Better chips and faster! Not from your local fast food outlet, but for your computer.
Researchers from The University of Queensland are using the Australian Synchrotron to test new chip production methods.
The computer chip manufacturing process involves shining light through a patterned mask and onto a thin polymer layer called a resist, which facilitates the transfer of the pattern into the silicon chip. The resist is designed to degrade in the specific locations where it is illuminated. Degradation must occur rapidly and fidelity is essential.
Rapid advances in technology mean that the density of the components on computer chips doubles roughly every two years. That means the size of the circuits on the chip has to shrink; from 40 nm (nanometres) to 30 nm and below. Current processes use 193 nm light, which is on the ultra-violet edge of the visible region, but for smaller circuits the wavelength of light needs to be reduced.
One of the newest technologies involves using 13.5 nm light, which is also referred to as extreme-ultra-violet (EUV) in the silicon chip industry or as 'soft' x-rays by synchrotron scientists. However, there is a catch - both the instruments for fabricating the chips and the polymeric resists have to be redesigned. For example, currently-used resist formulations lack the photosensitivity and veracity to allow for accurate printing of ultrafine features at rapid speeds.
In collaboration with Intel Corp., Prof. Andrew Whittaker's polymer group at The University of Queensland is designing and synthesising novel polymers that are photosensitive at 13.5 nm and robust enough to use as resists. These polymers also allow for inherently more precise patterning.
Kevin Jack, Idriss Blakey, James Blinco and Kirsten Lawrie from Prof. Whittaker's group are using the Australian Synchrotron to investigate the sensitivities and mechanisms of degradation in some of the newly-developed polymers. The soft x-ray beamline at the synchrotron is the only source of 13.5 nm light available in Australia and is one of very few sources worldwide.
Access to the synchrotron has greatly enhanced the group's ability to characterise these materials and validate their design models. Most importantly, the soft x-ray beamline enables them to simultaneously investigate the degradation mechanisms in these resists, which provides the ability to optimise and design even better materials for the future.
The team's first step was to characterise the profile of the beam and flux at 13.5 nm (an energy which is not routinely accessed by users) and to optimise the beamline for these investigations. Kevin Jack says this task was made easier by the expertise and enthusiasm of the beamline scientists, who were "brilliant at training us not only in the operation of the soft x-ray end station, but also in teaching us how the synchrotron, insertion devices and beamline elements function".
The researchers characterised the sensitivities of a small number of their recently-synthesised materials along with a standard benchmark material, showing that one polymer in particular demonstrated a very high degree of sensitivity at 13.5 nm. The findings validated the predictions of their design models and are helping to focus the team's research efforts. In addition, the collection of XPS data in situ has provided information on the degradation mechanism occurring in the polymers.
Kevin and his colleagues are looking forward to returning to the Australian Synchrotron to continue their investigations on second-generation materials developed in response to the team's preliminary findings and a number of new materials also predicted to be promising candidate materials.
Queensland researchers are using the Australian Synchrotron's soft x-ray beamline to develop new polymeric materials for computer chip manufacture. The new materials (LH) have better photosensitivity. (Image: Jack et al., The University of Queensland)