RECENT DEVELOPMENT IN MAGNETIC-BUBBLE MEMORY

Improvements in bubble materials, processing, and chip design, especially permalloy tracks, have led 4-Mb magnetic-bubble memory to devices which are now commercially available. Conventional permalloy tracks are, however, not suitable for devices with higher bit density because they require a large driving field. To overcome this problem, ion-implanted tracks have been developed. Physics of ion-implantation in garnets and the ion-implanted tracks have been studied. The ion-implanted devices have been developed as 16-Mb hybrid devices. The ion-implanted bubble technology is promising for 64-Mb devices in the near future. In packaging, innovative development has been done. PFC (Picture Frame Core) packages reduce device size drastically. In the future, the Bloch line memory--an ultrahigh-density memory--will be developed, based on bubble memory technology. These technologies are reviewed in detail.