Friday, July 20, 2007

Higher-Capacity Flash Memory

Continued from page 1

By Kate Greene

Nanosys overcame the biggest challenge facing metal-nanocrystal technology, says Edwin Kan, professor of electrical and computer engineering at Cornell University, in Ithaca, NY. "The main contribution," he says, "is that they've resolved one of the processing problems: how to put high-density, uniform-sized nanocrystals on a [semiconductor] wafer."

Nanosys's nanocrystals are grown in the solution, and by controlling the composition of the solution, engineers can control the crystals' size. After the crystals form, other chemicals are added that allow special molecules to grow on the particle. These molecules, called ligands, let the nanocrystals maintain a uniform distance. Finally, the liquid with the metal nanocrystals, which resembles ink, is spun onto the silicon wafers that will become flash-memory chips.

Kan says that the advantage of using metal nanocrystals in flash is "very apparent and large." MP3 players such as iPhones and iPods will be able to hold more songs, videos, and pictures. And the fact that metal nanocrystals use much less power than traditional flash could help make flash an even better replacement for magnetic hard drives in laptops.