Effects of conductor passivation on bubble propagation in contiguous disk devices

Abstract

The present work investigated the impact of conductor passivation on 1 μm bubble propagation in contiguous disk devices. Without conductor passivation, devices with overlying AlCu stripes showed good propagation margins. When the devices were passivated with a thick layer of SiO2, the elastically "hard" dielectric material imposes a constraint to AlCu deformation and increases the conductor edge force. Furthermore, the edge force of the SiO2 passivation at the conductor edges, being in the same sign as that of the AlCu stripe, contributes to the total force acting on the underlying garnet. This intensifies the lcoal stress fields in the magnetic devices and seriously reduces the bubble propagation margin. To alleviate this passivation-enhanced stress problem, contiguous disk devices were passivated by elastically "soft" polyimide instead of sputtered SiO2.