Ion-Enhanced Dry Etching of Magnetic Multilayers: Post-Etch Cleaning and Effects of UV Illumination

1999 ◽  
Vol 585 ◽  
Author(s):  
H. Cho ◽  
K. P. Lee ◽  
K. B. Jung ◽  
F. Sharifi ◽  
J. Marburger ◽  
...  
Keyword(s):  
Sample Surface ◽  
Magnetic Multilayers ◽  
Magnetic Multilayer ◽  
Reaction Products ◽  
Ion Milling ◽  
Ion Density ◽  
Long Term Stability ◽  
Uv Illumination ◽  
Micron Size ◽  
Etch Rates

AbstractPatterning of magnetic multilayer structures of the type used for MRAMs (e.g. NiFeCo/CoFe/Cu/CoFe/NiFeCo) is generally performed with ion milling, but this can degrade the coercivity of small (micron-size) MRAM elements and lead to sidewall redeposition. In high ion density reactive plasmas (Cl2/Ar) it is possible to produce ion-enhanced desorption of otherwise involatile halogenated reaction products, and achieve practical etch rates (∼600 Å/min) for the multilayers. However, removal of the chlorinated etch products from the feature sidewalls is critically important to avoid corrosion. We have used de-ionized water rinsing or in-situ exposure to H2, O2 or SF6 plasmas for removal of these etch residues. Some slight degradation in magnetization was observed in O2 plasma treated structures, but the other cleaning procedures produced no change in magnetic properties and excellent long-term stability. UV illumination of the sample surface during etching is also found to enhance etch rates, as has been reported previously for room temperature etching of Cu.[1]

Transport Measurements of Magnetic Multilayers at Reduced Lateral Dimensions

1997 ◽  
Vol 475 ◽  
Author(s):  
Y.D. Park ◽  
H.D. Hudspeth ◽  
T.J. Schultz ◽  
A. Cabbibo ◽  
J. A. Caballero ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Contact Resistance ◽  
Applied Field ◽  
Magnetic Multilayers ◽  
Magnetic Multilayer ◽  
Ion Milling ◽  
Multilayer Systems ◽  
Absolute Value ◽  
Lift Off ◽  
Nano Wires

Abstract We report on the fabrication and transport properties of magnetic multilayers with widths down to 100 nm. We employ e-beam processed nano-deposition masks to pattern magnetic multilayers which define nano-wires by lift-off or by a removal process such as ion-milling. Two different magnetic multilayer systems (antiferromagnetically coupled Co/Cu multilayers and NiFe/Cu/Co spin-valves) are investigated. Structures resulting from the lift-off process show high contact resistance and high resistivities while ion-milled structures show resistivities close to that of bulk. For Fe(50Å)/[Co(15Å)/Cu(20Å)]x20 /Cu(30Å), patterned nano-wire structures display no negative magnetoresistance but a positive magnetoresistance that is linear with applied field and no apparent hysteresis. For Ta(50Å)/NiFe(50Å)/Cu(35Å)/Co(20Å)/Cu(30Å), we found the resistance to decrease as the absolute value of magnetic field is decreased and found hysteresis to be present.

Iodine-Based dry Etching Chemistries for InP and Related Compounds

1992 ◽  
Vol 282 ◽  
Author(s):  
S. J. Pearton ◽  
U. K. Chakrabarti ◽  
A. Katz ◽  
C. R. Abernathy ◽  
W. S. Hobson ◽  
...  
Keyword(s):  
Room Temperature ◽  
Dry Etching ◽  
Reaction Products ◽  
Ion Density ◽  
Sample Heating ◽  
Polymer Deposition ◽  
Etch Rates ◽  
Microwave Discharges ◽  
Related Compounds

ABSTRACTA comparison is given of the dry etching characteristics of InP and related materials in high ion density (>1011 cm−2 ) microwave discharges of HI, CH3I, C2H5I, C3H7I and C2H3I. The InIx species are more volatile than their InClx counterparts near room temperature and rapid etch rates can therefore be achieved without the need for sample heating. HI discharges provide faster etch rates than the halocarbon-based mixtures, but are more corrosive. All of these gas chemistries offer faster rates than conventional CH4/H2 mixtures. Halocarbon-iodide discharges still suffer from polymer deposition on the mask and within the reactor, as with CH4/H2. AES analysis shows an absence of contaminating residues with all of the iodine-based chemistries, and highly anisotropic features are obtained since the etching is driven by ion-enhanced desorption of the reaction products.

Comparison of Ion-Milling Techniques For Cross-Sectional TEM of Semiconductors

1985 ◽  
Vol 43 ◽  
pp. 166-167
Author(s):  
Julia T. Luck ◽  
C. W. Boggs ◽  
S. J. Pennycook
Keyword(s):  
Analytical Techniques ◽  
Sample Surface ◽  
Ion Milling ◽  
Cross Sectional ◽  
Reliable Technique ◽  
Near Surface ◽  
Transmission Electron ◽  
Thin Region ◽  
Transient Thermal

The use of cross-sectional Transmission Electron Microscopy (TEM) has become invaluable for the characterization of the near-surface regions of semiconductors following ion-implantation and/or transient thermal processing. A fast and reliable technique is required which produces a large thin region while preserving the original sample surface. New analytical techniques, particularly the direct imaging of dopant distributions, also require good thickness uniformity. Two methods of ion milling are commonly used, and are compared below. The older method involves milling with a single gun from each side in turn, whereas a newer method uses two guns to mill from both sides simultaneously.

scholarly journals Cross-sectional TEM Sample Preparation for Nanowires or Porous Films Grown on a Substrate

2007 ◽  
Vol 15 (1) ◽  
pp. 44-45
Author(s):  
Chengyu Song
Keyword(s):  
Low Temperature ◽  
Sample Preparation ◽  
Traditional Method ◽  
Sample Surface ◽  
Specimen Preparation ◽  
Air Bubbles ◽  
Ion Milling ◽  
Porous Films ◽  
Cross Sectional ◽  
Single Section

Nanowires or porous films grown on a substrate normally lack mechanical strength, and may be subject to damage during specimen preparation. When we made cross-sectional TEM specimen for this type of sample, we modified the traditional method by covering the sample with epoxy to improve the film strength, and applying single-section ion milling to protect the film from over-milling.The sample surface is first covered with G1 epoxy. We choose G1 for this application because it is relatively thick and cures at low temperature. For samples with a dense-growth of nanowires or a thick porous film, a brief moment in vacuum helps to get rid of the air bubbles in the epoxy. The glue is cured at 100 degree C for 10 minutes, until its color turns to a reddish brown. To remove the excess glue and flatten the surface, the sample is then ground and polished until the glue is less than 0.1 mm thick.

X-ray Probes of Magnetic Multilayer Structure

2000 ◽  
Vol 615 ◽  
Author(s):  
B.K. Tanner ◽  
T.P.A. Hase ◽  
B.D. Fulthorpe ◽  
J. Clarke ◽  
G.M. Luo ◽  
...  
Keyword(s):  
Local Environment ◽  
Grazing Incidence ◽  
Magnetic Multilayers ◽  
Anomalous Scattering ◽  
Magnetic Multilayer ◽  
Compositional Gradient ◽  
X Ray ◽  
Buried Interfaces ◽  
Out Of Plane ◽  
Roughness Amplitude

ABSTRACTWe discuss the application of x-ray scattering and fluorescence to the problem of unravelling the relationship between the structural and magnetic properties of magnetic multilayers. Particular attention is paid to the use of grazing incidence diffuse scatter to determine the compositional gradient, out-of-plane roughness amplitude, in-plane correlation length and fractal parameter of buried interfaces. Anomalous scattering provides information on the local environment of specific atoms and grazing incidence fluorescence is a depth -sensitive probe of chemical composition. We present examples indicating the sensitivity limits and the reproducibility of the techniques, all from multiple layer structures of magnetic metals.

Effects of ultraviolet illumination on dry etch rates of NiFe-based magnetic multilayers

2000 ◽  
Vol 18 (4) ◽  
pp. 1273-1277 ◽  
Author(s):  
H. Cho ◽  
K. P. Lee ◽  
Y. B. Hahn ◽  
E. S. Lambers ◽  
S. J. Pearton
Keyword(s):  
Magnetic Multilayers ◽  
Ultraviolet Illumination ◽  
Etch Rates ◽  
Dry Etch

Dry Etching of Sol-Gel Pzt

1998 ◽  
Vol 546 ◽  
Author(s):  
R. Zeto ◽  
B. Rod ◽  
M. Dubey ◽  
M. Ervin ◽  
J. Conrad ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Etch Rate ◽  
Sol Gel ◽  
Reactive Ion Etching ◽  
Dry Etching ◽  
Ion Milling ◽  
Ion Etching ◽  
Wide Range ◽  
Etch Rates ◽  
Argon Ion

AbstractTwo techniques for dry etching of sol-gel lead zirconate titanate (PZT 52/48) thin films were investigated: reactive ion etching and argon ion milling. Etched profiles were characterized by scanning electron microscopy. For reactive ion etching, a parallel plate etcher was used with HC2ClF4, an environmentally safe etch gas, in a process described by other researchers. Etch rates were measured and compared as a function of electrode shield material (ardel, graphite, alumina) and RF input power (100 to 500 W). These etch rates varied from 10 to 100 nm/min. Reactive ion etched sidewall angles 12° off normal were consistently produced over a wide range of RF powers and etch times, but overetching was required to produce a clean sidewall. For argon ion milling, a 300 mA/500 V beam 40° off normal to the substrate operating in a 72 mPa argon pressure was used. These ion milling conditions produced an etch rate of 250 nm/min with a sidewall slope angle of about 70°. The ion milling etch rate for sol-gel PZT was significantly faster than rates reported for bulk PZT. The 500 nm thick PZT films used in this study were prepared by the sol-gel process that used methoxyethanol solvent, spin coating on t/Ti/SiO2 silicon substrates, and rapid thermal annealing for 30 s at 650 °C for crystallization of the perovskite phase.

Effects of hyperthermal atomic oxygen on a cyanate ester and its carbon fiber-reinforced composite

2018 ◽  
Vol 31 (4) ◽  
pp. 472-482 ◽  
Author(s):  
Heilong Wang ◽  
Min Qian ◽  
Vanessa J Murray ◽  
Bohan Wu ◽  
Yang Yang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Surface Topography ◽  
Photoelectron Spectroscopy ◽  
Atomic Oxygen ◽  
Sample Surface ◽  
Low Earth Orbit ◽  
Cyanate Ester ◽  
Fiber Reinforced ◽  
Reaction Products ◽  
Carbon Fiber Reinforced

The durability of cyanate ester (CE) to hyperthermal atomic oxygen (AO) attack in low Earth orbit may be enhanced by the addition of carbon fiber to form a carbon fiber-reinforced cyanate ester composite (CFCE). To investigate the durability of CFCE relative to CE, samples were exposed to a pulsed hyperthermal AO beam in two distinct types of experiments. In one type of experiment, samples were exposed to the beam, with pre- and post-characterization of mass (microbalance), surface topography (scanning electron microscopy (SEM)), and surface chemistry (X-ray photoelectron spectroscopy (XPS)). In the second type of experiment, the beam was directed at a sample surface, and volatile products that scattered from the surface were detected in situ with the use of a rotatable mass spectrometer detector. CFCE exhibited less mass loss than pure CE with a given AO fluence, confirming that the incorporation of carbon fiber adds AO resistance to CE. Erosion yields of CE and CFCE were 2.63 ± 0.16 × 10−24 and 1.46 ± 0.08 × 10−24 cm3 O-atom−1, respectively. The reduced reactivity of CFCE in comparison to CE was manifested in less oxidation of the CFCE surface in XPS measurements and reduced CO, CO2, and OH reaction products in beam-surface scattering experiments. The surface topographical images collected by SEM implied different surface deterioration processes for CE and CFCE. A change of surface topography with increasing AO fluence for CE indicated a threshold AO fluence, above which the erosion mechanism changed qualitatively. CFCE showed almost intact carbon fibers after relatively low AO fluences, and while the fibers eventually eroded, they did not erode as rapidly as the CE component of the composite.

Transport Properties in All Oxide Magnetic Multilayers

2008 ◽  
Vol 587-588 ◽  
pp. 318-322
Author(s):  
H. Sobreiro ◽  
B. Berini ◽  
N. Keller ◽  
David S. Schmool
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
Molecular Beam ◽  
Magnetic Layer ◽  
Magnetic Multilayers ◽  
Magnetic Multilayer ◽  
Electrical Transport Properties ◽  
Appreciable Increase ◽  
Magnetic Layers ◽  
Laser Mbe

The all oxide magnetic multilayer system [LaNiO3/SmFeO3]n (for n = 1 and 2), grown on single crystal SrTiO3(100) substrates, has been produced using the laser MBE (Molecular Beam Epitaxy) technique. We have made a systematic study of the electrical transport properties in the temperature range from 15–300K. As part of this work, we have made a detailed study of the metallic properties of the LaNiO3 layer as a function of the oxygen partial pressure (pO2) and substrate temperature (TS). We have measured magnetic layers of SmFeO3 with LaNiO3 electrodes as a function of the magnetic layer thickness (10 – 470 nm). A non-metallic behaviour is observed with evidence of a “hopping” mechanism at low temperatures. For the n = 2 multilayers, we have measured the temperature dependence of resistance for the sample series with varying LaNiO3 interlayer thickness (t = 2 – 30 nm). We observe an appreciable increase of the low temperature resistance for the interlayer thicknesses between 3.75 – 7.5 nm. This could indicate a change in coupling from ferromagnetic to antiferromagnetic between the magnetic layers.

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