Thin tantalum films on crystalline silicon – a metallic glass

Stella, Kevin; Bürstel, Damian; Hasselbrink, Eckart; Diesing, Detlef

doi:10.1002/pssr.201004510

Cited by 7 publications

(6 citation statements)

References 16 publications

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“…The valve metal oxides grow following the high-field mechanism [4] and are very difficult to reduce under cathodic polarization [5]. They are able to withstand an electric field equal to the film formation field strength [6], may be amorphous (glassy Ta) [7] and are used in various applications including orthopaedic implants and mesoporous materials [8, 9]. …”

Section: Introductionmentioning

confidence: 99%

Properties of anodic oxides grown on a hafnium–tantalum–titanium thin film library

Mardare

Ludwig

Savan

et al. 2014

Science and Technology of Advanced Materials

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A ternary thin film combinatorial materials library of the valve metal system Hf–Ta–Ti obtained by co-sputtering was studied. The microstructural and crystallographic analysis of the obtained compositions revealed a crystalline and textured surface, with the exception of compositions with Ta concentration above 48 at.% which are amorphous and show a flat surface. Electrochemical anodization of the composition spread thin films was used for analysing the growth of the mixed surface oxides. Oxide formation factors, obtained from the potentiodynamic anodization curves, as well as the dielectric constants and electrical resistances, obtained from electrochemical impedance spectroscopy, were mapped along two dimensions of the library using a scanning droplet cell microscope. The semiconducting properties of the anodic oxides were mapped using Mott–Schottky analysis. The degree of oxide mixing was analysed qualitatively using x-ray photoelectron spectroscopy depth profiling. A quantitative analysis of the surface oxides was performed and correlated to the as-deposited metal thin film compositions. In the concurrent transport of the three metal cations during oxide growth a clear speed order of Ti > Hf > Ta was proven.

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Section: Introductionmentioning

confidence: 99%

Properties of anodic oxides grown on a hafnium–tantalum–titanium thin film library

Mardare

Ludwig

Savan

et al. 2014

Science and Technology of Advanced Materials

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“…However, is important to note that this is not always the case, and amorphous Hf and Ta films with particular anodization characteristics were already reported. [ 43,44 ]…”

Section: Methodsmentioning

confidence: 99%

“…However, is important to note that this is not always the case, and amorphous Hf and Ta films with particular anodization characteristics were already reported. [43,44] The surface of the wafer holding the Hf/Ta parent metals was cut into two parts and each was anodized electrochemically in a potentiodynamic regime up to 7 V (vs. SHE) at a scan rate of 100 mV s À1 in 1 M PB, pH ¼ 7.5 or in 0.1 M CB, pH ¼ 6.0. The aimed thickness of the overall oxide was %20 nm, hence individual oxide formation factors of Hf and Ta were taken into account.…”

Section: Methodsmentioning

confidence: 99%

Memristive Characteristics of Composite Hafnium/Tantalum Anodic Oxides

Zrinski

Minenkov

Duchoslav

et al. 2022

Physica Status Solidi (a)

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A composite anodic oxide film is formed by electrochemical treatment of an ultra‐thin Hf film superimposed on Ta, due to the growth of Ta2O5 columns through HfO2. The oxidation dynamic is governed by an electrical version of the Rayleigh–Taylor effect, the current preferring the more conductive path via Ta during anodization of the superimposed Hf film. Memristive devices obtained by patterning Pt top electrodes are investigated and their electrical behavior is reported. The effect of electrolyte species incorporation on the memristive behavior is analyzed by anodization in different solutions. The influence of citrate‐buffered (CB) and phosphate‐buffered (PB) electrolytes is studied, and the presence of P in the composite anodic oxides is evidenced in the latter case leading to early device failure. Composite memristors grown in citrate electrolytes show both unipolar and bipolar switching, high stability, very good retention, and endurance. The coexistence of both switching mechanisms is related to the special composite oxide nanostructuring.

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“…However, especially from line scans, one can see that the aluminum film shows a quite high roughness (standard deviation in height σ = ±1.4 nm) whereas the tantalum film is quite smooth (σ = ±0.2 nm) which is consistent with our earlier results. 10,21,22 Electrochemical anodic oxidation of films.-Metal films are thinned by an electrochemical oxidation procedure whereby a part of the metal is used to form metal oxide. This electrochemical oxidation is carried out in an electrolytic droplet cell, 9,23 see upper half of figure 1.…”

Section: Methodsmentioning

confidence: 99%

Electrochemical Oxidation as Vertical Structuring Tool for Ultrathin (d < 10 nm) Valve Metal Films

Stella

Franzka

Bürstel

et al. 2014

ECS J. Solid State Sci. Technol.

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Stepwise potentiostatic oxidation is used to reduce the thickness of thin aluminum and tantalum films from an initial thickness of 10 nm down to 2 nm. The thicknesses of the oxide and the residual metal are adjusted by the finite potential of an electrochemical oxidation procedure which consumes the initially 10 nm thick metal films. The metal-metal oxide interfaces are smooth and sharply defined. The metal consumption and oxide formation are proportional to each other by the ratio of their specific densities. This enables the derivation of a metal consumption factor for the residual metal film. Residual aluminum films show a significant increase of the specific resistivity with decreasing film thicknesses. This can be explained by modified electronic transport in the residual aluminum for example by changed electronic scattering processes at the metal-metal oxide interface or in the metal. Residual tantalum films show a weaker dependence of the specific resistivity down to 3 nm pointing to only slightly changed transport properties for electrons in the thin tantalum layers.

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Thin tantalum films on crystalline silicon – a metallic glass

Cited by 7 publications

References 16 publications

Properties of anodic oxides grown on a hafnium–tantalum–titanium thin film library

Properties of anodic oxides grown on a hafnium–tantalum–titanium thin film library

Memristive Characteristics of Composite Hafnium/Tantalum Anodic Oxides

Electrochemical Oxidation as Vertical Structuring Tool for Ultrathin (d < 10 nm) Valve Metal Films

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