Atom Probe Field Ion Microscopy Of Multilayer Thin Films

Abstract

Multilayer film (MLF) structures which exhibit giant-magnetoresistance (GMR) properties have applications in the areas of magnetic recording and computer memory. The magnetic properties of MLF structures are dependent upon structural and compositional variations at the atomic level. Thus, structural characterization with high spatial resolution, especially at layer interfaces, is important in order to optimize device performance with respect to processing and operating conditions. Atom probe field ion microscopy (APFIM) is one technique that has the capability to characterize the local structure and composition of MLF devices with sufficiently high resolution. However, a major difficulty has been successful specimen preparation from MLF materials, which requires fabrication of a sharply pointed needle (radius <50 nm) containing the layers of interest in the apex region. Research on specialized field ion specimen preparation techniques which use focused ion beam milling has recently enabled nanoscale MLF structures to be investigated. In the present paper, the application of atom probe microanalysis to two different MLF structures is presented.