Improving fine striped memory magnetic properties

Evaporation, electroplating, and etching were used to develop high-density, high-speed, and low-cost fine striped memory (FSM) which is a planar film memory with completely closed digit line flux paths. The results of three important experiments on FSM and its development, structure, and production are described. Three conclusions have been obtained from the experiments. First, a 300-Åthick evaporated Permalloy undercoating is needed to improve the magnetic properties of the electroplated Permalloy. Second, a completely closed flux path assures full output and operating stability. Third, a flux keeper, which is applied to memory strips, and for which embedded word lines are apart from the strips, assures high signal-to-noise ratio and low driving current. An effective flux keeper has been used to make a high-density (5000 bit/cm²) memory.