• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1159-1162
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• 2007

We have developed $16{\mu}m{\times}16{\mu}m$ digital micromirror array suitable for seamless-picture projection display system. This structure can improve the picture quality by making seamlesspicture image when combined with high-fill-factor microlens array to focus lights onto the mirror center. The fabricated micromirror shows excellent dynamic performances including the resonant frequency of 400 kHz.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.416-418
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• 1996

A $50{\times}50{\mu}m^2$ aluminum micromirror array is fabricated using surface micromachining technology. $50{\times}50$ micromirrors are arrayed two dimensionally. The micromirror plate is supported by a vertical spring structure that is placed underneath the mirror plate. When the mirror plates reflect a light, the micromirror array un have large effective reflecting area. Fabrication of vertical spring uses only one mask and shadow evaporation process.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.274-279
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• 2007

This study focuses on the enhancement of maskless photolithography as well as the peptide synthesis application with single crystalline silicon micromirrors. A single crystalline silicon micromirror array has been designed and fabricated in order to improve its application to the peptide synthesis. A micromirror rotates about ${\pm}\;9^{\circ}$ at the pull-in voltage, which can range from 90.7 V to 115.1 V. A $210\;{\mu}m-by-210\;{\mu}m$ micromirror device with $270\;{\mu}m$ mirror pitch meets the requirements of an adequately precise separation for peptide synthesis. Synthetic 16 by 16 peptide array corresponds to the same number of micromirrors. The large size of peptide pattern and the separation facilitate biochip experiments using fluorescence assay. The peptide pattern has been synthesized on the GPTS-PEG200 surface with BSA-blocking and thereupon the background was acetylated to reject non-specific bindings. Hence, an averaged slope at the pattern edge has been distinguishably improved in comparison to patterning results from an aluminum micromirror.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.4
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• pp.288-294
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• 2002

This paper presents the design, fabrication and characterization of a 32 by 32 electroplated micromirror array on a glass, a low cost substrate. Approaches taken in this work for the fabrication of micromachined mirror arrays include a line addressing scheme, a seamless array design for high fill factor, planarization techniques of polymeric interlayers, a high yield methodology for the removal of sacrificial polymeric interlayers, and low temperature and chemically safe fabrication techniques. The micromirror is fabricated by aluminum and the size of a single micromirror is 200 $\mu\textrm{m}{\;}{\times}200{\;}\mu\textrm{m}$. Static deflection test of the micro-mirror has been carried out and pull-in voltage of 44V and releasing voltage of 30V was found.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2547-2549
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• 1998

Automatic yield-test equipment for micro mirror array using image processing was developed. This computerized test equipment can classify the error states of the micromirrors. The test results are displayed on the monitor as a map which shows the error states and position. It is possible to measure yield and reliability with this test equipment for micromirror array using image processing.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.618-620
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• 1997

A $50{\times}50{\mu}m^2$ aluminum micromirror array is fabricated using shadow evaporation process. The fabrication process is very simple with use of shadow evaporation process, and the micromirror array has a high fill-factor. The static and dynamic characteristics such as deflection angle vs. applied voltage, step response, and frequency response are measured using a contact free optical measurement technique. The downward threshold voltage was 8 V, step response time was $13.5{\mu}s$ when 32 V step voltage applied, and a resonance observed at 11kHz. The lifetime of micromirror with anti-stiction coating was tested and micromirror operated successfully over 200 million cycles of touch-down operations.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.2
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• pp.132-139
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• 2001

We considered the uniformity of fabricated micromirror arrays by characterizing the fabrication process and calculating the appropriate driving voltages of micromirrors used as virtual photomask in maskless photolithography. The uniformity of the micromirror array in terms of driving voltage and optical characteristics is adversely affected by factors, such as the air gap between the bottom electrode and the mirror plate, the spring shape and the deformation of the mirror plate or torsion spring. The thickness deviation of the photoresist sacrificial layer, the misalignment between mirror plate and bottom electrode, the aluminum deposition condition used to produce the spring and the mirror plate, and initial mirror deflection were identified as key factors. Their importance lies in the fact that they are related to air gap deviations under the mirror plate, asymmetric driving voltages in left and right mirror directions, and the deformation of the Al sring or mirror plate after removal of the sacrificial layer. The plasma ashing conditions used for removing the sacrificial layer also contributed to the deformation of the mirror plate and spring. Driving voltages were calculated for the pixel operation of the micromirror array, and the non-uniform characteristics of fabricated micromirrors were taken into consideration to improve driving performance reliability.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.49-52
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• 2003

Single crystalline silicon (SCS) was adopted for a reliable micromirror array of biochip fabrication applications. SCS has excellent mechanical properties and smooth surface, which is the best material for micromirror devices. The mirror array has $16{\times}16$ micromirrors and each mirror has a $120{\mu}m{\times}100{\mu}m$ reflective surface. The micromirror has simple torsional beam springs and electrostatic force was used for driving. The designed tilting angle was $9.6^{\circ}$, and the tilting angles were measured according to applied voltages. The surface roughness was measured by a laser profiler. The response time was measured using He-Ne laser and position sensitive diode (PSD), and the lifetime was checked for reliability proof.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2260-2262
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• 2000

In this paper, micromirror which can rotate 45 degree is designed, analyzed and fabricated. The micromirror is parallel to the substrate initially. When external magnetic field is applied, a micromirror can rotate to align its easy axis to the field. The size of micromirror array is $10{\times}10$. The mirror plate and spring is made of aluminium, and nickel is used as soft magnetic material. To obtain 45 degree angular deflection, dimension ratio between stopper length and thickness of sacrificial layer is properly selected. By using electrostatic force, individual actuation is possible.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.389-392
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• 2005

In the maskless photolithography based on the Digital Micromirror Device (DMD) by Texas Instruments Inc. (TI), the micromirror array works as a virtual photomask to write patterns directly onto Flat Panel Display (FPD) at high speed with low cost. However, it is neither simple to generate region-based patterns for the micromirror array nor easy to deliver sequences of patterns for the micromirror controller. Moreover, the quality of lithography yields the precise synchronization between generating sequence of patterns and irradiation rate off micromirrors. In this study, the region-based pattern generating system for maskless photolithography is devised. To verify salient features of devised functionalities, the prototype system is implemented and the system is evaluated with actual DMD based photolithography. The results show that proposed pattern generating method is proper and reliable. Moreover, the devised region-based pattern generating system is robust and precise enough to handle any possible user specified mandate and to achieve the quality of photolithography required by FPD manufacturer.