Researchers with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have shed light on the role of temperature in controlling a fabrication technique for drawing chemical patterns as small as 20 nanometers. This technique could provide an inexpensive, fast route to growing and patterning a wide variety of materials on surfaces to build electrical circuits and chemical sensors.
One way of directly writing nanoscale structures onto a substrate is to use an atomic force microscope (AFM) tip as a pen to deposit ink molecules through molecular diffusion onto the surface. Unlike conventional nanofabrication techniques that are expensive, require specialized environments, and usually work with only a few materials, this technique, called dip-pen nanolithography, can be used in almost any environment to write many different chemical compounds. A cousin of this technique – called thermal dip-pen nanolithography – extends this technique to solid materials by turning an AFM tip into a tiny soldering iron.
Dip-pen nanolithography can be used to pattern features as small as 20 nanometers, more than 40,000 times smaller than the width of a human hair. The writing tip also performs as a surface profiler, allowing a freshly writ surface to be imaged with nanoscale precision immediately after patterning.
In the study, the researchers investigated the effect of temperature on feature size. Using their results, the team developed a new model to deconstruct how ink molecules travel from the writing tip to the substrate, assemble into an ordered layer, and grow into a nanoscale feature.
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Also: Learn about creating high-performance, integrated optical circuits with nanolithography.
