[MURG] [>Htech] spacedaily: 20nm 3d-carving with pulsed lasers (fwd from alito@organicrobot.com)

[Eugen Leitl]

----- Forwarded message from Alejandro Dubrovsky <alito at organicrobot.com> -----

From: Alejandro Dubrovsky <alito at organicrobot.com>
Date: Thu, 22 Apr 2004 20:18:41 +1000
To: transhumantech <transhumantech at yahoogroups.com>
Subject: [>Htech] spacedaily: 20nm 3d-carving with pulsed lasers
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(
http://www.spacedaily.com/news/nanotech-04y.html
)

Ultra-Fast Laser Allows Efficient, Accessible Nanoscale Machining

Ann Arbor Mich - Apr 21, 2004
Think of a microscopic milling machine, capable of cutting just about
any material with better-than-laser precision, in 3-D---and at the
nanometer scale. In a paper published this week in the Proceedings of
the National Academy of Sciences, University of Michigan researchers
explain how and why using a femtosecond pulsed laser enables
extraordinarily precise nanomachining.

The capabilities of the ultra-fast or ultra-short pulsed laser have
significant implications for basic scientific research, and for
practical applications in the nanotechnology industry.

Initially, the researchers working at the Center for Ultrafast Optical
Science wanted to use the ultra-fast laser as a powerful tool to study
structures within living cells, said Alan Hunt, assistant professor,
Department of Biomedical Engineering.

"It turned out we could push much farther than expected and the
applications became broad, from microelectronics applications to MEMS
(microelectromechanical systems) to microfluidics," Hunt said. One of
the most perplexing problems in nanotechnology is finding an efficient
and precise way to build and machine the tiny devices. For example, a
human hair is about 100,000 nanometers across.

The unique physics of an ultra-short pulsed laser used at a very high
intensity make it possible to selectively ablate or cut away features as
small as 20 nanometers, Hunt said. This is possible because of the
unique physics of how extremely short pulses of light interact with
matter; specifically using femtosecond pulses, a blast of light just a
quadrillionth of a second long.

Currently, there is no easy way to machine a wide variety of materials
on the nanometer scale, Hunt said, and the technique with capabilities
closest to the ultrafast laser is electron beam lithography. Even this
approach does not allow machining below the surface or within a
material.

Photolithography, the technique used to make computer chips, is used to
do such machining on a larger scale but is difficult to get to the
nanometer scale, requires specific materials and can generally only be
used on one plane. For example, that means that channels on a chip
cannot cross without mixing, placing a severe constraint on the
microfluidics and "lab on a chip" designs.

But the unique physics of the femtosecond pulse allows machining in 3-D,
Hunt said.

"If we have three channels on a plane, we can link the outer two without
cutting into the center one, we can go down over and up, we can cut a
U-shape," Hunt said. "Not being constrained to one plane, the level of
complexity that can be achieved is much greater."

The research team included Hunt; Gerard Mourou, professor of electrical
engineering and computer science; Ajit Joglekar, who recently completed
his doctorate in biomedical engineering; Hsiao-hua Liu, a post doc at
the Center for Ultrafast Optical Science; and Edgar Meyhofer, associate
professor of biomedical engineering and mechanical engineering.




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