High density data storage based on the atomic force microscope

Summary form only given. The atomic force microscope (AFM) uses a sharp tip on the end of a micromachined cantilever to image surfaces at the nm scale. Such structures can be batch fabricated, with tip radii below 100 Å. The simplicity and high resolution of the technique have led to interest in its possible use as the basis for a high density data storage device. We have explored one approach to AFM-based storage based on mechanical readback of topographic data. To this end, we have fabricated low-mass Si cantilevers with integrated piezoresistive sensors. Integrating the sensor on the cantilever allows for very compact implementation. By reducing the cantilever mass, we have reduced the mechanical response time to as low as 90 ns. This corresponds to data rates of at least 10 Mb/s, comparable to that of the DVD. We have developed these cantilevers for both read-only applications and write-once applications. For read-only applications, electron beam lithography was used to create a master disk, which is then replicated using a stamping process into a photopolymer. Densities of 65 Gb/in², or 100× that of CDs, were achieved. To write, the tip is heated through an integrated resistive heater. The tip then softens and deforms the polymer material under it, creating a pit. Beyond demonstrating the basic techniques, considerable progress has been made in addressing critical issues such as data rate, reliability, and practical implementation. Significant challenges still remain, both in overcoming technical hurdles, and in finding applications that are well suited to the characteristics of such a device