• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2006년도 춘계종합학술대회
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• pp.924-926
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• 2006

저전력 집적회로 기술과 MEMS (micro electro-mechanical systems) 기술이 융합된 산물인 스마트 센서는 작은 크기, 저비용, 저전력의 특성을 가지고, 그와 더불어 임베디드 어플리케이션에 사용되기에 적합하므로 이동 환경 컴퓨팅 분야에서 주목을 받고 있다. 이 센서들이 이동 통신에 적용되면 어플리케이션의 특성에 따라 인간의 접촉이 쉽지 않은 곳과 원격 통신이 가능하다는 장점이 있다. 이러한 혁명적인 원격 네트워크 기술로 인하여 활동적인 연구자들에게 엄청난 연구의 장이 열린 것이다. 본 논문에서는 그 중 한가지의 어플리케이션인 열센서 카메라에 대한 응용 분야로, 적외선 열센서 카메라에 대한 미세 조정을 위한 시스템 구축 방안에 대하여 논의한다.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.106-109
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• 2012

A low power methane gas sensor with microheater was fabricated by silicon bulk micromachining technology. In order to heat up the sensing layer to operating temperature, a platinum (Pt) micro heater was embedded in the gas sensor. The line width and gap of the microheater was 20 ${\mu}m$ and 4.5 ${\mu}m$, respectively. Zinc oxide (ZnO) nanowhisker arrays were grown on a sensor from a ZnO seed layer using a hydrothermal method. A 200 ml aqueous solution of 0.1 mol zinc nitrate hexahydrate, 0.1 mol hexamethylenetetramine, and 0.02 mol polyethylenimine was used for growing ZnO nanowhiskers. Temperature distribution of the sensor was analyzed by infrared thermal camera. The optimum temperature for highest sensitivity was found to be $250^{\circ}C$ although relatively high (64%) sensitivity was obtained even at as low a temperature as $150^{\circ}C$. The power consumption was 72 mW at $250^{\circ}C$, and only 25 mW at $150^{\circ}C$.

• 한국전기전자재료학회논문지
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• 제23권2호
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• pp.89-92
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• 2010

A bolometer sensor used in an infrared thermal imaging system has many advantages on the process because it does not need a separate cooling system and its manufacturing is easy. However the sensitivity of the bolometer is low and the fixed pattern noise(FPN) is large, because the bolometer sensor is made by micro electro mechanical systems (MEMS). These problems can be fixed-by using the high performance readout integrated circuit(ROIC) with noise reduction techniques. In this paper, we propose differential delta sampling circuit to remove the mismatch noise of ROIC itself, the FPN of the bolometer. And for reduction of FPN noise, the reference signal compensation circuit which compensate the reference signal by using on-resistance of MOS transistor was proposed.

• 마이크로전자및패키징학회지
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• 제10권1호
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• pp.31-38
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• 2003

MEMS 소자는 현재의 전자산업환경에서 여러 요구조건을 만족시킬 수 있는 특징을 갖추고 있으며 이러한 MEMS 소자를 이용한 MEMS 구조물의 packaging 방법에 있어서는 내부 MEMS 소자의 동작을 위한 외부 환경으로부터의 보호를 위하여 Hermetic sealing에 대한 요구를 충분히 만족시켜야 한다. 본 논문에서는 이와 같은 MEMS device의 진공 패키지를 구현함에 있어서 기판내부에 수동소자를 실장할 수 있는 LTCC 기술$^{1)}$ 을 이용하여 진공 패키징하는 방법에 대하여 소개한다. 본 기술을 이용하는 경우 기존의 Hermetic sealing이외에 향후 적층 기판 내부에 수동소자를 내장시켜 배선 길이 및 노이즈 성분을 감소시켜 더욱 전기적 성능을 향상시킬 수 있는 장점이 있게된다. 본 논문에서는 LTCC기판을 이용하여 패키징 시킨 후, 내부 진공도에 영향을 줄 수 있는 계면들에서의 시간에 따른 진공도 변화로부터 leakage rate를 측정 (stacked via : $4.1{\pm}1.11{\times}10^{-12}$/Torr1/sec, LTCC 기판/AgPd/solder/Cu의 여러 가지 계면구조: $3.4{\pm}0.33{\times}10^{-12}$/ Torrl/sec)하여 LTCC 기판의 Hermetic sealing 특성에 관하여 조사하였다. 실제 적용의 한 예로 LTCC 기술을 이용하여 Bolometer를 성공적으로 진공패키징할 수 있었으며 실제 관찰된 이미지를 함께 소개한다.

• 센서학회지
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• 제17권4호
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• pp.250-255
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• 2008

A vanadium pentoxide ($V_2O_5$)-based bolometric infrared (IR) sensor has been designed and fabricated using micro electro mechanical systems (MEMS) technology for glucose detection and its resistive characteristics has been illustrated. The proposed bolometric infrared sensor is composed of the vanadium pentoxide array that shows superior temperature coefficient of resistance (TCR) and standard silicon micromachining compatibility. In order to achieve the best performance, deposited $V_2O_5$ thin film is optimized by adequate rapid thermal annealing (RTA) process. Annealed vanadium oxide thin film has demonstrated a linear characteristic and relatively high TCR value (${-4}%/^{\circ}C$). The resistance of vanadium oxide is changed by IR intensity based on glucose concentration.

• 센서학회지
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• 제24권6호
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• pp.379-384
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• 2015

An infrared image sensor is a core device in a thermal imaging system. The fabrication method of a focal plane array (FPA) is a key technology for a high resolution infrared image sensor. Each pixels in the FPA have $Si_3N_4/SiO_2$ membranes including legs to deposit bolometric materials and electrodes on Si readout circuits (ROIC). Instead of polyimide used to form a sacrificial layer, the feasibility of an amorphous silicon (${\alpha}-Si$) was verified experimentally in a $8{\times}8$ micro-bolometer array with a $50{\mu}m$ pitch. The elimination of the polyimide sacrificial layer hardened by a following plasma assisted deposition process is sometimes far from perfect, and thus requires longer plasma ashing times leading to the deformation of the membrane and leg. Since the amorphous Si could be removed in $XeF_2$ gas at room temperature, however, the fabricated micro-bolomertic structure was not damaged seriously. A radio frequency (RF) sputtered nickel oxide film was grown on a $Si_3N_4/SiO_2$ membrane fabricated using a low stress silicon nitride (LSSiN) technology with a LPCVD system. The deformation of the membrane was effectively reduced by a combining the ${\alpha}-Si$ and LSSiN process for a nickel oxide micro-bolometer.

• 제어로봇시스템학회논문지
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• 제18권1호
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• pp.54-61
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• 2012

In this paper, the pose estimation method for the satellite GTB (Ground Test Bed) using vision/MEMS IMU (Inertial Measurement Unit) integrated system is presented. The GTB for verifying a satellite system on the ground is similar to the mobile robot having thrusters and a reaction wheel as actuators and floating on the floor by compressed air. The EKF (Extended Kalman Filter) is also used for fusion of MEMS IMU and vision system that consists of a single camera and infrared LEDs that is ceiling landmarks. The fusion filter generally utilizes the position of feature points from the image as measurement. However, this method can cause position error due to the bias of MEMS IMU when the camera image is not obtained if the bias is not properly estimated through the filter. Therefore, it is proposed that the fusion method which uses the position of feature points and the velocity of the camera determined from optical flow of feature points. It is verified by experiments that the performance of the proposed method is robust to the bias of IMU compared to the method that uses only the position of feature points.

• 제어로봇시스템학회논문지
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• 제13권2호
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• pp.128-132
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• 2007

Thermal Imaging systems are reported to be crucial for fire fighting and beginning to be used by fire fighters. The performance of thermal imaging system is determined by both the radiation of infrared from the target and the attenuation of infrared signal in the optical path by the absorption, scattering, diffraction and reflection. In the scene of fire, water drops with various sizes such as vaporized water, wafer mist from sprinkler, and wafer to suppress the fire reside with various gas generated by burning. To measure the transmission of infrared radiation in the scene of fire, fire simulating system and thermal imagers with cooled detector which detects $3{\sim}5{\mu}m$ infrared and uncooled detector fabricated by the MEMS technology which detects $8{\sim}12{\mu}m$ infrared. are made. With thermal imagers and Ire simulating system, the change of thermal image with respect to the change of visibility controlled with the burned fas was measured. It was found that the transmission of infrared was not reduced by the burned gas, which could be explained by the long wavelength of infrared ray compared with visible ray. However, the transmission of infrared ray was largely reduced by the combination of burned gas and water mist supplied by sprinkler. This is contrary to the results of calculated transmission through the pure water mist and shows that the transmission of infrared ray is mostly affected by the compounds of water mist and burned gas. In this case, it was found that the uncooled detector which detects $8{\sim}12{\mu}m$ infrared ray is better than cooled detector which detects $3{\sim}5{\mu}m$ infrared ray for fire fighting.

• 센서학회지
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• 제18권4호
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• pp.301-306
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• 2009

This paper describes the design and fabrication of 16$\times$16 microbolometer infrared focal plane arrays based on iMEMS technology. Amorphous silicon was used for infrared-sensitive material, and it showed the resistance of 18 Mohm and the temperature coefficient of resistivity of -2.4 %. The fabricated sensors exhibited responsivity of 78 kV/W and thermal time constant of 8.0 msec at a bias voltage of 0.5 V. The array performances had satisfactory uniformity less than 5 % within one-sigma. Also, 1/f noise of pixel was measured and the noise factor of $6\times10^{-11}$ was extracted. Finally, we obtained detectivity of $1.27\times10^9cmHz^{0.5}/W$ and noise equivalent temperature difference of 200 mK at a frame rate of 30 Hz.

• 센서학회지
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• 제17권1호
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• pp.75-80
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• 2008

In this work, we optimized a microbolometer for application of a $CO_2$ detector by using MEMS technology. We fabricated a stable thermal isolation structure by varying the lengths of supporting legs which affect bolometer performance. We could fabricate more stable thermal isolation structure for the microbolometer through the results of ANSYS simulations, and minimize the fabrication processes by using bulk micromachining to use a $CO_2$ detector. The microbolometer shows a detectivity of $2.5{\times}109$ cmHz$^{1/2}$/W at a chopper frequency of 8 Hz and a bias current of $6.25\;{\mu}A$ with a vacuum package of about $3.0{\times}10.3$ torr. Therefore, we put to conclusion that the microbolometer optimized in this experiment could be useful for the application of a $CO_2$ detector.