Selective growth of platinum nanolines by helium ion beam induced deposition and atomic layer deposition.

Helium ion beam induced deposition (HIBID) is an attractive technique capable of precise fabrication of nanostructures. However, the damage caused by helium ion irradiation is the major drawback of conventional HIBID. In this study, area-selective atomic layer deposition (ALD) accompanied with the HIBID technique is explored to solve this problem. A platinum (Pt) seed layer was prepared by HIBID with a helium dose much lower than that of the conventional HIBID to reduce the damage due to the bombardment of energetic ions. Afterwards, Pt was selectively deposited on the seed layer to achieve area-selective ALD. Accordingly, the Pt nanolines with a feature size of ~15 nm are accomplished by the area-selective ALD and the HIBID technique under the condition of the damage-free does.

Novel Self-shrinking Mask for Sub-3 nm Pattern Fabrication.

It is very difficult to realize sub-3 nm patterns using conventional lithography for next-generation high-performance nanosensing, photonic, and computing devices. Here we propose a completely original and novel concept, termed self-shrinking dielectric mask (SDM), to fabricate sub-3 nm patterns. Instead of focusing the electron and ion beams or light to an extreme scale, the SDM method relies on a hard dielectric mask which shrinks the critical dimension of nanopatterns during the ion irradiation. Based on the SDM method, a linewidth as low as 2.1 nm was achieved along with a high aspect ratio in the sub-10 nm scale. In addition, numerous patterns with assorted shapes can be fabricated simultaneously using the SDM technique, exhibiting a much higher throughput than conventional ion beam lithography. Therefore, the SDM method can be widely applied in the fields which need extreme nanoscale fabrication.

Atomic-layer-deposited silver and dielectric nanostructures for plasmonic enhancement of Raman scattering from nanoscale ultrathin films.

Plasmonic silver nanostructures and a precise ZnO cover layer prepared by capacitively coupled plasma atomic layer deposition (ALD) were exploited to enhance the Raman scattering from nanoscale ultrathin films on a Si substrate. The plasmonic activity was supported by a nanostructured Ag (nano-Ag) layer, and a ZnO cover layer was introduced upon the nano-Ag layer to spectrally tailor the localized surface plasmon resonance to coincide with the laser excitation wavelength. Because of the optimized dielectric environment provided by the precise growth of ZnO cover layer using ALD, the intensity of Raman scattering from nanoscale ultrathin films was significantly enhanced by an additional order of magnitude, leading to the observation of the monoclinic and tetragonal phases in the nanoscale ZrO2 high-K gate dielectric as thin as ∼6 nm on Si substrate. The excellent agreement between the finite-difference time-domain simulation and experimental measurement further confirms the so-called [absolute value]E(->)[absolute value](4) dependence of the surface-enhanced Raman scattering. This technique of plasmonic enhancement of Raman spectroscopy, assisted by the nano-Ag layer and optimized dielectric environment prepared by ALD, can be applied to characterize the structures of ultrathin films in a variety of nanoscale materials and devices, even on a Si substrate with overwhelming Raman background.