of the total volume of the crystalline material comprises a non-ferroelectric phase component. 11. The crystalline material according to paragraph 1 above, wherein (iii) less than 60% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component. 12. The crystalline material according to claim 11, wherein less than 50% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component. 13. The crystalline material according to claim 11, wherein less than 40% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component. 14. The crystalline material according to claim 11, wherein less than 30% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component. 15. The crystalline material according to claim 11, wherein less than 25% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component. 16. The crystalline material according to claim 11, wherein less than 20% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component. 17. The crystalline material according to claim 11, wherein, when measured, less than 15% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component. 18. The crystalline material according to claim 11, wherein, when measured, less than 10% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component. 19. The crystalline material according to claim 11, wherein, when measured, less than 5% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component. 20. (i) greater than 50% of the total volume of the crystalline material is in the ferroelectric phase; (ii) less than 50% of the total volume of the crystalline material comprises a non-ferroelectric phase component; and (iii) less than 25% of the total volume of the crystalline material comprises a non-ferroelectric monoclinic phase component; The crystalline material described in 1 above. 21. The crystalline material described in any one of 1. to 20. above, wherein the ratio of hafnium oxide to zirconium oxide is between approximately 1:3 and approximately 3:1. 22. The crystalline material according to any one of 1. to 20. above, having a carbon content of less than approximately 6 atomic percent. 23. A crystalline material according to any one of 1. to 20. above, having a carbon content of less than approximately 5 atomic percent. 24. A crystalline material according to any one of 1. to 20. above, having a carbon content of less than approximately 4 atomic percent. 25. A crystalline material according to any one of 1. to 20. above, having a carbon content of approximately less than 3 atomic percent. 26. A crystalline material according to any one of 1. to 20. above, having a carbon content of approximately less than 2 atomic percent. 27. A crystalline material according to any one of 1. to 20. above, having a carbon content of approximately less than 1 atomic percent. 28. A crystalline material according to any one of 1. to 20. above, having a carbon content between approximately 1 atomic percent and approximately 6 atomic percent. 29. A crystalline material according to any one of 1. to 20. above, having a carbon content between approximately 1 atomic percent and approximately 5 atomic percent. 30. A crystalline material according to any one of 1. to 20. above, having a carbon content between approximately 1 atomic percent and approximately 4 atomic percent. 31. The crystalline material according to any one of 1. to 20. above, having a carbon content between approximately 1 atomic percent and approximately 3 atomic percent. 32. The crystalline material according to any one of 1. to 20. above, having a carbon content between approximately 1 atomic percent and approximately 2 atomic percent. 33. A crystalline material according to any one of 1. to 32. above, which is derived from one or more metallocene precursors having formula I or formula II.

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Claims

1. A thin film crystalline material comprising hafnium oxide and zirconium oxide, exhibits ferroelectric behavior in the as-deposited state; derived from one or more metallocene precursors having formula I or II: 【Chemical 1】 【Chemistry 2】 wherein (i) M is selected from Zr and Hf, and (ii) R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from C 1 to C 6 linear alkyl, C 1 to C 6 branched alkyl, C 1 to C 6 halogenated linear alkyl, and C 1 to C 6 halogenated branched alkyl. having a carbon content of less than approximately 1 atomic percent, or having a carbon content of between approximately 1 atomic percent and approximately 6 atomic percent, where "approximately" refers to the stated value of the variable, as well as all values ​​of the variable within experimental error of the stated value or within ±10% of the stated value, whichever is greater; Thin film crystalline materials.

2. (i) greater than 40% of the total volume of the crystalline material is in the ferroelectric phase; and (ii) less than 60% of the total volume of the crystalline material comprises a non-ferroelectric phase component; The crystalline material of claim 1.

3. 3. The crystalline material of claim 1 or 2, wherein the hafnium oxide:zirconium oxide ratio is between approximately 1:3 and approximately 3:1, wherein "approximately" refers to the stated value of the variable and all values ​​of the variable within experimental error of the stated value or within ±10% of the stated value, whichever is greater.

4. A crystalline material according to any one of claims 1 to 3, derived from one or more metallocene precursors having formula I or formula II. 【Chemistry 3】 【Chemistry 4】 wherein (i) M is selected from Zr and Hf, and (ii) R １ , R ２ , R ３ , R ４ , R ５ , R ６ , R ７ and R ８ are each independently C １ ~C ６ It is a linear alkyl.

5. A crystalline material according to any one of claims 1 to 3, derived from one or more metallocene precursors having formula I or formula II. 【Chemistry 5】 【Chemistry 6】 wherein (i) M is selected from Zr and Hf, and (ii) R １ , R ２ , R ３ , R ４ , R ５ , R ６ , R ７ and R ８ are each a methyl group.

6. A method for depositing a crystalline material according to any one of claims 1 to 5, comprising the steps of: (i) providing a substrate at a deposition temperature; (ii) exposing the substrate to a first precursor that does not decompose at deposition temperatures; (iii) exposing the substrate to a first reactive gas; (iv) exposing the substrate to a second precursor that does not decompose at the deposition temperature; and (v) exposing the substrate to a second reactive gas; This includes: The method, wherein one of the first precursor and the second precursor comprises zirconium and the other of the first precursor and the second precursor comprises hafnium.

7. 7. The method of claim 6, wherein the deposited crystalline material has a thickness between approximately 0.2 nm and approximately 20 nm, where "approximately" refers to the stated value of the variable and all values ​​of the variable within experimental error of the stated value or within ±10% of the stated value, whichever is greater.

8. The deposited crystalline material has a conductivity of 8 μC / cm ２ Remanent polarization (Pr) of greater than 16 μC / cm ２ 7. The method of claim 6, having a total loop opening of greater than 1 / 2.

9. 6. A thin film comprising the material of any one of claims 1 to 5, said thin film having a thickness of from about 0.2 nm to about 10 nm, wherein "approximately" refers to the stated value of the variable and all values ​​of the variable within experimental error of the stated value or within ±10% of the stated value, whichever is greater.

10. A thin film comprising the material according to any one of claims 1 to 5, having a resistivity of 8 μC / cm ２ Remanent polarization (Pr) of greater than 16 μC / cm ２ Thin film with super full loop opening.

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