• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2008.11a
• /
• pp.18-18
• /
• 2008

3차원 패키징 System In Package (SIP)구조에서 Chip to Chip 단위 Interconnection 역할을 하는 Through Silicon Via(TSV)를 형성하기 위하여 Pulsating RF bias가 장착된 Inductively Coupled Plasma Etcher 장비를 이용하였다. 이 Pulsating 플라즈마 공정 방법은 주기적인 펄스($50{\sim}500Hz$)와 듀티($20{\sim}99%$) cycle 조절이 가능하며, 플라즈마 에칭특성에 영향을 주는 플라즈마즈마 발생 On/Off타임을 조절할 수 있다. 예를 들면, 플라즈마 발생 Off일 경우에는 이온(SFx+, O+)과 래디컬(SF*, F*, O*)의 농도 및 활성도를 급격하게 줄이는 효과를 얻을 수가 있는데, 이러한 효과는 식각 에칭시, 이온폭격의 손상을 급격하게 줄일 수 있으며, 실리콘 표면과 래디컬의 화학적 반응을 조절하여 에칭 측벽 식각 보호막 (SiOxFy : Silicon- Oxy- Fluoride)을 형성하는데 영향을 미친다. 그리고, TSV 형성에 있어서 큰 문제점으로 지적되고 있는 언더컷과 수평에칭 (Horizontal etching)을 개선하기 위한 방법으로, Black-Siphenomenon을 이번 실험에 적용하였다. 이 Black-Si phenomenon은 Bare Si샘플을 이용하여, 언더컷(Undercut) 및 수평 에칭 (Horizontal etching)이 최소화 되는 공정 조건을 간편하게 평가 할 수 있는 방법으로써, 에칭 조건 및 비율을 최적화하는 데 효율적이었다. 결과적으로, Pulsating RF bias가 장착된 Inductively Coupled Plasma Etcher 장비를 이용한 에칭실험은 펄스 주파수($50{\sim}500Hz$)와 듀티($20{\sim}99%$) cycle 조절이 가능하여, 이온(SFx+, O+)과 래디컬(SF*, F*, O*)의 농도와 활성화를 조절 하는데 효과적이었으며, Through Silicon Via (TSV)를 형성 하는데 있어서 Black-Si phenomenon 적용은 기존의 Continuous 플라즈마 식각 결과보다 향상된 에칭 조건 및 에칭 프로파일 결과를 얻는데 효과적이었다.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.7 no.2
• /
• pp.57-64
• /
• 1999

The purpose of this study is to establish effective conditions for controlling $CH_4$, $N_2O$ emission from organic Waste / wastewater treatment processes. Continuous and batch experiments were conducted to treat the micro algae from polluted and eutrophicated lakes through the thermophilic oxic process. The microalgae used were mainly Microcystis sp.(collected from eutrophic lake) and Chlorella sp. (cultured in laboratory) Wasted cooking oil was added by aid-heating source. Physico-chemical components of sludges and microalgae were analyzed. In batch experiments, air supply was changed from 50ml/min to 150ml/min. The temperature. water content and drained water were affected by the air flow rate at initial stage. However, there was almost no influence of air flow rate on them in middle and last stages. At air flow rate of 100ml/min, the degradation rate of organic material was higher than that at other air flow rates. $CO_2$ concentration in exhaust was proportional to the strength of aeration, especially at initial stage when degradation was active. $CH_4$ with low concentration was detected only at starting stage when air diffusion was not enough. $N_2O$ production was not affected by variation of air supply. In continuous experiments no matter what the dewatering methods (with PAC and without PAC) and media (wood chip and reed chip) were changed, $N_2O$ was almost not affected by variation of injected air. Result showed that the reed chips using for lake purification could be used as media for thermophilic oxic process in lake and marshes area. $CO_2$ concentration was not so much affected by the change of dewatering methods and media types. $CH_4$ was not detected in the experimental period. So it can be shown that the thermophilic oxic process had been well operated in wide handling conditions regardless of media and dewatering methods.

• Korean Journal of Materials Research
• /
• v.10 no.12
• /
• pp.853-863
• /
• 2000

In this study, a new UBM materials system for solder flip chip interconnection of Cu pads were investigated using electroless copper (E-Cu) and electroless nickel (E-Ni) plating method. The interfacial reaction between several UBM structures and Sn-36Pb-2Ag solder and its effect on solder bump joint mechanical reliability were investigated to optimife the UBM materials design for solder bump on Cu pads. Fer the E-Cu UBM, continuous coarse scallop-like $Cu_{6}$ $Sn_{5}$ , intermetallic compound (IMC) was formed at the solder/E-Cu interface, and bump fracture occurred this interface under relative small load. In contrast, Fer the E-Ni/E-Cu UBM, it was observed that E-Ni effectively limited the growth of IMC at the interface, and the Polygonal $Ni_3$$Sn_4$ IMC was formed because of crystallographic mismatch between monoclinic $Ni_3$$Sn_4$ and amorphous E-Ni phase. Consequently, relatively higher bump adhesion strength was observed at E-Ni/E-Cu UBM than E-Cu UBM. As a result, it was fecund that E-Ni/E-Cu UBM material system was a better choice for solder flip chip interconnection on CU PadS.

• Korean Chemical Engineering Research
• /
• v.48 no.4
• /
• pp.470-474
• /
• 2010

In this study, we presents a simple microfluidic approach for generating uniform Poly(ethylene glycol)(PEG) microfiber. Elongated flow pattern of monomer induced by sheath flow of immiscible oil as continuous phase is generated in Y-shape junction and in situ polymerization by UV exposure. For uniform microfiber, we investigate the optimized flow condition and draw phase diagram as function of Ca and Qd. At the region for stable elongated flow pattern, the microfiber generated in microfluidic chip is very uniform and highly reproducible. Importantly, the thickness of microfibers can be easily controlled by flow rate of continuous and disperse phase. We also demonstrate the feasibility for biological application as encapsulating FITC-BSA in PEG microfiber.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.12
• /
• pp.71-79
• /
• 2013

This paper describes a 12.5 Gb/s low-power receiver design with equalizer adaptation. The receiver adapts to channel and chip process variation by adaptation circuit using sampler and serializer. The adaptation principle is explained. It describes technique receiving ground referenced differential signal of voltage-mode transmitter for low-power. The CTLE(Continuous Time Linear Equalizer) having 17.6 dB peaking gain to remove long tail ISI caused channel with -21 dB attenuation. The voltage margin is 210 mV and the timing margin is 0.75 UI in eye diagram. The receiver consumes 0.87 mW/Gb/s low power in 45 nm CMOS technology.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.12
• /
• pp.2628-2635
• /
• 2010

This paper analyzes the detection probability of FMCW (Frequency Modulated Continuous Wave) radar based on Doppler frequency and analog-digital converter bit and designs and implements signal processing part of FMCW radar. For performance evaluation, the FMCW radar system consists of a transmitted part and a received part and uses AWGN channel. The system model is verified through analysis and simulation. Frequency offset occurs in the received part caused by the mismatching between the received signal and the reference signal. In case of Doppler frequency less than about 38KHz, performance degradation of detection does not occur in FMCW radar with 75cm resolution The analog-digital converter needs at least 6 bit in order not to degrade the detection probability. And, we design and implement digital signal processing part based on DDS chip of digital transmitted signal generator for FMCW radar.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.4
• /
• pp.1068-1076
• /
• 1996

In this paper, a new continuous-time current-mode integrator as basic building block of the low-voltage analyog current-mode active filters is proposed. Compared to the current-mode integrator which is proposed by Zele, the proposed current-mode integrator had higher unity gain frequency and output impedance in addition to lower power dissipation. And also, a current-mode third-order lowpass active filter is designed with the proposed current-mode integrator. The designed circuits are fabricated using the ORBIT's $1.2{\mu}{\textrm{m}}$ deouble-poly double-metal CMOS n-well process. The experimental results show that the filter has -3dB cutoff frequency at 44.5MHz and 3mW power dissipation with single 3.3V power supply and also $0.12mm^{2}$ chip area.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.11C no.4
• /
• pp.127-132
• /
• 2001

We describe the pulse forming of pulsed $CO_2$laser using multi-pulse superposition technique. A various pulse length, high duty cycle pulse forming network(PFN) is constructed by time sequence. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on SCRs of three PFN modules consecutively at a desirable delay time with the aid of PIC one-chip microprocessor. The power supply for this experiment consists of three PFN modules. Each PFN module uses a capacitor, a pulse forming inductor, a SCR, a High voltage pulse transformer, and a bridge rectifier on each transformer secondary. The PFN modules operate at low voltage and drive the primary of HV pulse transformer. The secondary of the transformer has a full-wave rectifier, which passes the pulse energy to the load in a continuous sequence. We investigated laser pulse shape and duration as various trigger time intervals of SCRs among three PFN modules. As a result, we can obtain laser beam with various pulse shapes and durations from about 250 $mutextrm{s}$ to 600 $mutextrm{s}$.

• Journal of the Korean Society of Safety
• /
• v.19 no.4 s.68
• /
• pp.135-140
• /
• 2004

Wear mechanisms may be briefly classified by mechanical, chemical and thermal wear. A plane strain finite element method is used with a new material stress and temperature fields to simulate orthogonal machining with continuous chip formation. Deformation of the workpiece material is healed as elastic-viscoplastic with isotropic strain hardening and the numerical solution accounts for coupling between plastic deformation and the temperature field, including treatment of temperature-dependent material properties. Effect of the uncertainty in the constitutive model on the distributions of strait stress and temperature around the shear zone are presented, and the model is validated by comparing average values of the predicted stress, strain, and temperature at the shear zone with experimental results.

• Journal of the Korea Society of Computer and Information
• /
• v.3 no.2
• /
• pp.77-84
• /
• 1998

The continuous time signal system by development of CMOS technology have been receiving consideration attention. In this paper, Low pass filter using CMOS floating resistor have been designed with cut off frequency for speech signal processing. Especially a new floating resistor consisting entirely of CMOS devices in saturation has been developed. Linearity within $\pm$0.04% is achieved through nonlineartiy via current mirrors over an applied range of $\pm$1V. The frequency response exceeds 10MHz, and the resistors are expected to be useful in implementing integrated circuit active RC filters. The low pass filter designed using this method has simpler structure than switched capacitor filter. So reduce the chip area. The characteristics of the designed low pass filter using this method are simulated by pspice program.