Hak Kim

An inertial-grade laterally-driven MEMS differential resonant accelerometer

Inertial-grade laterally-driven differential resonant accelerometer (DRXL), using a gap sensitive electrostatic stiffness change effect, is designed, fabricated and tested using a mixed micromachining process based on (111) single crystal silicon. The resonant accelerometer consists of a double ended tuning fork (DETF) and two proof masses in the same plane, so it can detect in-plane acceleration. Each pair, with proof mass and resonator, is completely isolated, so the coupling of mechanical vibration between them is protected. The fabricated accelerometer shows a sensitivity of 64 Hz/g per resonator at nominal frequency of 24,888 Hz, bandwidth of 110 Hz, and a bias stability of 5.2 /spl mu/g.

Polarization-isolated electrical modulation of an etched long-period fiber grating with an outer liquid-crystal cladding

An etched long-period fiber grating with an outer liquid-crystal cladding capable of polarization-isolated electrical modulation, is de- scribed. A 5-dB transmission-dip modulation with 4-dB polarization iso- lation can be obtained at 225 V. The reduction in fiber diameter by a chemical etching process leads to an improvement in the long-range ordering of liquid-crystal molecules and a reduction in the controlling voltage. In addition, the experimental results are supported by numerical simulation.

The Novel Deflector for Multi Arrayed Microcolumn Using Microelectromechanical System (MEMS) Technology

This paper describes a new concept for a multiple arrayed deflector with a reduced amount of wiring by utilizing a fabrication technique using microelectromechanical system (MEMS) technology, such as multi wafer anodic bonding techniques and copper electroplating in order to produce a double layer structure. The double layer interconnection structure is a newly introduced interconnection method that reduces wiring among the components. A 3×3 arrayed deflector, which has an internal wiring structure, was fabricated. The deflection performance of the newly fabricated deflector displayed linear deflection results. Moreover, the difference in the signal delay between each deflector pole, which was caused by multiple interconnection structures, was calculated using a simulation program with integrated circuit emphasis (SPICE) simulator with an equivalent circuit model. The calculation results showed there was an approximate 3 ns signal delay difference. Therefore, this method is very useful for checking the difference in the signal delay. This work will be helpful for understanding the interconnections a multiple arrayed microcolumn system.

Full MEMS monolithic microcolumn for wafer-level arrayal

Recently, an advanced microcolumn concept for improved throughput was proposed. However, due to the complexity of the approach, the miniaturization was limited. In addition, microcolumns must run under ultrahigh vacuum conditions in order to obtain stable electron emission at the field-emission tip. Both signal and power lines need to be connected through the ultrahigh vacuum chamber. Therefore, increases in the number of microcolumn arrays necessitate more wiring from the external control unit to the internal units, and the number of wires can become prohibitive. To solve this problem, a new concept, exploiting the possibility of an arrayed microcolumn which uses microelectromechanical systems (MEMS) technology has been developed. This paper describes a monolithic (3×3 arrayed) microcolumn, which consists of a cold field-emission tip, an input lens, an einzel lens, and novel deflectors for multiple-arrayed microcolumns. We also describe its fabrication process, which relies on improved microfabrication a...

Fabrication of miniaturized electron beam system

A novel electron beam lithography system, microcolumn, was designed and fabricated using a wafer stacking and double metal interconnection process. This is the first monolithic microcolumn. All electrodes were made of highly doped Si wafer and Pyrex glass was used as an insulator. The system was assembled using a glass jig and several alignment methods including a conventional method using an aligner, laser diffraction image and refracted light were used and the misalignment was less than 10/spl mu/m. Anodic bonding was performed and the process condition was optimized to reduce the stress. The size of 3/spl times/3 arrayed microcolumn system including jig is 50mm /spl times/ 50mm and the height is 6.5mm. The size of 1 column is 6mm /spl times/ 6mm and it is the smallest size.

The novel deflector for multi arrayed microcolumn using MEMS technology

We present a novel design concept of deflectors for a 3 × 3 multiple arrayed microcolumn and its fabrication process using a improved microfabrication and novel MEMS technology, such as multi wafer anodic bonding techniques and copper electroplating for the double metallization process. The double metallization process is a newly introduced interconnection method to reduce wiring among the components. Moreover, a difference in the signal delay between pad site and each deflector pole, which was caused by multi interconnection structure, was calculated using the SPICE simulator with an equivalent circuit model. The calculation results were obtained with about 3ns signal delay difference. Therefore, in these arrayed systems, this method is very useful for checking the difference in signal delay.