Among the most useful tools for nanotechnology are various scanning probe tips for surface modification. A few years ago, the IBM Millipede project demonstrated the use of an array of silicon cantilevers as a nanotech memory device (see Millipede comes out of the lab) that operates by making and erasing nanometer-scale marks. In Technology Review, Kevin Bullis describes another approach to computer memory based upon similar arrays of atomic force probe tips. A few excerpts from “Higher-Capacity Memory“:
An alternative to the flash memory that stores and retrieves data with arrays of microscopic probes could soon be on the market. Nanochip, a company based in Fremont, CA, has recently raised $14 million to complete work on prototypes that it hopes to ship to electronics device makers for evaluation next year.
Nanochip’s technology offers advantages to flash memory, both in terms of the amount of data that can be stored and the cost per memory chip, says Gordon Knight, the company’s CEO. The first prototypes will store about 100 gigabytes, he says—more than the tens of gigabytes stored on flash memory cards today. Eventually, the devices could store terabytes’ worth of data, he says. That’s likely out of the reach of flash-type memory, says Stefan Lai, formerly the director of flash memory technology at Intel and now a scientific advisor to Nanochip.
In flash memory, information is stored using specialized transistors, each of which is addressed by a grid of conducting wires. The Nanochip technology, in contrast, stores information by writing data to a thin-film material using an array of microscopic cantilevers, each with an extremely sharp tip. The size of each bit will be 15 nanometers in the first devices, but it could theoretically be as small as just a couple of nanometers.
The Millipede array works by heating and indenting a polymer, while the Nanochip array uses voltage to write electronically. Apparently with both methods the integration of the tip arrays into a complete memory chip remains a challenge. If this challenge can be met, perhaps this type of highly parallel tip-directed surface modification will also prove useful as a path toward atomically precise manufacturing.
—Jim
