Showing papers on "Electron-beam lithography published in 1998"
TL;DR: In this article, surface-enhanced Raman scattering (SERS) was used to detect organic traces by electron-beam lithography, which is better reproducible than electrochemical roughened surfaces, island films or films over deposited particles.
Abstract: The detection of organic traces by surface-enhanced Raman scattering (SERS) requires rough metallic substrates with structures in the nanometer range. Regular metallic structures generated by electron-beam lithography are better reproducible than electrochemical roughened surfaces, island films or films over deposited particles. The lithography also allows optimisation of the dimensions of these structures. The SERS enhancement of optimised periodic structures was found to be at least one order of magnitude larger than that of island films.
290 citations
TL;DR: In this article, a new resist system providing small linewidth fluctuation has been developed for nanolithography Hydrogen silsesquioxane (HSQ) resist used here has a small polymer size because of its three-dimensional framework.
163 citations
TL;DR: In this article, the authors used electron beam lithography to make very small (<30 nm linewidth) mechanical structures in single-crystal silicon, which can be driven capacitively by applying a voltage between the suspended portion and the underlying substrate.
Abstract: We have used electron beam lithography to make very small (<30 nm linewidth) mechanical structures in single-crystal silicon. These structures can be driven capacitively by applying a voltage between the suspended portion and the underlying substrate. Optical interference techniques are used to detect and measure the motion of the structures with resonant frequencies above 40 MHz. We employed a design consisting of a square mesh with a 315 nm period, which results in a low mass (∼1×10−13 g) and large relative surface area (10−6 cm2). Also, by making suboptical-wavelength features, the optical properties can be altered, leading to an improved measurement sensitivity. We measured the oscillations at small amplitudes where the detected change in the optical reflection is proportional to the drive amplitude.
145 citations
TL;DR: Ions are particularly well suited for this because they suffer little or no scattering in the resist, the linewidth is not a strong function of dose (good process latitude), and the resist sensitivity is relatively independent to resist thickness or ion energy as discussed by the authors.
Abstract: Although optical lithography has been extended to far smaller dimensions than was predicted 15 years ago, there are definite physical barriers to extending it to the minimum dimensions of 70 nm that are projected to be required 15 years from now. Both focused, point electron beams and ion beams have been used to write dimensions in resist well below 20 nm, albeit at speeds far too slow for production lithography. Projection systems, which employ a mask and, in effect, produce a large array of beams, can provide both small minimum dimensions and high throughput. Ions are particularly well suited for this because they suffer little or no scattering in the resist, the linewidth is not a strong function of dose (good process latitude), and the resist sensitivity is relatively independent to resist thickness or ion energy. IMS in Vienna, Austria has built two generations of ion projection lithography systems which have demonstrated many of the features needed for high throughput lithography. In these systems a...
143 citations
TL;DR: In this paper, the authors developed scanning thermal microscopy probes for high resolution analysis of thermal properties in an atomic force microscope (AFM), which are patterned on the side of traditional style pyramidal AFM tips, giving a new shape of probe which is favorable for access to specimens containing significant topographic variation.
Abstract: We have developed scanning thermal microscopy probes for high resolution analysis of thermal properties in an atomic force microscope (AFM). Electron beam lithography and silicon micromachining have been used to batch fabricate Au/Pd thermocouples situated at the end of Si3N4 cantilevers. The cantilevers are patterned on the side of traditional style pyramidal AFM tips, giving a new shape of probe which is favorable for access to specimens containing significant topographic variation. Tip radius is approximately 50 nm and the probe has a macroscopic opening angle of 70°. The probes were scanned in the repulsive mode using a conventional AFM. Force feedback was optically employed to give topographic and thermal maps simultaneously by maintaining a constant force of approximately 5 nN. During initial scans using a photothermal test specimen, 80 nm period metal gratings were thermally resolved.
132 citations
TL;DR: In this article, high aspect ratio features as small as 40 nm with depth up to 840 nm were patterned in the hard SiC molds, and large arrays of nanostructures down to 40 nm were printed in Al with similar results for dots, short lines, and long lines.
Abstract: Nanostructures in Al were generated by printing with hard SiC molds. This nano-printing technology replaces the lithography and the etching or deposition processes to produce patterns directly in metal. Dots, short lines, and long lines were formed in the SiC molds by electron beam lithography and reactive ion etching. High aspect ratio features as small as 40 nm with depth up to 840 nm were patterned in the SiC molds. By pressing the SiC mold onto the Al substrate at room temperature, nanostructures in the SiC mold were reproduced accurately and uniformly in Al. Large arrays of nanostructures down to 40 nm were printed in Al with similar results for dots, short lines, and long lines. Using atomic force microscopy to analyze the cross sections of the SiC molds and printed Al nanostructures, depth dependence on feature size was observed. This nano-printing technology simplifies the processes for generating nanostructures with high throughput and high uniformity.
97 citations
TL;DR: In this paper, the authors used a quantum box array placed inside a GaAs/AlAs pillar microcavity as an internal broadband light source to split the twofold polarization degenerate fundamental mode of circular micropillars into a pair of orthogonal linearly polarized modes.
Abstract: GaAs/AlAs pillar microcavities with elliptical cross section have been fabricated by molecular beam epitaxy, electron-beam lithography, and reactive ion etching. We study their lowest energy confined photonic modes by photoluminescence, using a quantum box array placed inside the cavity as an internal broadband light source. Such an anisotropic cross section allows to split the twofold polarization degenerate fundamental mode of circular micropillars into a pair of orthogonal linearly polarized modes. Their energy splitting, which is well accounted for by a simple perturbative model, is studied experimentally and theoretically as a function of the eccentricity and average radius of the pillars. Splittings as large as 15 meV are observed, which is very encouraging for applications ranging from the improvement of the polarization locking in vertical cavity lasers to the fabrication of light emitting diodes with a better control of the spontaneous emission.
96 citations
TL;DR: In this article, a site-control method for self-organized InAs quantum dots on GaAs substrates by a combination of in situ electron-beam (EB) lithography and molecular-beam epitaxy (MBE) using an ultrahigh-vacuum multichamber system was studied.
Abstract: We studied a site-control method for self-organized InAs quantum dots on GaAs substrates by a combination of in situ electron-beam (EB) lithography and molecular-beam epitaxy (MBE) using an ultrahigh-vacuum multichamber system. Small and shallow holes were patterned on a MBE-grown GaAs (001) surface by in situ EB writing and Cl2-gas etching. When more than a 1.4 monolayer of InAs was applied to the patterned surface, In(Ga)As dots were preferentially self-organized in the holes while dot formation around the holes was sufficiently suppressed. When we further increased the amount of InAs, the dots enlarged remarkably, presumably due to a stress-relaxation effect.
92 citations
TL;DR: In this article, the authors compared the exposure properties of EBL and scanning probe lithography (SPL) and found that SPL requires a significantly higher incident electron dose for exposure than does EBL.
Abstract: Electron beam lithography (EBL) and scanning probe lithography (SPL) are electron exposure techniques capable of high resolution patterning of organic resists. This article compares the exposure properties of these two systems. We consider the resist sensitivity to EBL and SPL electrons, exposure tolerances, patterning linearity, and proximity effects. It is possible to print sub-50 nm features using both systems, but SPL has a wider exposure latitude at these small feature sizes. SPL requires a significantly higher incident electron dose for exposure than does EBL. In EBL, lithography control is most limited by proximity effects which arise from backscattered electrons whose range is considerably larger than the forward scattering range in the resist film. As a result, the exposed feature dimension depends strongly on the local feature density and size, leading to unacceptable linewidth variations across a wafer. These limitations are alleviated in the case of SPL exposures. We demonstrate improved linearity and reduced proximity effects with SPL. We have patterned 200 nm pitch grids with SPL where all individual features are resolved. The linewidth of features in these grids is the same as the width of an isolated line at the same dose. Finally, we suggest that the SPL exposure mechanism may be different than that for EBL.
85 citations
TL;DR: In this article, the authors demonstrate a fabrication method to define high-density, uniform nanostructures by electron beam lithography at conventional beam voltages (< 40 kV) using polymethylmethacrylate as positive resist and isopropyl alcohol as a developer.
Abstract: We demonstrate a fabrication method to define high-density, uniform nanostructures by electron beam lithography at conventional beam voltages (< 40 kV). Here we optimize the exposure and development conditions needed to generate such nanostructure arrays using polymethylmethacrylate as positive resist and isopropyl alcohol as a developer. Arrays of 12 nm dots with 25 nm period and 20 nm lines with 40 nm period were fabricated to show the resolution of this optimized process.
77 citations
TL;DR: In this paper, the use of carbon nanotubes as tips in atomic force microscopy for a systematic study of dry etching pattern transfer in GaAs is described, where GaAs samples are patterned via electron beam lithography and then etched using magnetron reactive ion or chemically assisted ion beam processing.
Abstract: The use of carbon nanotubes as tips in atomic force microscopy for a systematic study of dry etching pattern transfer in GaAs is described. The GaAs samples are patterned via electron beam lithography and then etched using magnetron reactive ion or chemically assisted ion beam processing. The technique allows diagnosis, in air, of etched features with scale sizes of <100 nm.
TL;DR: In this paper, the application of chemical derivatives of C60 as high-resolution electron beam resists was explored, and the results showed that these derivatives function as high resolution negative resists for electron beam lithography using monochlorobenzene as a developer.
Abstract: We have explored the application of chemical derivatives of C60 as high-resolution electron beam resists. Facile spin coating was used to produce ∼100-nm-thick films of a C60 tris adduct (three functional groups) on Si surfaces. We find that these films function as high-resolution negative resists for electron beam lithography using monochlorobenzene as a developer. The film has a sensitivity of ∼1 mC/cm2 for 20 keV electrons, an order of magnitude higher than that of C60 itself, and the dry-etch durability is much better than that of conventional novolac based electron beam resists. Features with widths of 20 nm were produced.
ENEA1
TL;DR: In this paper, photo-luminescent colored stripes have been fabricated by electron beam lithography in lithium fluoride crystals, and their guiding properties are demonstrated for the first time.
Patent•
24 Feb 1998TL;DR: In this paper, the authors describe an electron beam lithography system having a beamlet shaping section that includes a first multi-aperture array having m rows and n columns of apertures having a first shape and a second multi-approach array with m rows/columns having a second shape.
Abstract: An electron beam lithography system having a beamlet shaping section that includes a first multi-aperture array having m rows and n columns of apertures having a first shape and a second multi-aperture array with m rows and n columns of apertures having a second shape. Electron beamlets formed by the first multi-aperture array are deflected by a deflector unit before passing through the second multi-aperture array. The superposition of the electron beamlets on the second multi-aperture produces electron beamlets having a selected shape. Deflection logic on an active beam aperture array blank selected electron beamlets. The deflection logic can be updated with the next logic pattern as the current logic pattern is being executed. The unblanked electron beamlets are directed onto a surface to be exposed. The deflection logic on the active beam aperture array, and the multi-aperture arrays, are shielded from electrons and x-rays generated by the electrons striking surfaces within the electron beam lithography system. Sensitive deflection logic is radiation hardened to prevent degradation.
TL;DR: In this article, the thermal and chemical stability of supported silver catalysts in both oxidizing and reducing conditions was examined in an ordered metal nanocluster array fabricated by electron beam lithography, and a nanometer scale pattern was created on a poly(methyl methacrylate) (PMMA) surface by electronbeam lithography.
Abstract: Lithographic technologies are applied to fabricate model systems for surface science and heterogeneous catalysis studies. An ordered metal nanocluster array fabricated on oxide substrates is also an ideal model system of supported industrial catalysts. Taking advantage of an ordered nanocluster array fabricated by electron beam lithography, the thermal and chemical stability of supported silver catalysts are examined in both oxidizing and reducing conditions. In reducing conditions, the supported silver nanoparticles are stable up to {approx}700 C. In oxidizing conditions, however, the silver nanoparticles are oxidized below 200 C, and conglomerate to micrometer-size amorphous clusters {approx}400 C. The supported nanocluster sample can also be adapted to study reactivity of supported metal catalysts, as confirmed by measurement of ethylene hydrogenation turnover rates on platinum nanoparticle samples. Lithographic technologies can also fabricate model systems for other surface science research. A nanometer scale pattern is created on a poly(methyl methacrylate) (PMMA) surface by electron beam lithography. The sample is adapted to test a recent development in nanotribology, in which surface elastic modulus (hardness) is determined by a modified atomic force microscope. In addition, lithographically fabricated supported nanostructures are used to image the AFM tip (thereby determining the radius of curvature of the tip), whichmore » is a critical parameter for the quantification of surface mechanical properties such as elastic modulus. Finally, taking advantage of the uniform height profile of lithographically fabricated nanostructures, ion sputtering yield can be determined by the reduction of nanostructure height as a function of ion exposure.« less
TL;DR: In this article, electron-beam lithography on Si substrates has been used to construct submicrometric magnetic structures with high-quality patterns with typical length scale of the structures in the range of 100 nm.
Abstract: Submicrometric magnetic structures have been fabricated by electron-beam lithography on Si substrates. High-quality patterns have been obtained with typical length scale of the structures in the range of 100 nm. The designed geometrical configurations are suitable for investigation of their physical properties by transport measurements in a controlled way. In particular, long chains of connected magnetic dots are useful to analyze magnetization reversal processes, whereas ordered arrays of isolated dots can be used to study pinning effects in superconducting films.
TL;DR: DiVa as mentioned in this paper is a distributed system, employing multiple variable shaped beams for direct write (maskless) lithography, which utilizes a planar cathode, patterned with a rectilinear array of square emitters.
Abstract: The ultimate resolution obtainable with focused electron beams is, for practical purposes in lithography, unlimited. Existing e-beam lithography systems are too slow to be practical for high volume manufacturing of semiconductor devices, however. The usable current in probe forming systems is limited by the stochastic Coulomb interaction in the beam path, which causes loss of resolution at high current. This is due to the need to pass all of the writing current through an aperture. Distributed systems, by contrast, do not suffer from this problem, as the current is spread over a large volume. The purpose of this article is to propose a distributed system, employing multiple, variable shaped beams for direct write (maskless) lithography. We call this system DiVa, to emphasize the key attributes of distributed writing current, and variable beam shaping. It utilizes a planar cathode, patterned with a rectilinear array of square emitters. Focusing is accomplished by a uniform, axial magnetic field, oriented a...
TL;DR: In this article, Lohmann-coded binary-phase diffractive elements with restricted amplitude recording are fabricated by electron beam lithography and reactive ion etching, and the experimental results are in good agreement with theory.
Abstract: Transversally sharply structured optical fields are discussed, which rotate upon propagation without any lateral expansion of the intensity profile. Finite-aperture approximations of such fields, realizable with phase-only and complex-amplitude recording, are demonstrated. Recording of at least some of the amplitude information (rather than neglecting it completely) is shown to improve the field quality considerably, in particular close to the element. Lohmann-coded binary-phase diffractive elements with restricted amplitude recording are fabricated by electron beam lithography and reactive ion etching. The experimental results are in good agreement with theory.
Patent•
20 Mar 1998
TL;DR: In this article, the authors describe methods for fabricating nano-structured surfaces having geometries in which the passage of elementary particles through a potential barrier is enhanced using combinations of electron beam lithography, lift-off, and rolling, imprinting or stamping processes.
Abstract: Methods for fabricating nano-structured surfaces having geometries in which the passage of elementary particles through a potential barrier is enhanced are described. The methods use combinations of electron beam lithography, lift-off, and rolling, imprinting or stamping processes.
TL;DR: In this paper, a method for the fabrication of generic scanned-probe microscope probes by performing multiple level direct-write electron-beam lithography on the apex of micromachined atomic force microscope tips is presented.
Abstract: We present a novel method for the fabrication of generic scanned-probe microscope probes by performing multiple level direct-write electron-beam lithography on the apex of micromachined atomic force microscope tips. Pattern transfer is by conventional etching or liftoff in a wide range of materials. Lithographic resolution is 50 nm or better. The substrates support the use of automatic alignment and allow for the fabrication of 50 probes/in2. The integration of a force-sensing cantilever permits simple height regulation of the probes during operation. The technology is illustrated by the fabrication of thermocouple and near-field optical probes.
TL;DR: In this article, the authors proposed to use a high-power 257 nm laser in combination with the relatively high work function and low quantum efficiency of gold films to produce practical multicathode electron sources for electron beam lithography.
Abstract: Photoemission is a promising approach to electron sources for electron beam lithography because of the ease with which various shapes or arrays of independently modulated sources can be fabricated. However, most high-quantum-efficiency photoemitters are extremely sensitive to even partial monolayers of contamination, and therefore require some combination of differential pumping systems and photoemitter surface protection after activation. Here we propose to use a high-power 257 nm laser in combination with the relatively high work function and low quantum efficiency of gold films to produce practical multicathode electron sources for electron beam lithography. Gold films have the offsetting advantages that their photoemission characteristics are relatively reproducible and stable even in contaminating environments. It is possible, therefore, to prepare and handle them in air as well as operate them in less demanding vacuum environments. It is shown that a back-illuminated 15 nm gold film on a quartz or s...
Proceedings Article•
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TL;DR: In this paper, the growth technique used was low pressure chemical vapor deposition (LPCD) for SiGe as well as device applications such as light-emitting diodes.
Abstract: There is increasing interest in Si-based optoelectronics using Si/sub 1-x/Ge/sub x/ nanostructures due to the possibility of their integration with the Si technology. To overcome the problem of the indirect character of SiGe one is looking for means to increase the transition probability by realizing structures involving quantum size effects. Several fabrication strategies for semiconductor nanostructures have been proposed. One possible approach involves selective epitaxy to fill-in the small holes in patterned substrates. To realize the lateral confinement below 100 nm the patterned substrates are made either by e-beam lithography or by optical lithography. In the latter case, the sub-100 nm confinement is realized by the development of facets. Another approach for nanostructures is based on self-organized growth which leads to island formation in highly lattice-mismatched layers. In this paper these items are discussed for SiGe as well as device applications such as light emitting diodes. The growth technique used was low pressure chemical vapor deposition.
TL;DR: In this paper, a masked ion beam lithography using highly charged ions is demonstrated for the first time by producing an array of hundreds of ordered micrometer wide dots using Xe44+ on poly(methylmethacrylate) resist.
Abstract: Masked ion beam lithography using highly charged ions is demonstrated for the first time by producing an array of hundreds of ordered micrometer wide dots using Xe44+ on poly(methylmethacrylate) resist. At low dose, exposure of the resist is incomplete and isolated single-ion impact sites can be seen within the exposed areas. Atomic force microscope images of the single-ion impact sites show craters with a width of 24 nm. At high dose, the exposure is complete and the dot morphology is consistent with limitations from the mask. Scanning electron microscope images indicate that the sidewall slope is steeper than four.
TL;DR: In this paper, a line-and-space pattern for atomic force microscopy lithography using a current-controlled exposure feedback system is investigated by fabricating line and space patterns on the negative-type electron beam resist RD2100N.
Abstract: Characteristics of atomic force microscopy lithography using a current-controlled exposure feedback system are investigated by fabricating line-and-space patterns on the negative-type electron beam resist RD2100N. We find that the cross-sectional shape of the developed resist pattern depends on the amount of exposure. The resolution depends on the resist thickness,and a minimum line width of 27 nm is obtained for a 15-nm-thick resist. The proximity effect is evaluated by comparing a resist pattern with a model calculation. Electric-field mapping inside the resist is calculated,and an exposure mechanism is proposed to explain the characteristics.
TL;DR: In this paper, a strategy for arbitrary deep profile generation as well as results were achieved by using single and combined technologies of special gray scale masks (based on HEBS glass), e-beam lithography and photolithography.
Abstract: The fabrication of surface profile may become an interesting technology in the field of micro optics and micromachining. Recently, surface profiles are known and widely used in optics, especially in diffractive optics. In the last few years the demand on deep and arbitrarily shape profiles increased drastically. Laser beam writing and e-beam writing are technologies suitable for the fabrication of such profiles, but only for a limited range of profile depth. Photolithography is also able to realize surface profiles, much deeper profiles can be realized by combining of different technologies. In this paper we report about a strategy for arbitrary deep profile generation as well as results we achieved by using single and combined technologies of special gray scale masks (based on HEBS glass), e-beam lithography and photolithography.
TL;DR: In this paper, a binary diffractive axicon is fabricated by electron beam lithography to generate a uniform axial line focus over a specified interval, and a split-groove apodization method is introduced to suppress second-order interference.
TL;DR: In this article, direct electron-beam writing of surface relief diffractive elements into hybrid inorganic/organic sol-gel glass films is demonstrated. But the etch depth and phase delay can be controlled by the electron dose.
Abstract: The authors propose and demonstrate direct electron-beam writing of surface relief diffractive elements into hybrid inorganic/organic sol-gel glass films. The etch depth and phase delay can be controlled by the electron dose. The potential applications include multi-phase-level diffractive elements and apodised planar waveguide gratings.
TL;DR: In this article, a nanostructured integrated field emission electron source is built into a lithographically fabricated pattern of connecting lines on a chip, and current stabilizing resistors are integrated in to the connecting lines with the deposition technique.
Abstract: Additive nanolithography with electron-beam induced deposition is applied to generate a nanostructured integrated field emission electron source. The source is built into a lithographically fabricated pattern of connecting lines on a chip. Current stabilizing resistors are integrated in to the connecting lines with the deposition technique. Field emission microscope investigation of deposited supertips proves that a confined emission is delivered from conducting tips into a beam divergence angle of ±7°. The reduced brightness of the deposited supertips is evaluated. A tenfold higher reduced brightness is observed if compared to conventional Schottky field emitters.
TL;DR: In this paper, a doped-thin-Si-film single-electron transistors (DS-SETs) are proposed, which are fabricated from a highly doped Si film in a silicon-on-insulator substate by electron-beam lithography with a high-resolution resist (calixarene) and dry etching with CF4 gas.
Abstract: We propose doped-thin-Si-film single-electron transistors (DS-SETs), which are fabricated from a highly doped Si film in a silicon-on-insulator substate by electron-beam lithography with a high-resolution resist (calixarene) and dry etching with CF4 gas. Because the structure can be well controlled, the DS-SET with a 45-nm-diam island shows nearly ideal characteristics of SETs with a charging energy of 1.4 meV. The results demonstrate that single-electron tunneling occurs through a single island without any isolated islands formed in potential fluctuations. We also discuss the discreteness of energy levels in a Si island.
TL;DR: In this article, a low-cost gray-tone mask fabrication for thick resist UV lithography is described, and the experimental relation between the theoretical transmission and the remaining resist thickness after development is presented.
Abstract: A low-cost gray-tone mask fabrication for thick resist UV lithography is described. The experimental relation between the theoretical transmission and the remaining resist thickness after development is presented.