Topography control of plated wire memory elements

The paper deals with the control of substrate topography to achieve the magnetic properties necessary for electroplated wire memory elements. A number of surface preparation techniques have been studied using control of the plating variables of deposited copper films. Scanning electron microscopy has made possible quantitative measurements of some of the surface topographies. It is shown that the domain wall coercive force of Permalloy films is related to the film thickness by an inverse 4/3 power law providing the films were above 2000 Å in thickness. Measurements made of the coercive force for constant thickness Permalloy films as a function of surface roughness showed that it is related to the frequency and amplitude of nodular growths and that there is a maximum at a particular nodular frequency. Using the data obtained, a choice of substrate and film thickness can be made to match the requirements of a particular memory element.