US scientists have demonstrated a breakthrough method of computer chip lithography delivering imaging capabilities beyond those previously thought possible.

The method, known as evanescent wave lithography, or EWL, is capable of optically imaging the smallest-ever semiconductor device geometry.

EWL was discovered by a team of engineering students at the Rochester Institute of Technology (RIT), under the leadership of Bruce Smith, RIT professor of microelectronic engineering and director of the Centre for Nanolithography Research in the Kate Gleason College of Engineering.

Smith explained that EWL is an "enabling technology" permitting better understanding of how building blocks could be created for future microelectronic and nanotechnology devices that consumers will use over the next five to 10 years.

"Immersion lithography has pushed the limits of optical imaging, and EWL continues to extend this reach well into the future," he said. "The results are very exciting as images can be formed that are not supposed to exist."

Yongfa Fan, a doctoral student in RIT's microsystems engineering PhD programme, accomplished imaging rendered to 26 nanometres, a size previously possible only via extreme ultraviolet wavelength.

By capturing images that are beyond the limits of classical physics, the breakthrough has allowed resolution to smaller than one-twentieth the wavelength of visible light, Smith explained.

The development comes at least five years sooner than anticipated, using the International Technology Roadmap for Semiconductors as a guide.

The roadmap, created by a consortium of industry groups, government organisations, universities, manufacturers and suppliers, assesses semiconductor technology requirements to ensure advancements in the performance of integrated circuits to meet future needs.