To speed up miniaturisation of electronic devices

Scientists from Singapore A*STAR’s Institute of Materials Research and Engineering (IMRE), University of Cambridge (UK) and Sungkyunkwan University (South Korea) have created metallic lines so thin and smooth that they can only be seen using powerful electron microscopes. At line widths of just 7nm, their line width roughness , which are the variations in thickness along the line itself, stands at 2.9 nm, a value which is below the 2010 target of 3.2nm and closer to 2011’s target line width roughness of 2.8 nm indicated in the International Technology Roadmap for Semiconductors. The ability to create such distinct lines and patterns on a sub-10nm scale level is essential in the further miniaturisation of electronic components. Rough, undefined patterns and lines results in poorly made, energy-inefficient devices. The process is very delicate and precise because of the scale at which the work is done. For comparison, the width of the average human hair is 100µm, which is about 14'000 times the width of a single 7nm-wide metal line. “Our thin, unbroken and smooth lines are important in ensuring the efficiency of ever shrinking electronic devices and may lead to more powerful processors. Furthermore, our work shows that continuous metallic lines as small as 4nm are possible to make”, says Dr MSM Saifullah, a Research Scientist with IMRE. The method could be potentially used to make interconnects, the ‘highways’ that carry electrical pulses and data in extremely small integrated circuits (ICs). The smoother and uninterrupted ‘highways’ lead to faster data transfer rates and less energy wasted, in the form of heat. The novelty of the method was in the material and the technique that was used. The current “lift-off” approach for making metal lines at this scale requires more steps, uses more materials and results in rough, and quite often broken lines on a sub-10 nm scale. The researchers used an organometallic material which is made up of a metallic and an organic component. Using a combination of electron beam lithography and subsequent gas treatment, the researchers were able to easily chip away the organic portions in a uniform manner, leaving the desired metallic patterns, in this case, thin metal lines. “Our obvious expertise in the area of nanopatterning is also a reason why we are driving a concerted effort for the industry to adopt technologies such as this into their manufacturing processes”, explains Prof Hor.