Tech agency ups chip speed on two fronts
NIST, the federal government's standards arm, advances a technology for bettering optical resolution and a standard for measuring elements in silicon composites.
The National Institute of Standards and Technology (NIST), a division of the U.S. Commerce Department's Technology Administration, detailed a technique for improving the resolution of chip optics and a standard for measuring the proportions of the silicon-germanium composite used in computer chips.
The optics technology involves the creation of a so-called "liquid lens" in the reading of a silicon wafer. The insertion of a liquid layer between the optical element and the silicon could improve resolution to 65 nanometers (billionths of a meter) from the 100 nanometers now possible.
The idea behind applying the liquid lens concept to computer optics is to make computer chips smaller and, therefore, faster.
NIST scientists showed in a paper that will appear in the publication "Proceedings of SPIE Optical Microlithography XVI" that the use of high-purity water as an interface between the optical unit and the silicon could significantly reduce the degree to which light diffraction hindered resolution.
The authors of the paper, titled "Measurement of the refractive index and thermooptic coefficient of water near 193 nanometers," warned that the liquid lens is highly sensitive to changes in temperature, a factor that will significantly affect optics design using the technique.
NIST's other advance in chip speed is a proposed standard for helping calibrate instruments that measure the amount of germanium in silicon-germanium thin films.
Germanium, an element that is both a semiconductor and alloying agent, strains the silicon lattice in a way that speeds the flow of electrons through it. Its use can double the operating speed of a device, according to NIST.
But exact measurements of the amount of the alloy in a silicon film is hard to come by, so NIST produced a standard consisting of sets of the films with varying proportions of germanium and silicon.
NIST described the standard as an interim measure and a first in terms of the cooperation between the government agency and private industry.
"The new standard...is among the first to be developed through interactions between industrial participants who supply and characterize the materials and NIST staff who coordinate the process, conduct additional measurements and tests and assign values," the agency said. "The process is less rigorous than the traditional Standard Reference Material (SRM) approach and may not result in certified values. But interactive materials can be made available relatively quickly--just one to two years after a need is identified, compared to about five years for a new SRM."
NIST said its standard would reduce the degree of uncertainty of germanium composition to 1 percent from 5 percent by using currently available techniques.