A subsidiary electrode was introduced between the extractor and anode in our newly developed source lens design of a micro electron column to improve the probe beam characteristics. At the same field enhancement factor of 3.95, the probe beam current showed a drastic increase compared to that of the conventional source lens structure. The design parameters of the newly developed source lens structure and the equipotential line distribution are presented with simulation results.
Nano-pattering process by low-voltage electron beam lithography based on microcolumn with beam energy of 500 eV
has been developed. Low kV exposure provides the advantages of high sensitivity, reduced charging, and a lack of
proximity and heating effects. However a low-voltage electron beam has very thin penetration range. At 500 V, the
penetration range is less than 20 nm, while typical resist thickness is > 200 nm. A resist process with bilayer scheme, 17
nm-thick PMMA resist on 100 nm-thick SiO<sub>2</sub> layer, and wet etch method was demonstrated for 250 nm line patterns
transfer to Si substrate. The process was applied to fabricate periodic grating patterns on a silicon substrate. The results
of nano-pattern process by low energy microcolumn lithography will be discussed in detail.
We report on the design, fabrication and integration of micro/nano-scale optical waveguide arrays and devices for optical printed circuit board (O-PCB) and VLSI photonic applications. The O-PCBs perform the functions of transporting, switching, routing and distributing optical signals on flat modular boards or chips in a manner similar to the electrical printed circuit boards (E-PCBs). The photonic devices include microlasers, microlenses, micro-reflectors, couplers, arrayed waveguide grating structures, multimode interference (MMI) devices and photodetectors. For VLSI micro/nano-photonics we used photonic crystals and plasmonic metal waveguide structures. We also describe device characterization using near filed scanning microscopy. We examine the scientific and technological issues concerning the miniaturization, interconnection, and integration of photonic devices, circuits and systems in micron or submicron scale. In miniaturization, the issues include size effect, proximity effect, energy confinement effect, microcavitiy effect, single photon effect, optical interference effect, high field effect, nonlinear effect, noise effect, quantum optical effect, and chaotic noise effect. In interconnection, the issues include homogeneous interconnection (between identical devices) and heterogeneous interconnection (non-identical devices). In integration, the issues of interfacing same kind of devices, two different kinds of devices, and several or many different kinds of devices are addressed. The discussion includes the nano-scale electron beam system and techniques to characterize nano-scale structures.
The small size of the microcolumn opens the possibility for arrayed operation on a scale commensurate. An arrayed microcolumn test-bed system has been developed for high throughput applications. The arrayed microcolumns based on of Single Column Module (SCM), and Wafer-Scale Column Module (WCM) concepts have been fabricated and successfully demonstrated. Low energy microcolumn lithography has been operated in the energy range from 100 eV to 1 keV for the generation of nano patterns. Probe beam current at the sample was measured about 2 nA at a total beam current of ~0.4 mA. The magnitude of probe beam current is strong enough for the low energy lithography. The thin layers of PMMA resist have been employed. The results of nano-patterning by low energy microcolumn lithography will be discussed.
As lithography pushes to the nanoline dimensions, even less drastic changes during photoresist processes can have a non-disregarding impact on proximity behavior, thus these changes can affect the optical proximity correction rules and models. In this study, after the descriptions of the modified mechanical method of rinse and dry processes and the model of etch simulation for dense and isolated lines, the impact on proximity behavior is described and analyzed by using the quantitative sensitivity of the pattern collapse and etch properties on the critical dimension. The effect for optical proximity correction rules and the characterization of the mask error enhancement factor are discussed.
In a conventional, strip-type one-dimensional (1-D) position sensitive detector (PSD) the sensitive area and the position resistance area are combined together, the contact structure of the device is handicapped, so its accuracy and linearity is affected adversely. The sensitive area and the position resistance area in a new, comb-type 1-D PSD are separated to become the comb teeth and the comb ridge area respectively, moreover the position resistance area is made very narrow, thus the doping uniformity of that area is greatly improved. On the other hand, its position resistance can be largely increased owing to its narrower shape, if doping level is kept the same, so the restriction that is imposed on the contact structure previously can be lifted. Our measurements made on a strip-type 1-D PSD and a comb type 1-D PSD confirmed this difference, and showed that the accuracy and linearity of the comb type 1-D PSD has been increased markedly, especially the RMS nonlinearity of the comb type 1-D PSD is reduced to 0.090% from that of the strip-type 1-D PSD, 0.94%.
The single crystals of neodymium doped lanthanum scandium borate were grown for the microchip laser fabrication. The crystal structure and parameters were analyzed to define the crystal phase and characteristics. The optical properties, such as fluorescent lifetime, refractive indices, absorption and emission spectra with doping concentration, were investigated and compared to the other neodymium doped single crystals in laser application. The fundamental lasing experiment with 808 nm, consistent with commercial diode laser wavelength, was done with Ti:sapphire laser. And we showed that the direct pumping to the level of <sup>4</sup>F<sub>3/2</sub> make an improvement in slope efficiency and threshold when it is compared to the result of conventional pumping to the level of <sup>4</sup>F<sub>5/2</sub> absorption band. The direct pumping played a role for reduction of dissipative heat generation in microchip laser crystal, because its quantum efficiency is higher than the conventional pumping to the level of <sup>4</sup>F<sub>5/2</sub>.