Surface Mobility of Copper Ions on Cuprous Oxide

Frerichs, Rudolf; Liberman, I.

doi:10.1103/physrev.121.991

Cited by 14 publications

(8 citation statements)

References 11 publications

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“…This difference in the final phase reflects difference in the oxidation mechanism and driving force during the stage II and stage III. The last two stages of the overall Cu thin film oxidation mechanism explain the reason for the only and further formation of the Cu 2 O layer in the current work, which is compared to previous work mentioned earlier [16][17][18][19][20][21]. In any previous results, impurities in the polycrystalline Cu thin film and recrystallization of the polycrystalline Cu thin film during the proceeding of the Cu thin film oxidation have not been addressed on the effects of them on the oxidation mechanism and electrical resistance evolution of the Cu thin film.…”

Section: Sims Depth Profiles Insupporting

confidence: 67%

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Electrical Resistance Evolution of Cu Redistribution Layer Electroplated on a Si Interposer

Lee¹

2015

Int J Metall Mater Eng

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The changes in electrical and microstructural properties of electroplated Cu films on a Si-interposer substrate were investigated. When Cu films were exposed in an air environment after electroplating on SiO 2 /Si-substrate as a Si interposer, the resistance increased slightly until 7 days with a uniform distribution of it, and then increased very rapidly after 19 days with broader resistance distribution than those of the initial 7 days. It took 129 days to have much broader resistance distribution than that of 19 days. Secondary ion mass spectroscopy, X-ray photoelectron spectroscopy, and thin film X-ray diffraction demonstrated that the increase in electrical resistance of electroplated Cu films can be significantly influenced by the chlorine redistribution of impurity in electroplated Cu film to the surface of it, by the oxidation behavior on the surface of electroplated Cu film in an air environment, and the microstructural changes of electroplated Cu film with time, respectively. These phenomena can be explained by the ionic neutrality behavior due to the oxidation on the surface of electroplated Cu film and the microstructural changes with time at room temperature caused by recrystallization of electroplated Cu film. This study will be helpful in understanding the necessity of passivating or encapsulating the electroplated Cu film and will also give guidance to the 3-D integration of stacking many chips on a Si interposer.

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Section: Sims Depth Profiles Insupporting

confidence: 67%

“…The driving force for transport of Cu ions from the metal to the oxide/oxygen interface at low temperature is an electric field formed by positive ions of Cu at the metal/oxide interface and negative ions at the oxide/air interface. This is described by the following reaction [16][17][18][19][20]:…”

Section: Resultsmentioning

confidence: 99%

Electrical Resistance Evolution of Cu Redistribution Layer Electroplated on a Si Interposer

Lee¹

2015

Int J Metall Mater Eng

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“…The growth of the Cu 2 O layer in this stage is affected by the microstructure and morphology of the surface and by the content of lattice defects that will induce the metal cations to migrate. 12,50 (e) The metastable Cu(OH) 2 and CuO layer formation can be described by the following reaction: The Cu(OH) 2 layer formation is affected by the concentration of adsorbed OH, which reacts with the Cu + of the surface. (f) The transformation phase of the metastable Cu(OH) 2 to CuO can be described by the following reaction: The transformation phase rate of this step depends on the relative humidity of the air.…”

Section: Resultsmentioning

confidence: 99%

XPS and DFT Studies on the Autoxidation Process of Cu Sheet at Room Temperature

Zuo

Han

et al. 2014

J. Phys. Chem. C

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To better understand the autoxidation mechanism of Cu-based catalysts, we studied the oxidation of Cu sheet exposed to ultrahigh vacuum and air at ambient temperature using X-ray photoelectron spectroscopy (XPS) and density functional theory. Six main stages of Cu autoxidation are revealed: (1) dissociative adsorption of O 2 , (2) coexistence of nondissociative and dissociative H 2 O adsorption, (3) diffusion of O and OH into Cu bulk, (4) formation of metastable Cu 2 O layer, (5) further oxidation and formation of metastable Cu(OH) 2 and CuO layer, and (6) transformation phase of the metastable Cu(OH) 2 to CuO. The formation of Cu(OH) 2 depends on the relative humidity of air and the concentration of adsorbed OH of the Cu sheet. On the basis of these results, we propose that the preservation time of the Cu-based catalysts should be decreased or the catalysts should be preserved in a high vacuum and at low relative humidity. Considering the time of the sample preparation before ex situ XPS analysis and other surface characterizations, the Cu-based catalysts need to be etched by ∼10 s using an Ar ion gun. These findings serve as a guide for the preservation and preparation of Cu-based catalysts before actual measurement.

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“…Additionally, the time required to reach steady state in the oxide growth rate for annealed Cu is much shorter (28 days) compared to 66 days for nonannealed Cu. The growth of the Cu 2 O layer for different samples under similar exposure conditions is induced by an electric field (as a driving force under low-temperature conditions) formed by positive ions of Cu at the metal/oxide interface and negative ions at the oxide/air interface , and is affected mainly by the microstructure and morphology of the surface and by the content of lattice defects, which magnify the electric field and affect the number of ion lattice vacancies. Therefore, the improvement in surface properties such as roughness, homogeneity, and the grain structure by annealing modifications and the reduction of the total surface area and surface energy lead to a slower rate of oxidation and a smaller thickness of the native oxide grown on the surface.…”

Section: Resultsmentioning

confidence: 99%

Formation of Ultrasmooth and Highly Stable Copper Surfaces through Annealing and Self-Assembly of Organic Monolayers

Platzman¹,

Saguy²,

Brener³

et al. 2009

Langmuir

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Copper (Cu) has been extensively used as an interconnect material for microelectronic devices because of its high electrical and thermal conductivity and excellent electromigration resistance. However, the formation of relatively rough Cu surfaces ( approximately 5 nm roughness) and Cu-oxide layers upon exposure to air still hinders their reliable application in a wide range of fields. In this article, we show the potential values of highly stable and ultrasmooth polycrystalline bare Cu obtained by simple annealing and chemical modification for a wide range of Cu-based electronic devices. The morphological properties and oxidation behavior of annealed Cu surfaces, before and after coating by self-assembled monolayers of terephthalic acid (TPA), were examined upon exposure to ambient air conditions ( approximately 110 days). Thin films of polycrystalline Cu, deposited on top of an adhesion layer of tantalum nitride (TaN) and annealed for 8 h at 580 degrees C under 2 x 10(-7) Torr, provided ultrasmooth Cu surfaces (R(rms) = 0.15-1.1 nm for fresh samples) and had a stable Cu-oxide layer after 65 days ( approximately 3.5 nm). These observations were perceived to be superior to nonannealed polycrystalline Cu samples. Coating fresh (oxide-free) samples of ultrasmooth Cu with TPA molecules created a closely packed monolayer with a standing-up phase configuration and molecular coverage of approximately 90%. The TPA-coated Cu surface has not shown any detectable oxidation during the first 2 weeks of exposure. The protection efficiency of this layer was found to be superior to those reported earlier on polycrystalline Cu surfaces. The oxidation mechanisms of both annealed and nonannealed Cu surfaces are presented and discussed.

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Surface Mobility of Copper Ions on Cuprous Oxide

Cited by 14 publications

References 11 publications

Electrical Resistance Evolution of Cu Redistribution Layer Electroplated on a Si Interposer

Electrical Resistance Evolution of Cu Redistribution Layer Electroplated on a Si Interposer

XPS and DFT Studies on the Autoxidation Process of Cu Sheet at Room Temperature

Formation of Ultrasmooth and Highly Stable Copper Surfaces through Annealing and Self-Assembly of Organic Monolayers

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