Tunable high-κ ZrxAl1−xOy thin film dielectrics from all-inorganic aqueous precursor solutions

Woods, Keenan N.; Waddington, E. C.; Crump, Cameron; Bryan, E. A.; Gleckler, T. S.; Nellist, Michael R.; Duell, B. A.; Nguyen, Duc-Duy; Boettcher, Shannon W.; Page, Catherine J.

doi:10.1039/c7ra08362a

Cited by 10 publications

(3 citation statements)

References 72 publications

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“…Although traditional vapor-phase approaches produce high-quality aluminum oxide thin films, they generally involve expensive equipment and significant waste material. By contrast, solution deposition offers a cost-effective and scalable alternative, and solution-based routes to high-quality aluminum oxide films have been reported. − Here, we track the formation of aluminum oxide thin films deposited from aqueous aluminum precursors using high-field (19.96 T) 27 Al SSNMR in conjunction with conventional analysis techniques. Because local structure is likely very sensitive to deposition route and processing conditions, we have determined the evolution of aluminum site coordination from aqueous-derived aluminum oxide films and correlated the structure with film properties.…”

Section: Introductionmentioning

confidence: 99%

Aluminum Oxide Thin Films from Aqueous Solutions: Insights from Solid-State NMR and Dielectric Response

et al. 2018

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Here, we employ a combination of 27 Al solidstate nuclear magnetic resonance (SSNMR) and conventional spectroscopic and microscopic techniques to investigate the structural evolution of aqueous aluminum precursors to a uniform and smooth aluminum oxide film. The route involves no organic ligands and relies on dehydration, dehydroxylation, and nitrate loss for condensation and formation of the threedimensional aluminum oxide structure. Local chemical environments are tracked as films evolve over the temperature range 200−1100 °C. 27 Al SSNMR reveals that Al centers are predominantly four-and five-coordinate in amorphous films annealed between 200 and 800 °C and four-and six-coordinate in crystalline phases that form above 800 °C. The Al coordination of the aqueous-deposited aluminum oxide films are compared to data from SSNMR studies on vapor-phasedeposited aluminum oxide thin films. Additionally, dielectric constants of aluminum oxide-based capacitors are measured and correlated with the SSNMR results. Aluminum oxide is an important material for protective coatings, catalysis, and microelectronic applications. For the latter application, amorphous materials are preferred, but a lack of long-range order complicates structural characterization and determination of structure−property relationships. Solution deposition approaches are attractive alternatives to traditional vapor-phase deposition methods because precursors are commonly stable in air, and they enable printing and direct lithographic patterning on common semiconductor wafers as well as large-area and flexible substratesuseful for scale-up to applications in windows and photovoltaic devices.

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Section: Introductionmentioning

confidence: 99%

Aluminum Oxide Thin Films from Aqueous Solutions: Insights from Solid-State NMR and Dielectric Response

et al. 2018

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“…The need for high-volume manufacturing has fueled interest in new deposition methods with capabilities to produce complex compositions, control morphologies, and increase throughput. In particular, solution deposition presents a potentially scalable, inexpensive route to address these demands. − Sol−gel and similar metal−organic methods, which utilize organic ligation to form stable solutions and control condensation reactions, currently dominate solution deposition. − In contrast, inorganic aqueous solution deposition avoids organic additives and solvents, instead employing simple metal salts or precondensed oxo-hydroxo metal clusters to produce dense films with ultrasmooth surfaces. ,− …”

Section: Introductionmentioning

confidence: 99%

Low-Temperature Steam Annealing of Metal Oxide Thin Films from Aqueous Precursors: Enhanced Counterion Removal, Resistance to Water Absorption, and Dielectric Constant

et al. 2017

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Aqueous solution deposition has emerged as a potentially scalable, high-throughput route to functional metal oxide thin films. Aqueous routes, however, generally require elevated processing temperatures to produce fully condensed films that are resistant to water absorption. Herein, we report a low-processing-temperature method for preparing more fully condensed, stable metal oxide films from aqueous precursors. We show that a steam anneal at ≤200 °C reduces residual nitrates in zinc oxide, yttrium aluminum oxide, and lanthanum zirconium oxide (LZO) films. An in-depth study on LZO dielectric films reveals steam annealing also reduces residual chloride content, increases resistance to post-anneal water absorption, eliminates void formation, and enhances the dielectric constant. This investigation demonstrates that steam annealing directly affects the decomposition temperatures and chemical evolution of aqueous precursors, suggesting a general means for producing high-quality films at low processing temperatures.

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“…The diversity of chemical and physical properties exhibited by metal oxide thin films make them critical components in a number of technological applications, including electronic display, − photovoltaic, − and fuel cell technologies. − For many applications, oxide films with multiple metal components are necessary to achieve desired properties. Solution deposition is an attractive method for producing multimetal oxides because it enables facile manipulation of metal compositions by controlling precursor stoichiometry and offers the promise of high-throughput processing and large area coverage. − Sol–gel routes are the most common solution deposition methods, but all-inorganic aqueous routes produce high-quality, dense films without the need for organic additives. − In some cases, aqueous solution deposition yields films with device properties comparable to those of films made using atomic layer deposition. , …”

Section: Introductionmentioning

confidence: 99%

Nonuniform Composition Profiles in Amorphous Multimetal Oxide Thin Films Deposited from Aqueous Solution

Woods

Thomas

Mitchson

et al. 2017

ACS Appl. Mater. Interfaces

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Metal oxide thin films are ubiquitous in technological applications. Often, multiple metal components are used to achieve desired film properties for specific functions. Solution deposition offers an attractive route for producing these multimetal oxides because it allows for careful control of film composition through the manipulation of precursor stoichiometry. Although it has been generally assumed that homogeneous precursor solutions yield homogeneous thin films, we recently reported evidence of nonuniform electron density profiles in aqueous-deposited films. Herein, we show that nonuniform electron densities in lanthanum zirconium oxide (LZO) thin films are the result of inhomogeneous distributions of metal components. Specifically, La aggregates at the film surface, whereas Zr is relatively evenly distributed throughout single-layer films. This inhomogeneous metal distribution persists in stacked multilayer films, resulting in La-rich interfaces between the sequentially deposited layers. Testing of metal-insulator-semiconductor devices fabricated from single and multilayer LZO films shows that multilayer films have higher dielectric constants, indicating that La-rich interfaces in multilayer films do not detrimentally impact film properties. We attribute the enhanced dielectric properties of multilayer films to greater condensation and densification relative to single-layer films, and these results suggest that multilayer films may be preferred for device applications despite the presence of layering artifacts.

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Tunable high-κ Zr_xAl_1−xO_y thin film dielectrics from all-inorganic aqueous precursor solutions

Cited by 10 publications

References 72 publications

Aluminum Oxide Thin Films from Aqueous Solutions: Insights from Solid-State NMR and Dielectric Response

Aluminum Oxide Thin Films from Aqueous Solutions: Insights from Solid-State NMR and Dielectric Response

Low-Temperature Steam Annealing of Metal Oxide Thin Films from Aqueous Precursors: Enhanced Counterion Removal, Resistance to Water Absorption, and Dielectric Constant

Nonuniform Composition Profiles in Amorphous Multimetal Oxide Thin Films Deposited from Aqueous Solution

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