Tai-Chin Lo and Miu-Ying Chan “Downsiting bald Wires to Submirron Range: A Self-Planorited Au Metallization Process by Selective Electroplating Fas: LSI Applications” Jasbulge Journal of Applied Physics; vol. 34, 1995, Part 2, No. 78, pp L945–L947, Jul. 15, 1995. “X-ray lithography atr 100A linewidths using X-ray masks fabricated by shadowing techniques' D.C. Flanders, Journal of Vacuum Science and Technology, 16(6), Nov./Dec. 1979 pp. 1615–1619. “Features of gold having micrometer to centimeter can be formed through a combination of Stamping with an elasto meric Stamp and on alkanethiel ink followed by chemical etching Amit Kumar & George M. Whitesides, Applied Physics Letters 63(14), Oct. 4, 1993 pp 2002–2004. “Fabrication of large arrays of metallic nanowires on v-grooved substrates' J. Jorritsma, M.A.M Gijs, C. Schouenberger, and J.G.H Stienen, Applied Physics Letters 67(10), Sep. 4, 1995 pp 1489–1491.

Magnetic island arrays with a period of 50nm and uniform over 20×20μm2 have been fabricated by depositing Co∕Pd multilayer films on prepatterned SiOx pillars produced by extreme ultraviolet interference lithography. Scanning electron microscopy and magnetic force microscopy measurements made on the same islands give a direct, island-by-island comparison of the size and remanent switching field. The results demonstrate that the switching field distribution (SFD) is not primarily due to magnetostatic interactions, and a strong dependence of SFD on size is also not observed, indicating that a distribution of material properties is likely to be responsible for the SFD.

A flexible imprinter can be used to accommodate substrate or template roughness in nanoimprint lithography. The contact mechanics of a multi-layer imprinter incorporating bending and local deformation is described. With the right combination of dimensions, moduli, and viscosity, the imprinter can transfer a pattern evenly to a non-flat substrate. These concepts have been used to pattern magnetic media for high density information storage.

Physical properties, such as soil moisture, magnetic susceptibility and electrical conductivity (EC) are sources of signal interference for many landmine detectors. Soil EC mechanisms and their relationship to moisture are being studied to increase the soil EC prediction accuracy by radar remote sensing, airborne and ground electromagnetic (EM) methods. This is required for effective detection operations in problematic regions of the world. Results indicate that responses of free water and bound water to drying rates and EC are very different, to the extent that moist clay-poor soil may have lower EC compared to dryer clay-rich soil at certain moisture contents. These suggest that soil EC prediction should start with analyses of radar remote sensing data acquired on separate days, followed by high frequency airborne EM surveys, and validation by ground EM surveys and laboratory soil sample analyses. Due to the various expertise required, a team of relevant experts (e.g., geology, geophysics, remote sensing, petrophysics, agriculture, soil physics, electrical engineering and demining) should be organized to provide information on detector viability for demining in problematic areas in the world. It is also proposed to develop wide frequency band EM systems to provide much of the required information in one measurement.

Magnetically isolated single domain islands with perpendicular anisotropy have been prepared by depositing Co/Pd multilayer films on prepatterned sub-50 nm SiO2/Si islands. The island arrays were fabricated by both direct write electron beam lithography and nanoimprinting. Nanoimprinting allows the creation of large area, 4 mm×4 mm, samples appropriate for characterization by conventional measurement techniques. Magnetic force microscopy and vibrating sample magnetometry showed that the reversal behavior of the patterned islands is quite different from that of the continuous films with a large increase in both switching field and switching field distribution. Recording on island arrays with a periodicity of 100 nm, produced from prepatterned substrates, was demonstrated using a quasistatic tester.

Isolated tracks of single-domain magnetic islands have been fabricated using focused ion beam lithography. Islands were fabricated in thin films having either perpendicular or longitudinal magnetic anisotropy, and in both cases writing and reading of individual islands was demonstrated using a static write/read tester. Additionally, we have investigated the synchronization requirements (write margin) needed for writing the different flavors of patterned media. We have found that the write margin is strongly dependent on the switching field distribution of the islands and on the head field gradient. In the presented study, the write margin is much larger for the longitudinal patterned media than for perpendicular patterned media.

Magnetic patterns were created by locally altering the magnetic coercivity of a perpendicular anisotropy film by ion irradiation. The resulting pattern, after dc magnetizing, consists of regions having alternating up/down magnetization patterns in remanence. In this case, the magnetization of the soft magnetic material in the exposed segments is reversed and stabilized by the demagnetization fields of the adjacent unexposed media. A magnetic pattern generated in this manner can be used as a type of servo pattern for recording head positioning. An accuracy in positioning of better than 10 nm was demonstrated and deliberate magnetic patterns were written and read back by addressing individual 80 nm single-domain nanostructures.

Summary form only given. Co/sub 70/Cr/sub 18/Pt/sub 12/ perpendicular media has been patterned using a focussed beam of Ga/sup +/ ions (FIB) into arrays of sub -100nm islands suitable for demonstrating high density recording. The islands show single domain behaviour below a critical size, which in this case is approximately 110nm. In order to characterise the change to the magnetic properties introduced by FIB patterning, we have measured reversal properties including switching field distributions and thermal decay rates by magnetic force microscopy (MFM) imaging and Kerr rotation. The MFM was used to measure small arrays of islands by counting reversed islands at remanence as a function of reverse field or decay time. The Kerr measurements were averaged over larger arrays using a /spl sim/20/spl mu/m focussed laser beam. As a comparison unpatterned media was measured both using Kerr rotation and vibrating sample magnetometer (VSM).

A nanomolding process for producing 55-nm-diameter magnetic islands over 3-cm-wide areas is described. A master pattern of SiO2 pillars is used to form a polymeric mold, which is in turn used to mold a photopolymer resist film. This latter film is used as a resist for etching SiO2, yielding a pattern of pillars. Finally, an 11-nm-CoPt multilayer is deposited. Magnetic force microscopy reveals that the film on top of each pillar is a magnetically isolated single domain that switches independently.

Patterned magnetic media, where the bit cells are predefined, offer a potential path to ultrahigh density data storage. Here we report results on the magnetic and recording properties of islands with lateral dimensions on the order of 80 nm. Prototype nanometer-scale magnetic structures were made by patterning single-layer Co70Cr18Pt12 perpendicular media using a focused ion beam of Ga+. The effects of patterning were investigated by comparing patterned and unpatterned regions of the same medium. The magnetic reversal properties of the patterned media were obtained from magnetic force microscopy images, while those for the unpatterned media were obtained from vibrating sample magnetometer measurements. At remanence the unpatterned region decays at 1.4% per decade, whereas the patterned region shows no measurable change over the course of the experiment (5×105 s). We have also studied aspects of the recording physics of patterned media using a quasistatic write/read tester with a giant magnetoresistance head. We have written a square wave bit pattern that matches the respective island periodicity and investigated the readback signal for out-of-phase and in-phase writing.

A lithographically patterned magnetic medium is one of the proposed routes to magnetic recording at a density beyond that thought to be possible using conventional recording media due to thermal instability caused by superparamagnetism. Using a focused ion beam to pattern a granular Co/sub 70/Cr/sub 18/Pt/sub 12/ film, we have fabricated sub-80-nm size islands that are single domain and with a narrowed switching field distribution and an enhanced thermal stability. Magnetic isolation of the islands is shown to be a result of vanishing of magnetic remanence and coercivity in the irradiated region and not a result of sputtering. Recording measurements using a quasi-static giant magnetoresistive head demonstrate the sensitivity to detect single 80-nm islands. The readback jitter from the patterned region is dramatically reduced compared to that measured for continuous media at the same linear density.

Electromagnetic (EM: Magnetic Susceptibility [MS], Electrical Conductivity) and soil texture characteristics were determined for a Cambodian soil from an area where landmine detection interference has been experienced., The purpose was to collect information for developing techniques to discriminate between EM signals from small metallic particles in landmines and from iron-oxides or ferromagnetic mineral grains in soil. Ferromagnetic minerals are iron-oxides with strong MS characteristics. Results indicate that this soil consisted of four textural components: clasts (2-10 mm), medium-coarse-sand (<2.0 mm), fine-sand (<0.25 mm) and clay-silt (<0.063 mm). The coarse-sand had high MS values (similar to550x10(-8) SI/kg) due to high ferromagnetic mineral content (similar to20 wt.%). Some large rounded clasts, however, had considerably higher MS values (similar to11000x10(-8) SI/kg) due to high ferromagnetic mineral concentrations (30-60 wt.%), a likely source of significant landmine detection interference. The finer components had smaller MS values and iron-oxide contents. Complex electrical conductivity (1-10(6) Hz) of iron-oxides showed significant frequency dependence due to capacitance effects of electrochemical double layers on their surfaces in contact with soil moisture. This frequency dependence of iron-oxides may provide opportunities for potential EM system's design to discriminate between soil and landmine responses.

The limits to scaling the relevant physical dimensions required to increase the areal density of magnetic storage devices will be reached soon, if the storage density continues to double annually. Two approaches to overcoming the limit of the minimum particle size required for thermal stability are presented. In the first approach, a narrow particle size distribution is produced using self-assembled layers of magnetic Fe–Pt nanoparticles. The very narrow particle size distribution offers the potential for increased storage density by utilizing a smaller mean particle size and ultimately storage of one bit per individual nanoparticle. The second approach involves patterned magnetic Co–Cr–Pt nanostructures produced using a focused ion beam, which offers the possibility of single bit per island storage on thermally stable sub-100-nm islands.

Isolated tracks of magnetic single-domain islands have been fabricated by patterning perpendicular Co70Cr18Pt12 continuous films using focused-ion-beam lithography, reaching areal densities as high as ∼200 Gbit/in2. We demonstrate writing and reading of individual islands using a quasistatic write/read tester. We present results on transition position jitter and signal-to-noise ratio (SNR) for patterned media and compare them with those on equivalent unpatterned strips of the media. We observe that patterning dramatically reduces jitter and improves SNR, which is independent of track width. Moreover, the synchronization requirements needed for writing bits in patterned media was investigated on a single row of islands revealing a significant “write window,” where islands can be written correctly, of about half the island period.

We have written and read bit patterns on arrays of square islands cut with a focused ion beam into granular perpendicular magnetic recording media. Using a static write–read tester, we have written square-wave bit patterns on arrays of islands with sizes between 60 and 230 nm, matching the recording linear density to the pattern period. These measurements reveal the onset of single-domain behavior for islands smaller than 130 nm, in agreement with magnetic force microscope images. The recording performance of patterned regions is systematically compared to that of unpatterned regions.

Electron beam evaporated Co/Pt multilayers {[Co(tCo nm)/Pt(1 nm)]10, 0.2250 °C show fine-grained MFM features on the sub-100-nm length scale indicating reversal dominated by localized switching of small clusters. High-resolution cross-sectional transmission electron microscopy (TEM) with elemental analysis shows columnar grains extending throughout the multilayer stack. Co depletion and structural defects at the grain boundaries provide a mechanism for exchange decoupling of adjacent grains, which may result in the high coercivities observed.