The "millipede"-nanotechnology entering data storage

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We present a new scanning-probe-based data-storage concept called the "millipede" that combines ultrahigh density, terabit capacity, small form factor, and high data rate. Ultrahigh storage density has been demonstrated by a new thermomechanical local-probe technique to store, read back, and erase data in very thin polymer films. With this new technique, nanometer-sized bit indentations and pitch sizes have been made by a single cantilever/tip into thin polymer layers, resulting in a data storage densities of up to 1 Tb/in 2. High data rates are achieved by parallel operation of large two-dimensional (2-D) atomic force microscope (AFM) arrays that have been batch-fabricated by silicon surface-micromachining techniques. The very large-scale integration (VLSI) of micro/nanomechanical devices (cantilevers/tips) on a single chip leads to the largest and densest 2-D array of 32 × 32 (1024) AFM cantilevers with integrated write/read/erase storage functionality ever built. Time-multiplexed electronics control the functional storage cycles for parallel operation of the millipede array chip. Initial areal densities of 100-200 Gb/in 2 have been achieved with the 32 × 32 array chip, which has potential for further improvements. A complete prototype system demonstrating the basic millipede functions has been built, and an integrated five-axis scanner device used in this prototype is described in detail. For millipede storage applications the polymer medium plays a crucial role. Based on a systematic study of different polymers with varying glass-transition temperatures, the underlying physical mechanism of bit writing has been identified, allowing the correlation of polymer properties with millipede-relevant parameters. In addition, a novel erase mechanism has been established that exploits the metastable nature of written bits. © 2002 IEEE.