A Pre-Embossed Rigid Magnetic (PERM) disk technology has recently been developed and has demonstrated track densities in excess of 5000 TPI. This new technology uses a stamping process (from CD technology) to imprint the desired patterns on plastic substrates. This-film magnetic layers are sputtered over the patterned surface of the pre-embossed substrate. Since the magnetic layer has no discontinuities, a two-step magnetization process is required to differentiate elevated layer magnetization from recessed regions in servo zones. Physical properties of the disk, including runout amplitude (<20μm), warp (<10μm), and glide height (40nm), are within acceptable tolerances.

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A Pre-Embossed Rigid Magnetic (PERM) disk technology has recently been developed and has demonstrated track densities in excess of 5000 TPI. This new technology uses a stamping process (from CD technology) to imprint the desired patterns on plastic substrates. This-film magnetic layers are sputtered over the patterned surface of the pre-embossed substrate. Since the magnetic layer has no discontinuities, a two-step magnetization process is required to differentiate elevated layer magnetization from recessed regions in servo zones. Physical properties of the disk, including runout amplitude (<20μm), warp (<10μm), and glide height (40nm), are within acceptable tolerances.

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The solid state file is surveyed to show its potential application in hand-held computers and computers intended for use in rugged conditions. NAND-type flash EEPROMs have several advantages over NOR-type flash EEPROMs as components of a solid state file. These include a capability for write operations to two thousand cells at a time, a short erase cycle time, and a large write/erase cycle limit. A solid state file prototype has been developed with control algorithms for dynamic sector allocation, background garbage collection, and erase count monitoring and leveling. It has a higher speed performance than 2.5-inch hard disks.

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This paper reports on a new type head scanning mechanism we have contrived for ultra thin tape. The mechanism generates helical tracks on the tape by moving rotating heads perpendicularly to the tape run direction. Since this on transports using the mechanism. We have performed a series of tests using heads with a 20-micron track width, which has proved that the new mechanism will possibly help in realizing a more compact, larger-capacity recording system for Hi-Vision or digital VTRs.

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Several configurations and preparation methods of perpendicular magnetic recording tape media have been proposed in this study. Co-Cr thin films with large saturation magnetization M_s and good c-axis orientation could be prepared by two step sputtcring method. The crystallinity of Co-Cr recording layer and Ni-Fe backlayer seemed to be important for perpendicular magnetic recording media with Co-Cr/Ni-Fe double layer. Two step sputtering method was also applicable to improve the crystallinity of not only Co-Cr layer but also Ni-Fe one. The Co-Cr underlayer as ultra-thin as 100Å was very helpful for enhancing the c-axis orientation of Co-Cr crystallites and <111> orientation of Ni-Fe ones. The multilayers composed of Ni-Fe and ultra-thin Co-Cr layers revealed very soft magnetism and excellent <111> orientation for the Ni-Fe layers. These multilayers were properly effective for the hetero-epitaxial growth of Co-Cr recording layer deposited on them. In addition, Co-Zr-Ta amorphous alloy films were also proposed as the backlayer with large M_s and soft magnetic properties. Very thin Ti interlayer deposited of the Co-Cr layer was effective to improve the c-axis orientation of Co-Cr crystallites deposited on it. At last, Fe-Mo-B thin films also were proposed as the top coat and back coat layers with sufficient durability and electrical conductivity.

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Recently reported new approach for sputter-deposition ofCo-Cr media is reviewed. Sputtermg at high Ar pressures over 50Pa enabled low discharge voltages below 300V with high stability. Well oriented Co-Cr films with Δθ_<50> ofaround 5°which exhibit fine columnar structures with distinct grain boundaries could be obtained by the deposition on well oriented Ti underlayers even at extremely high Ar pressures. These microstructures may have some advantages for a high density recording media such as low noise characteristics.

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The effect of Ta addition in Co_<83>Cr_<17> base composition was studied to investigate the origin of an increase in the coercivity. For this purpose, the perpendicular magnetic anisotropy of Co-Cr and Co-Cr-Ta films was measured before and after annealing at 550℃. The Co_<81.4>Cr_<16.6>Ta_2 film showed larger perpendicular anisotropy than the Co_<81>Cr_<19> film in the as-sputtered states. However, after the anneal, perpendicular anisotropy value of the two specimens were almost the same. The cause of this was interpretated as the enhauced segregation of solute atoms in the Ta added film in the as-deposited state. The change of d-spacings for the (0002) plane with the Ta addition was also studied. The linear increase of d-spacing with increasing Ta addition suggests that Ta is randomly distributed rather than segregated. This result implicates that the coercivity increase with Ta addition is not due to Ta segregation but due to enhanced segregation of Cr.

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In order to develope new magnetic media with higher coercivity, we have investigated the magnetic properties of Co-P/Cr and Co-P-Cr/Cr films. The coercivity of Co-P binary films deposited at RT was around 835 Oe in the range of 9 - 12 at.% P. In the Co-P binary system coercivity decreased with increasing substrate temperature for P contents of 9 -12 at.%. However, the coercivity of the films containing more than 12 at.%. P is very low due to the formation of amorphous phase. The coercivity of Co-P-Cr ternary films increased with increasing Cr contents and reached the maximum value of 1020 Oe in the water cooled CO_<84>P_<10>Cr_6 film.

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Magnetic anisotropy in magnetron in-line sputter deposited Co-alloy thin film disks was studied. The amount of dispersion in magnetic properties determined by using a transfer curve magnetometer was 85 Oe in film coercivity, 0.15 emu/cm^2 in remanenee-thiekness product, and 0.03 in coercivity squareness within a disk. Angular variation in magnetic properties showed a sinusoidal curve with two maxima and minima, corresponding to two regions which are parallel and normal to the pallet movement, respectively. The micro-structural examination revealed Co-alloy grains locally elongated in the direction of pallet movement. It was shown from the present study that approximately 45 % of Co-alloy grains on Cr-underlayer have in-plane c-axis and the resultant c-axis vector component of grains orients to the texture groove direction.

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The distribution of the magnetic field and plasma diagnosis in the facing targets sputtering apparatus have been investigated and performed by using a gaussmeter and single probe method, respectively, and the field distribution was compared with calculated one by computer aided finite element method. Perpendicular line of force between target planes and extremely high magnetic field above target edge confined plasma almost perfectly and substrates could be placed in plasma-free region even for ferromagnetic targets. The measured radial field distribution at the central plane between two facing targets agreed well with calculated one. Parameters important for controlling distribution and strength of magnetic field in FTS system seemed to be distance between targets, target magnetism, performance of magnet and distance between target and magnet, in the order of influence degree. It was shown that the size of permanent magnets for confining plasma may influence the strength of magnetic field but may not do the distribution of magnetic flux.

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The Henkel plots are linearlized when the field compensating the interparticle interaction field is applied during measurements. Using this method, the mean field constant was investigated for longitudinally oriented Ba-ferrite media having the various squareness. The mean field was simulated by a geometrical arrangement of particles. The positive mean field was shown in a Ba-ferrite medium because the distance between particles placed in series to the magnetization direction is much shorter than in parallel. The mean field decreased as the particle orientation became broader because the location of magnetic particles changed. To consider the interparticle interaction in the recording simulation, the mean field was introduced into our simulator based on a FEM and the curling model. The reproducing voltage in low recording densities was increased by the positive mean field in a longitudinally oriented Ba-ferrite medium. In a perpendicularly oriented medium, the high density performance was extremely improved by the mean field.

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