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Posted: May 18, 2006
A cool way to strip hydrogen
(Nanowerk News) Using lasers to clear silicon surfaces could make for cheaper, better computer chips and solar cells.
Researchers have demonstrated a new laser-based technique for stripping hydrogen atoms from the surface of silicon, an advance that could significantly reduce the cost and improve the quality of computer chips, solar cells and a wide variety of other semiconductor devices.
The scientists' work was supported in part by the National Science Foundation, and is reported in the May 19 issue of the journal Science. The team includes Philip I. Cohen at the University of Minnesota, Leonard C. Feldman, Norman Tolk and Zhiheng Liu at Vanderbilt University, and Zhenyu Zhang from Oak Ridge National Laboratory and the University of Tennessee.
The laser technique addresses a key step in the production of microchips, which are typically built by laying down multiple layers of silicon in sequence. To keep each new surface from oxidizing, manufacturers routinely expose it to hydrogen atoms that attach to all the available silicon bonds. Then they remove the hydrogen atoms before adding the next layer. Unfortunately, their usual method – applying heat – can destroy the silicon's crystalline perfection and ruin the chip.
By stripping the hydrogen off with lasers, however, manufacturers could potentially work at much lower temperatures, which should dramatically improve yields.
An animation of the laser process is also available.