CAMBRIDGE, Mass.--Researchers at MIT have found a novel method for etching extremely narrow lines on a microchip, using a material that can be switched from transparent to opaque, and vice versa, just by exposing it to certain wavelengths of light.
Such materials are not new, but the researchers found a novel way of harnessing that property to create a mask with exceptionally fine lines of transparency. This mask can then be used to create a correspondingly fine line on the underlying material.
Producing such fine lines is crucial to many new technologies, from microchip manufacturing that is constantly seeking ways to cram more components onto a single chip, to a whole host of emerging fields based on nano-scale patterns. But these technologies have faced fundamental limits because they tend to rely on light to produce these patterns, and most techniques cannot produce patterns much smaller than the wavelengths of light itself. This method is a way of overcoming that limit.
The key is using interference patterns, in which different wavelengths of light sometimes reinforce each other and in other places cancel each other out. The researchers exposed the photochromic material one that changes its color, and therefore its transparency, in response to light to a pair of such patterns, each of a different wavelength, simultaneously. When the bright lines at one wavelength coincide with the dark lines at the other wavelength, extremely narrow lines of clear material are formed interspersed with the opaque material. This banded layer then serves as a mask through which the first wavelength illuminates a layer of material underneath, similarly to the way a photographic negative is used to make a print by shining light through it onto a sheet of photo paper underneath.
The research was carried out by research engineer Rajesh Menon of the Research Laboratory of Electronics and graduate students Trisha Andrew in the Department of Ch
|Contact: Elizabeth Thomson|
Massachusetts Institute of Technology