Photocathodes with relatively low energy spread ͑Ͻ0.5 eV͒ are required for electron sources in several applications including single and multiple electron beam inspection and lithography tools and free electron lasers. CsBr based photocathodes have been shown to be very robust and capable of operation at high current density ͑Ͼ150 A / cm 2 ͒ with very long lifetime ͑approximately hundreds of hours/spot͒. Experimental results of the photoelectron energy spread obtained in CsBr films deposited on both metal and InGaN substrates will be presented in this paper.
The magnetic limiter and helical divertor geometry predicted by vacuum magnetic field calculations has been confirmed by measurements with various probe and calorimeter arrays in Heliotron-E. The effect of modification of these configurations with auxiliary magnetic fields or a material limiter on the edge plasma profile is studied. The relation of the edge plasma properties with the main plasma parameters (density, heating power, etc.) are described. The amount of total heat loss to the divertor region is almost the same as that of the heating power. The edge plasma density is approximately proportional to the core plasma density.
Electron and ion optical design software for integrated circuit manufacturing equipmentA novel single-column multi-electron-beam system, called a beam-split array, has been developed for a high-resolution, high-throughput lithography tool. In this system, a single electron beam is divided into 1024 beams by a multisource module ͑MSM͒ composed of an aperture array ͑a beam-dividing aperture͒, a static lens array ͑Einzel lenses for each divided beam͒, and a blanker array ͑BLA, blanking electrode pairs for each focused beam͒. The MSM is used to form multiple intermediate images of the electron source at the BLA. These images are demagnified to form final images through a projection optics consisting of a double lens doublet with a blanking aperture and deflector. To align the multiple beam paths in the MSM, aligners between these arrays are used, and the aligner conditions are determined by monitoring the blanking-aperture image. Moreover, because each beam current is about 0.1% of the total beam current on the specimen, a high-contrast transmission detection method is used to detect the electrons at the final image plane. As a result, 1024 point beams are successfully formed. In the final image, the measured beam size is less than 55 nm, and the displacement due to distortion is less than 56 nm, even on the off-axial beams. In addition, individual beam blanking by BLA is verified, and cross-talk at the BLA is confirmed to be negligible at present accuracy. Moreover, 65 nm patterns can be simultaneously delineated by nearand off-axial beams. These results verify the concept of their single-column multibeam formation and indicate that this optics can be applied to lithography for manufacturing on semiconductor devices.
A novel optical system for a multiple-beam scanning electron microscope (SEM) is proposed. In the case of multiple-beam SEM, multiple secondary-electron beams passing through the column are inherently blurred because of the large energy spread and broad angular distribution of secondary electrons. To avoid cross-talk between the multiple secondary-electron beams, the optical system is designed such that it is divided into two independent parts: one for primary-beam illumination and one for secondary-electron detection. As the key components for the secondary-electron detection, a scan-cancelling deflector, and accelerating electric field were applied. To demonstrate the proposed optical system, a prototype column with four beams was developed. This column enables four SEM images to be separately but simultaneously acquired with more than 99% of the generated secondary electrons. This result demonstrates that high-speed imaging with the proposed multiple-beam SEM is possible in the near future.
An EGS4 Monte Carlo examination of the response of a PTW-diamond radiation detector in megavoltage electron beams Med.The attractiveness of electron beam systems would be greatly enhanced if the throughput could be improved. One approach, described previously by the authors employs a uniform axial magnetic field to focus thousands of electron beams simultaneously ͓D. S. Pickard et al., J. Vac. Sci. Technol. B 21, 2709 ͑2003͒; T. R. Groves and R. A. Kendall, ibid., 16, 3168 ͑1998͔͒. The beamlets never combine to form a common crossover, thereby avoiding the throughput limitations due to space charge blurring. With this approach, one challenge was to fashion a detection scheme that maintains a tight beamlet packing density ͑250 m pitch͒ while minimizing cross-talk between adjacent secondary electron signals, either by crossing trajectories or within the detector. A pin-diode-based detector was investigated as a potential component of the multielement detection scheme for the authors' system. The detector features a two-dimensional array of elements on high resistivity float-zone silicon. The detector attributes that were attractive to their application include modest internal amplification ͑Ͼ5000 at 25 kV͒, fast response time ͑measured at Ͻ10 ns͒, ability to be made compact and with dense packed electrodes ͑Ͻ250 m͒, low electrode capacitance ͑Ͻ1 pF͒, and ability for ͑complementary metal-oxide semiconductor͒ circuitry to be integrated directly onto the detector array so that low noise amplification of each signal can be performed. This detector requires a retarding field for the primary beam, which accelerates the secondary electrons to energies sufficient to excite a large number of internal secondaries.
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