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nanotimes News in Brief

11-06/07 :: June/July 2011

Chip Manufacturing // Electron-Beam Lithography in Hydrogen Silsesquioxane Resist © Text: Larry Hardesty, MIT

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esearchers at MIT’s Research Laboratory of Electronics (RLE) present a way to get the resolu-

tion of high-speed e-beam lithography down to just nine nanometers. Combined with other emerging technologies, it could point the way toward making e-beam lithography practical as a mass-production technique.

The researchers used two tricks to improve the resolution of high-speed e-beam lithography. The first was to use a thinner resist layer, to minimize electron scattering. The second was to use a solution containing ordinary table salt to “develop” the resist, hardening the regions that received slightly more electrons but not those that received slightly less.

Pieter Kruit, a professor of physics at the Delft University of Technology in the Netherlands and co-founder of Mapper, a company that has built lithographic systems with 110 parallel e-beams, says that in addition to being faster, e-beam systems that deliver smaller doses of electrons are much easier to build. The larger the dose of electrons, the more en- ergy the system consumes, and the more insulation it requires between electrodes.

“That takes so much space that it’s impossible to build an instrument,” Kruit says. Kruit doubts ma-

Research Laboratory of Electronics graduate students Vitor Manfrinato and Lin Lee Cheong, with the electron-beam lithography system they used in their experiments. © Melanie Gonick

nufacturers will use exactly the resist that the MIT researchers did in their experiments. Although the researchers’ goal was to find a resist that would re- spond to small doses of electrons, the one that they settled on is actually “a little bit too sensitive,” Kruit says: The amount of electricity that an electrode de- livers to a chip surface will vary slightly, he explains, and if the resist is too sensitive to those variations, the width of the chip features will vary, too. “But that is a matter of modifying the resist slightly, and that’s what resist companies do all the time,” he adds.