Small Beam Spot Size Research Articles

A novel harmless trimming for micro-device with defects and particles in arbitrary geometry by fine milling of focused ion beam

A novel method combining focused ion beam (FIB) milling and image processing for fine trimming of micro-device is introduced in detail in this paper. By using small beam spot size and beam current, selective milling can be realized according to requirement in terms of the difference of gray scale color intensity between defects and useful areas of the FIB images. A magnetoresistive head and ink jet spray head of color printer trimming were described as examples. Trimming result shows that the method is practical and suitable for the fine trimming of micro-device by the selective milling.

근접장 기록을 위한 부상형 광학 헤드의 최적설계

This paper presents an approach to optimally design the air-hearing surface (ABS) of the optical flying head for near-field recording technology (NFR) NFR is an optical recording technology using very small beam spot size by overcoming the limit of beam diffraction. One of the most important problems in NFR Is a head disk interface (HDI) issue over the recording band during the operation. A multi-criteria optimization problem is formulated to enhance the flying performances over the entire recording band during the steady state. The optimal solution of the slider, whose target flying height is 50 nm, is automatically obtained. The flying height during the steady state operation becomes closer to the target values than those for the Initial one. The pitch and roll angles are also kept within suitable ranges over the recording band. Especially. all of the all-hearing stiffness are drastically increased by the optimized geometry of the air hearing surface.

Compact focusing system for ion and electron beams

A compact ion and electron beam focusing column design has been developed in Plasma and Ion Source Technology Group at Lawrence Berkeley National Laboratory. The electrostatic ion beam-focusing column was simulated using 2D IGUN [R. Becker and W. B. Herrmansfeldt, Rev. Sci. Instrum. 63, 2756 (1992)] ion extraction and beam transport code. A new method has been developed to include finite ion temperature to the IGUN simulation (Reijonen et al., Proceedings of the LINAC Conference, 2000). The focused ion beam system includes an ion temperature collimator, which eliminates the large angle beam trajectories resulting in a small beam spot size. The small holes in the column electrodes are laser drilled, and are aligned by an optical comparator. Simulations show that focused beam spot size as small as 147 nm is achievable for a 40 keV argon beam. The compact electron beam focusing system consists of three elements: the plasma cathode, an electron temperature collimator (similar to the ion beam temperature collimator), and the focusing electrode elements. The total length of the system is less than 10 mm. The column design is performed using EGUN (W. B. Herrmansfeldt, Slac Report No. 331, 1988), electron beam computation code, and IGUN. Space charge effects as well as the electron temperature are incorporated in the computation. The simulations show that focused beam spot size of 60 nm can be achieved. Both columns use similar type rf-induction plasma generator. P+, BF2+, and O2+ ion species production by such source is also demonstrated.

Theoretical study of short electrostatic lens for the Columbia ion microprobe

A short probe-forming system is developed for the Columbia Microprobe that includes four electrostatic quadrupoles with a Russian quadruplet configuration. The smallest beam spot size and appropriate optimal parameters of the probe-forming systems have been found. These parameters of the system are compared with appropriate parameters of other field configurations including the electrostatic and magnetic fields with dipole, quadrupole, and rotational symmetry. The new original construction of the electrostatic quadruplet has been manufactured. The sensitivity of this quadruplet to some misalignments of the construction is investigated.

A Novel Technique to Measure Laser Beam Spot Sizes

In this letter we report a novel technique to measure small laser beam spot sizes. We use the open aperture z-scan technique as a tool to measure the laser beam spot size. This technique measures small spot sizes with accuracy better than 10%.

High-efficiency multilevel zone plates for keV X-rays

The development of high brilliance X-ray sources coupled with advances in manufacturing technologies has led to significant improvements in submicrometre probes for spectroscopy, diffraction and imaging applications. The generation of a small beam spot size is commonly based on three principles1: total reflection (as used in optical elements involving mirrors or capillaries), refraction (such as in refractive lenses2) and diffraction. The latter effect is employed in Bragg–Fresnel or Soret lenses, commonly known as Fresnel zone plate lenses. These lenses currently give the best spatial resolution, but are traditionally limited to rather soft X-rays—at high energies, their use is still limited by their efficiency. Here we report the fabrication of high-efficiency, high-contrast gold and nickel multistep (quaternary) Fresnel zone plates using electron beam lithography. We achieve a maximum efficiency of 55% for the nickel plate at 7 keV. In addition to their high efficiency, the lenses offer the advantages of low background signal and effective reduction of unwanted diffraction orders. We anticipate that these lenses should have a significant impact on techniques such as microscopy3, micro-fluorescence4 and micro-diffraction5, which require medium resolution (500–100 nm) and high flux at fixed energies.

EXPERIMENTATION AT e−e− LINEAR COLLIDERS

The design of the interaction region for an e−e− collider will involve an understanding of beam-beam effects, detector backgrounds, and the constraints required to maintain very small beam spot sizes. This paper reviews progress in the design of the e+e− interaction region of the proposed SLAC X-band NLC as a base design for the e−e− detector.

Recent astrophysical measurements at NSCL

The A1200 projectile fragment separator at the NSCL has been used to produce secondary beams for a series of experiments with astrophysically interesting nuclei far from stability. Studies of A ≤ 20 nuclei include measurements of the β-decay branching ratios of 15B, β-delayed neutron emission from 18N and 17,18C, and β-delayed proton emission from 20Mg. In the 60 < A < 100 region, several experiments have been performed to map out the proton drip-line. By measuring the half-lives and binding energies of nuclei such as 65As and 69Br, the path and extent of the rapid proton capture (rp) process can be determined. Recently the performance of the A1200 separator was enhanced by installing a quadrupole doublet just upstream of the target position. The smaller beam spot size provides a larger brightness for secondary beams and a higher resolution for the chromatic modes. A summary of some recent experiments and a description of the separator upgrade will be presented.

A study of damage induced in semiconductors and metals during microchanneling measurements

The combination of nuclear analysis techniques and the spatial resolution obtained by microbeams is of great interest in materials characterization. The nuclear microbeam of the laboratory LARN (Namur, Belgium) has been equipped with a goniometer, allowing the use of the microchanneling technique. When using the nuclear microprobe with MeV energy helium ions in RBS channeling analysis we can produce a significant number of defects: the small beam spot size obtained with the microbeam leads to an increase of several orders of magnitude in the ion dose (ions/surface unit) required for the analysis. In this paper investigations of the defect buildup (increasing rate of dechanneling) for semiconductors (GaSb, GaAs, Si) and metals (Fe, Al, W) as a function of the total incident fluence for a 2.0 MeV focused helium microbeam (about 100 μm in diameter) are discussed. We have observed that, when the microchanneling analysis technique is used, the beam-induced defects accumulate very rapidly on compound semiconductors, but less rapidly on monoatomic samples. We have determined the evolution of χ Min values as a function of total helium beam fluences for several targets. These data can be used to estimate the highest ion dose (ions/surface unit) that is compatible with a low sample degradation during the collection of RBS spectra in channeling measurements.

脳組織の活動電位分布のレーザー光による光化学的計測

Optical measurement of cortical activity in the brain using laser beam has the following advantages compared to white light: (1) laser beam is easy to be focused on the cell stained with voltage-sensitive dye (the beam waist is nearly equal to the wavelength): (2) the light is monochromatic, then, the overlap between the excitation and the emission from the dye stained in the cell is negligible: (3) the optical measurement system of the cortical activity is a small size and a simple design. We propose the system of the laser image mapping applied to the intact brain with the voltage-sensitive dye. An optical fiber with a short length can be used for transmitting the laser light. The beam spot emerged out of the fiber can be controlled by using SELFOC micro-lens. The optical image mapping of cortical activity from a few cells or aggregated cells is produced from the small or large laser beam spot size.

The application of reflection infrared and surface enhanced Raman spectroscopy to the characterization of chemisorbed organic disulfides on Au

We have found that a variety of organic molecules containing the SS linkage strongly adsorb on freshly evaporated or electrochemically cleaned gold surfaces. Adsorption stops at monolayer coverage and the packing density of the molecules can be close to the limit set by the size of the molecules. Reflection infrared spectra show that the films are strongly oriented and in the case of long alkyl-chain-substituted disulfides the films have structures similar to those of Langmuir-Blodgett type films. Most of the films were prepared by freshly evaporating gold onto polished single crystal silicon substrates. Immediately after the deposition the films were removed from the vacuum system (under N 2) and placed in solutions of the disulfides. After rinsing the films were examined by ellipsometry at 6328Å and 4420Å and in general, the results are consistent with monolayer structures with close packing similar to bulk crystallites. Infrared spectra were obtained using a Digilab 15B Fourier transform infrared spectrometer with a high f/number optical system and small beam spot size for glancing reflection. Spectra were obtained between 800 and 3200cm −1 using a mercury cadmium telluride detector. The spectrum of a monolayer of the di-p-nitrobenzoate ester of trans-o-Dithiane-4,5-diol is shown in Figure 1. The structure of the diol is given below. The spectrum of the monolayer of the di-ester of the C 16 acid (n-C 15H 31CO 2H) is given in Figure 2. Notice the alkyl chain mode band series in the monolayer spectrum which indicates crystalline packing of the chains. The infrared spectra are consistent with oriented structures which maximize packing densities. No direct evidence is yet available for defining a AuS bond. However, a sample in which the monolayer of the p-nitrobenzoate derivative has been covered with 400Å average thickness of CaF 2 and 200Å of smooth silver has yielded an enhanced Raman spectrum (λ(excite)=4880Å ∼50mW power) in which the normally strong S-S stretching mode observed at 504cm −1 in bulk samples is absent in the monolayer. These studies demonstrate an application of surface vibrational spectroscopy to defining molecular structures at surfaces. Work is presently underway to quantitatively calculate molecular orientation from the infrared spectra and to more carefully determine the extent of any ordering in appropriate monolayers.