No abstract

We designed a scheme to introduce the LIGA process, reduce the coil line width while improving the performance, and thereby drastically cut the production costs. Consequently, we succeeded in fabricating prototype microcoils (line width: 10 gtm, aspect ratio: approx. 1). However, improvement in performance of the microcoils requires an increased aspect ratio. We set an objective to fabricate microcoil lines of a high aspect ratio with the dipping method and 3D X-ray lithography in an effort to improve the performance of microcoils.And we succeeded in fabricating microcoil line with a line width of 10 jm and an aspect ratio greater than 5.

Coils are used in many electronic devices as inductors in mobile units such as mobile phone, digital cameras, etc. Inductance and quality factor of coils are very important value of the performance. Therefore, the requests for coils are small size, high inductance, low power consumption, etc. However, coils are unsuitable for miniaturization because of its structure. Therefore, we have proposed and developed the microcoils of high aspect ratio with the dipping method and an X-ray lithography technique. In dipping method, centrifugal force and highly viscous photoresist solution were key points to evenly apply resist in the form of thick film on metal bar. The film thickness of resist on bar was achieved about 50 µm after single coating. Using these techniques, we succeeded in creating threaded groove structure with 10 µm lines and spaces on 1 mm brass bar. In this case, the aspect ratio was achieved five. It is very expected the high performance microcoil with high aspect ratio lines could be manufactured in spite of the miniature size.

With the recent progress in downsizing and the sophistication of various industrial products, the need for more compact actuators is increasing. Actuators account for the larger percentage of volume and weight of a product compared with other parts and devices. We have proposed fabrication process of spiral micro coils that employs X-ray lithography. This process will be effective for fabricating coils of a high aspect ratio lines. Reducing the size of coil lines and increasing their aspect ratio are expected to reduce the size and increase the output of actuators. Using this process, we formed spiral coil lines that can be used in electromagnetic actuators. X-ray lithography was used to form a high aspect ratio helical structure on the surface of an acrylic resin pipe. As a measure to suppress void generation, which is one of the shortcomings of electroplating processes, the sputtering apparatus and plating equipment were improved, a pretreatment process was additionally provided, and the actual electroplating method was improved. As a result, a void-free metallic deposit could be formed on a thin coil line. At the final step of this research study, we etched the coil line to determine optimal etching conditions.

a-plane InN nanostructures were fabricated on a hole-patterned a-plane GaN template by electron-cyclotron-resonance plasmaexcited molecular beam epitaxy (ECR-MBE). The growth temperature should be optimized to realize precise nucleation at the patterned holes with sufficient In desorption and a sufficiently long In migration length. Polarity determination clearly revealed that a-plane InN crystals have an anisotropic growth morphology. The InN growth rate in the N-polar [000-1] direction is higher than those in the In-polar [0001] and [1-100] directions. a-plane InN nanowalls were fabricated by exploiting the different the growth rates in the h0001i and h1-100i directions.SEM image of position-controlled a-plane InN nanostructures grown by ECR-MBE on a hole-patterned a-plane GaN template.