Kenji Tamamori

Optical properties of a multibeam column with a single-electron source

A 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 (MSM) composed of an aperture array (a beam-dividing aperture), a static lens array (Einzel lenses for each divided beam), and a blanker array (BLA, blanking electrode pairs for each focused beam). 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 electr...

High precision binary optical element fabricated by novel self aligned process

Binary optical elements (BOE) tend to be used frequently in optical equipment because aspherical type BOE is easy to fabricate and the BOE can easily correct chromatic aberration. What makes this technology attractive to industry is that the BOE can be fabricated precisely by the semiconductor micro fabrication technique. However when it is used for more precise optics e.g. semiconductor exposure equipment, more precise BOE are necessary. In some manufacturing processes, we have confirmed that the alignment error between masks is the dominant factor to decrease diffraction efficiency by optical simulation. To study this problem, we have produced a BOE using a novel self-alignment method we have devised, then compared it to a BOE which has being made by a conventional method.

Fabrication of Three-Dimensional Photonic Crystal Device for Terahertz Wave

We have fabricated a simple-cubic-lattice photonic crystal (PhC) device based on high-resistivity silicon in the terahertz (THz) range by micro-electro-mechanical system (MEMS) techniques. The lattice constant of the three-dimensional (3D) PhC device is 120 µm, resulting in a photonic band gap (PBG) centered at 1 THz. The 3D PhC device was constructed by stacking ten 120-µm-thick chips with periodic pillars and holes patterned respectively on both of their sides by Si deep reactive ion etching. By THz time-domain spectroscopy, the PBG of the device was observed between 0.83 and 1.17 THz in the Γ–Z direction with a transmittance attenuation of about 35 dB, which is in good agreement with a numerical calculation result.

Inspection of all beams in multielectron beam system

A testing apparatus for inspecting the beams formed by a multisource module (MSM) was built for the feasibility study of a beam splitting array (BSA), a multielectron beam system the authors are developing. In this BSA, the MSM plays the following three key roles: splitting the beam from a single cathode into 32×32 beams, converging the 32×32 beams, and blanking them individually. Accordingly, the inspection of all beams formed by the MSM is essential for the feasibility study of the system. The testing apparatus was therefore designed for measuring all the beams formed by the MSM without demagnifying them. To maintain the accuracy during the inspection of all 32×32 beams, the measurement process was automated. This testing apparatus was used to measure the diameters and misalignments of all beams formed by a prototype MSM. As a result, the mean values of the transverse and the longitudinal diameters were found to be 0.88 and 0.92μm, respectively. A single stigmator can cancel the difference between these...