<i>In-situ</i> plasma treatment of Cu surfaces for reducing the generation of vacuum arc breakdowns

Saressalo, Anton; Kilpeläinen, Aarre; Mizohata, Kenichiro; Profatilova, Iaroslava; Nolvi, Anton; Kassamakov, Ivan; Tikkanen, P.; Calatroni, S.; Wuensch, Walter; Djurabekova, Flyura

doi:10.1063/5.0062674

Cited by 4 publications

(3 citation statements)

References 35 publications

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“…Yet, oxidation during the bonding process is a particularly challenging issue for Cu-Cu bonding. Many studies have reported the removal of Cu oxides and impurities through acid treatment, wet or dry chemical treatment, laser cleaning, and plasma treatment before bonding for the prevention of re-oxidation of the Cu film surface [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

In-situ temperature-dependent sheet resistance study of Cu films in oxygen ambient for heterogeneous integrations

Chavan,

Kim,

Choi

et al. 2024

Nanotechnology

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Controlling and preventing Cu oxidation is crucial for improving the performance and reliability of Cu-Cu bonding. Ni-B films were selectively deposited on Cu films to block the Cu oxidation. The resistivity changes of the Cu films in N2 and O2 ambient were measured by using a four-point probe in the in-situ temperature-dependent resistance measurements at the temperature from room temperature to 400°C. The resistivity changes of the 100nm-thick Cu films without Ni-B increased rapidly at a higher temperature (284°C) in the O2 ambiance. The change of resistivity-increase of 100nm-thick Cu with ~50 nm-thick Ni-B (top) film was lower than the Cu films without Ni-B films due to the blocking diffusion of O2 atoms by the Ni-B films. The resistivity-change and oxidation barrier properties were studied using SEM, FIB, TEM, EDX, and SIMS tools. The proposed article will be helpful for the upcoming advancement in Cu-Cu bonding using selected-area deposition.

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Section: Introductionmentioning

confidence: 99%

In-situ temperature-dependent sheet resistance study of Cu films in oxygen ambient for heterogeneous integrations

Chavan,

Kim,

Choi

et al. 2024

Nanotechnology

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“…Microscopy of surfaces that have experienced multiple breakdowns reveal a large number of breakdown spots in the shape of solidified molten regions known as craters, see e.g. [3,7,8]. The crater edges are jagged, and thus they themselves can function as field enhancing features [3].…”

Section: Introductionmentioning

confidence: 99%

Biased self-diffusion on Cu surface due to electric field gradients

Kimari¹,

Wang²,

Kyritsakis³

et al. 2022

J. Phys. D: Appl. Phys.

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Under strong electric fields, an arc of strong current flowing through plasma can link two metal surfaces even in ultra high vacuum. Despite decades of research, the chain of events leading to vacuum arc breakdowns is hitherto unknown. Previously we showed that a tall and sharp Cu nanotip exposed to strong electric fields heats up by field emission currents and eventually melts, evaporating neutral atoms that can contribute to plasma buildup. In this work, we investigate by means of molecular dynamics simulations whether surface diffusion biased by the presence of an electric field gradient can provide sufficient mass transport of atoms toward the top of the nanotip to maintain supply of neutrals for feeding plasma. To reach the necessary timescales and to add electric field in MD, we utilized a novel combination of collective variable~-driven hyperdynamics acceleration and coupling to a finite element mesh. In our simulations, we observed biased self-diffusion on Cu surfaces, that can contribute to the continuous replenishment of particle-emitting nanotips. This mechanism implies a need to reduce the rate of surface diffusion in devices that are susceptible to vacuum arcs. Finding suitable alloys or surface treatments that hinder the observed biased diffusion could guide the design of future devices, and greatly improve their efficiency.

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“…Refs. [7,3,8]. The crater edges are jagged, and thus they themselves can function as field enhancing features [3].…”

Section: Introductionmentioning

confidence: 99%

Biased self-diffusion on Cu surface due to electric field gradients

Kimari¹,

Wang²,

Kyritsakis³

et al. 2022

Preprint

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Under strong electric fields, an arc of strong current flowing through plasma can link two metal surfaces even in ultra high vacuum. Despite decades of research, the chain of events leading to vacuum arc breakdowns is hitherto unknown. Previously we showed that a tall and sharp Cu nanotip exposed to strong electric fields heats up by field emission currents and eventually melts, evaporating neutral atoms that can contribute to plasma buildup.In this work, we investigate by means of molecular dynamics simulations whether surface diffusion biased by the presence of an electric field gradient can provide sufficient mass transport of atoms toward the top of the nanotip to maintain supply of neutrals for feeding plasma. To reach the necessary timescales and to add electric field in MD, we utilized a novel combination of collective variable -driven hyperdynamics acceleration and coupling to a finite element mesh. In our simulations, we observed biased self-diffusion on Cu surfaces, that can contribute to the continuous replenishment of particle-emitting nanotips. This mechanism implies a need to reduce the rate of surface diffusion in devices that are susceptible to vacuum arcs. Finding suitable alloys or surface treatments that hinder the observed biased diffusion could guide the design of future devices, and greatly improve their efficiency.

show abstract

In-situ plasma treatment of Cu surfaces for reducing the generation of vacuum arc breakdowns

Cited by 4 publications

References 35 publications

In-situ temperature-dependent sheet resistance study of Cu films in oxygen ambient for heterogeneous integrations

In-situ temperature-dependent sheet resistance study of Cu films in oxygen ambient for heterogeneous integrations

Biased self-diffusion on Cu surface due to electric field gradients

Biased self-diffusion on Cu surface due to electric field gradients

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