Bubble material and device effects associated with an aluminum copper metal layer - Garnet film interface

The planar top down process reported by Bullock et. al. [1] for the fabrication of 1Mbit/cm
²
bubble memory devices [2] uses no spacer between the garnet surface and the AlCu metallization layer. The presence of this metal-garnet interface does not alter the magnetic properties of the epitaxial film and does result in a favorable reduction in generate current amplitudes. During the time-temperature cycles of the bubble device fabrication sequence, the changes in anisotropy, static coercivity, and the dynamic properties of films with this AlCu interface do not differ from observed changes in the material parameters of films having a first oxide buffer layer. Generate current threshold amplitudes are reduced by 30% when the spacer layer is removed. Successive temperature anneals at 375°C, the maximum temperature in planar process, decrease the generate current threshold value. This effect is identified with a reduction reaction which removes O
2
from the garnet surface at the film - AlCu interface.