Ferroelectric mixed metal oxide films, methods of manufacture thereof and articles comprising the same

Abstract

Disclosed herein is a mixed metal oxide film having a composition comprising Hf(1-x)MxO(2-y) (1) where M is zirconium, cerium, aluminum, silicon, lanthanum, yttrium, strontium, gadolinum, strontium, gallium, calcium, magnesium, or a combination thereof; where x is 0.05 to 0.95 and where the mixed metal oxide film is formed in the presence of a plasma; where the plasma is formed in an atmosphere that comprises nitrogen and oxygen in a molar ratio of 0.5:1 to 10:1; and where y is 0 to 0.5.

Description

FERROELECTRIC MIXED METAL OXIDE FILMS, METHODS OFMANUFACTURE THEREOF AND ARTICLES COMPRISING THE SAMECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Non-Provisional Application having Serial No. 63 / 540,292 filed on September 25, 2023, the entire contents of which are hereby incorporated by reference.STATEMENT OF GOVERNMENT INTEREST

[0002] This invention was made with government support under Grant No. DE- SC0021118, awarded by the Department of Energy. The government has certain rights in the invention.BACKGROUND

[0003] This disclosure relates to ferroelectric mixed metal oxide films, methods of manufacture thereof and to articles comprising the same.

[0004] Hafnia (HI'O?). or hafnium dioxide, is widely used as a dielectric material in advanced semiconductor devices, particularly in field-effect transistors (FETs), because of its unique properties that make it suitable for gate oxides in modern transistors. Pure hafnia or hafnia substituted with at least one of Si, Ga, La, Y, Zr, Sr, Gd, Ce, Mg, and Ca, among others, can be stabilized into a crystal structure that has a spontaneous polarization. This spontaneous polarization can be reoriented with the application of a sufficient electric field. The electric field used to switch the polarization is known as the coercive field. In ferroelectric hafnium oxide, this field is typically larger than 1 megavolt per centimeter (MV / cm). Upon switching the polarization using alternating electric fields of opposing polarities, the insulating properties of the hafnium oxide will degrade. The leakage current will increase and, eventually, a catastrophic failure of the device will occur rendering it unable to store charge.

[0005] It is therefore desirable to develop hafnia that does not exhibit some of these disadvantages.SUMMARY

[0006] Disclosed herein is a mixed metal oxide film having a composition comprisingHf(l.x)MxO(2.y) (1) where M is zirconium, cerium, aluminum, silicon, lanthanum, yttrium, strontium, gadolinum, strontium, gallium, calcium, magnesium, or a combination thereof; where x is 0.05 to 0.95 and where the mixed metal oxide film is formed in the presence of a plasma; where the plasma is formed in an atmosphere that comprises nitrogen and oxygen in a molar ratio of 0.5: 1 to 10: 1; and where y is 0 to 0.5.

[0007] Disclosed herein too is a ferroelectric capacitor comprising a substrate; a first electrode disposed opposite the substrate; and a mixed metal oxide film disposed between the substrate and the electrode; where the mixed metal oxide film has a composition comprising:Hf(|-x)MxO(2-y) (1) where M is zirconium, cerium, aluminum, silicon, lanthanum, yttrium, strontium, gadolinum, strontium, gallium, calcium, magnesium, or a combination thereof; where x is 0.05 to 0.95 and where the mixed metal oxide film is formed in the presence of a plasma; where the plasma is formed in an atmosphere that comprises nitrogen and oxygen in a molar ratio of 0.5: 1 to 10: 1; and where y is 0 to 0.5.

[0008] Disclosed herein too is a method of manufacturing a mixed metal oxide film having ferroelectric properties, the method comprising disposing a substrate in a reactor; introducing a first metal precursor into the reactor; introducing a combination of a nitrogen-containing gas and an oxygen-containing gas into the reactor; energizing the nitrogcn-containing gas and an oxygcn-containing gas in the reactor to create a plasma; disposing a first metal oxide on the substrate; introducing a second metal precursor into the reactor; and disposing a second metal oxide on the substrate.BRIEF DESCRIPTION OF THE FIGURES

[0009] FIG. 1 depicts an embodiment of the ferroelectric capacitor that comprises a substrate upon which is disposed two electrodes with the mixed metal oxide film disposed therebetween;

[0010] FIG. 2 depicts a flow diagram for the manufacturing of the ferroelectric capacitor;

[0011] FIG. 3 is a graph that shows the polarization versus electric field response for the hafnium zirconium mixed metal oxide films prepared with differing ratios of N :O2 in the plasma;

[0012] FIG. 4 is a graph that shows the coercive field for the hafnium zirconium mixed metal oxide films at various points during lield cycling for the different O: ratios; and

[0013] FIG. 5 shows the leakage current for the hafnium zirconium mixed metal oxide films after differing numbers of electric field cycles.DETAILED DESCRIPTION

[0014] The term “coercive field” refers to the amount of external electric field required to reduce the polarization of a material to zero after it has been polarized. Lowering the coercive field can make a material more efficient in applications like memory' devices.

[0015] The term “comparative film” refers to a mixed metal oxide film that has the same base composition (the same metal oxides combined in the same ratio) as the disclosed mixed metal oxide film but is not treated or processed in the same manner.

[0016] Disclosed herein are multicomponent oxide films or mixed metal oxide films that comprise hafnia in addition to one or more metal oxides that do not contain hafnium (hereinafter mixed metal oxide films). These mixed metal oxide films are ferroelectric materials and preferably comprise binary or ternary oxides. Ferroelectric materials have a spontaneous electric polarization that can be reversed upon the application of an external electric field. These mixed metal oxides films are more durable than other “comparative films” that have similar compositions but that arc not treated (processed) in a similar manner. The disclosed mixed metal oxide films are more efficient because they possess a reduced coercive field as compared with other comparative films. They are also advantageous because they can endure an increased number of cycles (over a comparative film) before exhibiting higher a leakage current or failure. Disclosed herein too is a method for manufacturing the mixed metal oxide films that comprises manufacturing the films using a vapor deposition technique in a nitrogen containing atmosphere. The mixed metal oxide films are then annealed at a temperature greater than 300°C for a period spanning 10 seconds to 2 hours to yield a film that requires a reduced coercive field when compared with other comparative filmsand that can endure the increased number of cycles before exhibiting higher a leakage current or failure.

[0017] In an embodiment, the mixed metal oxide films may be used in a ferroelectric capacitor. Ferroelectric capacitors are used in various applications, including non-volatile memories (such as FeRAM), dynamic random-access memories (DRAMs), and other electronic components that leverage the unique properties of ferroelectric materials. A ferroelectric thin film capacitor comprises a substrate upon which are disposed at least one electrode and the mixed metal oxide film. In an embodiment, the mixed metal oxide film lies in between the at least one electrode and the substrate. In another embodiment, the ferroelectric capacitor comprises a substrate upon which are disposed two electrodes with the mixed metal oxide film disposed therebetween.

[0018] FIG. 1 depicts an embodiment of the ferroelectric capacitor 100 that comprises a substrate 102 upon which is disposed two electrodes - an optional first electrode 104 and a second electrode 108 with the mixed metal oxide film 106 (the ferroelectric layer) disposed therebetween. The optional first electrode 104 contacts the substrate 102, while the mixed metal oxide film 106 contacts the optional first electrode 104. The second electrode 108 contacts an opposing face 107 of the mixed metal oxide film 106 from the face 105 that contacts the first electrode 104.

[0019] FIG. 2 depicts a flow diagram for the manufacturing of the ferroelectric capacitor 100. In step 202, an optional first electrode 104 or the mixed metal oxide layer 106 is disposed on the substrate 102. In step 204, a second electrode 108 is deposited on the mixed metal oxide layer 106. After the multilayered device is formed, it is subjected to annealing (see step 206) at a temperature of 1000°C or less to convert the amorphous mixed metal oxide film to a crystalline mixed metal oxide film and forming the ferroelectric capacitor 100 in the process.

[0020] The substrate 102 provides mechanical support and often influences the performance of the ferroelectric mixed metal oxide film. The choice of a substrate depends on factors such as the required film quality, device performance, temperature stability, and compatibility with the ferroelectric material being used. Common substrates for ferroelectric capacitors include silicon, gallium nitride (GaN), aluminum nitride (AIN), platinum, strontium titanate (SrTiCh), magnesium oxide (MgO), sapphire (AI2O3), lanthanum aluminate (LaAlCh), quartz, or a combination thereof. It is to benoted that while platinum is often used as an electrode material in ferroelectric capacitors, it can also serve as a substrate for the deposition of the ferroelectric layer.

[0021] The substrate 102 generally has a thickness of 100 nanometers to 1000 micrometers, preferably 100 micrometers to 950 micrometers, and more preferably 200 micrometers to 925 micrometers.

[0022] The optional first electrode 104 and the second electrode 108 are disposed on opposite faces of the mixed metal oxide film 106. The first electrode 104 is optional and may not be used in the ferroelectric capacitor if so desired. The electrodes 104 and 108 in the ferroelectric capacitor 100 arc electrically conducting or semiconducting. Their primary function is to apply an electric field across the mixed metal oxide film 106 (i.e., the ferroelectric layer) and allow the flow of charge during operation. These electrodes are typically deposited as thin films on either side of the mixed metal oxide film 106, forming a capacitor structure. Their high electrical conductivity ensures efficient charge transfer and electric field generation, which is useful for the polarization and functioning of the mixed metal oxide film 106 (i.e., the ferroelectric layer).

[0023] The electrodes 104 and 108 can be deposited by a variety of different deposition processes including chemical vapor deposition, physical vapor deposition, plasma enhanced chemical vapor deposition, sputtering, electron beam evaporation, pulsed laser deposition, ion assisted deposition, metalorganic chemical vapor deposition, low pressure chemical vapor deposition, atomic layer deposition, plasma-enhanced atomic layer deposition, or the like, or a combination thereof.

[0024] Common materials used as electrodes in ferroelectric capacitors include metals, electrically conducting metal oxides, electrically conducting metal nitrides, or a combination thereof. In an embodiment, the metals include noble metals. It is desirable for the materials used in the electrode to be able to withstand the temperatures at which any manufacturing processes and / or annealing processes are conducted.

[0025] Examples of materials that may be used in the electrodes include platinum, gold, silver, titanium, aluminum, tantalum, copper, nickel, molybdenum, niobium, chromium, cobalt, ruthenium, iridium, tungsten, indium tungsten oxide, indium tin oxide, TiN, TaN, TaAlN, RuCh, NbN, HfN, ZrN, I1O2, and SrRuOs. In an embodiment, tungsten, is preferable.

[0026] In an embodiment, the electrodes 104 and 108 are of the same thickness. In another embodiment, one of the electrodes may be thicker than the other. Theelectrodes 104 and 108 generally have a thickness of 1 nanometer to 5 micrometers, preferably 2 nanometers to 2 micrometers, and more preferably 3 nanometers to 10 nanometers.

[0027] The deposition of the second electrode 108 typically occurs after the formation of the mixed metal oxide film 106 on the substrate 102 or on the optional first electrode 104.

[0028] With reference to the FIGS. 1 and 2, the mixed metal oxide film 106 may be disposed directly on either the substrate 102 or on the first electrode 104. It can be in direct contact with the substrate 102 or with the first electrode 104. The mixed metal oxide film 106 is typically manufactured by a vapor deposition process where a precursor to each of the desired metals (present in the metal oxides of the film) are transported into a vapor deposition chamber (also referred to herein as a reactor) and decomposed in the presence of a plasma that comprises a combination of an oxygen-containing gas and a nitrogcn-containing gas. The oxygen present in the plasma oxidizes the decomposed metal precursors (to form the respective metal oxide) and facilitates the formation of a combination of metal oxides in the mixed metal oxide film 106. It is desirable for the metal precursors used herein and for the metal oxides formed on the substrate to lend themselves to methods employed in semiconductor processing, which often occurs at temperatures of less than or equal to 600°C, preferably less than or equal to 450nC.

[0029] At least one of the metal precursors (e.g., a first metal precursor) includes hafnium. The other metal precursor (e.g., the second metal precursor) may include zirconium, cerium, aluminum, silicon, lanthanum, yttrium, strontium, gadolinum, strontium, gallium, calcium, magnesium, or the like, or a combination thereof. The respective metal precursors may be introduced into the vapor deposition chamber simultaneously or sequentially. In a preferred embodiment, the metal precursors are introduced into the vapor deposition chamber sequentially, with the first metal precursor and the second metal precursor being introduced into the chamber in an alternating fashion to produce a multilayered oxide film that has alternating layers of hafnia and a metal oxide that is dependent on the metal contained in the second metal precursor.

[0030] In an embodiment, the respective metal precursors are introduced into the deposition chamber at rates that produce the appropriate atomic ratios of the respective metal oxides desired in the mixed metal oxide film. For example, if a mixed metal oxide film containing 50 atomic percent (at%) hafnia and 50 at% zirconia is to be produced,then the hafnium precursor is introduced at three times the rate at which the zirconium precursor is introduced into the deposition chamber. Alternatively, three layers of hafnia may be deposited for every one layer of zirconia deposited in order to produce a mixed metal oxide film having 50 atomic percent (at%) hafnia and 50 at% zirconia. The hafnia and zirconia layers are deposited in alternating fashion. It is to be noted that when atomic layer deposition is used to produce the mixed metal oxide layer, the rate of introduction of the precursors into the vapor deposition chamber (the reactor) does not matter. The precursors do not stick to themselves, so each dose will form a single monolayer, regardless of how fast it is injected into the chamber, or how long that dose is.

[0031] Suitable metal precursors for hafnium (the first metal precursor) and the second metal precursor include metal salts, organometallic, or metal-organic precursors of the respective metal oxides desired in the mixed metal oxide film. Suitable precursors for hafnium include hafnium halides (hafnium chloride, hafnium iodide, or a combination thereof), hafnium alkoxides (c.g., hafnium tertiary-butoxide), tetrakis(ethylmethylamido)hafnium, tetrakis(dimethylamido)hafnium, tris(dimethylamido)cyclopentadienyl hafnium, hafnium acetylacetonate, or a combination thereof. Suitable second metal precursors include zirconium tetrachloride, tetrakis(ethylmethylamido)zirconium, tctrakis(dimcthylamido)zirconium, zirconium tert-butoxide, zirconium acetylacetonate, cerium(III) acetylacetonate, tris(dimethylamido)cyclopentadienyl zirconium, cerium(IV) tert-butoxide, cerium chloride, cerium(IV) nitrate, or the like, or a combination thereof. Precursors of the other metals listed above (e.g., aluminum, silicon, lanthanum, yttrium, strontium, gadolinum, strontium, gallium, calcium, magnesium, or the like), may also be used.

[0032] It is to be noted that when metal salts are used in the vapor deposition chamber, they may be dissolved in a suitable organic solvent that can be vaporized in the chamber. Suitable solvents include water, alcohols (e.g., methanol, ethanol, isopropanol, butanol, ethylene glycol, or the like, or a combination thereof), ketones (e.g., acetone, methyl ethyl ketone, or the like, or a combination thereof), acetonitrile, dimethyl sulfoxide, or the like, or a combination thereof. Other solvents not listed here may also be used.

[0033] Examples of suitable vapor deposition processes that may be used to produce the mixed metal oxide film include plasma-enhanced chemical vapor deposition,rf magnetron sputtering, ion beam sputtering, reactive ion plating, chemical solution deposition, pulsed laser deposition, molecular-beam deposition, thermal atomic layer deposition, plasma enhanced atomic layer deposition ( ALD), or the like. Plasma- enhanced atomic layer deposition is preferred.

[0034] The plasma in the vapor deposition chamber is created by energizing the combination of oxygen and nitrogen-containing gases. When nitrogen- containing gases and oxygen-containing gases are used to create plasma, they are ionized to generate reactive species like radicals, ions, and excited molecules, which then interact with the metal precursor molecules on the substrate surface to deposit thin films. In an embodiment, nitrogen-containing gases and oxygen-containing gases are introduced into the vapor deposition chamber while a radio frequency (RF) power source or microwave energy is applied to the chamber to generate an electric field.The electric field accelerates free electrons in the chamber, which collide with nitrogen and oxygen gas molecules. These collisions transfer energy to the gas molecules, causing ionization and excitation, breaking the molecular bonds of N2 and O2 to produce nitrogen radicals (N ), nitrogen ions (N+, N2+), excited nitrogen molecules (N2)*, oxygen radicals (O ), oxygen ions (O' , O2 ), and excited oxygen molecules (O2)*. These reactive nitrogen and oxygen species then interact with the substrate and film surface during the deposition process. The oxygen species can react with metal precursors to form oxide films (e.g., HfCh, AI2O3). The plasma species are highly reactive, which helps in reducing the deposition temperature and improving film quality by removing unwanted ligands or unreacted precursors on the surface.

[0035] In an embodiment, in one method of manufacturing a mixed metal oxide film having ferroelectric properties, a substrate is disposed in the vapor deposition chamber (also referred to herein as a reactor). An argon gas is introduced into the vapor deposition chamber to raise the pressure. A first metal precursor is introduced into the vapor deposition chamber. The vapor deposition chamber is then purged with argon gas. A nitrogen-containing gas and an oxygen-containing gas are then introduced into the vapor deposition chamber and energized to create a plasma. A first metal oxide is disposed on the substrate. The oxygen and nitrogen are purged from the vapor deposition system with argon gas. A second metal precursor is introduced into the vapor deposition chamber. A second metal oxide is disposed on the substrate in the presence of theplasma. Additional layers of the metal oxide may be formed on the substrate in this manner.

[0036] In an embodiment, the oxygen-containing gases include oxygen, ozone, hydrogen peroxide, water, carbon dioxide, carbon monoxide, nitrous oxide, or the like, or a combination thereof. The nitrogen-containing gases include nitrogen, ammonia, nitrous oxide, primary amines, secondary' amines, tertiary amines, or the like, or a combination thereof.

[0037] Examples of primary amines include methylamine, ethylamine, propylamine, cthylcncdiaminc, monocthanolaminc, or the like, or a combination thereof. Examples of secondary amines include dialkylamines such as dimethylamine, diethylamine, dipropylamine, dibutylamine, diethanolamine, or the like, or a combination thereof. Examples of tertiary amines include trimethylamine, triethylamine, tertbutylamine, diisopropylethylamine, N,N-dimethylaniline, N-methylmorpholine, N,N- dicthylanilinc, N,N-dimcthylpipcridinc, or the like, or a combination thereof.

[0038] In an embodiment, the molar ratio of the nitrogen- containing gas to the oxygen-containing gas in the plasma may vary from 0.5:1 to 10:1, preferably greater than 2: 1 , preferably greater than 4: 1 , and more preferably greater than 5: 1.

[0039] A preferred nitrogen-containing gas is nitrogen while a preferred oxygencontaining gas is oxygen. In a preferred embodiment, the molar ratio of nitrogen gas to oxygen gas in the plasma may vary from 0.5:1 to 10:1, preferably greater than 2:1, preferably greater than 4:1, and more preferably greater than 5:1.

[0040] The vapor deposition chamber operates at a temperature of 100 to 450°C, preferably 125 to 425°C. As noted above, the mixed metal oxide film 106 formed on the substrate 102 or on the first electrode 104. It is typically an amorphous film.

[0041] In an embodiment, the mixed metal oxide film 106 may have a metal oxide composition represented by formula (1):Hf(i-x)MxO(2.y) ( 1 ), where x represents the number of moles of metal M present in the mixed metal oxide film. M represents zirconium, cerium, aluminum, silicon, lanthanum, yttrium, strontium, gadolinum, strontium, gallium, calcium, magnesium, or a combination thereof. In a preferred embodiment, M is zirconium, cerium, or a combination thereof. In the equation ( 1 ), x can vary from 0.05 to 0.95, preferably 0.3 to 0.7, preferably 0.4 to 0.6 and more preferably 0.45 to 0.55. In a preferred embodiment, M is zirconium. In equation (1), '‘y”represents inherent oxygen deficiencies (e.g., oxygen vacancies) that exist owing to thermodynamic considerations and processing and has a value of 0 to 0.5, preferably 0.0001 to 0.3, and more preferably 0.001 to 0.2.

[0042] Following the formation of the mixed metal oxide film 106, a second electrode 108 may be disposed on the mixed metal oxide film 106 as seen in the FIGS. 1 and 2. The multilayered device thus obtained is then subjected to annealing to form the ferroelectric capacitor 100. The mixed metal oxide film typically has a thickness of 0.5 nanometers to 150 nanometers, preferably 1 to 100 nanometers and more preferably 2 to 30 nanometers.

[0043] Alternatively, the multilayered device may be annealed prior to the disposing of the second electrode 108 on the mixed metal oxide film 106. After the annealing, the second electrode 108 is disposed on the mixed metal oxide film 106 to form the ferro electric capacitor 100.

[0044] After the formation of the mixed metal oxide film 106 on the substrate 102 or on the first electrode 104, the multilayered device is subjected to annealing at a temperature of less than 1100°C, preferably less than 900°C, preferably less than 700°C, preferably less than 550°C, preferably less than 500°C, preferably less than 475°C, preferably less than or equal to about 450°C. The film may be annealed at a temperature of greater than or equal to 250°C. Annealing is generally conducted for a time period of 30 seconds to 20 hours, preferably 1 hour to 10 hours. In an exemplary embodiment, the annealing is conducted at a temperature of less than 600°C, preferably less than or equal to 450°C for a time period of 30 seconds to 1 hour.

[0045] During the annealing the mixed metal oxide film 106 is converted from an amorphous film to crystalline film. The crystalline films preferably comprise a metastable phase that may be the polar orthorhombic (o-p), tetragonal (t) or antipolar orthorhombic (o-ap).

[0046] The crystalline mixed metal oxide film 106 is a dielectric film, i.e., it is electrically insulating and has ferroelectric properties, i.e., it exhibits spontaneous electric polarization, which can be reversed by applying an external electric field.

[0047] The ferroelectric films manufactured using the foregoing method displays a number of advantages. It displays an increased polarization magnitude, a reduced leakage current, a reduced coercive field and an increased endurance over ferroelectric films that have the same ratio of metals in the metal oxide, but that arc not manufacturedin the same manner (i.e., using an atmosphere of nitrogen and oxygen in the plasma enhanced vapor deposition chamber).

[0048] The method of manufacturing these films has the following advantages. Plasma enhanced atomic layer deposition provides more reactive species, allowing for deposition at lower temperatures compared to thermal atomic layer deposition.

[0049] Plasma-enhanced atomic layer deposition often leads to films with better density, purity, and electrical properties. The use of nitrogen and oxygen plasmas expands the range of materials that can be deposited, including nitrides and oxides.

[0050] This process allows precise control over the thickness and composition of thin films, making plasma enhanced atomic layer deposition with nitrogen and oxygen plasma highly useful for semiconductor manufacturing and other advanced material applications. In plasma enhanced atomic layer deposition, the surface reactions remain self-limiting, meaning that the plasma species react only with specific sites on the surface, forming a single atomic layer per cycle. Once the surface is saturated, the reaction stops until the next precursor is introduced, ensuring uniform and conformal thin films.

[0051] Tn an embodiment, the crystalline mixed metal oxide films disclosed herein shows no degradation at up to 106cycles. They display coercive fields of less than 900 kilovolt per centimeter (kV / cm), preferably less than 800 kV / cm. They display remanent polarization values (polarization at zero applied field) of greater than 15 picocoulombs per square centimeter (pC / cm2), preferably greater than 18 pC / cm2.

[0052] The mixed metal oxide films (e.g., the ferroelectric films) disclosed herein may be used in a number of products, methods, and services. Ferroelectric hafnium oxide has applications in computer memory as ferroelectric random access memory (FeRAM), ferroelectric field effect transistors (FeFETs) and ferroelectric tunnel junctions (FTJs). It can also be used as a pyroelectric element to sense infrared radiation and generate electricity from thermal transients.

[0053] The mixed metal oxide layer disclosed herein is exemplified by the following non-limiting example.EXAMPLEExample 1

[0054] This example was conducted to demonstrate a method of manufacturing the mixed metal oxide film (the ferroelectric film) used in the ferroelectric capacitors disclosed herein. A substrate comprising silicon (the substrate 102-see FIG. 1) and coated with a layer of tungsten (the first electrode 104) is placed in the deposition chamber of an atomic layer deposition reactor. The mixed metal oxide film 106 (see FIG. 1 ) is produced as follows. The plasma contained a mixture of nitrogen and / or oxygen in varying ratios. The control sample is prepared with an oxygen plasma atmosphere (an atmosphere devoid of nitrogen). The other samples were prepared in a plasma atmosphere that contained both nitrogen gas and oxygen gas. The hafnium and zirconium precursors were tetrakis (ethylmethyl) amido hafnium and tetrakis (ethylmethyl) amido zirconium.

[0055] After a dose of the metal precursor, a plasma was struck in the atomic layer deposition system with varying ratios of NI:O2. The nitrogen in the plasma provides the source of nitrogen to the hafnium zirconium oxide film (the mixed metal oxide film) and the oxygen in the plasma provides the source of oxygen in the hafnium zirconium oxide film formed on the substrate. The growth proceeds with doses of the metal species (hafnium or zirconium) followed by a plasma.

[0056] The metal precursors are introduced sequentially with the hafnium precursor being introduced first followed by the zirconia precursor. This is continued for several cycles till a multilayer film having the following composition (Hfo.5Zro.5O2) is obtained. The typical thickness of the mixed metal oxide films is 0.5 nm to 40 nm.

[0057] After the deposition of the mixed metal oxide film, a second electrode (108) comprising tungsten is disposed on the mixed metal oxide film. The multilayer device thus obtained is annealed at 600°C for 30 seconds and then subjected to the following tests.

[0058] Each of the samples was subjected to the following tests. Polarization versus electric field was measured using a dedicated ferroelectric tester with a 1 millisecond (ms) measurement period (time to traverse the entire hysteresis loop. The devices were field cycled with a 50% duty cycle 2.5 megavolt per centimeter (MV / cm) square wave at 1 megahertz (MHz) using an Analog Discovery 2 instrument. Thecorresponding evolution of the leakage current and coercive field was measured using a Keithley 4200 Parameter Analyzer.

[0059] FIG. 3 shows the polarization versus electric field response for the nitrogen-plasma-processed hafnium zirconium oxide films prepared with differing ratios of N2:O2in the plasma. The N2:O2molar ratios are 0:1, 1:2, 1: 1, 2:1 and 3:1 respectively. It can be seen that increasing the nitrogen content decreases the coercive field (the electric field at which the polarization equals zero). The remanent polarization (polarization at zero electric field) is also observed to increase. FIG. 4 shows the coercive field at various points during field cycling for the different N2:O2ratios. The lowest coercive field is for the 1:2 molar ratio.

[0060] FIG. 5 shows the leakage current after differing numbers of electric field cycles. The lowest leakage current is observed for the 1 :2 molar ratio of N2:O2and it shows no degradation at up to 106cycles. It is to be noted that the legends in the FIGs. 4 and 5 indicate the N2:O2molar ratios.

[0061] Although example embodiments of the present disclosure are explained in some instances in detail herein, it is to be understood that other embodiments are contemplated. Accordingly, it is not intended that the present disclosure be limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or carried out in various ways.

[0062] It should be appreciated that any element, part, section, subsection, or component described with reference to any specific embodiment above may be incorporated with, integrated into, or otherwise adapted for use with any other embodiment described herein unless specifically noted otherwise or if it should render the embodiment device non-functional. Likewise, any step described with reference to a particular method or process may be integrated, incorporated, or otherwise combined with other methods or processes described herein unless specifically stated otherwise or if it should render the embodiment method nonfunctional. Furthermore, multiple embodiment devices or embodiment methods may be combined, incorporated, or otherwise integrated into one another to construct or develop further embodiments of the invention described herein.

[0063] It should be appreciated that the device and related components discussed herein may take on all shapes along the entire continual geometric spectrum ofmanipulation of x, y and z planes to provide and meet the environmental, anatomical, and structural demands and operational requirements. Moreover, locations and alignments of the various components may vary as desired or required.

[0064] It should be appreciated that various sizes, dimensions, contours, rigidity, shapes, flexibility and materials of any of the components or portions of components in the various embodiments discussed throughout may be varied and utilized as desired or required.

[0065] It should be appreciated that while some dimensions are provided on the aforementioned figures, the device may constitute various sizes, dimensions, contours, rigidity, shapes, flexibility and materials as it pertains to the components or portions of components of the device, and therefore may be varied and utilized as desired or required.

[0066] It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” or “approximately” one particular value and / or to “about” or “approximately” another particular value. When such a range is expressed, other exemplary embodiments include from the one particular value and / or to the other particular value.

[0067] By “comprising” or “containing” or “including” is meant that at least the named compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, or method steps, even if the other such compounds, material, particles, or method steps have the same function as what is named.

[0068] In describing example embodiments, terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. It is also to be understood that the mention of one or more steps of a method does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Steps of a method may be performed in a different order than those described herein without departing from the scope of the present disclosure. Similarly, it is also to be understood that the mention of one or more components in a device or system does not preclude thepresence of additional components or intervening components between those components expressly identified.

[0069] Some references, which may include various patents, patent applications, and publications, are cited in a reference list and discussed in the disclosure provided herein. The citation and / or discussion of such references is provided merely to clarify the description of the present disclosure and is not an admission that any such reference is “prior art” to any aspects of the present disclosure described herein. In terms of notation, “[n]” corresponds to the nth reference in the list. All references cited and discussed in this specification arc incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference.

[0070] The term “about,” as used herein, means approximately, in the region of, roughly, or around. When the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term “about” is used herein to modify a numerical value above and below the stated value by a variance of 10%. In one aspect, the term “about” means plus or minus 10% of the numerical value of the number with which it is being used. Therefore, about 50% means in the range of 45%-55%. Numerical ranges recited herein by endpoints include all numbers and fractions subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.90, 4, 4.24, and 5). Similarly, numerical ranges recited herein by endpoints include subranges subsumed within that range (e.g. 1 to 5 includes 1- 1.5, 1.5-2, 2-2.75, 2.75-3, 3-3.90, 3.90-4, 4-4.24, 4.24-5, 2-5, 3-5, 1-4, and 2-4). It is also to be understood that all numbers and fractions thereof are presumed to be modified by the term “about.”

[0071] Additional descriptions of aspects of the present disclosure will now be provided with reference to the accompanying drawings. The drawings form a part hereof and show, by way of illustration, specific embodiments or examples.

[0072] While the invention has been described with reference to some embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out thisinvention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

CLAIMSWhat is claimed is:1 . A mixed metal oxide film having a composition comprising:Hf(l.x)MxO(2.y) (1) where M is zirconium, cerium, aluminum, silicon, lanthanum, yttrium, strontium, gadolinum, strontium, gallium, calcium, magnesium, or a combination thereof; where x is 0.05 to 0.95 and where the mixed metal oxide film is formed in the presence of a plasma; where the plasma is formed in an atmosphere that comprises nitrogen and oxygen in a molar ratio of 0.5:1 to 10:1; and where y is 0 to 0.5.

2. The mixed metal oxide film of Claim 1, where x is 0.3 to 0.7.

3. The mixed metal oxide film of any one of Claims 1 or 2, where x is 0.4 to 0.6.

4. The mixed metal oxide film of any one of Claims 1 to 3, where M is zirconium.

5. The mixed metal oxide film of any one of Claims 1 to 4, having a thickness of 0.5 to 150 nanometers.

6. The mixed metal oxide film of any one of Claims 1 to 5, having a thickness of 0.5 to 50 nanometers.

7. The mixed metal oxide film of any one of Claims 1 to 6, comprising an amorphous phase.

8. The mixed metal oxide film of any one of Claims 1 to 6, comprising a crystalline phase.

9. The mixed metal oxide film of any one of Claims 1 to 8, where the crystalline phase comprises a metastable phase that includes at least one of a polar orthorhombic (o-p) phase, a tetragonal (t) phase or an antipolar orthorhombic (o-ap) phase.

10. The mixed metal oxide film of any one of Claims 1 to 9, where the film is electrically insulating.

11. A ferroelectric capacitor comprising: a substrate; a first electrode disposed opposite the substrate; and a mixed metal oxide film disposed between the substrate and the electrode; where the mixed metal oxide film has a composition comprising:Hf(l-x)MxO(2-y) (1) where M is zirconium, cerium, aluminum, silicon, lanthanum, yttrium, strontium, gadolinum, strontium, gallium, calcium, magnesium, or a combination thereof; where x is 0.05 to 0.95 and where the mixed metal oxide fdm is formed in the presence of a plasma; where the plasma is formed in an atmosphere that comprises nitrogen and oxygen in a molar ratio of 0.5:1 to 10:1; and where y is 0 to 0.5.

12. The ferroelectric capacitor of Claim 11, further comprising a second electrode disposed between the substrate and the mixed metal oxide fdm.

13. The ferroelectric capacitor of any one of Claims 11 or 12, where the first electrode and / or the second electrode are electrically conducting, while the mixed metal oxide film is electrically insulating.

14. The ferroelectric capacitor of Claim 13, where the first electrode and / or the second electrode comprises platinum, gold, silver, titanium, aluminum, tantalum, copper, nickel, molybdenum, niobium, chromium, cobalt, ruthenium, iridium, tungsten, indium tin oxide, TiN, TaN, TaAlN, RuCh, NbN, HfN, ZrN, TrCb, and SrRuCh.

15. The ferroelectric capacitor of any one of Claims 11 through 14, wherein M is zirconium, and x is 0.3 to 0.7.

16. The ferroelectric capacitor of any one of Claims 1 1 through 15, wherein the mixed metal oxide film is electrically insulating and comprises a crystalline phase.

17. The ferroelectric capacitor of any one of Claims 11 through 16, where the crystalline phase comprises a metastable phase that includes at least one of a polar orthorhombic (o-p) phase, a tetragonal (t) phase or an antipolar orthorhombic (o-ap) phase.

18. A method of manufacturing a mixed metal oxide film having ferroelectric properties, the method comprising: disposing a substrate in a reactor; introducing a first metal precursor into the reactor; introducing a combination of a nitrogen-containing gas and an oxygen-containing gas into the reactor; energizing the nitrogen-containing gas and an oxygen-containing gas in the reactor to create a plasma; disposing a first metal oxide on the substrate; introducing a second metal precursor into the reactor; and disposing a second metal oxide on the substrate.

19. The method of Claim 18, where the second metal oxide is disposed on the first metal oxide.

20. The method of Claim 18, where the plasma is formed in an atmosphere that comprises nitrogen and oxygen in a molar ratio of 0.5: 1 to 10: 1 .

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