Surface Smoothing Effects of Materials Used in Underlayer of MTJ with Gas Cluster Ion Beams

MRS Advances ◽  
2016 ◽  
Vol 1 (5) ◽  
pp. 357-362 ◽  
Author(s):  
Noriaki Toyoda
Keyword(s):  
Surface Roughness ◽  
Ion Beam ◽  
Random Access ◽  
Resistive Random Access Memory ◽  
Surface Smoothing ◽  
Smoothing Effects ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Materials Used ◽  
Gas Cluster Ion Beam

ABSTRACTSurface smoothing of Ru used as underlayer of magnetic tunneling junctions (MTJ) in magneto-resistive random access memory (MRAM) was carried out with gas cluster ion beam (GCIB) in order to improve device characteristics. For Ru films, surface smoothing with 5 kV N2-GCIB irradiation was effective, and CoFe films deposited on smoothed Ru surface also showed smooth surface. From the hysteresis loop measurements of MTJ formed on smoothed Ru with N2-GCIB, it showed improvement of inter-layer coupling magnetic field (Hin) with decreasing the surface roughness of underlayer Ru. It is expected that surface roughness of MgO in MTJ was also improved by smoothing of underlayer Ru with N2-GCIB.

Improvement of surface roughness by ultra-thin film deposition with oxygen cluster ion beam assist deposition

2002 ◽  
Vol 749 ◽  
Author(s):  
Noriaki Toyoda ◽  
Isao Yamada
Keyword(s):  
Surface Roughness ◽  
Morphological Evolution ◽  
Ion Beam ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Average Roughness ◽  
Original Surface ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Gas Cluster Ion Beam

ABSTRACTTa2O5 films were deposited on a rough surface (average roughness 1.3nm, peak-to-valley 14nm) and surface roughness evolutions and improvements by O2 gas cluster ion beam (O2-GCIB) assisted deposition was studied. The average roughness dramatically decreased from 1.3nm to 0.5nm after deposition of Ta2O5 films 20nm in thickness with 7 keV of O2 cluster ion beams. As there was no etching or sputtering of Ta2O5 film by 7keV O2-GCIB irradiations, O2-GCIB assist deposition realized significant improvement of surface roughness by additional deposition of Ta2O5 film whose thickness was close to the peak-to-valley of original surface. It is expected that morphological evolution of the film by GCIB assist deposition becomes completely different from conventional ion assist deposition due to energetic cluster ion impacts.

Smoothing Thin Films with Gas-Cluster Ion Beams

2000 ◽  
Vol 614 ◽  
Author(s):  
D.B. Fenner ◽  
J. Hautala ◽  
L.P. Allen ◽  
J.A. Greer ◽  
W.J. Skinner ◽  
...  
Keyword(s):  
Thin Film ◽  
Ion Beam ◽  
Spin Valve ◽  
High Spatial Frequency ◽  
Atomic Scale ◽  
Force Microscopy ◽  
Tantalum Films ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Gas Cluster Ion Beam

ABSTRACTThin-film magnetic sensor and memory devices in future generations may benefit from a processing tool for final-step etching and smoothing of surfaces to nearly an atomic scale. Gas-cluster ion-beam (GCIB) systems make possible improved surface sputtering and processing for many types of materials. We propose application of GCIB processing as a key smoothing step in thin-film magnetic-materials technology, especially spin-valve GMR. Results of argon GCIB etching and smoothing of surfaces of alumina, silicon, permalloy and tantalum films are reported. No accumulating roughness or damage is observed. The distinct scratches and tracks seen in atomic-force microscopy of CMP-processed surfaces, are removed almost entirely by subsequent GCIB processing. The technique primarily reduces high spatial-frequency roughness and renders the topographic surface elevations more nearly gaussian (randomly distributed).

Etching and Surface Smoothing with Gas-Cluster Ion Beams

1999 ◽  
Vol 585 ◽  
Author(s):  
D. B. Fenner ◽  
R. P. Torti ◽  
L. P. Allen ◽  
N. Toyoda ◽  
A. R. Kirkpatrick ◽  
...  
Keyword(s):  
Surface Science ◽  
Ion Beam ◽  
Surface Processing ◽  
Figures Of Merit ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Gas Clusters ◽  
Gas Cluster Ion Beam ◽  
Microelectronic Materials ◽  
Very High

AbstractSurface processing of microelectronic materials by bombardment with nanoparticles of condensed gases (i.e., clusters) in the form of an ion beam, makes possible etching and smoothing of those surfaces to very high figures of merit. As this is not possible with any conventional ion method, gas-cluster ion-beam systems have great potential in manufacturing. The formation of gas clusters and their collision with surfaces provides an interesting arena for novel physics and surface science. This paper outlines a physical model for the clusters and surface interactions, and provides examples of surface processing. In particular, the reduction of surface roughness while etching by cluster-ion bombardment is illustrated for various materials utilized in microelectronics.

scholarly journals J111022 Changes of Surface Roughness and Surface Energy of Glass Surfaces with Gas Cluster Ion Beam Treatment

2011 ◽  
Vol 2011 (0) ◽  
pp. _J111022-1-_J111022-3
Author(s):  
Katsuya NAMBA ◽  
Hiroyuki SAKAKIBARA ◽  
Hedong ZHANG ◽  
Yasunaga MITSUYA ◽  
Kenji FUKUZAWA ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Energy ◽  
Ion Beam ◽  
Ion Beam Treatment ◽  
Cluster Ion ◽  
Gas Cluster Ion Beam ◽  
Glass Surfaces

Roughness Analysis of Episurfaces Grown on Ion-Beam Processed GaSb Substrates

2004 ◽  
Vol 829 ◽  
Author(s):  
K. Krishnaswami ◽  
D. B. Fenner ◽  
S. R. Vangala ◽  
C. Santeufemio ◽  
M. Grzesik ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Statistical Analysis ◽  
Ion Beam ◽  
Molecular Beam Epitaxial ◽  
Power Spectral ◽  
Sharp Point ◽  
Roughness Analysis ◽  
Cluster Ion ◽  
Gas Cluster Ion Beam ◽  
Substrate Surfaces

ABSTRACTHigh-quality GaSb substrates with minimal surface roughness and thin, uniform oxide layers are critical for developing low-power, epitaxy-based, electronic and optoelectronic devices. Ion-beam processing techniques of gas-cluster ion beam (GCIB) and bromine ion-beam assisted etching (Br-IBAE) were investigated as to their potential for improving the suitability of substrate surfaces for molecular beam epitaxial (MBE) growth. Statistical analysis of the residual surface roughness provides insight into ion-beam processing and its impact on epitaxial growth. Images of episurfaces grown on chemical mechanical polished (CMP), Br-IBAE, and GCIB finished substrates were obtained using atomic force microscopy (AFM) and these were statistically analyzed to characterize their surface roughness properties. Autocorrelation analysis of the first two types of episurfaces showed a quick loss of correlation within ∼100 nm. The episurface with Br-IBAE also showed isotropic mound roughness with sharp point-like protrusions. The GCIB prepared episurfaces exhibited the formation of uniform step-terrace patterns with monatomic steps and wide terraces as indicated by the strong, long range (>0.5 μm) correlations. Statistical analysis of the GCIB episurfaces showed self-similar random fractal behavior over eight orders of magnitude in the power spectral density (PSD) with a fractal dimension of ∼2.5.

Cluster Ion Beam Process for Nanofabrication

2007 ◽  
Vol 1020 ◽  
Author(s):  
Isao Yamada ◽  
Noriaki Toyoda
Keyword(s):  
Ion Beam ◽  
Industrial Applications ◽  
Significant Events ◽  
Junction Formation ◽  
Cluster Ion Beams ◽  
Experimental Laboratory ◽  
Cluster Ion ◽  
Linear Effects ◽  
Gas Cluster Ion Beam ◽  
Cluster Beams

AbstractThis paper reviews gas cluster ion beam (GCIB) technology, including the generation of cluster beams, fundamental characteristics of cluster ion to solid surface interactions, emerging industrial applications, and identification of some of the significant events which occurred as the technology has evolved into what it is today. More than 20 years have passed since the author (I.Y) first began to explore feasibility of processing by gas cluster ion beams at the Ion Beam Engineering Experimental Laboratory of Kyoto University. Processes employing ions of gaseous material clusters comprised of a few hundred to many thousand atoms are now being developed into a new field of ion beam technology. Cluster-surface collisions produce important non-linear effects which are being applied to shallow junction formation, to etching and smoothing of semiconductors, metals, and dielectrics, to assisted formation of thin films with nano-scale accuracy, and to other surface modification applications.

Surface smoothing effects with reactive cluster ion beams

1998 ◽  
Vol 54 (1-3) ◽  
pp. 106-110 ◽  
Author(s):  
Noriaki Toyoda ◽  
Hiroaki Kitani ◽  
Norihisa Hagiwara ◽  
Jiro Matsuo ◽  
Isao Yamada
Keyword(s):  
Ion Beams ◽  
Surface Smoothing ◽  
Smoothing Effects ◽  
Cluster Ion Beams ◽  
Cluster Ion ◽  
Reactive Cluster

scholarly journals Dependence of Pin Surface Roughness for Friction Forces of Ultrathin Perfluoropolyether Lubricant Film on Magnetic Disks by Pin-on-Disk Test

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
H. Tani ◽  
Y. Mitsuya ◽  
T. Kitagawa ◽  
N. Tagawa
Keyword(s):  
Surface Roughness ◽  
Ion Beam ◽  
Lubricant Film ◽  
Friction Forces ◽  
Magnetic Disks ◽  
End Groups ◽  
Cluster Ion ◽  
Perfluoropolyether Lubricant ◽  
Gas Cluster Ion Beam ◽  
Pin On Disk

We fabricated supersmooth probes for use in pin-on-disk sliding tests by applying gas cluster ion beam irradiation to glass convex lenses. In the fabrication process, various changes were made to the irradiation conditions; these included one-step irradiation of Ar clusters or two-step irradiation of Ar and N2clusters, with or without Ar cluster-assisted tough carbon deposition prior to N2irradiation, and the application of various ion doses onto the surface. We successfully obtained probes with a centerline averaged surface roughness that ranged widely from 1.08 to 4.30 nm. Using these probes, we measured the friction forces exerted on magnetic disks coated with a molecularly thin lubricant film. Perfluoropolyether lubricant films with different numbers of hydroxyl end groups were compared, and our results indicated that the friction force increases as the surface roughness of the pin decreases and that increases as the number of hydroxyl end groups increases.

Gas Cluster Ion Beam Processing of GaSb and InSb Surfaces

2003 ◽  
Vol 792 ◽  
Author(s):  
K. Krishnaswami ◽  
S.R. Vangala ◽  
B. Krejca ◽  
L.P. Allen ◽  
C. Santeufemio ◽  
...  
Keyword(s):  
Oxide Layer ◽  
Molecular Beam ◽  
Ion Beam ◽  
Total Charge ◽  
Surface Smoothing ◽  
Average Roughness ◽  
Molecular Beam Epitaxial ◽  
Cluster Ion ◽  
Gas Cluster Ion Beam ◽  
A Charge

ABSTRACTGas Cluster Ion Beam (GCIB) processing has recently emerged as a novel surface smoothing technique to improve the finish of chemical-mechanical polished (CMP) GaSb (100) and InSb (111) wafers. This technique is capable of improving the smoothness CMP surfaces and simultaneously producing a thin desorbable oxide layer for molecular beam epitaxial growth. By implementing recipes with specific gas mixtures, cluster energy sequences, and doses, an engineered oxide can be produced. Using GaSb wafers with a high quality CMP finish, we have demonstrated surface smoothing of GaSb by reducing the average roughness from 2.8Å to 1.7Å using a dual energy CF4/O2-GCIB process with a total charge fluence of 4×1015ions/cm2. For the first time, a GCIB grown oxide layer that is comprised of mostly gallium oxides which desorbed at 530°C in our molecular beam epitaxy system is reported, after which GaSb/AlGaSb epilayers have been successfully grown. Using InSb, we successfully demonstrated substrate smoothing by reducing the average roughness from 2.5Å to 1.6Å using a triple energy O2-GCIB process with a charge fluence 9×1015ions/cm2. In order to further demonstrate the ability of GCIB to smooth InSb surfaces, sharp ∼900nm high tips have been formed on a poorly mechanically polished InSb (111)A wafer and subsequently reduced to a height of ∼100nm, an improvement by a factor of eight, using a triple energy SF6/O2-GCIB process with a total charge fluence of 6×1016ions/cm3.

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