Heat-Treatment of Anodic Oxide Films on Tantalum

Smyth, D. M.; Shirn, G. A.; Tripp, Terrance B.

doi:10.1149/1.2425638

Cited by 47 publications

(16 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…14, [16][17][18][19][20] Temperature and atmosphere are the main parameters controlling the oxide transformation. Specifically, it is known that heating the as-grown, amorphous ATO to high temperatures around will result in the formation of crystallization oxide.…”

Section: -15mentioning

confidence: 99%

“…[11][12][13][14][15] However, some of the details of the oxide transformation and structural change of ATO during heat treating below its crystallization temperature remain unclear. 14,[16][17][18][19][20] Temperature and atmosphere are the main parameters controlling the oxide transformation. Specifically, it is known that heating the as-grown, amorphous ATO to high temperatures around will result in the formation of crystallization oxide.…”

mentioning

confidence: 99%

“…Evidently, dehydration of the ATO and generating neutral oxygen vacancies at the metal oxide interface reduces the leakage current. According to Smyth et al, 19,20 the reason for the decrease in leakage current is a heat-treatment-induced shift in the conductivity profile through the dielectric: As discussed above, heat-treatment produces neutral oxygen vacancies at the metal-oxide interface. Due to the two electronic charges associated with each vacancy, the effect of the neutral vacancies is analogous to creating n-type semi-conductivity.…”

mentioning

confidence: 99%

See 2 more Smart Citations

In-Situ Stress Measurement during Heat Treatment of Amorphous Tantalum Oxide

Viste

Hossick-Schott

et al. 2015

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

Heat treatment is known to improve the electrical and mechanical properties of amorphous tantalum oxide (ATO) in tantalum capacitor anodes. In-situ, multi-beam optical stress sensor (MOSS) measurements were performed on the ATO / tantalum system during heat-treatment in air and vacuum. Thermal desorption mass spectroscopy was also used to monitor species desorbing from the oxide during heating in vacuum. In addition, scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the heat-treated samples. The results suggest that the ATO/Ta system undergoes changes as a function of annealing temperature and atmosphere. At temperatures below ∼400 • C, the main effects are oxide dehydration and densification, indicated by a net compressive stress. After heat-treatment at temperatures above 400 • C in air, the net stress becomes increasingly compressive with increasing temperature. Oxide growth due to oxygen uptake is the likely cause for the compressive stress. In vacuum, the net stress remains tensile even after heat-treating at high temperatures above 400 • C. Dehydration and the formation of a high density of oxygen vacancies at the metal-oxide interface during heat-treatment are the likely causes for the net tensile stress-thickness. Tantalum capacitors are widely used in various electrical systems.1-3 Amorphous tantalum oxide (ATO) serves as the dielectric. The use of tantalum capacitors in high reliability applications generated intensive research on the electrical properties of the ATO, specifically on phenomena related to dielectric breakdown in high electric fields.3-7 Oxide defects such as interstitial oxygen ions and oxygen vacancies can significantly influence electrical and mechanical properties of ATO. [8][9][10] Heat treatment below the crystallization temperature of ATO is known to improve its electrical properties. 11-15However, some of the details of the oxide transformation and structural change of ATO during heat treating below its crystallization temperature remain unclear.14, [16][17][18][19][20] Temperature and atmosphere are the main parameters controlling the oxide transformation. Specifically, it is known that heating the as-grown, amorphous ATO to high temperatures around will result in the formation of crystallization oxide. 13,21,22 Phase transformations and reactions in solids are typically accompanied by volume changes that can induce stresses when the material is subjected to a mechanical constraint. In Ta capacitors, this occurs because the ATO dielectric is constrained by the underlying Ta metal. In-situ stress measurements have been previously employed to explore the details of phase transformations and reactions in thin solid films. 3,18,[23][24][25] In our recent work, this approach has been used to study the amorphous-to-crystalline phase transition in ATO under high electrical fields.3,26 For example, compressive stress of 0.06 GPa was generated in the ATO along with morphological changes that lead to cracking in the dielectric. 26 In the present stud...

show abstract

Section: -15mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

In-Situ Stress Measurement during Heat Treatment of Amorphous Tantalum Oxide

Viste

Hossick-Schott

et al. 2015

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…The possibility of non-conducting oxide layers forming on untreated titanium -manganese oxide and titanium -ruthenium oxide substrate has been known to be a source of failure for dimensionally stable anodes (DSA) over several decades ( Smyth, 1966). In this illustration a recently developed experimental DSA is supposed to carry a prohibiting additive embedded in the conducting oxide matrix in order to reduce the presence of nonconductors.…”

Section: Non-conducting Oxide Layer Formation On Ti-mno 2 and Ti-ruo mentioning

confidence: 99%

Application of the Negative Binomial/Pascal Distribution in Probability Theory to Electrochemical Processes

Fahidy¹

2012

Recent Trend in Electrochemical Science and Technology

View full text Add to dashboard Cite

“…As shown in the MOM current measurements, the symmetry between polarities suggests that interfacial defect densities do not play a significant role for these films. Oxygen vacancies have been observed as the primary defect for the bulk conduction mechanisms in tantalum oxide films [101], [102], closely tied to the energies observed for Poole-Frenkel conduction [103]. …”

Section: Electronic Processesmentioning

confidence: 70%

Low Voltage Electrowetting-on-Dielectric for Microfluidic Systems

Mibus¹

View full text Add to dashboard Cite

Manipulating fluids in micro to nano-liter volumes poses significant challenges, due to the dominance of surface forces with increasingly large surface to volume ratios. Commonly, external pumps or precisely micromachined on-chip pumps were used to generate pressure gradients to induce fluid motion. Alternatively, the wettability of a surface can be manipulated by an applied electric field. This phenomenon, known as electrowetting, consists in the spread of a liquid drop placed on an electrode upon application of a voltage. Electrowetting based devices flourished upon the discovery that an added dielectric layer between the drop and a conductive electrode would tolerate the application of large voltages, allowing for significant contact angle change. Several current commercial devices exploiting this effect include electro-optic displays, electronic paper, and variable focus lenses.Additionally, electrowetting has achieved particular prominence in lab-on-a-chip applications, controlling drop transport across patterned electrode structures.Initially, polymers were utilized as the dielectric layer preventing current flow between the fluid and electrode, while providing a hydrophobic surface to minimize the resistance of drop movement.However, these layers were typically in excess of one micron thickness. As a consequence, these layers required over 100 Volts to achieve appreciable contact angle change. This dissertation aims to reduce the voltage dependence for contact angle change by optimization of a dual layer structure utilizing a dielectric and hydrophobic layer. The dielectric layer uses aluminum and tantalum oxides (15-44 nm thick) formed by electrochemical anodization. The electronic and ionic conduction, breakdown characteristics, and dielectric properties of these films were studied in detail, achieving a comprehensive understanding of the charge transport and failure mechanisms. Three hydrophobic layer were investigated: a commercial fluoropolymer Cytop, and two self-assembled monolayers 3

show abstract

Heat-Treatment of Anodic Oxide Films on Tantalum

Cited by 47 publications

References 11 publications

In-Situ Stress Measurement during Heat Treatment of Amorphous Tantalum Oxide

In-Situ Stress Measurement during Heat Treatment of Amorphous Tantalum Oxide

Application of the Negative Binomial/Pascal Distribution in Probability Theory to Electrochemical Processes

Low Voltage Electrowetting-on-Dielectric for Microfluidic Systems

Contact Info

Product

Resources

About