Showing papers on "Electron-beam lithography published in 2001"
TL;DR: A method of constructing <30-nanometer structures in close proximity with precise spacings is presented that uses the step-by-step application of organic molecules and metal ions as size-controlled resists on predetermined patterns, such as those formed by electron-beam lithography.
Abstract: The present invention is a method and apparatus relating to manufacturing nanostructure patterns and components using molecular science. The method includes overlaying a multilayer organic molecule resist on at least a portion of a parent structure selectively deposited on a substrate, depositing a layer over the parent structure and in contact with at least a portion of the multilayer organic resist, and removing the multilayer organic molecule resist to leave a residual structure.
2,301 citations
TL;DR: In this paper, a point dipole analysis predicts group velocities of energy transport that exceed 0.1c along straight arrays and shows that energy transmission and switching through chain networks such as corners and tee structures is possible at high efficiencies.
Abstract: The further integration of optical devices will require the fabrication of waveguides for electromagnetic energy below the diffraction limit of light. We investigate the possibility of using arrays of closely spaced metal nanoparticles for this purpose. Coupling between adjacent particles sets up coupled plasmon modes that give rise to coherent propagation of energy along the array. A point dipole analysis predicts group velocities of energy transport that exceed 0.1c along straight arrays and shows that energy transmission and switching through chain networks such as corners (see Figure) and tee structures is possible at high efficiencies. Radiation losses into the far field are expected to be negligible due to the near-field nature of the coupling, and resistive heating leads to transmission losses of about 6 dB/lm for gold and silver particles. We analyze macroscopic analogues operating in the microwave regime consisting of closely spaced metal rods by experiments and full field electrodynamic simulations. The guiding structures show a high confinement of the electromagnetic energy and allow for highly variable geometries and switching. Also, we have fabricated gold nanoparticle arrays using electron beam lithography and atomic force microscopy manipulation. These plasmon waveguides and switches could be the smallest devices with optical functionality.
1,650 citations
TL;DR: In this paper, a surface nanomachining process is described that involves electron beam lithography followed by dry anisotropic and selective electron cyclotron resonance plasma etching steps.
Abstract: SiC is an extremely promising material for nanoelectromechanical systems given its large Young's modulus and robust surface properties. We have patterned nanometer scale electromechanical resonators from single-crystal 3C-SiC layers grown epitaxially upon Si substrates. A surface nanomachining process is described that involves electron beam lithography followed by dry anisotropic and selective electron cyclotron resonance plasma etching steps. Measurements on a representative family of the resulting devices demonstrate that, for a given geometry, nanometer-scale SiC resonators are capable of yielding substantially higher frequencies than GaAs and Si resonators.
279 citations
TL;DR: In this article, the feasibility of immersion lithography at 157 nm for patterning below 70 nm was investigated and it was shown that this technology can enable an enhancement in resolution of ∼40% without radical changes in lasers, optics, or resist technology.
Abstract: We present a preliminary study on the feasibility of immersion lithography at 157 nm for patterning below 70 nm. This technology can enable an enhancement in resolution of ∼40% without radical changes in lasers, optics, or resist technology. We have identified a class of commercially available liquids, perfluoropolyethers, which are good candidates for use as immersion liquids. They are transparent (α≈10−3 μm−1 base 10), optically clean, chemically inert, and compatible with at least some current resist materials and with the semiconductor manufacturing environment. We have also constructed a high-resolution lensless interference immersion lithography system, preserving much of the design of a previous nonimmersion interference system. With this immersion interference tool, we have patterned resist with 30 nm dense features.
272 citations
TL;DR: With increasing diameter and decreasing film thickness a metastable near single domain state can be obtained during the reversal process in an in-plane applied field.
Abstract: Measurements are reported on the magnetization reversal in submicron magnetic rings fabricated by high-resolution electron beam lithography and lift-off from cobalt thin films. For all dimensions investigated, with diameters of 300-800 nm and a thickness of 10-50 nm, the flux closure state is the stable magnetization configuration. However, with increasing diameter and decreasing film thickness a metastable near single domain state can be obtained during the reversal process in an in-plane applied field.
272 citations
TL;DR: In this article, a heat-depolymerizable polycarbonate (HDP) was used as a sacrificial layer in fabricating nanofluidic devices by electron beam lithography.
Abstract: This research investigates a heat-depolymerizable polycarbonate (HDP) for use as a sacrificial layer in fabricating nanofluidic devices by electron beam lithography. When solid HDP films are heated to 300 °C, the monomer units separate into a nontoxic vapor. This property suggests that a patterned HDP film may be used as a temporary support for another film which is stable at the depolymerization temperature. Heating the structure removes the HDP, leaving a network of nanofluidic tubes without the use of solvents or other chemicals as required in most other sacrificial layer processes. We found that HDP films may be patterned directly by electron beam lithography, followed by immersion in isopropanol to remove HDP from the exposed areas. The patterns are then sputter coated with silicon dioxide at low temperature, provided with access holes for venting, heated to clear out HDP remaining inside the tubes, and injected with fluorescent dye for observation. Tube dimensions of 140 nm height, 1 μm width, and 1...
133 citations
20 May 2001
TL;DR: In this article, a planar multiplier circuit for 200 GHz to 2700 GHz has been demonstrated using a variety of metal and GaAs membrane configurations made available by these fabrication techniques.
Abstract: Multiplier device fabrication techniques have been developed to enable robust implementation of monolithic circuits well into the THz frequency range. To minimize the dielectric loading of the waveguides, some circuits are realized entirely on a 3 /spl mu/m thick GaAs membrane with metal beamleads acting as RF probes and DC contact points. Other designs retain some thicker GaAs as a support and handling structure, allowing a membrane of bare metal or thin GaAs to be suspended across an input or output waveguide. Extensive use is made of selective etches, both reactive ion (RIE) and wet chemical, to maintain critical dimensions. Electron beam (e-beam) lithography provides the small contact areas required at the highest frequencies. Planar multiplier circuits for 200 GHz to 2700 GHz have been demonstrated using a variety of metal and GaAs membrane configurations made available by these fabrication techniques.
107 citations
TL;DR: In this paper, lines of 20-nm polystyrene beads were formed on gold by exposing a mercaptohexadecanoic acid (MHDA) monolayer, then backfilling with cysteamine, and selectively attaching aldehyde-coated beads to the amines.
Abstract: Adhesive templates for biomolecule patterning were fabricated on silicon and gold by low-voltage (1 kV) electron beam lithography of an inert self-assembled monolayer, followed by backfilling the exposed regions with an amine-terminated monolayer. Amine-terminated monolayers selectively attached either the desired materials or linker molecules that subsequently bound other materials including antibodies. Lines (300 nm wide) of 20-nm polystyrene beads were formed on gold by exposing a mercaptohexadecanoic acid (MHDA) monolayer, then backfilling with cysteamine, and selectively attaching aldehyde-coated beads to the amines. Attachment density was found to vary sharply around a critical dose, making the technique useful for patterns such as gradients which require varying density. An optimal dose of 200 μC/cm2 was found for attaching fluorescent polystyrene spheres to MHDA−cysteamine templates. A cycling process was developed for aligning patterns of two or more kinds of polystyrene spheres. Biotin was tethe...
105 citations
TL;DR: In this paper, a record low threshold current density of 94 A/cm/sup 2/ among 1.55-/spl mu/m GaInAsP-InP strongly index-coupled and gain-matched distributed-feedback (DFB) lasers with periodic wire-like active regions fabricated by electron beam lithography, CH/sub 4/H/sub 2/-reactive ion etching, and organometallic vapor-phase epitaxial regrowth, whose index coupling coefficient was more than 300 cm/sup -1/.
Abstract: High-performance 1.55-/spl mu/m wavelength GaInAsP-InP strongly index-coupled and gain-matched distributed-feedback (DFB) lasers with periodic wirelike active regions mere fabricated by electron beam lithography, CH/sub 4//H/sub 2/-reactive ion etching, and organometallic vapor-phase epitaxial regrowth, whose index-coupling coefficient was more than 300 cm/sup -1/. In order to design lasers for low threshold current operation, threshold current dependences on the number of quantum wells and the wire width mere investigated both theoretically and experimentally. A record low threshold current density of 94 A/cm/sup 2/ among 1.55-/spl mu/m DFB lasers was successfully obtained for a stripe width of 19.5 /spl mu/m and a cavity length of 600 /spl mu/m. Moreover, a record low threshold current of 0.7 mA was also realized at room temperature under CW condition for a 2.3-/spl mu/m-wide buried heterostructure with a 200-/spl mu/m-long cavity. Finally, we confirmed stable single-mode operation due to a gain-matching effect between the standing-wave profile and the wirelike active region.
87 citations
TL;DR: In this paper, the fabrication, calculations, and transmission measurements for finite two-dimensional polymer photonic crystal (PC) slab waveguides were presented, which were fabricated from a benzocyclobutene polymer on a low refractive index substrate from Teflon.
Abstract: We present details of the fabrication, calculations, and transmission measurements for finite two-dimensional (2D) polymer photonic crystal (PC) slab waveguides, which were fabricated from a benzocyclobutene polymer on a low refractive index substrate from Teflon. A square air hole lattice (500 nm lattice constant, 300 nm hole diameter) was realized by electron beam lithography and reactive ion etching. Polarization and wavelength dependent transmission results show TE-like and TM-like stop gaps at 1.3 μm excitation wavelengths and are in good agreement with the calculated data obtained by 2D and three-dimensional finite difference time domain methods. Transmission was suppressed by 15 dB in the center of the TE-like stop gap for a PC length of ten lattice constants.
75 citations
TL;DR: In this article, the lifetime of a single electron stored in a nanocrystalline Si (nc-Si) dot has been studied in order to understand the physical processes for memory applications.
Abstract: The lifetime of the emission of a single electron stored in a nanocrystalline Si (nc-Si) dot has been studied in order to understand the physical processes for memory applications. A small active area field effect transistor channel (50×25 nm) is defined by electron-beam lithography on a thin (20 nm) silicon-on-insulator channel and allows for the electrical isolation of a single nc-Si dot. Remote plasma enhanced chemical vapor deposition is used to form 8±1 nm diameter nc-Si dots in the gas phase from a pulsed SiH4 source. Electrons stored in a dot results in an observed discrete threshold shift of 90 mV. Analysis of lifetime as a function of applied potential and temperature show the dot to be an acceptor site with nearly Poisson time distributions. An observed 1/T2 dependence of lifetime is consistent with a direct tunneling process, and interface states are not the dominant mechanism for electron storage in this device structure. Median emission lifetimes as a function of applied gate bias are readily...
TL;DR: In this article, the amplified spontaneous emission of the red light from LiF:F2 centers in active channel waveguides realized by electron-beam lithography in lithium fluoride crystals is reported.
Abstract: In this letter we report the observation of amplified spontaneous emission of the red light from LiF:F2 centers in active channel waveguides realized by electron-beam lithography in lithium fluoride crystals. Low pumping power densities have been used in quasi-continuous-wave regime at room temperature; the appreciable values of the gain coefficients, 4.67 cm−1 with an exciting power density of 0.31 W/cm2 at 458 nm, make this material a good candidate for the realization of active integrated optical devices.
TL;DR: In this article, a process for fabricating gated cathode structures that uses a single in situ grown carbon nanofiber as a field emission element was described, and the electrostatic gating structure was fabricated using a combination of traditional micro-and nanofabrication techniques.
Abstract: Vertically aligned carbon nanofibers (VACNFs) are extremely promising cathode materials for microfabricated field emission devices, due to their low threshold field to initiate electron emission, inherent stability, and ruggedness, and relative ease of fabrication at moderate growth temperatures. We report on a process for fabricating gated cathode structures that uses a single in situ grown carbon nanofiber as a field emission element. The electrostatic gating structure was fabricated using a combination of traditional micro- and nanofabrication techniques. High-resolution electron beam lithography was used to define the first layer of features consisting of catalyst sites for VACNF growth and alignment marks for subsequent photolithography steps. Following metallization of these features, plasma enhanced chemical vapor deposition (PECVD) was used to deposit a 1-μm-thick interlayer dielectric. Photolithography was then used to expose the gate electrode pattern consisting of 1 μm apertures aligned to the buried catalyst sites. After metallizing the electrode pattern the structures were reactive ion etched until the buried catalyst sites were released. To complete the devices, a novel PECVD process using a dc acetylene/ammonia/helium plasma was used to grow single VACNFs inside the electrostatic gating structures. The issues associated with the fabrication of these devices are discussed along with their potential applications.
Patent•
28 Jun 2001TL;DR: In this article, a method for fabricating a stencil mask for use in electron beam lithography which improves resolution by effectively reducing beam blur resulting from coulomb repulsion effects in the electron beam is described.
Abstract: Disclosed is a method for fabricating a stencil mask for use in electron beam lithography which improves resolution by effectively reducing beam blur resulting from coulomb repulsion effects in the electron beam The disclosed method includes fabricating a first mask and a second mask that are then aligned and joined to form the final stencil mask The structure of the second mask limits the number and controls the initial pattern of the electrons that pass through the stencil mask to limit beam blur, narrow the incident energy distribution, and improve the resolution of the final image
TL;DR: In this article, an analytical electron-resist interaction (ERI) model is developed based on detailed investigation of secondary electron production and binding energy related exposure events. But the model is limited to chemically amplified resists.
Abstract: An analytical electron-resist interaction (ERI) model is developed based on detailed investigation of secondary electron production and binding energy related exposure events. Analysis shows that 80% of the exposure events are directly caused by secondary electrons for 100 keV primary electron energy. The number of secondary electrons and further cascade electrons is 1/20 and 1/300, respectively, of the incoming electrons. An algebraic expression is derived to describe the spatial distribution of the exposure events. The ERI model can be extended to chemically amplified resists.
TL;DR: In this paper, electron-beam writing is used to locally modify the terminal nitro functionality in self-assembled monolayers of 4′-nitro-1,1′-biphenyl-4-thiol to amino groups, while the underlying aromatic layer is dehydrogenated and cross linked.
Abstract: We demonstrate a simple scheme to generate chemical surface nanostructures. Electron-beam writing is used to locally modify the terminal nitro functionality in self-assembled monolayers of 4′-nitro-1,1′-biphenyl-4-thiol to amino groups, while the underlying aromatic layer is dehydrogenated and cross linked. Using low energy electron proximity printing and conventional electron-beam lithography with a beam energy of 2.5 keV and doses from 2500 to 50 000 μC/cm2, templates of reactive amino sites with lateral dimensions down to ∼20 nm could be fabricated. The templates were used for the surface immobilization of fluorinated carboxylic acid anhydrides and rhodamine dyes. The molecular structures were then imaged and analyzed by atomic force and scanning confocal fluorescence microscopy.
09 Nov 2001
TL;DR: A review of the current state of the art in optical and electron beam lithography simulation is presented in this paper, where basic physical models are described and examples are given, and rigorous electromagnetic simulation for mask topography is shown and the use of statistical modeling to predict feature size distributions in manufacturing is described.
Abstract: A review of the current state of the art in optical and electron beam lithography simulation is presented. Basic physical models are described and examples are given. In addition, rigorous electromagnetic simulation for mask topography is shown and the use of statistical modeling to predict feature size distributions in manufacturing is described. Finally, numerous examples of the use of lithography simulation and its impact on the semiconductor industry are offered.
TL;DR: In this paper, a fast parallel method for the fabrication of continuous profile structures in polymer surfaces using a XeCl excimer laser at a wavelength of 308 nm was investigated, where the used quartz grey tone phase masks consist of diffractive gratings which diffract a fraction of the impinging light out of the aperture of the projection lens.
TL;DR: In this article, the field emission properties of vertically aligned carbon nanofibers (VACNFs) were measured using a moveable current probe and found that they have low FE turn-on fields and can achieve stable emission for extended periods of time in moderate vacuum.
Abstract: The digital electrostatic electron beam array lithography concept under development at the Oak Ridge National Laboratory proposes performing direct write electron beam lithography with a massively parallel array of electron emitters operating simultaneously within a digitally programmable microfabricated field emitter array (FEA). Recently we have concentrated our research efforts on the field emission (FE) properties of deterministically grown vertically aligned carbon nanofibers (VACNFs). We have measured the FE properties of isolated VACNFs using a moveable current probe and found that they have low FE turn-on fields and can achieve stable emission for extended periods of time in moderate vacuum. In order to use the VACNF in microfabricated FEA devices we have subjected them to a variety of processing phenomenon including reactive ion etching and plasma enhanced chemical vapor deposition, and found them to be quite robust. Using these processes we have fabricated operational gated cathode structures wi...
TL;DR: In this paper, the displacement of noncovalently bound amine ligands from a siloxane host film was used as templates for the selective deposition of an electroless nickel film resulting in a positive tone imaging mechanism.
Abstract: We report the development of an imaging layer technology for 50 kV electron-beam lithography based upon the displacement of noncovalently bound amine ligands from a siloxane host film. The patterned films were used as templates for the selective deposition of an electroless nickel film resulting in a positive tone imaging mechanism. The deposited nickel was sufficiently robust to function as an etch mask for pattern transfer by reactive ion etching. Metallized and etched patterns with linewidths to approximately 40 nm are demonstrated using an exposure dose of 500 μC/cm2.
31 Oct 2001
TL;DR: In this article, the early processes of radiation chemistry in the chemically amplified resists within 100 ps after irradiation in an electron beam lithography system were investigated, and the sub-picosecond pulse radiolysis with good signal/noise ratio was constructed to investigate radiation-induced reactions of an onium salt.
Abstract: To fabricate a structure with nanoscale dimension or even with the line edge roughness of less than several nanometers, it is important to understand the early process of radiation chemistry in resist materials. In this paper, we focussed on the early processes of radiation chemistry in the chemically amplified resists within 100 ps after irradiation in an electron beam lithography system. We constructed the subpicosecond pulse radiolysis with good signal/noise ratio to investigate radiation-induced reactions of an onium salt.
TL;DR: In this article, the authors report on the fabrication and testing of linear transmission Fresnel zone plates for hard x-rays, which are generated by electron beam lithography and chemical wet etching of 〈110〉 oriented silicon substrates.
Abstract: We report on the fabrication and testing of linear transmission Fresnel zone plates for hard x rays. The diffractive elements are generated by electron beam lithography and chemical wet etching of 〈110〉 oriented silicon substrates. By tilting the cylindrical lenses with respect to the x-ray beam, the effective path through the phase shifting zones can be varied. This makes it possible to optimize the diffraction efficiency over a wide range of photon energies, and to obtain effective aspect ratios not accessible with untilted optics. The diffraction efficiency of such a lens was measured as a function of the tilt angles for various energies between 8 and 29 keV. Values close to the theoretical limit were obtained for all energies. Because of the coherence preserving properties of diffractive optics, the method opens up opportunities for experiments using coherent hard x rays.
TL;DR: In this article, a fabrication scheme for two-dimensional (2D) triangular photonic crystals (PCs) on InP-based material systems involving high resolution electron beam lithography, pattern transfer to a SiO2 etch mask, and a Cl2/Ar electron cyclotron resonance reactive ion etch step yielding PCs with periods of a=300-450 nm and air fill factors of f=18%−63.
Abstract: We have developed a fabrication scheme for two-dimensional (2D) triangular photonic crystals (PCs) on InP-based material systems involving high resolution electron beam lithography, pattern transfer to a SiO2 etch mask, and a Cl2/Ar electron cyclotron resonance reactive ion etch step yielding PCs with periods of a=300–450 nm and air fill factors of f=18%–63%. These PCs are employed as high reflectivity mirrors for 1.5 μm short cavity lasers, which are key components in future highly integrated PC based photonic circuits. We have fabricated lasers with 2 PC mirrors and cavity lengths down to 100 μm. Threshold currents as low as 7.6 mA were achieved for the shortest lasers with 2 PC mirrors. The short laser cavity results in a large Fabry–Perot mode spacing and mode competition leads to single mode lasing over a reasonably large current range up to 4.5× threshold. Lasers with one PC back mirror and a cleaved output facet show a higher threshold current of 13 mA and a maximum output power of more than 4 mW. ...
TL;DR: In this article, the optical properties of arrays of submicrometer sized InGaN/GaN MQW posts, created by patterning and etching of epitaxially grown wafer material, were studied.
Abstract: We have developed fabrication approaches and studied the optical properties of arrays of submicrometer sized InGaN/GaN MQW posts, created by patterning and etching of epitaxially grown wafer material. Two approaches have been employed: a) electron beam lithography, by which posts of individual diameter of 100 nm have been realized; b) the use of nanometer-scale self-assembled templates of porous alumina as masks, to fabricate posts on a 50 nm scale. Robust violet light emission at room temperature has been observed in such nanoscale structures.
TL;DR: In this article, the performance of a Raith 150 electron-beam lithography system was evaluated for patterning sub-20 nm features, and the largest intra-field distortion for a 100 μm field was measured to be 15 nm.
Abstract: The performance of a Raith 150 electron-beam lithography system is reported. The system’s resolution, stability, intrafield distortion, stitching, and overlay performance are evaluated. Patterning at low- and high-acceleration voltages is compared. The system was used to pattern sub-20 nm features, and the largest intrafield distortion for a 100 μm field was measured to be 15 nm. Pattern-placement accuracy below 35 nm, mean plus twice the standard deviation, was demonstrated.
01 Sep 2001
TL;DR: In this paper, the mesoscopic Josephson junction qubits are fabricated by electron beam lithography using single-layer and multilayer resists, which is simpler and more accurate to implement, and avoids the significant areas of redundant metallisation that are an unavoidable byproduct of the tri-layer shadow mask method.
Abstract: The authors have developed two distinct processes for the fabrication of mesoscopic Josephson junction qubits that are compatible with conventional CMOS processing. These devices, based on superconducting Al/Al/sub 2/O/sub 3//Al tunnel junctions, are fabricated by electron beam lithography using single-layer and multilayer resists. The new single-layer resist process is found to have significant advantages over conventional fabrication methods using suspended tri-layer shadow masks. It is simpler and more accurate to implement, and avoids the significant areas of redundant metallisation that are an unavoidable by-product of the tri-layer shadow mask method.
01 Jan 2001
TL;DR: In this paper, a two-dimensional subwavelength-structure (SWS) surface on GaAlAs wafer was fabricated using EB lithography and fast atom beam (FAB) etching with the process gases of SF/sub 6/ and Cl/sub 2/ were used.
Abstract: In this study, we fabricated a two-dimensional subwavelength-structure (SWS) surface on GaAlAs wafer. The SWS surface consists of 200 nm period tapered grating. In the fabrication, electron-beam (EB) lithography and fast atom beam (FAB) etching with the process gases of SF/sub 6/ and Cl/sub 2/ were used. We demonstrated that the SWS surfaces worked well for enhancing the emission from GaAlAs light emitting diode (LED) and for suppressing the reflection from GaAlAs photodiode.
TL;DR: In this article, the backscatter range for 100 kV on silicon is about 27 μm compared to 8 μm at 50 kV, and scattering in an intermediate range is observed and must be taken into account in order to achieve good linewidth control at...
Abstract: Electron beam lithography tools have evolved in the direction of higher beam energy in order to achieve high-resolution, fine feature definition. As the beam energy is increased, the “forward” scattering is reduced and the “backscatter” range is increased. Over the years, tools became available data 20 then 50 kV, and now 100 kV operation is common. Operation at higher voltages has several advantages, such as better resolution and process latitude due to reduced forward scattering, and a few disadvantages such as higher dose requirements, substrate heating, and lower contrast for backscatter electron alignment and calibration signals (due to reduced primary electron backscattering generation in thin film). The backscatter range for 100 kV on silicon is about 27 μm compared to 8 μm at 50 kV resulting in different strategies for efficient proximity correction. However, even at 100 kV, scattering in an intermediate range is observed and must be taken into account in order to achieve good linewidth control at...
TL;DR: In this paper, a novel nanocomposite resist system was developed for sub-100 nm resolution e-beam lithography by dispersing surface-treated silica nanoparticles in a commercial ZEP520 resist.