Lithography

About: Lithography is a research topic. Over the lifetime, 23507 publications have been published within this topic receiving 348321 citations.

Some recent advances in multi-material micro- and nano-manufacturing

Abstract: The increasing demand for micro-products and components can be met only partly by the lithography-based micro-electromechanical systems fabrication processes that originated from the silicon-based microelectronics revolution of the late twentieth century. In particular, such processes have limitations when applied to new micro-devices which require the use of a variety of materials and complex 3D microstructures with high aspect ratios. In this context, the paper presents technologies complementary to lithography-based processes for the manufacture of devices or components incorporating micro- and nano-scale features. More specifically, special attention is given to the main findings obtained over the last 5 years from the authors’ research programme on a range of micro- and nano-manufacturing technologies, namely, micro-electrodischarge machining, laser ablation, micro-milling, focussed-ion beam machining, micro-injection moulding, nano-imprint lithography, hot embossing and electroforming.

Making electrical contacts to nanowires with a thick oxide coating

Abstract: Techniques are presented for making ohmic contacts to nanowires with a thick oxide coating. Although experiments were carried out on Bi nanowires, the techniques described in this paper are generally applicable to other nanowire systems. Metal electrodes are patterned to individual Bi nanowires using, electron beam lithography. Imaging the chemical reaction on the atomic scale with in situ high-resolution transmission electron microscopy shows that annealing in H-2 or NH3 can reduce the nanowires' oxide coating completely. The high temperatures required for this annealing, however, are not compatible with the lithographic techniques. Low-resistance ohmic contacts to individual bismuth nanowires are achieved using a focused ion beam (FIB) to first sputter away the oxide layer and then deposit Pt contacts. By combining electron beam lithography and FIB techniques, ohmic contacts stable from 2 to 400 K are successfully made to the nanowires. A method for preventing the burnout of nanowires from electrostatic discharge is also developed.

Development of a deep silicon phase Fresnel lens using Gray-scale lithography and deep reactive ion etching

Abstract: We report the first fabrication and development of a deep phase Fresnel lens (PFL) in silicon through the use of gray-scale lithography and deep-reactive ion etching (DRIE). A Gaussian tail approximation is introduced as a method of predicting the height of photoresist gray levels given the relative amount of transmitted light through a gray-scale optical mask. Device mask design is accomplished through command-line scripting in a CAD tool to precisely define the millions of pixels required to generate the appropriate profile in photoresist. Etch selectivity during DRIE pattern transfer is accurately controlled to produce the desired scaling factor between the photoresist and silicon profiles. As a demonstration of this technology, a 1.6-mm diameter PFL is etched 43 /spl mu/m into silicon with each grating profile designed to focus 8.4 keV photons a distance of 118 m.

Conductive dots, wires, and supertips for field electron emitters produced by electron‐beam induced deposition on samples having increased temperature

Abstract: The procedure for three‐dimensional additive lithography with electron‐beam induced deposition is applied in a scanning electron microscope equipped with an image processor beam control system for lithography. Employing organometallic materials, which contain gold or platinum, quantum dots, resistors, and field emitter tips are deposited. Changing the current, the properties of the deposited nanocrystalline compound materials can be selected to be insulating or conducting. High resolution and high aspect ratio structures are grown with this technique. To find the mechanism responsible for conductivity in the deposited material, resistors are characterized at temperatures ranging from −150 °C to +180 °C. Measurements are performed in a high‐vacuum chamber equipped with a gas cooling system cooled with liquid nitrogen and a resistive heater. Poole–Frenkel plots show that field electron emission and hopping of electrons is the dominant mechanism of conduction. The metal content of the deposits is increased w...

Matching the Resolution of Electron Beam Lithography by Scanning Near-Field Photolithography

Abstract: Molecular features with widths of only 20 nm have been fabricated in self-assembled monolayers of alkanethiols on gold using a new lithographic tool, scanning near-field photolithography, based upon the use of a near-field scanning optical microscope (NSOM) coupled to a UV laser. Quite unexpectedly it has proved possible to routinely fabricate structures significantly smaller than the aperture in the NSOM probe. This exceptional performance is strongly correlated with the morphology of the gold film. In particular, the best results are achieved on films with comparatively small grain sizes. In contrast, the use of atomically flat, epitaxially deposited gold films leads to a minimum feature size comparable to the aperture diameter (ca 50 nm). It is concluded that nonradiative interactions (possibly the excitation of surface plasmons) between the gold substrate and the fiber lead to a pronounced focusing of the electric field beneath the aperture.