Quasistatic Bubble Propagation in 1.5 μm Period Ion-Implanted Tracks for 64 Mbit Magnetic Bubble Memory Devices
Ion-implanted tracks with a 1.5 μm period for use in 64 Mbit magnetic bubble memory devices have been fabricated and operated. The bubble material used was (BiSmLu)3 (FeAl)5O12 garnet film, supporting 0.45 μm bubbles. The resist mask patterns for implantation were formed using a 1/10 reduction projection aligner, using rectangular patterns on a reticle. The bubble propagation tracks were fabricated by double deuterium implantation and annealed at 400°C for 30 minutes, with an SiO2 layer deposited on the garnet surface to stabilize the implanted layer. An operating bias field margin in excess of 7% was stably obtained in quasistatic bubble propagation. This shows that the ion-implanted devices have great potential for use in 64 Mbit magnetic bubble memory devices.
Hydrogen out‐diffusion suppression effect of overlayers in H+2 ‐implanted magnetic bubble garnet
Hydrogen out‐diffusion suppression effect of overlayer deposited on H+2 ‐implanted magnetic bubble garnet has been investigated using gas mass spectroscopy and secondary ion mass spectroscopy. It has been found that oxide films such as SiO2, SiO, TiO2, and Al2O3 or nitride film such as Si3N4 effectively suppress out‐diffusion of hydrogen during annealing, keeping a large anisotropy field change induced by hydrogen implantation after the annealing. Hydrogen depth profiles have also been found to have a sharp peak at the boundary between overlayer and garnet which can suppress out‐diffusion of hydrogen. Metal films such as Au, Mo, and Ni–Fe alloy have been found not to act as suppressors of hydrogen out‐diffusion. Annealing hydrogen‐implanted garnet with an oxide overlayer on the surface is useful for ion‐implanted bubble device fabrication because of thermal stability of large anisotropy change induced by implantation.
The Effectiveness of Two Approaches to the Teaching of High School American History
The purpose of this study was to test the effectiveness of studies in depth utilizing selected materials which had been developed for teaching high school American history.