Scanning Probes Entering Data Storage: From Promise to Reality

Micro-electro-mechanical-system (MEMS)-based scanning-probe data storage devices are emerging as ultra-high-density, low-access-time, and low-power alternatives to conventional data storage. The probe-storage technique explored at IBM utilizes AFM probes and thermomechanical means to store and retrieve information in thin polymer films. High data rates are achieved by parallel operation of large 2D arrays with thousands of micro/nanomechanical cantilevers/tips that can be batch-fabricated by silicon surface micromachining techniques. The very high precision required to navigate the probe-tips over the storage medium is achieved by MEMS-based x/y actuators that position the large arrays of probe tips for parallel write/read/erase operations. For thermomechanical scanning-probe storage the polymer medium plays a crucial role. Based on a systematic study of different polymers it has been identified that the glass-transition temperature is the most important property that needs to be controlled for indentation writing and erasing at very narrow spacing. A prototype system demonstrating all the basic functions of a storage device based on scanning probes has been built and its main building blocks will be described in this paper. The inherent parallelism, the ultrahigh areal densities and the small form factor that probe storage techniques offer may open up new perspectives and opportunities for application in areas beyond those envisaged today.