RESUMO
The nanoimprint lithography process consists of two mechanical steps: molding and stamp removal. While many publications dealing with anti-sticking layer properties or the understanding of polymer flow during imprinting have recently been published, only a few studies have been carried out to deeply characterize the demolding step. Regarding the small amount of theoretical work dedicated to this issue, in this paper both experimental and first theoretical approaches are proposed to characterize the demolding process in a peeling scheme. Full 200 mm stamp and imprinted wafers were used to identify the experimental limitation of such a full wafer peeling demolding scheme. A rectangular stamp and substrate samples with or without nanoscale features combined with an augmented beam theory are proposed to extract quantitative data for the required demolding force as well as the friction stress along the feature sidewall. Therefore both adhesion and friction forces were characterized on single stamp structures.
RESUMO
We report a remarkable enhancement of the magnetic moments of excitons as a result of their motion. This surprising result, which we have observed in magneto-optical studies of three distinct zinc-blende semiconductors, GaAs, CdTe, and ZnSe, becomes significant as the kinetic energy of the exciton becomes comparable with its Rydberg energy and is attributed to motionally induced changes in the internal structure of the exciton. The enhancement of the magnetic moment as a function of the exciton translational wave vector can be represented by a universal equation.
RESUMO
Sub-100 nm resolution on a 200 mm silicon stamp has been hot embossed into commercial Sumitomo NEB 22 resist. A single pattern, exposed with electron beam lithography, has been considered to define the stamp and thus make it possible to point out the impact of stamp design on the printing. These results may be considered as a first attempt to define rules to solve the proximity printing effects (PPEs). Moreover, a large range of initial resist thickness, from 56 to 506 nm, has been spin coated to assess the effect of polymer flow properties for the stamp cavity filling and the printed defects. A detailed analysis of the printed resist in dense hole patterns showed that the application volume conservation is enough to calculate the residual layer thickness as the height of the printed resist feature. Good accordance has been obtained between the theoretical approach and experimental results. Moreover, the impact of the pattern symmetry breakdown on mould deformation is clearly shown in this paper in the printed areas as well as in the unprinted areas.
RESUMO
Sub-100 nm patterns can be duplicated by nanoimprint lithography with high reproducibility, even on 200 mm wafers. Nevertheless, several problems have to be solved before this technique reaches a mature state for industrial applications. Several kinds of defect appear frequently in printed polymers. Some of them are induced by capillary effects and are related to mould deformation. Capillary bridges are observed on the flat surfaces around the pattern areas, or inside the printed structures. In this paper, the influence of the polymer molecular weight (M(w)) on the capillary bridge distribution is presented. It will be shown that for smaller M(w), they appear first around the pattern areas and move towards the structures more rapidly. It is also demonstrated that this evolution depends directly on the printing temperature and pattern filling related to the feature density and the film thickness. Finally, it is shown that the influence of these parameters is related to the polymer viscosity, which is the dominant property of the capillary effects, and a trade-off has to be made between the limitation due to the capillary bridges, the decrease of the temperature, which is important to reduce the cycle time, and the sticking defects.
