Analysis and reduction of conductor stress in magnetic bubble memory devices
Hiroshi Umezaki, Seiichi Isomae, Tomohiko Sato, Takashi Toyooka, Ryō Suzuki · Journal of Vacuum Science & Technology A Vacuum Surfaces and Films · 1990
Stress from the overlay conductor patterns in ion-implanted magnetic bubble memory devices has been investigated using computer simulations (Boundary Element Method). In the case of the conventional SiO2 spacer which lays under the conductors, the concentrated stress at the edge of the conductors is transferred to the garnet directly. In order to reduce the stress, an elastically ‘‘soft’’ material, such as polyimide, was introduced as the spacer. The simulation shows that the stress under the polyimide spacer is reduced to about 1/3 of that under the SiO2 spacer. This is caused both by the internal stress relaxation in the conductors themselves and by the stress dispersion effect of polyimide. The devices with the polyimide spacer were evaluated and showed no influence of the conductor stress.