Rapid-turnaround characterization methods for MRAM development

Magnetic random access memory (MRAM) technology, based on the use of magnetic tunnel junctions (MTJs), holds the promise of improving on the capabilities of existing charge-based memories by offering the combination of nonvolatility, speed, and density in a single technology. In this paper we review rapid-turnaround methods which have been developed or applied in new ways to characterize MRAM chips at various stages during processing, with particular emphasis on the MTJs. The methods include current-in-plane tunneling (CIPT), Kerr magnetometry, vibrating sample magnetometry (VSM), and conducting atomic force microscopy (CAFM). Use of the methods has enabled rapid learning with respect to the materials used for the MTJs, as well as tuning of the MTJ geometry in terms of size and shape and of the patterning methods employed. Examples of the use of each of the methods are presented along with interpretation of the data via critical operating parameters.