Toward a single-mask processing of ion-implanted bubble devices

Essential fabrication steps have been developed for ion-implanted bubble devices using only one mask. The previously used three level masking was reduced to one level. During the optical photolithography process, the sensor level is underexposed whereas the conductors and ion implantation patterns are fully exposed. After the first development, conductors and ion implantation patterns are electroplated, while the sensors are fabricated after the second development. Bubble propagation data taken on chips fabricated by this process show essentially the same bias-field margins as obtained in samples made by the conventional multilevel lithograhy. Step-by-step description of the process is presented.