Che-Heung Kim

Silicon micro XY-stage with a large area shuttle and no-etching holes for SPM-based data storage

A micro XY-stage with a 5/spl times/5 mm/sup 2/-area shuttle is fabricated for application in a nanometer-scale data storage device. A central shuttle of the device is designed as a large square on which a high-density recording medium is deposited. Perpendicularly combined comb-drive actuators allow the large shuttle free access in the x-y plane. No etching holes on the central shuttle are preferred in order to maximize the effective recording area. Therefore, a novel release process, Micro-Channel Assisted Release Process (/spl mu/CARP) is proposed to release a large plate structure without any etching holes and to resist downward sticking. The static and dynamic strokes of the device were measured. Mechanical interferences between x-and y-directional drives were estimated by finite-element method (FEM) analysis and compared with the experimental results.

Micro XY-stage using silicon on a glass substrate

In this paper we describe a single-crystal silicon (SCS) micro XY-stage with a 50 ? 50 ?m2 scanning range. A simple fabrication process using a silicon-on-glass substrate is proposed for a silicon high aspect ratio structure (HARS) and easy release. The high aspect ratio SCS actuator is achieved by deep reactive ion etching and is released simply by glass etching in a hydrofluoric acid solution. The sticking problem is removed by a 100 ?m deep etching of the glass substrate during the release process. The static travel range of the fabricated actuator is measured using a built-in scale and a map of the mechanical cross talk between the X- and Y-axis driving is constructed. The resonant frequency is measured at 360 Hz in air.

MEMS reflective type variable optical attenuator using off-axis misalignment

This paper proposes a reflective type microelectromechanical system variable optical attenuator (MEMS VOA) which uses 45 degree tilted vertical movable mirror fabricated by a deep reactive ion etching (DRIE). The optical attenuation is generated by an optical axis offset controlled by the vertical mirror. Fibers are aligned passively on the vertical grooves which are formed at the same plane with the control actuator.

Integration of a microlens on a micro XY-stage

The precise position control of an optic element is a quite important technology and thus has many applications in modern optic system. This paper describes the optic system composed of a micro lens and positioning actuator. Two types of the micro Fresnel lens and the micro spherical lens are fabricated by using UV-lithography and reactive ion etching (RIE). The monolithic spherical lens is fabricated through the photo-thermal technique of photoresist. 3 mm-focal length with 246 micrometers -diameter Fresnel lens and 31 micrometers - focal length with 50 micrometers -diameter spherical lens are fabricated. The XY-stage is proposed as a control actuator, which is a 2-degree of freedom-stage structure with a pari of perpendicularly combined comb drive. The travel range of the micro XY-stage is measured 48 micrometers in each X and Y direction. The mechanical interference between X- and Y-axis is negligible. Integration process of these two parts is based on the concept of in-situ process using anodic bonding. This device is expected to be applicable for the fields of optical pickup, light beam aligning and optical signal sensing.

A Bulk-Micromachined Single Crystal Silicon Gyroscope Operating at Atmospheric Pressure

A novel bulk-micromachined gyroscope operating at atmospheric pressure is designed, fabricated and tested. It is fabricated by a simple single-mask process and has high-aspect ratio comb fingers for driving and sensing electrodes. It also has a large gap between the substrate and the structure for high Q value. Since the proposed gyroscope has a large driven displacement and a large mechanical sensitivity, it has good performances such as sensitivity of 116.8mV/° /s, the noise equivalent level of smaller than 0.05° and wide dynamic range of ±189° with non-linearity of smaller than 0.3% at atmospheric pressure.

MEMS fiber-optic variable optical attenuator using collimating lensed fiber

A reflective type MEMS VOA using lensed fiber-coupling scheme was fabricated. A linear bi-directional comb actuator is used to translate vertical mirror to improve attenuation characteristics in small attenuation range. Various coupling loss factors are analyzed by CODE V. The insertion loss of the fabricated VOA is 0.98 dB. The PDL measurement shows good uniformity in broad attenuation range. The maximum value of PDL is 0.24 dB. The wavelength dependency of VOA is measured below 0.7 dB in whole attenuation range and the return loss is -38 dB.

Fabrication of Micro XY-Stage with Large-Area Rectangular Shuttle using Anodic Bonding Process

The Micro XY-stage with the large area rectangular shuttle (5 mm×5 mm) is fabricated using an anodically bonded fixture. The large area of a stage is prepared for the integration of a large number of nano-structure array or data-recording media with high density. No etching hole on the central stage is preferred to maximize effective area. The novel release process, μ -CARP (Micro Channel Assisted Release Process) is developed to release a large plate structure without etching hole and to resist a downward sticking. The mechanical characteristics of a fabricated device is measured and discussed.

Modeling of the comb actuator deformed by microloading effect in deep reactive ion etching

The comb actuator deformed by microloading effect in DRIE process generally has í«Lí» shape comb electrodes. Therefore, the actuator shows nonlinear differential driving characteristics. A simple modeling is suggested and simulated to explain the driving characteristics. For modeling convenience, the damaged comb electrode is assumed to be a simple í«Lí» shape. According to the modeling, the resonant frequency is estimated to increase as the bias voltage increases. The static displacement curve shows í«Sí» shape.

Integration of a micro 2/sup N/-level quantized binary Fresnel lens on a micro XY-stage

In certain applications, diffractive optical elements have more significant benefits than refractive or reflective elements because of their light volume and specific optical characteristics such as the ability for multiple simultaneous focal points. A micro Fresnel lens was designed and fabricated following the principles of a binary lens on silicon and glass substrates using micromachining. The micro XY-stage was also fabricated on single crystalline silicon as a positioning actuator. Lastly integration of these two parts to one system was proposed. The integrated optic system will be helpful to control the position of a light beam.