Thin film processing by biased target ion beam deposition

Hylton, T. L.; Ciorneiu, B.; Baldwin, David A.; Escorcia, Orlando; Son, Jae-Han; McClure, M. T.; Waters, G.

doi:10.1109/20.908643

Cited by 34 publications

(18 citation statements)

References 8 publications

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“…The key feature of this BTIBD system is that, instead of using conventional gridded ion source, it uses low energy ion sources that combine with end-Hall ion and hollow cathode electron sources. 4 High purity methane (CH 4 ) gas was mixed with Argon (Ar) gas in the ratio of 1:1 and used as a carbon source to deposit both DLC and W-DLC¯lms. The hydrocarbon ion energy was optimized and adjusted to 35 eV with an ion current of 1.75 A and this was kept constant throughout the deposition.…”

Section: Methodsmentioning

confidence: 99%

Influence of Tungsten Content in W-DLC Nanocomposite Thin Films Prepared by Hybrid Target Biased Ion Beam Assisted Deposition Technique

et al. 2011

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Tungsten incorporated diamond like carbon nanocomposite¯lms were deposited onto Si substrate by using target biased ion beam assisted deposition. The e®ect of W target bias voltage on the chemical bonding, structure, surface morphology and mechanical properties of DLC¯lms were investigated by means of XPS, Raman spectroscopy, AFM and Nanoindentation. It was found that the content of W in the¯lms increased from 6 at.% to 13.7 at.% due to the increase in target bias voltage from À300 V to À700 V. XPS analysis revealed that most of the tungsten starts to react with carbon to form WC nanoparticles. Raman analysis shows that with the increase of W fraction in the DLC matrix, the intensity ratio I D /I G increases and the G band shifts to higher wavenumber. Thus it proves that the incorporation of tungsten leads to increase in sp 2 hybridized carbon content, and hence decrease in the hardness of W-DLC¯lms compared to that of the pure DLC¯lms. The result of AFM indicates that the surface roughness of the DLC gets modi¯ed with the incorporation of tungsten.

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Section: Methodsmentioning

confidence: 99%

Influence of Tungsten Content in W-DLC Nanocomposite Thin Films Prepared by Hybrid Target Biased Ion Beam Assisted Deposition Technique

et al. 2011

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“…Additional details of our BTIBD system can also be found elsewhere. 2,12 There are two identical ion guns installed in the BTIBD, one for main deposition and the other for ion beam assisted deposition. In the present work, for simplicity, only the main gun was used for the MTJ depositions.…”

Section: Methodsmentioning

confidence: 99%

“…3 This is because it is harder to focus the sputtering ion beam at low energies, meaning a larger fraction of the ion beam could miss the targets and sputter off undesired materials from the vacuum system hardware, causing an overspill contamination. 2 Hence, using higher acceleration voltages better focuses the ion beam on the target. Unfortunately, this also gives the adatoms higher kinetic energies when they reach the substrate, causing intermixing problems at the interfaces, which is detrimental to the TMR performance.…”

Section: Introductionmentioning

confidence: 99%

Effects of target bias voltage in magnetic tunnel junctions grown by ion beam deposition

Chen

Nam

et al. 2009

Journal of Applied Physics

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Magnetic tunnel junctions (MTJ) with AlOx barrier were fabricated by a deposition tool called Biased Target Ion Beam Deposition (BTIBD) using low energy ion source (0-50 eV) and voltage biased targets. The BTIBD system applies bias voltage directly and only on the desired targets, providing enough sputtering energy and avoiding "overspill" contamination during film deposition. The successful deposition of AlOx-MTJs demonstrated the capability of BTIBD to make multilayer structures with good film quality. MTJ thin film surface roughness and intermixing between layers are among the key problems leading to low TMR performance. Here by studying the bias voltage effect on MTJ properties via the measurement of Néel coupling field and TMR, we suggest that the lower bias voltage reduces the intermixing that occurs when top CoFe free layer is deposited on AlOx barrier, but produces relatively high surface roughness. On the other hand, higher energy deposition enhances both interlayer mixing and surface flattening. Such understanding of bias voltage effects on film properties could be used to optimize the MTJ performances.

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“…The IBD has the advantages of independent control of target and substrate environments, low processing pressures, low sputtering rate, directional sputtered flux, and high adatom flux energy; however it is not suitable for optimum conditions for multilayer deposition, because conventional IBD uses relatively high sputtering ion energies to better focus the ion beam on the target 14,15 . The focused beam is used to prevent the overspill contamination when a large fraction of an unfocused ion beam miss the targets and sputters off other materials from hardware inside the vacuum chamber 16 .…”

Section: A Recently Proposed Josephsonmentioning

confidence: 99%

Surface morphology control of Nb thin films by biased target ion beam deposition

Kittiwatanakul

Anuniwat

Dao

et al. 2018

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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One of many challenges for niobium (Nb) based superconducting devices is the improvement over the surface morphology and superconducting properties as well as the reduction of defects. We employed a novel deposition technique, i.e. biased target ion beam deposition technique (BTIBD) to prepare Nb thin films with controlled crystallinity and surface morphology. We found that the target current (I Target ) and the target bias (V Target ) were critical to the crystallinity and surface morphology of Nb films. The high target current (I Target >500 mA and V Target = 400 V bias) during the deposition degraded the Nb crystallinity, and subsequently reduced the critical temperature for superconductivity (T c ). V Target was critical to the surface morphology, i.e. grain size and shape and the surface roughness. The optimized growth condition yielded very smooth film with RMS roughness of 0.4 nm that was an order of magnitude smoother than that of Nb films by sputtering process. The critical temperature for superconductivity was also close to the value of the bulk Nb. The quality of Nb film was evident in the presence of a very thin proximity layer (~ 0.8 nm). The experimental results demonstrated that the preparation of smooth Nb films with adequate superconductivity by BTIBD could serve as a base electrode for the in-situ magnetic layer or insulating layer for superconducting electronic devices.

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Thin film processing by biased target ion beam deposition

Cited by 34 publications

References 8 publications

Influence of Tungsten Content in W-DLC Nanocomposite Thin Films Prepared by Hybrid Target Biased Ion Beam Assisted Deposition Technique

Influence of Tungsten Content in W-DLC Nanocomposite Thin Films Prepared by Hybrid Target Biased Ion Beam Assisted Deposition Technique

Effects of target bias voltage in magnetic tunnel junctions grown by ion beam deposition

Surface morphology control of Nb thin films by biased target ion beam deposition

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