Fierce competition in the magnetic storage industry has focused on the reduction of device form factors. Disk-drive read heads use thin films whose surfaces - ideally atomically smooth - are exceptionally difficult to analyze. Interface attributes - roughness, composition chemistry, and impurities - are critical to performance. The Imago LEAP® Microscope enables engineers to better understand film structure, especially at materials interfaces, so film behaviors can be accurately characterized.

Further advances would require techniques to parameterize attributes such as:

• Interface roughness
• Amount and location of contaminants
• Thickness of buried films
• Stack stability
• Nano-oxide layers

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Disk-drive read heads are exceptionally difficult devices to analyze. The structure and composition of an aluminum oxide barrier [1] (widely used material for tunnel barriers) and the interfaces between the barrier and the ferromagnetic layers (Co, Ni, Fe, etc.) play a major role in determining the properties of devices that rely on the TMR effect. The dielectric oxide layer is the crucial component yet is only ~1 nm thick. Transmission electron microscopy (TEM) is often used to analyze these devices. A TEM image (as shown in Figure 1a) provides good information about the morphology of the oxide interface, but it is limited to two dimensions and is a projection through tens of nanometers of material so it does not truly represent the interface morphology on a nanometer scale. Atom probe tomography analysis of TMR structures provides the positions of the majority of the atoms in such a device with sub-nm resolution in all three dimensions as shown in Figure 1b. Using this data interface attributes such as roughness, composition and impurities, all critical to performance, can be quantified.

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