Shingi Hashioka

DNA Separation in Nanowall Array Chips

A nanowall array structure was fabricated on a quartz chip as a separation matrix of DNA fragments, and a 30 s separation was realized for a mixture of DNA fragments (48.5 and 1 kbp fragments) by applying the electric voltage. A longer DNA fragment migrates faster than a shorter one in a nanowall array chip, and it is completely different from the separation of DNA based on gel electrophoresis, nanopillar chips, and nanoparticle array chips. Although the result is similar to DNA separation by entropic trapping, it could not be fully explained by entropic trapping phenomena. Direct observation of single-DNA molecular dynamics inside a nanowall array structure indicates that both confined elongation and relaxation recoiling of a DNA molecule occur, and an elongated DNA molecule migrates faster than a recoiled DNA molecule. Numerical fitting of DNA molecular dynamics reveals that the balance between times for the transverse of a DNA molecule in the nanowall array chip and the relaxation-recoiling of a DNA molecule governs the separation of DNA.

Plasma and fluorocarbon-gas free Si dry etching process using a Cat-CVD system

Abstract A heated tungsten filament was used to cataltyze the gas phase etching of crystalline silicon with hydrogen at a substrate temperature of 200°C for obtaining plasma and contamination free etching. Etch rates, between 100 and 200 nm/min were obtained in a pure hydrogen ambient in the pressure range of 0.01–0.5 Torr. No etching effect was observed in the case of SiO 2 . No tungsten or other metal and carbon contaminations on the etched silicon surface were detected by X-ray photoelectron spectroscopy.

Fabrication and Characterization of Quartz Nanopillars for DNA Separation by Size

We fabricated two different distributions of nanopillars–tilted and square distributions. There are difficulties in fabricating a chip containing these nanopillars, particularly in Ni plating and quartz bonding. We improved the Ni plating by applying stable electric current and the reliability of the quartz bonding. In nanopillars with a square distribution, DNA showed conformational changes, and did not show any reptile motion, but moved in a straight line in contrast with its behavior in nanopillars with a tilted distribution. Nanopillars with a tilted distribution acted effectively as sieves for DNA separation by size.

10 nm size fabrication of semiconductor substrates and metal thin lines by conventional photolithography

The novel nano-technology is required for realizing the nano-scale devices such as single electron transistor (SET) and metal/insulator tunnel transistor (MITT). Recently, new methods to fabricate a nanometer region of metals by using such as a tip of a scanning tunneling microscope (STM) have been reported. However, these do not appear as industrially acceptable techniques. Then, a new nano-technology utilizing conventional photolithography was proposed. A contact pattern-mask with nanometer-size slits was fabricated by combination of conventional photo-lithography and anodic oxidation of side-wall of metal. In this study the application of the pattern-mask is shown. Nanometer-size fabrication of semiconductor substrates and metal thin lines by using the pattern-mask is attempted.

Deoxyribonucleic acid sensing device with 40-nm-gap-electrodes fabricated by low-cost conventional techniques

A sensing device for the detection of a very small amount of the deoxyribonucleic acid (DNA) with the order of femtoliter is described. Such a sensing device has metal electrodes with a 40nm gap, and is fabricated by low-cost technology with the conventional photolithography and anodic oxidation. Gold (Au) electrodes are used to fix DNA, and the electric currents between two electrodes are measured to detect the existence of DNA. The results indicate that the present device is promising as future very low-cost DNA analyzing chips.

The novel nano-fabrication technique with low edge roughness

This paper demonstrates the novel nano-fabrication technique usable in the mass-production with low cost and high through-put.. The F/sub 2/ stepper and the electron beam stepper are expected as future technologies for sub-0.1/spl mu/m node. However, such a stepper costs as much as about

Fabrication Technique for Preparing Nanogap Electrodes by Conventional Silicon Processes

20,000,000. Nano-scale devices such as a single electron transistor are sometimes fabricated by using a tip of an atomic force microscope (AFM). However, it does not appear as an industrially acceptable technique. Hence, if a novel method utilizing only conventional photolithographic technique is developed for nano-size fabrication, it surely opens the new stages. For its purpose, we have developed a new method, in which a contact patternmask with nanometer-size slits (nanometer slit mask) is fabricated by combining the conventional photolithography and anodic oxidation.

Arrangement of a Nanostructure Array To Control Equilibrium and Nonequilibrium Transports of Macromolecules

A fabrication technique for preparing nanogap electrodes, such as a gold (Au) nano electrode, using conventional silicon (Si) processes–photolithography, etching, thermal oxidation and deposition–is proposed. Stencil substrates are prepared using the Si processes. Then, without requiring complicated technology, nanogap structures can be formed using the technique. Numerous kinds of materials can be selected as an electrode. The mass production of a sensing device for the detection of deoxyribonucleic acid (DNA), or a so-called DNA chip, can be realized at a low cost.

Metal nanogap devices fabricated by conventional photolithography and their application to deoxyribose nucleic acid analysis

Exploiting the nonequilibrium transport of macromolecules makes it possible to increase the separation speed without any loss of separation resolution. Here we report the arrangement of a nanostructure array in microchannels to control equilibrium and nonequilibrium transports of macromolecules. The direct observation and separation of macromolecules in the nanopillar array reported here are the first to reveal the nonequilibrium transport, which has a potential to overcome the intrinsic trade-off between the separation speed and resolution.

One-Chip Integration of Rapid Diagnosis Infectious-Disease Chip Based on New Phenomena of DNA Trap and Denature in Nanogaps

A low-cost and simple fabrication technique is proposed to prepare the metal nanogap devices (MNGDs) of sub-50 nm size. Only currently available mass-production technologies such as photolithography and anodic oxidation of patterned metal films are utilized in the technique. The gap width of MNGD can be easily and accurately controlled by the applied voltage of the anodic oxidation process. For example, the gap width formed between titanium electrodes by anodic voltage 15 V is about 10 nm, and the standard deviation (σ) of the width fluctuation is about only 2 nm (20% of the fabrication size). Thus, the accuracy of the fabrication technique is on the almost same level with the electron beam (EB) lithography. Multigap MNGD containing several different gap widths were fabricated for the use of deoxyribose nucleic acid (DNA) analysis. As an application of MNGD, pure water containing DNA was dropped on MNGD, dried in air and the current–voltage characteristics of DNA were measured. From these results, it is e...