Controlled Patterning of Vertical Silicon Structures Using Polymer Lithography and Wet Chemical Etching.

In order to improve their performance for various applications, a facile method for the wafer-scale fabrication of micro/nano-patterned vertical silicon (Si) structures such as silicon nanowires (SiNWs), silicon nanorods (SiNRs), and porous silicon (p-Si) was developed. The method is based on the combination of lithography techniques (photolithography, thermal nano-imprint lithography, nanosphere lithography) and wet chemical etching (electro-chemical etching, metal-assisted chemical etching) processes. Micro-patterned p-Si with various pore diameters from 30 nm to 1.

Rapid Low-Temperature 3D Integration of Silicon Nanowires on Flexible Substrates.

The vertical integration of 1D nanostructures onto the 2D substrates has the potential to offer significant performance gains to flexible electronic devices due to high integration density, large surface area, and improved light absorption and trapping. A simple, rapid, and low temperature transfer bonding method has been developed for this purpose. Ultrasonic vibration is used to achieve a low temperature bonding within a few seconds, resulting in a polymer-matrix-free, electrically conducting vertical assembly of silicon nanowires (SiNWs) with a graphene/PET substrate.

Interior-architectured ZnO nanostructure for enhanced electrical conductivity via stepwise fabrication process.

Fabrication of ZnO nanostructure via direct patterning based on sol-gel process has advantages of low-cost, vacuum-free, and rapid process and producibility on flexible or non-uniform substrates. Recently, it has been applied in light-emitting devices and advanced nanopatterning. However, application as an electrically conducting layer processed at low temperature has been limited by its high resistivity due to interior structure.

High-durable AgNi nanomesh film for a transparent conducting electrode.

Uniform metal nanomesh structures are promising candidates that may replace of indium-tin oxide (ITO) in transparent conducting electrodes (TCEs). However, the durability of the uniform metal mesh has not yet been studied. For this reason, a comparative analysis of the durability of TCEs based on pure Ag and AgNi nanomesh, which are fabricated by using simple transfer printing, is performed.

Lead sulfide nanocrystal quantum dot solar cells with trenched ZnO fabricated via nanoimprinting.

The improvement of power conversion efficiency, especially current density (Jsc), for nanocrystal quantum dot based heterojunction solar cells was realized by employing a trenched ZnO film fabricated using nanoimprint techniques. For an optimization of ZnO patterns, various patterned ZnO films were investigated using electrical and optical analysis methods by varying the line width, interpattern distance, pattern height, and residual layer. Analyzing the features of patterned ZnO films allowed us to simultaneously optimize both the pronounced electrical effects as well as optical properties.

Pattern-definable and low cost fabrication of nanopatterned conducting polymer film on flexible substrates.

This study reports the pattern definable and low cost fabrication of nanopatterned conducting polymer film on flexible substrates. Noble nanopatterned polymer hard template was fabricated by using nanoimprint lithography (NIL) and used for electropolymerization of conducting polymer. Conducting polymer was electrochemically deposited on the template and transferred over to flexible substrates.

Measurement of surface adhesion force of adhesion promoter and release layer for UV-nanoimprint lithography.

In this work, we investigated the effect of surface treatment as release layer and adhesion promoter for UV-Nanoimprint lithography and measured the surface adhesion force by using tensile separation force of Instron equipment. Several Self-Assembled Monolayers (SAMs) of 3-Acryloxypropyl methyl dichlorosilane (APMDS) 3-Aminopropyl-triethoxysilane (APTS), and 3-Glycidoxypropyltrimethoxysilane (GPTS) as adhesion promoters and (1H,1H,2H,2H-perfluorooctyl)trichlorosilane (FOTS) as release layer were fabricated by vapor deposition method and were compared with oxygen plasma treatment. APMDS could strongly improve the adhesion force between UV-curable acrylate resin and silicon substrate because of strong covalent bonding.

Stamping-based planarization of flexible substrate for low-pressure UV nanoimprint lithography.

Patterning flexible substrates in nano scale is an important and challenging issue in the fabrication of next-generation devices based on a non-silicon substrate. Step and Flash imprint lithography (S-FIL) which is a room temperature and low pressure process offers several important advantages, such as the use of a smaller and therefore cheaper stamp or the possibility of the overlay imprinting, as a transparent stamp is utilized. However, it is very difficult to perform S-FIL on a flexible substrate successfully due to the high waviness.

The fabrication of a flexible mold for high resolution soft ultraviolet nanoimprint lithography.

One key issue for all nanoimprint techniques is an appropriate method for the fabrication of desirable molds. We report on a novel flexible mold fabrication process-pressure-assisted molding (PAM)-for high resolution soft ultraviolet nanoimprint lithography (soft UV-NIL). In PAM, enhanced master filling is achieved by applying an external pressure during the mold fabrication process.

Application of Design of Experiment Method for Thrust Force Minimization in Step-feed Micro Drilling.

Micro drilled holes are utilized in many of today's fabrication processes.Precision production processes in industries are trending toward the use of smaller holeswith higher aspect ratios, and higher speed operation for micro deep hole drilling. However,undesirable characteristics related to micro drilling such as small signal-to-noise ratios,wandering drill motion, high aspect ratio, and excessive cutting forces can be observedwhen cutting depth increases.

Boron nitride stamp for ultra-violet nanoimprinting lithography fabricated by focused ion beam lithography.

Cubic boron nitride (c-BN) is one of the hardest known materials (second after diamond). It has a high level of chemical resistance and high UV transmittance. In this study, a stamp for ultra-violet nanoimprint lithography (UV-NIL) was fabricated using a bi-layered BN film deposited on a quartz substrate.

Fabrication of nano- and micro-scale UV imprint stamp using diamond-like carbon coating technology.

Two-dimensional (2-D) and three-dimensional (3-D) diamond-like carbon (DLC) stamps for ultraviolet nanoimprint lithography were fabricated with two methods: namely, a DLC coating process, followed by focused ion beam lithography; and two-photon polymerization patterning, followed by nanoscale-thick DLC coating. We used focused ion beam lithography to fabricate 70 nm deep lines with a width of 100 nm, as well as 70 nm deep lines with a width of 150 nm, on 100 nm thick DLC layers coated on quartz substrates. We also used two-photon polymerization patterning and a DLC coating process to successfully fabricate 200 nm wide lines, as well as 3-D rings with a diameter of 1.

Nanoscopic Pd line arrays using nanocontact printed dendrimers.

High-density Pd line arrays with 55 nm line-width were obtained using nanocontact-printed dendrimer monolayers. Elastomeric PDMS stamps for nanocontact printing were replicated from silicon master molds which were fabricated by UV nanoimprinting in combination with reactive ion etching. The fabrication method effectively controlled the aspect ratios of high-density lines for resolving the problems encountered in both replicating silicon masters to PDMS stamps and printing with the replicated PDMS stamps.

Fluorinated organic-inorganic hybrid mold as a new stamp for nanoimprint and soft lithography.

In this paper, we fabricated a fluorinated organic-inorganic hybrid mold using a nonhydrolytic sol-gel process which can produce a crack-free mold without leaving any trace of solvent. No special chemical treatment of a release layer is needed because the fluorinated hybrid mold has fluorine molecules in the backbone. The other advantages of the hybrid mold are thermal stability over 300 degrees C.