Large capacity ion-implanted bubble devices

Half-megabit bubble memory chips, with patterned ion implants used to propagate bubbles, have been designed and characterized. Bubbles with 1.7-μm diameter were used on a 6-μm to 8-μm circuit period and were propagated by rotating fields of 40 Oe at 50 kHz. The chips had 284 2051-bit storage loops, of which 258 were required to operate. Overall bias field margin ranges of 16 Oe to 19 Oe have been demonstrated on functionally complete, nonvolatile chips with nondestructive readout. Most functional parameters have wide margin ranges, but further design improvements are necessary to widen the margin ranges of the drive field and the transfer-out trailing edge phase.