N. Chaix

Tailoring nanostructures using copolymer nanoimprint lithography.

The generation of defect-free polymer nanostructures by nanoimprinting methods is described. Long-range nanorheology and shorter-range surface energy effects can be efficiently combined to provide alignment of copolymer lamellae over several micrometers. As an example, a perpendicular organization with respect to circular tracks is shown, demonstrating the possibility of writing ordered radial nanostructures over large distances.

Thin polymer films viscosity measurements from nanopatterning method

Polystyrene films, with thickness ranging from a few tens of nanometers up to several hundreds of nanometers and molecular weight of 27.5 kg mol−1, were patterned with nanoimprint lithography (NIL) technique. A rigid silicon stamp containing nanoscale features was printed into a thin spin coated polystyrene film. Then these patterns were annealed above the glass transition temperature in order to characterize the viscous reflow of the topography. Special attention was paid to provide, at initial times, imprinted nanoscale patterns with a very small aspect ratio and amplitude/wavelength as well as to avoid the nucleation of holes during imprinting or during the course of the reflow. This allowed the authors to process topography data with a high degree of accuracy from a linear viscous stability model. Atomic force microscopy measurements, with a spatial resolution lower than 1 nm, were used to characterize smooth or steep shapes. The mechanical measurements of earlier stages of pattern reflow were directl...

Nano-imprint of sub-100-nm dots and complex shape features on 8-inch wafer: influence of layout design

Sub 100 nm resolution on 200 mm silicon stamp have been hot embossed into commercial Sumitomo NEB 22 resist. A single dot pattern, exposed with electron beam lithography, has been considered to define the stamp and make thus possible to point out the impact of stamp design onto the printing. Moreover, more complex shapes (triangular, elliptic, random...) with sub 200 nm resolution with and without uniform surrounding frame have been also designed. A large scale of initial resist thickness, from 56 nm to 506 nm, has been printed to assess the effect of polymer flow properties onto the stamp cavities filling and the printed defects. The impact of the pattern symmetry breakdown onto defect generation is clearly shown in this paper in the printed areas as well as in the unprinted areas.

Impact of planarization sheet addition on full wafer printing uniformity

Uniformity of nanoimprint lithography has been quantitatively studied through the ability to replicate regular lines arrays by wafer-to-wafer imprint. Two statistic coefficients have been defined in order to quantify the local uniformity and the ability to identically imprint two similar areas respectively. Those coefficients enable to compare different imprint profiles in terms of uniformity and to point out the efficiency of soft layers insertion into the imprint stack.

Demolding strategy to improve the hot embossing throughput

Hot embossing throughput is a key issue, which has been addressed in this paper. We show how it is possible to remove the mold from the imprinted resist at the imprint temperature. We study reflow behavior of imprinted patterns, and make a cooling and quenching simulation. This work can lead to design of cooling tools adapted to a given application, and suits as well for the full wafer imprint, as well for the roll imprint.