Showing papers on "Lithography published in 2005"

On-wire lithography.

Abstract: We report a high-throughput procedure for lithographically processing one-dimensional nanowires. This procedure, termed on-wire lithography, combines advances in template-directed synthesis of nanowires with electrochemical deposition and wet-chemical etching and allows routine fabrication of face-to-face disk arrays and gap structures in the range of five to several hundred nanometers. We studied the transport properties of 13-nanometer gaps with and without nanoscopic amounts of conducting polymers deposited within by dip-pen nanolithography.

Optical and Interferometric Lithography - Nanotechnology Enablers

Abstract: Interferometric lithography (IL), the interference of a small number of coherent optical beams, is a powerful technique for the fabrication of a wide array of samples of interest for nanoscience and nanotechnology. The techniques and limits of IL are discussed with particular attention to the smallest scales achievable. With immersion techniques, the smallest pattern size for a single exposure is a half-pitch of /spl lambda//4n where /spl lambda/ is the optical wavelength and n is the refractive index of the immersion material. Currently with a 193-nm excimer laser source and H/sub 2/O immersion, this limiting dimension is /spl sim/34 nm. With nonlinear spatial frequency multiplication techniques, this limit is extended by factors of 1/2, 1/3, etc.-extending well into the nanoscale regime. IL provides an inexpensive, large-area capability as a result of its parallelism. Multiple exposures, multiple beams, and mix-and-match with other lithographies extend the range of applicability. Imaging IL provides an approach to arbitrary structures with comparable resolution. Numerous application areas, including nanoscale epitaxial growth for semiconductor heterostructures; nanofluidics for biological separations; nanomagnetics for increased storage density; nanophotonics including distributed feedback and distributed Bragg reflectors, two- and three-dimensional photonic crystals, metamaterials, and negative refractive index materials for enhanced optical interactions are briefly reviewed.

Vapor-phase self-assembled monolayer for improved mold release in nanoimprint lithography

Abstract: Resist adhesion to the mold is one of the challenges for nanoimprint lithography. The main approach to overcoming it is to apply a self-assembled monolayer of an organosilane release agent to the mold surface, either in the solution phase or vapor phase. We compared the atomic force microscopy, ellipsometry, reflection−absorption infrared spectroscopy, and contact angle results collected from substrates treated by two different application processes and found that the vapor-phase process was superior. The vapor-treated substrates had fewer aggregates of the silane molecules on the surface, because the lower density of the agent in the vapor phase was not conducive to aggregation formation, and received a superior coating of the releasing agent, because the vapor was more effective than the solution in penetrating into the nanoscale gaps of the mold. A pattern transfer of 20 parallel nanowires with a line width of 40 nm at 100 nm pitch-size was performed faithfully with the vapor-treated mold without any r...

Characterization of buried photonic crystal waveguides and microcavities fabricated by deep ultraviolet lithography

Abstract: We present results of the optical characterization of silicon photonic crystal waveguides and microcavities that are completely buried in a silicon dioxide cladding and are fabricated by deep ultraviolet (UV) lithography. The advantages of buried waveguides and deep UV lithography are discussed. Transmission spectra and loss factors for photonic crystal waveguides, as well as quality factors for resonant microcavities, are obtained. The observed characteristics are in good agreement with three-dimensional simulations.

Two-photon lithography of nanorods in SU-8 photoresist

Abstract: Studies on two-photon lithography in negative SU-8 photoresist demonstrate the possibility of obtaining mechanically stable, stress-free, extended nanorods having lateral sizes of about 30 nm (corresponding to λ/25 resolution). The high resolution achievable with the given combination of materials and fabrication techniques demonstrates its potential for the fabrication of large-scale nanostructures, such as photonic crystals with photonic stop gaps at visible wavelengths.

Stamp collapse in soft lithography.

Abstract: We have studied the so-called roof collapse in soft lithography. Roof collapse is due to the adhesion between the PDMS stamp and substrate, and it may affect the quality of soft lithography. Our analysis accounts for the interactions of multiple punches and the effect of elastic mismatch between the PDMS stamp and substrate. A scaling law among the stamp modulus, punch height and spacing, and work of adhesion between the stamp and substrate is established. Such a scaling law leads to a simple criterion against the unwanted roof collapse. The present study agrees well with the experimental data.

Method and apparatus for angular-resolved spectroscopic lithography characterisation

Abstract: An apparatus and method to determine a property of a substrate by measuring, in the pupil plane of a high numerical aperture lens, an angle-resolved spectrum as a result of radiation being reflected off the substrate. The property may be angle and wavelength dependent and may include the intensity of TM- and TE-polarized light and their relative phase difference.

Lithography apparatus, and device manufacturing method

Abstract: A lithography apparatus and device manufacturing methods are disclosed A lithography apparatus includes a support stage, and a measurement system including a sensor part and a reference part, the measurement system being configured to determine the position and/or orientation of the support stage, or of a component mounted on the support stage, relative to a reference frame by using the sensor part to interact with the reference part, wherein: the reference frame comprises N sub-frames coupled together so as to behave predominantly as a single rigid body with respect to vibrations below a first reference frequency and predominantly as an N-body system with respect to vibrations above a second reference frequency, where N is an integer greater than 1

Method and apparatus for angular-resolved spectroscopic lithography characterization

Abstract: According to the present invention, an apparatus and method are disclosed for determining the properties of a substrate by measuring the angle-resolved spectrum as a result of the radiation being reflected off the substrate in the pupil plane of the high numerical aperture lens. The properties may be dependent on angle and wavelength and may include the intensity of TM- and TE-polarized light and their associated phase differences.

Electrochemical Tuning of Silver Nanoparticles Fabricated by Nanosphere Lithography

Abstract: An electrochemical method is developed to quantitatively modify and spectroscopically monitor the size and shape of Ag nanotriangles fabricated by nanosphere lithography (NSL) on an indium tin oxide (ITO) electrode surface. AFM and SEM results demonstrate that the preferential order of electrochemical oxidation for a nanotriangle is, surprisingly, bottom edges first, then triangular tips, then out-of-plane height.

Microfabrication of 3D silicon MEMS structures using gray-scale lithography and deep reactive ion etching

Abstract: Micromachining arbitrary 3D silicon structures for micro-electromechanical systems can be accomplished using gray-scale lithography along with dry anisotropic etching. In this study, we have investigated the use of deep reactive ion etching (DRIE) and the tailoring of etch selectivity for precise fabrication. Silicon loading, the introduction of an O 2 step, wafer electrode power, and wafer temperature are evaluated and determined to be effective for coarsely controlling etch selectivity in DRIE. The non-uniformity and surface roughness characteristics are evaluated and found to be scaled by the etch selectivity when the 3D profile is transferred into the silicon. A micro-compressor is demonstrated using gray-scale lithography and DRIE showing that etch selectivity can be successfully tailored for a specific application. © 2004 Elsevier B.V. All rights reserved.

GaN-based light-emitting diodes with indium tin oxide texturing window layers using natural lithography

Abstract: There is a significant gap between the internal and external efficiencies of conventional GaN light-emitting diodes (LEDs). The reason for this shortfall is the narrow escape cone for light in high refractive index semiconductors. In this letter, the p-side-up GaN∕sapphire LEDs with surface textured indium tin oxide (ITO) widow layers were investigated using natural lithography with polystyrene spheres as the etching mask. Under optimum etching conditions, the surface roughness of the ITO film can reach 140 nm while the polystyrene sphere on the textured ITO surface is maintained at about 250–300 nm in diameter. The output power of the ITO∕GaN LED with and without surface texturing is 10.9, and 8.5 mW at 20 mA, respectively. The LEDs fabricated using the surface-textured ITO produced an output power that exceeded that of the planar-surface LED by about 28% at 20 mA.

Efficient silicon-on-insulator fiber coupler fabricated using 248-nm-deep UV lithography

Abstract: We present a silicon-on-insulator (SOI) waveguide to fiber coupler fabricated using 248-nm-deep ultraviolet lithography. The loss of the taper structure is around 1 dB while the coupling loss from a lensed fiber into a 590-nm-wide SOI waveguide was measured to be 1.9 dB.

Fabrication of large area two- and three-dimensional polymer photonic crystals using single refracting prism holographic lithography

Abstract: We demonstrate an approach for easy fabrication of two-dimensional (2D) hexagonal and three-dimensional (3D) face-centered-cubic (fcc)-type photonic crystal (PhC) microstructures in a photosensitive polymer by applying a simple single refracting prism. This prism enables the splitting and recombining of a single incoming laser beam to form multiple-beam interference pattern simultaneously. Thus, antivibration equipment and complicated optical alignment system are not required, leading to a much more simple optical setup than previously reported laser holographic lithography techniques. Large-scale (over 1cm2) 2D hexagonal and 3D fcc-type PhCs have been produced. Reflection/transmission measurements performed on the fabricated 3D fcc-type PhC structures agree well with the corresponding band structure calculation.

Effect of low numerical-aperture femtosecond two-photon absorption on (SU-8) resist for ultrahigh-aspect-ratio microstereolithography

Abstract: We report the quantitative characterization and analysis on the solidification of SU-8, a chemically amplified near-ultraviolet ultrathick resist, based on two-photon-absorbed (TPA) near-infrared photopolymerization. The resolution of TPA photopolymerized SU-8 voxels and lines is studied as a function of laser-pulse energy, single-shot exposure time, and scanning speed. Two-photon microstereolithography using SU-8 as the matrix material was verified by the fabrication of SU-8 photoplastic structures with subdiffraction-limit resolution. We show that the nonlinear velocity dependence of TPA photopolymerization can be used as the shutter mechanism for disruptive three-dimensional (3D) lithography. This mechanism, when combined with low numerical-aperture optics is exploited for the rapid 3D microfabrication of ultrahigh-aspect-ratio (up to 50:1) photoplastic pillars, planes, and cage structures.

Resist underlayer film material and pattern forming method

Abstract: PROBLEM TO BE SOLVED: To provide a resist underlayer film material which is a resist underlayer film material for a multilayered resist process for, for example, a resist upperlayer film containing silicon, and more particularly for a two-layer resist process, functions as an excellent antireflection film to exposure of a short wavelength in particular, i.e., has the transparency higher than that of polyhydroxy strene, cresol novolak, naphthol novolak, etc., has an optimum (n) value (refractive index), and (k) value (extinction coefficient) and has excellent etching resistance in substrate working, and a method for forming the pattern to a substrate by lithography using the same. SOLUTION: The resist underlayer film material for the multilayered resist films used for lithography contains at least the polymer expressed by general formula (1). COPYRIGHT: (C)2004,JPO&NCIPI

Characterization of buried photonic crystal waveguides and microcavities fabricated by deep ultraviolet lithography

Abstract: We present results of the optical characterization of silicon photonic crystal waveguides and microcavities that are completely buried in a silicon dioxide cladding and are fabricated by deep ultraviolet (UV) lithography. The advantages of buried waveguides and deep UV lithography are discussed. Transmission spectra and loss factors for photonic crystal waveguides, as well as quality factors for resonant microcavities, are obtained. The observed characteristics are in good agreement with three-dimensional simulations.

RADAR: RET-aware detailed routing using fast lithography simulations

Abstract: This paper attempts to reconcile the growing interdependency between nanometer lithography and physical design. We first introduce the concept of lithography hotspots and the edge placement error (EPE) map to measure the overall printability and manufacturing effort. We then adapt fast lithography simulation models to generate EPE map. Guided by the EPE map, we develop effective RET-aware detailed routing (RADAR) techniques that can handle full-chip capacity to enhance the overall printability while maintaining other design closure. RADAR is implemented in an industry strength detailed router, and tested using some 65nm designs. Our experimental results show that we can achieve up to 40% EPE reduction with reasonable CPU time.

Photolithographic route to the fabrication of micro/nanowires of III-V semiconductors

Abstract: Nano/microwires of semiconducting materials (e.g., GaAs and InP) with triangular cross-sections can be fabricated by "top-down" approaches that combine lithography of high-quality bulk wafers (using either traditional photolithography or phase-shift optical lithography) with anisotropic chemical etching. This method gives good control over the lateral dimensions, lengths, and morphologies of free-standing wires. The behaviors of many different resist layers and etching chemistries are presented. It is shown how wire arrays with highly ordered alignments can be transfer printed onto plastic substrates. This "top-down" approach provides a simple, effective, and versatile way of generating high-quality single-crystalline wires of various compound semiconductors. The resultant wires and wire arrays have potential applications in electronics, optics, optoelectronics, and sensing.

Room-temperature, continuous-wave, single-mode quantum-cascade lasers at λ≃5.4μm

Abstract: We demonstrate room-temperature, single-mode, continuous-wave operation of a λ≃5.4μm quantum-cascade laser up to the temperature of 30°C. Processing is done using standard lithography in a ridge waveguide mounted junction-up. The active region is based on a bound-to-continuum transition. The high performances were achieved with a low active region doping and a thick electroplated gold deposition, resulting in a characteristic temperature of T0=155K in continuous-wave with a threshold current density of jth=2.05kA∕cm2 at 300K.

Rectangular contact lithography for circuit performance improvement and manufacture cost reduction

Abstract: An optical lithography method is disclosed that uses double exposure of a reusable template mask and a trim mask to fabricate regularly-placed rectangular contacts in standard cells of application-specific integrated circuits (ASICs). A first exposure of the reusable template mask with periodic patterns forms periodic dark lines on a wafer and a second exposure of an application-specific trim mask remove the unwanted part of the dark lines and the small cuts of the dark lines left form the rectangular regularly-placed contacts. All contacts are placed regularly in one direction while unrestrictedly in the perpendicular direction. The regular placement of patterns on the template mask enable more effective use of resolution enhancement technologies, which in turn allows a decrease in manufacturing cost and the minimum contact size and pitch. Since there is no extra application-specific mask needed comparing with the conventional lithography method for unrestrictedly-placed contacts, the extra cost is kept to the lowest. The method of the invention can be used in the fabrication of standard cells in application-specific integrated circuits (ASICs) to improve circuit performance and decrease circuit area and manufacturing cost.

High performance plasmonic crystal sensor formed by soft nanoimprint lithography.

Abstract: This paper describes a new type of plasmonic sensor fabricated by imprint lithography using a soft, elastomeric mold. Angle-dependent, zero-order transmission experiments demonstrate the sensing potential of this device, which uses a two dimensional plasmonic crystal. Full angle-dependent mapping shows that the sensitivity to surface chemical binding events reaches maxima near regions of the plasmonic Brillouin zone where the dispersion curves of multiple surface plasmon polariton modes converge. This behavior, together with the simple, low cost procedures for building the structures, suggests a potentially important role for these devices in high performance chemical and biological sensing.

Chiral microstructures (spirals) fabrication by holographic lithography.

Abstract: We present an optical interference model to create chiral microstructures (spirals) and its realization in photoresist using holographic lithography. The model is based on the interference of six equally-spaced circumpolar linear polarized side beams and a circular polarized central beam. The pitch and separation of the spirals can be varied by changing the angle between the side beams and the central beam. The realization of the model is carried out using the 325 nm line of a He-Cd laser and spirals of sub-micron size are fabricated in photoresist.

A numerical and experimental study on gap compensation and wavelength selection in UV-lithography of ultra-high aspect ratio SU-8 microstructures

Abstract: This paper presents a study on UV-lithography of thick SU-8 resist using air gap compensation and optimal wavelength selection for ultra-high aspect ratio microstructures. Both numerical simulations and experiments were conducted to study effects of different lithography conditions: broadband light source with and without air gap compensation, filtered light source with glycerol liquid, and filtered light source with Cargille refractive index matching liquid. A thick PMMA sheet was used as an optical filter to eliminate most of the i-line components of a broadband light source. Using the filtered light source and gap compensation with the Cargille refractive index liquid perfectly matching that of SU-8, patterns with feature sizes of 6 μm thick, 1150 μm tall (aspect ratio of more than 190:1) and high quality sidewalls were obtained. Microstructures with height up to 2 mm and good sidewall quality were also obtained and presented. The study also proved that Cargille refractive index matching liquid is compatible with UV-lithography of SU-8 and may be used as an effective air gap compensation solution.

Super-hydrophobic/super-hydrophilic patterning of gold surfaces by photocatalytic lithography

Abstract: Super-hydrophobic and super-hydrophilic gold surfaces were prepared by modifying microstructured gold surfaces with thiols. The perfluorodecanethiol (PFDT)-modified rough gold surface was converted from super-hydrophobic (water contact angle = 150–160°) to super-hydrophilic (0–10°) by photocatalytic remote oxidation using a TiO2 film. During the remote oxidation, oxygen-containing groups were introduced to the thiol, and finally, even sulfur atoms were removed. Super-hydrophobic/super-hydrophilic patterns were also obtained by photocatalytic lithography, by using a TiO2-coated photomask. On the basis of this technique, enzymes and algal cells were patterned on the gold surfaces to fabricate biochips.