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  • C23C16/45523—Pulsed gas flow or change of composition over time
  • C23C16/45525—Atomic layer deposition [ALD]
  • C23C16/45527—Atomic layer deposition [ALD] characterized by the ALD cycle, e.g. different flows or temperatures during half-reactions, unusual pulsing sequence, use of precursor mixtures or auxiliary reactants or activations
  • C23C16/45531—Atomic layer deposition [ALD] characterized by the ALD cycle, e.g. different flows or temperatures during half-reactions, unusual pulsing sequence, use of precursor mixtures or auxiliary reactants or activations specially adapted for making ternary or higher compositions
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  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/4401—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
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  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
  • C23C16/45523—Pulsed gas flow or change of composition over time
  • C23C16/45525—Atomic layer deposition [ALD]
  • C23C16/45553—Atomic layer deposition [ALD] characterized by the use of precursors specially adapted for ALD
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  • H10D64/689—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes characterised by the insulator, e.g. by the gate insulator having ferroelectric layers
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  • H10P14/6334—Deposition from the gas or vapour phase using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
  • H10P14/6339—Deposition from the gas or vapour phase using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition deposition by cyclic CVD, e.g. ALD, ALE or pulsed CVD
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  • H10P14/65—Formation of materials, e.g. in the shape of layers or pillars of insulating materials characterised by treatments performed before or after the formation of the materials
  • H10P14/6502—Formation of materials, e.g. in the shape of layers or pillars of insulating materials characterised by treatments performed before or after the formation of the materials of treatments performed before formation of the materials
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  • H10P14/69392—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides characterised by the metal the material containing hafnium, e.g. HfO2
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  • H10P14/69395—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides characterised by the metal the material containing zirconium, e.g. ZrO2
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Definitions

• the disclosed and claimed subject matter relates generally to ferroelectric materials deposited using vapor techniques, including atomic layer deposition (ALD). More specifically, the disclosed and claimed subject matter relates to thin film crystalline ferroelectric materials that include a mixture of hafnium oxide and zirconium oxide having a substantial (i.e., approximately 40% or more) portion of the material in a ferroelectric phase and methods for preparing and depositing these materials. Significantly, these materials exhibit ferroelectric properties without the need for further processing, such as a subsequent capping or annealing.
• ALD atomic layer deposition
• Hafnium and zirconium oxide-based ferroelectric materials enable a variety of computing devices, including non-volatile memories and power-efficient logic devices, owing to their strong non-linear capacitance and remanent polarization. These materials may also be useful for a variety of other thermal and magnetic applications. Materials containing hafnium oxide and zirconium oxide are highly desirable for these applications owing to their compatibility with many CMOS fabrication processes and materials.
• Hafnium and zirconium oxide-based materials are polymorphic. Thus, their atoms can be arranged in several crystal structures (i.e., different ordered atomic arrangements). It is well known that the most stable bulk structure of hafnium and zirconium oxide-based materials is a monoclinic phase (FIG. 7A); however, this phase does not support ferroelectricity. Other polymorphs (e.g., some orthorhombic (FIG.
• FIG. 7B and rhombohedral phases (FIG. 7C)) have the symmetry required to support ferroelectric switching behavior, while still others (e.g., a tetragonal phase (FIG. 7D) common in zirconium oxide thin films) can be anti-ferroelectric-like.
• FIG. 7D tetragonal phase
• FIG. 1 illustrates the grazing-incidence x-ray diffraction (GIXRD) pattern for a 7 nm film material composed of alternating atomic layer deposited Hfo . 45Zro . 55O2 from amide-type precursors and ozone at 285°C.
• GIXRD grazing-incidence x-ray diffraction
• section B illustrates the same material as illustrated in section A following a thermal annealing treatment at 500 °C in nitrogen for 10 minutes.
• the material has a dominant monoclinic phase (as evidenced by the peak area between 2Q of 27° and 30°) mixed with other phases that could be ferroelectric or anti-ferroelectric (as evidenced by the peak areas between 2Q of 30° and 32°).
• section C illustrates the same material as the one illustrated in section A that has been capped with a 5 nm thick PVD titanium nitride layer and then thermally processed at 500 °C in nitrogen for 10 minutes.
• the capped fdm of section C shows almost complete suppression of the monoclinic phase (as evidenced by the peak area between 2Q of 27° and 30°).
• obtaining a desired ferroelectric phase traditionally depends on a complicated and complex combination of (i) the deposition conditions of the material itself, (ii) the choice of dopants, interfaces, importantly the top interface and (iii) thermal treatments after deposition.
• this combination of factors places significant limitations on the usefulness of such materials with respect to possible substrates, interlayers, electrodes, compositions and processes.
• the thermal profile in devices implementing such ferroelectric materials may not be compatible with all necessary or desirable applications for which ferroelectric materials may be useful. For example, it has been observed that specific electrodes may be needed to modulate electronic work functions, that interfaces may be needed to create barrier layers against chemical reactions and atomic diffusion, and that thermal processing conditions may be limited by stresses introduced in other layers in a multilayer stack.
• the disclosed subject matter relates to ferroelectric thin film materials derived from a mixture of hafnium oxide and zirconium oxide, deposited from vapor, having a substantial volume fraction of a ferroelectric phase as deposited (i.e., without further annealing and/or capping) and as measured by a phase determining technique 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-electrical field testing, piezo force microscopy, or combinations thereof).
• XRD x-ray diffraction
• XAS x-ray absorption spectroscopy
• TEM transmission electron microscopy
• the ferroelectric materials have a majority volume fraction of a ferroelectric phase as deposited.
• the materials exhibit ferroelectric properties as thin films of approximately 20 nm or less. In a further aspect the materials exhibit ferroelectric properties as thin films of approximately 15 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 10 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 5 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 3 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 1 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 0.5 nm or less.
• the materials exhibit ferroelectric properties as thin films of approximately 0.2 nm or less . In a further aspect, the materials exhibit ferroelectric properties as thin fdms of between approximately 0.2 nm to approximately 20 nm. In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 15 nm. In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 10 nm. In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 5 nm. In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 3 nm.
• the materials exhibit ferroelectric properties as thin fdms of between approximately 0.2 nm to approximately 1 nm. In a further aspect, the materials exhibit ferroelectric properties as thin fdms of between approximately 0.2 nm to approximately 0.5 nm.
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from a C1-C6 linear alkyl, a C1-C6 branched alkyl, a C1-C6 halogenated linear alkyl and a C1-C6 halogenated branched alkyl.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably a C1-C6 linear alkyl.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably the same C1-C6 linear alkyl.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably a methyl group.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably an ethyl group. In a further aspect, in Formula I each of R 1 , R 2 , R 5 and R 6 is preferably an ethyl group. In a further aspect, in Formula I each of R 3 , R 4 , R 7 and R 8 is preferably a methyl group. In a further aspect, in Formula I each of R 1 , R 2 , R 5 and R 6 is preferably an ethyl group and each of R 3 , R 4 , R 7 and R 8 is preferably a methyl group.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably a Ci-C 6 linear alkyl.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably the same Ci-Ce linear alkyl.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably a methyl group.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably an ethyl group. In a further aspect, in Formula II each of R 1 , R 2 , R 5 and R 6 is preferably an ethyl group. In a further aspect, in Formula P each of R 3 , R 4 , R 7 and R 8 is preferably a methyl group. In a further aspect, in Formula P each of R 1 , R 2 , R 5 and R 6 is preferably an ethyl group and each of R 3 , R 4 , R 7 and R 8 is preferably a methyl group.
• the advanced metallocene precursor is one or more of
• the advanced metallocene precursor is one or more mixture of
• the advanced metallocene precursor is one or more of the precursors disclosed and/or claimed in U.S. Patent No. 8,568,530 the contents of which is incorporated herein in its entirety.
• the disclosed subject matter provides a method for preparing and depositing the ferroelectric thin film materials on a substrate using vapor techniques.
• the ferroelectric materials on a substrate by and ALD process and/or other known deposition processes (e.g ., CVD, pulsed CVD).
• the method uses a reaction gas containing one or more of oxygen (e.g., ozone, elemental oxygen, molecular oxygen/0 2 ), water, hydrogen peroxide and nitrous oxide as a reactant gas at a deposition temperature above approximately 200 °C and below approximately 570 °C, more preferably between approximately 265 °C and approximately 500 °C.
• oxygen e.g., ozone, elemental oxygen, molecular oxygen/0 2
• water hydrogen peroxide and nitrous oxide
• the deposition temperature is preferably below approximately 340 °C. In yet a further aspect, the deposition temperature is preferably between approximately 280 °C to approximately 300 °C. In yet a further aspect, ozone is a preferred reactant gas. In yet a further aspect, water is a preferred reactant gas.
• FIG. 1 illustrates the grazing-incidence x-ray diffraction pattern for a 7 nm thin film material composed of alternating atomic layer deposited Hfo . 45Zro . 55O2 from amide-type precursors and ozone at 285 °C;
• FIG. 2 illustrates an embodiment of a process for depositing an example of the inherently ferroelectric materials disclosed herein on a substrate
• FIG. 3 illustrates another embodiment of a process for depositing an example of the inherently ferroelectric materials disclosed herein on a substrate
• FIG. 4 illustrates the grazing-incidence XRD pattern for the inherently ferroelectric materials formed and deposited in the process illustrated in FIG. 3;
• FIG. 5 illustrates the polarization-electric field plot for the inherently ferroelectric materials formed and deposited in the process illustrated in FIG. 3 as measured using a radiant ferroelectric tester;
• FIG. 6 illustrates another embodiment of a process for depositing an example of the inherently ferroelectric materials disclosed herein on a substrate; and [0027] FIG. 7A-D illustrate known crystalline phases: monoclinic P2Jc (FIG. 7A); orthorhombic Pea 2 (FIG. 7B) rhombohedral R3 (FIG. 7C) and tetragonal l1 ⁇ 4 Jnmc (FIG. 7D).
• an and “the” mean “at least one” unless specifically stated otherwise.
• the use of the term “including,” as well as other forms such as “includes” and “included,” is not limiting.
• terms such as “element” or “component” encompass both elements or components including one unit and elements or components that include more than one unit, unless specifically stated otherwise.
• the conjunction “and” is intended to be inclusive and the conjunction “or” is not intended to be exclusive, unless otherwise indicated.
• the phrase “or, alternatively” is intended to be exclusive.
• the term “and/or” refers to any combination of the foregoing elements including using a single element.
• Periodic Table Groups is according to the IUPAC Periodic Table of Elements.
• metal-containing complex (or more simply, “complex”) and “precursor” are used interchangeably and refer to a metal-containing molecule or compound which can be used to prepare a metal-containing film by a deposition process such as, for example, ALD or CVD.
• the metal-containing complex may be deposited on, adsorbed to, decomposed on, delivered to, and/or passed over a substrate or surface thereof, as to form a metal-containing film.
• metal-containing film includes not only an elemental metal film as more fully defined below, but also a film which includes a metal along with one or more elements, for example a metal nitride film, metal silicide film, a metal carbide film and the like.
• an elemental metal film may include 100% pure metal or the elemental metal film may include 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.
• a film comprising an elemental metal is distinguished from binary films including a metal and a non-metal (e.g ., C, N, O) and ternary films including a metal and two non-metals (e.g., C, N, O), though, a film comprising elemental metal may include some amount of impurities.
• a film comprising elemental metal may include some amount of impurities.
• the term “metal film” shall be interpreted to mean an elemental metal film.
• CVD may take the form of conventional (i.e., continuous flow) CVD, liquid injection CVD, plasma-enhanced CVD, or photo-assisted CVD.
• CVD may also take the form of a pulsed technique, i.e., pulsed CVD.
• ALD is used to form a metal-containing film by vaporizing and/or passing at least one metal complex disclosed herein over a substrate surface. For conventional ALD processes see, for example, George S. M., et ah, J. Phys.
• ALD may take the form of conventional (i.e., pulsed injection) ALD, liquid injection ALD, photo-assisted ALD, plasma-assisted ALD, or plasma-enhanced ALD.
• vapor deposition process further includes various vapor deposition techniques described in Chemical Vapour Deposition: Precursors, Processes, and Applications, Jones, A. C.; Hitchman, M. L., Eds. The Royal Society of Chemistry: Cambridge, 2009; Chapter 1, pp 1-36.
• alkyl refers to hydrocarbon groups which 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 multi cyclic (e.g., norbomyl, adamantly and the like).
• Suitable acyclic groups can be methyl, ethyl, n-or iso-propyl, n-,iso, or tert-butyl, linear or branched pentyl, hexyl, heptyl, octyl, decyl, dodecyl, tetradecyl and hexadecyl. Unless otherwise stated, alkyl refers to 1-10 carbon atom moieties.
• the cyclic alkyl groups may be mono cyclic or polycyclic. Suitable examples of mono-cyclic alkyl groups include substituted cyclopentyl, cyclohexyl, and cycloheptyl groups.
• the substituents may be any of the acyclic alkyl groups described herein. As mentioned herein the cyclic alkyl groups may have any of the acyclic alkyl groups as substituent. These alkyl moieties may be substituted or unsubstituted.
• Halogenated alkyl refers to a linear, cyclic or branched saturated alkyl group as defined above in which one or more of the hydrogens has been replaced by a halogen (e.g ., F, Cl, Br and I).
• a fluorinated alkyl (a.k.a. “fluoroalkyl”) refers to a linear, cyclic or branched saturated alkyl group as defined above in which one or more of the hydrogens has been replaced by fluorine (e.g., trifluoromethyl, pefluoroethyl, 2,2,2-trifluoroethyl, prefluoroisopropyl, perfluorocyclohexyl and the like).
• fluorine e.g., trifluoromethyl, pefluoroethyl, 2,2,2-trifluoroethyl, prefluoroisopropyl, perfluorocyclohexyl and the like.
• Such haloalkyl moieties
• the disclosed and claimed subject matter relates to crystalline ferroelectric thin film materials that include a mixture of hafnium oxide and zirconium oxide having a substantial (i.e., approximately 40% or more) portion of the material in a ferroelectric phase and methods for preparing and depositing these materials.
• the ferroelectric materials have a majority volume fraction of a ferroelectric phase.
• these materials exhibit ferroelectric properties without the need for further processing, such as a subsequent capping step (as illustrated in FIG. 1) or annealing step.
• the produced materials have one or more of (i) remanent polarization or (ii) a polarization field curve with hysteresis and a loop opening.
• the material In order to be ferroelectric, the material must have an arrangement of atoms that can support ferroelectricity in some fraction of the film. It is preferable that a substantial portion of the volume of the film have an arrangement of atoms that can support ferroelectricity. It is understood that for thin films, doped materials, and some laminated materials, the phase distribution in the material may not be easily determined by x-ray diffraction.
• 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 combinations thereof, may be used to determine the phase distribution.
• Raman spectroscopy infrared spectroscopy
• x-ray absorption spectroscopy x-ray absorption spectroscopy
• transmission electron microscopy or combinations thereof.
• the material can be comprised of any suitable molar ratio of hafnium oxide and zirconium oxide - ratios between 1 :3 and 3:1 are preferred.
• the thickness of the ferroelectric material is any thickness that is suitable for the given application; the material can be made thicker to increase the remanent polarization or reduce the electrical leakage current through the thickness of the material, or be made thinner because of geometric constraints or to increase the capacitance of the film.
• the preferred range of thicknesses for this invention is approximately 0.2 nm to approximately 20 nm and is more preferably approximately 0.2 nm to 10 nm. It is also preferable that the materials form films having a thickness of approximately 10 nm and less. In some embodiments it is preferable that the materials form films having a thickness of approximately 5 nm and less.
• the materials exhibit ferroelectric properties as thin films of approximately 20 nm or less. In a further aspect the materials exhibit ferroelectric properties as thin films of approximately 15 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 10 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 5 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 3 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 1 nm or less.
• the materials exhibit ferroelectric properties as thin films of approximately 0.5 nm or less. In a further aspect, the materials exhibit ferroelectric properties as thin films of approximately 0.2 nm or less . In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 20 nm. In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 15 nm. In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 10 nm. In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 5 nm.
• the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 3 nm. In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 1 nm. In a further aspect, the materials exhibit ferroelectric properties as thin films of between approximately 0.2 nm to approximately 1 nm.
• the total non- ferroelectric atomic arrangement components are less than approximately 60% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic arrangement components are less than approximately 50% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic arrangement components are less than approximately 40% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic arrangement components are less than approximately 30% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic arrangement components are less than approximately 25% of the total volume of the material.
• the total non- ferroelectric atomic arrangement components are less than approximately 20% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic arrangement components are less than approximately 15% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic arrangement components are less than approximately 10% of the total volume of the material. In another embodiment, the total non-ferroelectric atomic arrangement components are less than approximately 5% of the total volume of the material. [0050] Moreover, in the disclosed and claimed materials less than approximately 60% of the of the total volume of the material constitutes a non-ferroelectric monoclinic phase component. Thus, in one embodiment of the disclosed and claimed materials, a monoclinic phase component is less than approximately 50% of the total volume of the material.
• a monoclinic phase component is less than approximately 40% of the total volume of the material. In another embodiment, a monoclinic phase component is less than approximately 30% of the total volume of the material. In another embodiment, a monoclinic phase component is less than approximately 25% of the total volume of the material. In another embodiment, a monoclinic phase component is less than approximately 20% of the total volume of the material. In another embodiment, a monoclinic phase component is less than approximately 15% of the total volume of the material. In another embodiment, a monoclinic phase component is less than approximately 10% of the total volume of the material. In another embodiment, a monoclinic phase component is less than approximately 5% of the total volume of the material.
• greater than 50% of the total volume of the crystalline material is in a ferroelectric phase, less than 50% of the total volume of the crystalline material constitutes a non-ferroelectric phase component, and less than 25% of the total volume of the crystalline material constitutes a non-ferroelectric monoclinic phase component.
• the preferred carbon content of the material is below approximately 6 atomic percent as measured by a suitable technique, such as x- ray photo electron spectroscopy. In a further aspect, the carbon content below approximately 5 atomic percent. In a further aspect, the carbon content below approximately 4 atomic percent. In a further aspect, the carbon content below approximately 3 atomic percent. In a further aspect, the carbon content below approximately 2 atomic percent. In a further aspect, the carbon content below approximately 1 atomic percent. In a further aspect, the carbon content is between approximately 1 atomic percent and approximately 6 atomic percent. In a further aspect, the carbon content is between approximately 1 atomic percent and approximately 5 atomic percent.
• the carbon content is between approximately 1 atomic percent and approximately 4 atomic percent. In a further aspect, the carbon content is between approximately 1 atomic percent and approximately 3 atomic percent. In a further aspect, the carbon content is between approximately 1 atomic percent and approximately 2 atomic percent.
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from a C1-C6 linear alkyl, a C1-C6 branched alkyl, a C1-C6 halogenated linear alkyl and a C1-C6 halogenated branched alkyl.
• each of R 1 , R 2 , R 3 and R 4 is preferably a C1-C6 linear alkyl. In a further aspect, in Formula I each of R 1 , R 2 , R 3 and R 4 , is preferably the same C1-C6 linear alkyl. In a further aspect, in Formula I each of R 1 , R 2 , R 3 and R 4 , is preferably a methyl group. In a further aspect, in Formula I each of R 1 , R 2 , R 3 and R 4 , is preferably an ethyl group. In a further aspect, in Formula I each of R 1 and R 2 , is preferably an ethyl group.
• each of R 3 and R 4 is preferably a methyl group.
• each of R 1 and R 2 is preferably an ethyl group and each of R 3 and R 4 , is preferably a methyl group.
• each of R 5 , R 6 , R 7 and R 8 is preferably a C1-C6 linear alkyl.
• each of R 5 , R 6 , R 7 and R 8 is preferably the same Ci- Ce linear alkyl.
• each of R 5 , R 6 , R 7 and R 8 is preferably a methyl group.
• each ofR 5 , R 6 , R 7 and R 8 is preferably an ethyl group. In a further aspect, in Formula II each of R 5 and R 6 is preferably an ethyl group. In a further aspect, in Formula P each of R 7 and R 8 is preferably a methyl group. In a further aspect, in Formula P each of R 5 and R 6 is preferably an ethyl group and each of R 7 and R 8 is preferably a methyl group. [0055] In another aspect, in Formula I and Formula II each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably independently a Ci-Ce linear alkyl.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably the same Ci-Ce linear alkyl.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably a methyl group.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably an ethyl group.
• each of R 1 , R 2 , R 5 and R 6 is preferably an ethyl group.
• each of R 3 , R 4 , R 7 and R 8 is preferably a methyl group.
• each of R 1 , R 2 , R 5 and R 6 is preferably an ethyl group and each of R 3 , R 4 , R 7 and R 8 is preferably a methyl group.
• the advanced metallocene precursor is one or more of
• the advanced metallocene precursor is one or more mixture of
• the advanced metallocene precursor is one or more of the precursors disclosed and/or claimed in U.S. Patent No. 8,568,530 the contents of which is incorporated herein in its entirety.
• the disclosed and claimed subject matter is directed to a process for preparing and/or depositing the inherently ferroelectric materials disclosed herein.
• the disclosed and claimed inherently ferroelectric materials are prepared by iterative depositions and purges (i) of a metallocene precursor and (ii) a reactant.
• the ferroelectric materials are derived from advanced metallocene precursors having the Formula I (“(R 1 -Cp)(R 2 -Cp)-M-(OR 3 )(R 4 )” where 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):
• M Zr or Hf
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from a C 1 -C 6 linear alkyl, a C 1 -C 6 branched alkyl, a C 1 -C 6 halogenated linear alkyl and a C 1 -C 6 halogenated branched alkyl.
• each of R 1 , R 2 , R 3 and R 4 is preferably a C 1 -C 6 linear alkyl. In a further aspect, in Formula I each of R 1 , R 2 , R 3 and R 4 , is preferably the same C 1 -C 6 linear alkyl. In a further aspect, in Formula I each of R 1 , R 2 , R 3 and R 4 is preferably a methyl group. In a further aspect, in Formula I each of R 1 , R 2 , R 3 and R 4 , is preferably an ethyl group. In a further aspect, in Formula I each of R 1 and R 2 , is preferably an ethyl group.
• each of R 3 and R 4 is preferably a methyl group.
• each of R 1 and R 2 is preferably an ethyl group and each of R 3 and R 4 , is preferably a methyl group.
• each of R 5 , R 6 , R 7 and R 8 is preferably a C 1 -C 6 linear alkyl.
• each of R 5 , R 6 , R 7 and R 8 is preferably the same Ci- Ce linear alkyl.
• each of R 5 , R 6 , R 7 and R 8 is preferably a methyl group.
• each of R 5 , R 6 , R 7 and R 8 is preferably an ethyl group.
• each of R 5 and R 6 is preferably an ethyl group.
• each of R 7 and R 8 is preferably a methyl group.
• each of R 5 and R 6 is preferably an ethyl group and each of R 7 and R 8 is preferably a methyl group.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably independently a C 1 -C 6 linear alkyl.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably the same C 1 -C 6 linear alkyl.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably a methyl group.
• each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is preferably an ethyl group.
• each of R 1 , R 2 , R 5 and R 6 is preferably an ethyl group.
• each of R 3 , R 4 , R 7 and R 8 is preferably a methyl group.
• each of R 1 , R 2 , R 5 and R 6 is preferably an ethyl group and each of R 3 , R 4 , R 7 and R 8 is preferably a methyl group.
• the advanced metallocene precursor is one or more of
• the advanced metallocene precursor is one or more mixture of
• the advanced metallocene precursor is one or more of the precursors disclosed and/or claimed in U.S. Patent No. 8,568,530 the contents of which is incorporated herein in its entirety.
• suitable precursors for preparing the inherently ferroelectric materials are able to 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 composition of the material, 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 below approximately 450 °C and more preferably below approximately 340 °C.
• those skilled in the art should recognize that other temperatures may be possible depending on the specific precursor used and that such precursors also fall within the scope of the disclosed and claimed subject matter.
• decomposition of the precursor can occur within the temperature range described.
• Decomposition products in particular carbon and organic species, can become incorporated in the deposited hafnium oxide or zirconium oxide material. While this incorporation of carbon may assist with the stabilization of the ferroelectric phase, it may be undesirable for material purity reasons.
• the preferred carbon content of the material is below approximately 6 atomic percent.
• the reactant is a reaction gas containing one or more of oxygen (e.g ., ozone, elemental oxygen, molecular oxygen/0 2 ), water, hydrogen peroxide and nitrous oxide.
• oxygen e.g ., ozone, elemental oxygen, molecular oxygen/0 2
• water is a preferred reactant gas.
• An aspect of the disclosed and claimed subject matter is a method for depositing the crystalline material including:
• the method further includes at least one purging step.
• the first reaction gas and the second reaction gas are each independently a gas containing one or more of oxygen, water, hydrogen peroxide and nitrous oxide.
• the first reaction gas and the second reaction gas are each independently a gas containing oxygen.
• the first reaction gas and the second reaction gas are each independently a gas containing ozone.
• the first reaction gas and the second reaction gas are each independently a gas containing water.
• the first reaction gas and the second reaction gas are the same gas.
• the first reaction gas and the second reaction gas are different gases.
• the first precursor and the second precursor are each independently a precursor having Formula I or Formula II as described above.
• the method comprises an ALD process. In another embodiment, the method comprises a CVD process.
• the crystalline material deposited in the method of the invention has a thickness between approximately 0.2 nm and approximately 20 nm. [0078] In one embodiment, the crystalline material deposited in the disclosed and claimed method exhibits remanent polarization without additional thermal processing. In another embodiment, the crystalline material deposited in the disclosed and claimed method has a remanent polarization (Pr) of greater than 8 pC/cirr or a total loop opening of greater than 16 pC/cirr. In another embodiment, the crystalline material deposited in the disclosed and claimed method has hysteresis and remanent polarization in a polarization-electric field measurement.
• Pr remanent polarization
• FIG. 2 illustrates an embodiment of a process for preparing and depositing the inherently ferroelectric materials descried herein.
• substrate 202 undergoes an ALD cycle 204 in which substrate 202 is exposed to vapor 201 to form and deposit an inherently ferroelectric material as thin film layer 200
• Layer 200 was formed without further thermal processing or capping and exhibited ferroelectric properties as such (i.e., as deposited).
• layer 200 could be subsequently annealed and/or capped as desired but that doing so was not necessary to observe ferroelectric behavior of the layer as deposited.
• energy can subsequently be applied to the material by, 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.
• ALD is a preferred vapor deposition technique
• any suitable vapor phase deposition technique can be utilized, such as CVD or pulsed CVD.
• ALD cycle 204 could be replaced by a CVD process in which metallocene precursor 205 and reactant 206 are provided as a mixture in vapor 201 and provided simultaneously to substrate 202
• An appropriate molar ratio of hafnium oxide to zirconium oxide can be created by several methods, including introducing a hafnium-containing precursor during a fraction of these cycles, and a zirconium-containing precursor during other cycles.
• the cycles could alternate, be grouped together, or arranged in any other suitable sequence to produce the overall desired molar ratio, as both intimately blended materials and nanolaminated materials have been shown to have desirable ferroelectric properties.
• other elements may be added into the hafnium oxide-zirconium oxide material by adding appropriate precursors either along with the hafnium and zirconium precursors, or in separate cycles.
• the substrate e.g.
• substrate 202 on which the inherently ferroelectric material is formed, e.g. as layer 200, can include any suitable material, including semiconducting materials like silicon, germanium, group IH-V materials, transition metal dichalcogenides, and mixtures thereof, metals and conductive ceramics like titanium nitride, titanium, tantalum, tantalum nitride, tungsten, platinum, rhodium, molybdenum, cobalt, ruthenium, palladium, or mixtures thereof, or dielectrics like silicon oxide, silicon nitride, aluminum oxide, titanium oxide, other ferroelectric materials, including compositions of hafnium oxide and zirconium oxide, magnetic materials, and mixtures or stacks thereof.
• suitable material including semiconducting materials like silicon, germanium, group IH-V materials, transition metal dichalcogenides, and mixtures thereof, metals and conductive ceramics like titanium nitride, titanium, tantalum, tantalum nitride, tungsten, platinum,
• substrate 202 can be patterned or textured, as appropriate, with any suitable topography, including flat surfaces, trenches, vias, or nanostructured surfaces.
• This list represents typical substrates that may be useful in ferroelectric applications, but should not be considered limiting, as many other suitable compositions and surface patterns would be obvious to those skilled in the art.
• the substrate can have some influence on the atomic arrangement and phase of the film formed thereon, including affecting the crystalline orientation and crystallization temperature of the film. Regardless of the particular substrate and the extent of this effect, the inherently ferroelectric materials described herein and deposited on such substrates nevertheless have a substantial fraction of their volume in the ferroelectric phase as deposited.
• FIG. 3 illustrates another embodiment of a process for preparing and depositing the inherently ferroelectric materials descried herein.
• a mixed hafnium oxide and zirconium oxide inherently ferroelectric material is prepared and deposited as layer 301 with a thickness of approximately 8.4 nm is on a stacked substrate 302 of PVD TiN (which is in direct contact with the ferroelectric material), a thermally grown SiC layer and a Si wafer.
• Layer 301 was formed without further thermal processing or capping.
• the molar ratio of hafnium oxide to zirconium oxide is approximately 1 :1, with a margin of error of approximately 10%.
• the ferroelectric material is prepared and deposited as layer 301 from the vapor by ALD by alternating First Cycle 303 (which includes the steps of (i) pulsing (MeCp)2Zr(OMe)Me 304, (ii) purging, (iii) pulsing ozone 305 and (iv) purging) and Second Cycle 306 (which includes the steps of (i) pulsing (MeCp)2Hf(OMe)Me 307, (ii) purging, (iii) pulsing ozone 308 and (iv) purging).
• First Cycle 303 which includes the steps of (i) pulsing (MeCp)2Zr(OMe)Me 304, (ii) purging, (iii) pulsing ozone 305 and (iv) purging
• Second Cycle 306 which includes the steps of (i) pulsing (MeCp)2Hf(OMe)Me 307, (
• pulsing and purging times can each respectively vary depending on equipment. In one embodiment, pulses last from approximately 2 to approximately 3 seconds followed by a purge of approximately 10 seconds. In another embodiment, pulses last from approximately 10 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.
• FIG. 4 illustrates the grazing-incidence XRD pattern for the inherently ferroelectric material prepared and deposited as layer 301 in FIG. 3 without further thermal processing or capping.
• the crystalline peaks of the material constituting layer 301 show monoclinic 401 and non-monoclinic 402 components.
• the calculated monoclinic fraction of the volume of the of the material constituting layer 301 is less than 25%, which is the preferred maximum volume fraction of monoclinic, non-ferroelectric material.
• FIG. 5 illustrates the polarization-electric field plot for the inherently ferroelectric materials formed and deposited in the process illustrated in FIG. 3 as measured using a radiant ferroelectric tester.
• a top electrode contact was formed on top of the ferroelectric material by applying PVD TiN through shadow mask 501.
• First curve 502 is measured using a triangular bipolar waveform from -3V to 3 V in steps of 25V with a frequency of 250 Hz and a period of 8ms.
• First curve 502 shows a clear opening, demonstrating a remanent (non-zero) polarization at 0V and therefore ferroelectric behavior.
• Second curve 503 shows a larger remanent polarization from the same device after the application of 1000 cycles of a bipolar square waveform from -3 V to 3 V with a period of 1ms and a frequency of 1 kHz. This behavior is common in ferroelectric materials comprising hafnium oxide and zirconium oxide. It should be noted that polarization-electric field curves are not required for all applications; other techniques, such as piezo force microscopy or optical experiments, could also establish ferroelectricity.
• FIG. 6 illustrates another embodiment of a process for preparing and depositing the inherently ferroelectric materials descried herein using ALD.
• the method includes several steps that can be augmented with additional and/or optional steps.
• Step 1 includes providing a substrate at a deposition temperature of between approximately 265 °C and approximately 500 °C, but that is preferably at or around approximately 300 °C (e.g., above approximately 285 °C and at or below approximately 300 °C) and below 340 °C.
• Step 2 includes (i) exposing the substrate to a first precursor containing hafnium or zirconium or both hafnium and zirconium that does not decompose at the deposition temperature and (ii) purging.
• Step 3 includes (i) exposing the substrate to a reaction gas containing oxygen and (ii) purging.
• Step 4 includes (i) exposing the substrate to a second precursor containing zirconium or hafnium or both hafnium and zirconium that does not decompose at the deposition temperature and (ii) purging.
• Step 5 includes exposing the substrate to a reaction gas containing oxygen.
• Optional Step 6 includes repeating Steps 2-5 until a fdm of hafnium oxide and zirconium oxide of desired thickness is formed with a molar ratio between approximately 1:3 and approximately 3:1.
• the inherently ferroelectric materials are formed and deposited as films having a substantial volume fraction of a ferroelectric phase as deposited (i.e., without further annealing and/or capping) and as measured by a phase determining technique or electrical testing known to those skilled in the art (e.g ., XRD, XAS, TEM, polarization-voltage testing, piezo force microscopy, or combinations thereof).
• a phase determining technique or electrical testing known to those skilled in the art (e.g ., XRD, XAS, TEM, polarization-voltage testing, piezo force microscopy, or combinations thereof).
• the metallocene precursors utilized and/or that can be utilized in the process of FIG 6 include all of those disclosed and discussed above and include, in particular, (MeCp)2Zr(OMe)Me, (MeCp)2Hf(OMe)Me, (MeCp)2Zr(Me)2 and (MeCp)2Hf(Me)2.
• the reaction gas containing oxygen of Step 3 and/or Step 5 is preferably ozone.
• reaction gases can be used including those specifically described above (e.g., water, hydrogen peroxide).
• the film has a thickness of approximately 0.2 nm to approximately 10 nm. In another embodiment, the film has a thickness of approximately 0.2 nm to approximately 5 nm. In another embodiment, the film has a thickness of approximately 0.2 nm to approximately 1 nm. In another embodiment, the film has a thickness of approximately 0.2 nm to approximately 0.5 nm. In another embodiment, the film has a thickness of approximately 15 nm or less. In another embodiment, the film has a thickness of approximately 10 nm or less. In another embodiment, the film has a thickness of approximately 5 nm or less.
• the film has a thickness of approximately 3 nm or less. In another embodiment, the fdm has a thickness of approximately 1 nm or less. In some embodiments, the film has a remanent polarization (Pr) of greater than 8 pC/cm 2 or a total loop opening of greater than 16 pC/cm 2 .
• Pr remanent polarization
• Another aspect of the disclosed and claimed subject matter is the use of the thin film crystalline material as described above for forming a thin film that exhibits ferroelectric behavior.
• Another aspect of the disclosed and claimed subj ect matter is the use of the thin film as described above as a ferroelectric material in a computing device.
• metallocene precursors were or otherwise can be prepared according to U.S.
• Patent No. 8,568,530 the contents of which is incorporated herein in its entirety.
• ALD reactor with a substrate temperature of 300 °C and an outer ring temperature of 290 °C.
• a substrate consisting of a 45 mm x 45 mm p-type Si wafer covered with 1000 A 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.
• Ozone was provided using an InUSA ozone generator, model AC -2025, set to 200 g/m 3 of ozone.
• the oxygen flow going into the ozone generator is approximately 300 seem.
• the ampule temperatures were 125 °C
• the precursor doses were 3 seconds
• the reactant doses were 2 seconds
• the purges were 10 seconds.
• the base pressure is maintained at an average pressure between 0.37 to 0.42 Torr during purge steps, between 0.42 and 0.48 Torr during precursor pulses, and between 1 and 1.5 Torr during reactant pulses.
• the process can employ intermittently or consistently higher pressures. In one embodiment, for example, a maximum instantaneous pressure of 6 Torr during the first few pulses of ozone was employed.
• the films were characterized by grazing-incidence XRD on a Bruker
• Polarization field data were collected with a bipolar triangular waveform (0.25 kHz, -3V to 3V in 0.25V steps) before and after applying a wake-up stress of ⁇ 3 V at 1 kHz for 1 s.
• the as-deposited layer has remanent polarization (Pr) of greater than 8 pC/cirf, or a total loop opening of greater than 16 pC/cm 2 , when measured using triangular bipolar waveform with a maximum applied field of approximately 3 8M V/cm.

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