Using innovative nanotechnology, IBM scientists have demonstrated a data storage density of a trillion bits per square inch -- 20 times higher than the densest magnetic storage available today. Rather than using traditional magnetic or electronic means to store data, Millipede uses thousands of nano-sharp tips to punch indentations representing individual bits into a thin plastic film. The result is akin to a nanotech version of the venerable data processing punch card developed more than 110 years ago, but with two crucial differences: the Millipede technology is re-writeable (meaning it can be used over and over again), and may be able to store more than 3 billion bits of data in the space occupied by just hole in a standard punch card. While flash memory is not expected to surpass 1-2 gigabytes of capacity in the near term, Millipede technology could pack 10 - 15 gigabytes of data into the same tiny format, without requiring more power for device operation. The Millipede project could bring tremendous data capacity to mobile devices such as personal digital assistants, cellular phones, and multifunctional watches. In addition, we are also exploring the use of this concept in a variety of other applications, such as large-area microscopic imaging, nanoscale lithography or atomic and molecular manipulation.
INTRODUCTION
Today data storage is dominated by the use of magnetic disks. Storage densities of about more than 5 Gb/cm 2 have been achieved. In the past 40 years areal density has increased by 6 orders of magnitude. But there is a physical limit. It has been predicted that super paramagnetic effects- the bit size at which stored information become volatile as a function of time- will limit the densities of current longitudinal recording media to about 15.5 Gb/cm 2 . In the near future century nanometer scale will presumably pervade the field of data storage. In magnetic storage used today, there is no clear-cut way to achieve the nanometer scale in all three dimensions. So new techniques like holographic memory and probe based data storage are emerging. If an emerging technology is to be considered as a serious candidate to replace an existing technology, it should offer long-term perspectives. Any new technology with better areal density than today's magnetic storage should have long-term potential for further scaling, desirably down to nanometer or even atomic scale. The only available tool known today that is simple and yet offer these long-term perspectives is a nanometer-sharp tip like in atomic force microscope (AFM) and scanning tunneling microscope (STM). The simple tip is a very reliable tool that concentrates on one functionality: the ultimate local confinement of interaction. In local probe based data storage we have a cantilever that has a very small tip at its end. Small indentations are made in a polymer medium laid over a silicon substrate. These indentations serve as data storage locations. A single AFM operates best on the microsecond time scale. Conventional magnetic storage, however, operates at best on the nanosecond time scale, making it clear that AFM data rates have to be improved by at least three orders of magnitude to be competitive with current and future magnetic recording. The "millipede" concept is a new approach for storing data at high speed and with an ultrahigh density.

"Millipede" is a new (AFM)-based data storage concept that has a potentially ultrahigh density, terabit capacity, small form factor, and high data rate. Its potential for ultrahigh storage density has been demonstrated by a new thermomechanical local-probe technique to store and read back data in very thin polymer films. With this new technique, 3040-nm-sized bit indentations of similar pitch size have been made by a single cantilever/tip in a thin (50-nm) polymethylmethacrylate (PMMA) layer, resulting in a data storage density of 400500 Gb/in.2
High data rates are achieved by parallel operation of large two-dimensional (2D) AFM arrays that have been batch-fabricated by silicon surface-nMcromachining techniques. The very large scale integration (VLSI) of micro/nanomechanical devices (cantilevers/tips) on a single chip leads to the largest and densest 2D array of 32 x 32 (1024) AFM cantilevers with integrated write/read storage functionality ever built. Initial areal densities of 100200 Gb/in.2 have been achieved with the 32 x 32 array chip, which has potential for further improvements.
In addition to data storage in polymers or other media, and not excluding magnetics, we envision areas in nanoscale science and technology such as lithography, high-speed/large-scale imaging, molecular and atomic manipulation, and many others in which Millipede may open up new perspectives and opportunities.

INTRODUCTION
In the 21st century, the nanometer will very likely play a role similar to the one played by the micrometer in the 20th century. The nanometer scale will presumably pervade the field of data storage. Within a few years, however, magnetic storage technology will arrive at a stage of its exciting and successful evolution at which fundamental changes are likely to occur when current storage technology hits the superparamagnetic limit.
In any case, an emerging technology being considered as a serious candidate to replace an existing but the technology must offer long-term perspectives. The only available tool known today that is simple and yet provides these very long-term perspectives is a nanometer sharp tip. Such tips are now used in every atomic force microscope (AFM) and scanning tunneling microscope (STM) for imaging and structuring down to the atomic scale.
The objectives of our research activities within the Micro- and Nanomechanics Project at the IBM Zurich Research Laboratory are to explore highly parallel AFM data storage with areal storage densities far beyond the expected superparamagnetic limit (60100 Gb/in.2) and data rates comparable to those of today's magnetic recording. The "Millipede" concept presented here is a new approach for storing data at high speed and with an ultrahigh density. Our current effort is focused on demonstrating the Millipede concept with areal densities up to 500 Gb/in.2 and parallel operation of very large 2D (32 x 32) AFM cantilever arrays with integrated tips and write/read storage functionality.
MILLIPEDE CONCEPT
"Millipede" is based on a mechanical parallel x/y scanning of either the entire cantilever array chip or the storage medium. In addition, a feedback-controlled z-approaching and -leveling scheme brings the entire cantilever array chip into contact with the storage medium. This tip, medium contact is maintained and controlled while x/y scanning is performed for write/read. It is important to note that the Millipede approach is not based on individual z-feedback for each cantilever; rather, it uses a feedback control for the entire chip, which greatly simplifies the system. However, this requires stringent control and uniformity of tip height and cantilever bending. Chip approach and leveling make use of four integrated approaching cantilever sensors in the corners of the array chip to control the approach of the chip to the storage medium. Signals from three sensors (the fourth being a spare) provide feedback signals to adjust three magnetic z-actuators until the three approaching sensors are in contact with the medium. The three sensors with the individual feedback loop maintain the chip leveled and in contact with the surface while x/y scanning is performed for write/read operations. The system is thus leveled in a manner similar to an antivibration air table. This basic concept of the entire chip approach/leveling has been tested and demonstrated for the first time by parallel imaging with a 5 * 5 array chip. These parallel imaging results have shown that all 25 cantilever tips have approached the substrate within less than 1 um of z-activation. This promising result has led us to believe that chips with a tip-apex height control of less than 500 nm are feasible. This stringent requirement for tip-apex uniformity over the entire chip is a consequence of the uniform force needed to minimize or eliminate tip and medium wear due to large force variations resulting from large tip-height nonuniformities.

Millipede is storage technology developed by IBM.

Millipede is a non-volatile computer memory stored on nanoscopic pits.

It promises a data density of more than 1 terabit per square inch (1 gigabit per square millimeter), about 4 times the density of magnetic storage available today.

Millipede storage technology is being pursued as a potential replacement for magnetic recording in hard drives, at the same time reducing the form-factor to that of Flash media.


IBM says flash memory probably won't surpass 1GB to 2GB of capacity in the near term, but Millipede technology could pack 10GB to 15GB of data into the same small format without requiring additional power for device operation.

Working procedure:
Thousands of extremely fine tips "write" tiny pits representing individual bits into a thin film of highly specific polymer.
Bits are written by heating the tip to a temperature above the glass transition temperature of the polymer by means of the heating resistor integrated in the cantilever.
The principle is comparable with the old punch cards, but now with structural dimensions in the nanometer scale and the ability to erase data and rewrite the medium.