Temperature effects on film memory drive current margins

Negligible reversible changes in magnetic properties of thin metallic films exhibiting high Curie temperatures are expected over normally encountered temperature ranges. However, irreversible changes of the magnetic properties of vacuum-deposited films have been observed when they are subjected to high magnetic fields at temperatures in the order of 100°C. A similar effect is also observed in some electroplated films at lower temperatures. This investigation attempts to determine the significance of these effects in vacuum-deposited planar films when operated in a practical memory. Reversible and irreversible temperature-induced changes of restore digit current and disturb digit current thresholds, IdRand IdD, respectively, due to pulsed word and digit fields, were measured experimentally for temperatures between 20°C and 135°C. The pulsed fields simulated typical operational word and digit fields. Average threshold variations are given and discussed. Data on average film output variations is also presented.