High-density data storage based on the atomic force microscope

The atomic force microscope (AFM), with its ability to image and modify surfaces on the nanometer scale, offers the potential for simple, compact, high-density data-storage devices. At the heart of the technique is a microfabricated cantilever with a sharp tip on the end. Using modern micromachining techniques, it is possible to batch fabricate cantilevers with tips that are sharp on the scale of 100 angstrom. We have pursued a particular AFM storage scheme based on mechanical readback of topographic data using high-frequency, piezoresistive silicon cantilevers. Areal densities of 65 Gbit/in2 have been demonstrated, with readback rates greater than 10 Mbit/s. Nanoreplication techniques have been used to produce read-only disks. In addition, a write-once scheme was developed that uses integrated heating elements on the cantilevers in order to perform thermomechanical writing on a polymer substrate. Considerable progress has been made in addressing critical issues such as data rate, reliability, and practical implementation, but significant challenges still remain, both in the technology and in finding the most suitable applications.