• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.148-149
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• 2008

As infrared light is radiated, the CMOS Readout IC (ROIC) for the microbolometer type infrared sensor detects voltage or current when the resistance value in the bolometer sensor varies. One of the serious problems in designing the ROIC is that resistances in the bolometer and reference resistor have process variation. This means that each pixel does not have the same resistance, causing serious fixed pattern noise problems in sensor operations. In this paper, Reference resistor compensation technique was proposed. This technique is to compensate the reference resistance considering the process variation, and it has the same reference resistance value as a bolometer cell resistance by using a comparator and a cross coupled latch.

• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.366-370
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• 2022

A 12 ㎛ pixel-sized 360 × 240 microbolometer focal plane array (MBFPA) was fabricated using a complementary metaloxide-semiconductor (CMOS)-compatible process. To release the MBFPA membrane, an amorphous carbon layer (ACL) processed at a low temperature (<400 ℃) was deposited as a sacrificial layer. The thermal time constant of the MBFPA was improved by using serpentine legs and controlling the thickness of the SiNx layers at 110, 130, and 150 nm on the membrane, with response times of 6.13, 6.28, and 7.48 msec, respectively. Boron-doped amorphous Si (a-Si), which exhibits a high-temperature coefficient of resistance (TCR) and CMOS compatibility, was deposited on top of the membrane as an IR absorption layer to provide heat energy transformation. The structural stability of the thin SiNx membrane and serpentine legs was observed using field-emission scanning electron microscopy (FE-SEM). The fabrication yield was evaluated by measuring the resistance of a representative pixel in the array, which was in the range of 0.8-1.2 Mohm (as designed). The yields for SiNx thicknesses of SiNx at 110, 130, and 150 nm were 75, 86, and 86%, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.226-231
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• 2014

Thin thermistor films of solutions with nickel and manganese oxides were prepared by metal-organic decomposition (MOD). The structural properties of the thin films were investigated as a function of annealing temperature. Field emission scanning electron microscope (FE-SEM) results indicated that the thin films had a thin thickness, smooth and dense surface. The crystallization temperature of $414.9^{\circ}C$ was confirmed from thermogavimetric-differential thermal analysis (TG-DTA) curve. A single phase of cubic spinel structure was obtained for the thin film annealed from $700^{\circ}C$ to $800^{\circ}C$, which was confirmed from the X-ray diffraction (XRD). From the selected area electron diffraction (SAED) in high resolution transmission electron microscope (HRTEM), the nano grains (2~3 nm) of spinel phase with (311) and (222) planes were detected for the thin film annealed at $500^{\circ}C$, which could be applicable to read-out integrated circuit (ROIC) substrate of the uncooled microbolometer with low processing temperature.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.4
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• pp.170-175
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• 2004

A three dimensional feed horn 10${\mu}{\textrm}{m}$ wavelength infrared antenna has been suggested, fabricated and characterized. It was applied to an infrared detector for efficient collecting of IR radiation and for reducing background noise. The horn antenna size was designed for maximum antenna directivity. The 3D feed horn antenna mold was fabricated using rotating and tilted illumination while the antenna plate was constructed by way of electroplating. Antenna characteristics were measured by coupling with a microbolometer. Measurement results indicated that the directivity of the antenna is 16.1㏈ and the background noise is reduced by approximately two times.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.238-239
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• 2009

The amorphous silicon microbolometer array has been developed by the MEMS design and fabrication technology. Before the bolometer array for the image sensor being designed, the structure of unit cell and $16\times16$ array of it was simulated, designed and fabricated. The properties of bolometer have been measured as such that the TCR -3%/K.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.7-8
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• 2009

In the presence of infrared light, a CMOS Readout IC (ROIC) for a microbolometer typed infrared sensor detects the voltage or current that is caused by the changing in resistance in the bolometer sensor. A serious problem in designing the ROIC is how the value of the bolometer and reference resistors vary because of variations in manufacturing process. Since different pixel have different, resistance values, sensor operations must contend with fixed pattern noise (FPN) problems. In this paper, we propose a novel technique to compensate for the fluctuation in reference resistance by tiling into account the process variation. By using constant current source basing and correlated double sampling, we solved FPN.

• ETRI Journal
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• v.31 no.6
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• pp.703-708
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• 2009

Silicon antimony films are studied as resistors for uncooled microbolometers. We present the fabrication of silicon films and their alloy films using sputtering and plasma-enhanced chemical vapor deposition. The sputtered silicon antimony films show a low 1/f noise level compared to plasma-enhanced chemical vapor deposition (PECVD)-deposited amorphous silicon due to their very fine nanostructure. Material parameter K is controlled using the sputtering conditions to obtain a low 1/f noise. The calculation for specific detectivity assuming similar properties of silicon antimony and PECVD amorphous silicon shows that silicon antimony film demonstrates an outstanding value compared with PECVD Si film.

• Journal of Electrical Engineering and Technology
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• v.7 no.2
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• pp.221-224
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• 2012

We propose a Readout Integrated Circuit (ROIC), which applies a fixed current bias sensing method to the input stage in order to simplify the circuit structure and the infrared sensor characteristic control. For the sample-and-hold stage to display and control a signal detected by the infrared sensor using a two-dimensional (2D) focal plane array, a differential delta sampling (DDS) circuit is proposed, which effectively removes the FPN. In addition, the output characteristic is improved to have wider bandwidth and higher gain by applying a two-stage variable gain amplifier (VGA). The output characteristic of the proposed device was 23.91 mV/$^{\circ}C$, and the linearity error rate was less than 0.22%. After checking the performance of the ROIC using HSPICE simulation, the chip was manufactured and measured using the SMIC 0.35 um standard CMOS process to confirm that the simulation results from the actual design are in good agreement with the measurement results.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.450-455
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• 2010

The performance modeling of a $25{\mu}m$ pitch VGA ${\mu}$-bolometer with the self-aligned thermal resistor structure is carried out. The self-aligned thermal resistor can be utilized for the maximizing the thermal resistance and the fill factor of a bolometer, so the performance improvement can be expected. From the results of the performance modeling of the micro-bolometer with self-align thermal resistor for a $25{\mu}m$ pitch $640{\times}480$ microbolometer designed with $0.6{\mu}m$ minimum feature size, the drastic improvements of NETD from 38.7 mK to 19.1 mK, responsivity of 1.9 times are expected with a self aligned thermal resistor structure. The main reason for the performance improvements with a self-aligned thermal resistor structure comes from the increasement of the thermal resistance.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1914-1917
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• 2001

3D Feed Horn Shape MEMS Antenna Array는 적외선 이미지 소자 또는 Tera hertz band 등에서 많은 응용을 할 수 있는 장점을 가진 MEMS 구조체 이다. 하지만 일반적인 MEMS 공정을 이용해서 3D Feed Horn Shape MEMS antenna array를 구현하기는 적합하지 않았다. 본 논문에서는 마스크와 웨이퍼가 일체 된 형태의 경사된 척이 초 저속으로 회전하면서 노광을 할 수 있는 새로운 방식과 미러 반사구조를 이용해서 평행광을 얻을수 있는 노광장치 (MRPBI : Mirror Reflected Parallel Beam Illuminator) System제작방법을 제안하였다. 3D Feed Horn Shape MEMS Antenna의 구조적인 high apect ratio의 특성에 의해서 SU-8과 PMER Negative Photo resist를 이용한 기본적인 실험을 통해 3D 구조체의 구현 가능성을 증명하였다. 또한 Microbolometer의 성능향상을 위한 이론적인 3D MEMS Antenna Model들을 HFSS(High Frequency Structure Simulator)을 이용해서 그 최적구조를 제안하고 3D MEMS Antenna Gain 값을 비교 분석하였다.