• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.10
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• pp.838-843
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• 2002

Chemical mechanical polishing(CMP) process has been widely used to planarize dielectric layers, which can be applied to the integrated circuits for deep sub-micron technology. The reverse moat etch process has been used for the shallow trench isolation(STI)-chemical mechanical polishing(CMP) process with conventional low selectivity slurries. Thus, the process became more complex, and the defects were seriously increased. In this paper, we studied the direct STI-CMP process without reverse moat etch step using high selectivity slurry(HSS). As our experimental results show, it was possible to achieve a global planarization without the complicated reverse moat process, the STI-CMP process could be dramatically simplified, and the defect level was reduced. Therefore the throughput, yield, and stability in the ULSI semiconductor device fabrication could be greatly improved.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.43-49
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• 1997

The dependence of the electrical properties in planar MQW - APD & pn, and p - i - n photodiode implanted with oxygen on the annealing emperatures and ion dose has been investigated. The oxygen implantation was performed for inter-device isolation. The leakage current of as-impanted p-i-n photodiode obtained was less than 50 nA. An annelaing temperature dependence study shows an abrupt increase of leakge current at 600.deg.C for all devices under study. This indicates that donor complex centers introduced by the chemical activity of oxygen increase with increasing annelaing temperatures. Furthermore, leakage current was highly correlated with oxygen dose due to th eimplanted related defects.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.724-729
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• 2003

Installing vibration isolation in structures, such as structures adjacent to subways, may be delicatebecause of the proximity with the vibration source or because of the wave propagation path. This paper discusses on method that install isolation Pads on underground walls as a part of the vibration mitigation system, and also on its efficiency, The proposed method is proven to affect significantly the distribution of acceleration in the neighborhood of the structure and to reduce efficiently the maximum amplitude of the vibration. It is also seen that installing isolating pads until the depth of the foundations and deeper is more efficient than installing such device separately from the structure. This Study being limited to the comparison of installation methods, further Studies considering the thickness, stiffness and other parameters should be required.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.7
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• pp.311-315
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• 2002

Chemical mechanical polishing (CMP) process was required for the global planarization of inter-metal dielectric(IMD), inter-level dielectric (ILD) layers of multi-layer interconnections. In this paper, we studied the characteristics of polishing pad, which can apply shallow trench isolation (STI)-CMP process for global planarization of multi-level interconnection structure. Also, we investigated the effects of different sets of polishing pad, such as soft and hard pad. As an experimental result, hard pad showed center-fast type, and soft pad showed edge-fast type. Totally, the defect level has shown little difference, however, the counts of scratch was detected less than 2 on JR111 pad. Through the above results, we can select optimum polishing pad, so we can expect the improvements of throughput and device yield.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.1021-1026
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• 1995

The seismic responses of a base isolated Pressurized Water Reactor (PWR) are investigated using a mathematical model which expresses the superstructure as lumped mass-spring model and the seismic isolator as an equivalent spring-damper. Time history analyses are performed for the 1940 E1 Centre earthquakes in both horizontal and vertical directions. In the analysis, structural damping of 5% is used for the superstructure. The isolator damping ratios of 12% for horizontal and 5% for vertical directions are used. The acceleration responses in base isolated PWR superstructure with high damping rubber bearings are much smaller than those in fixed base structure in horizontal direction. However, the vertical acceleration responses at the superstructure in the base isolation system are amplified to some extent. It is suggested that the vertical seismic responses at the superstructure should be reduced by introducing a soft vertical isolation device.

• Journal of Korean Association for Spatial Structures
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• v.17 no.2
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• pp.71-77
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• 2017

In this study, the boundary non-linear analysis of the sky bridge subjected to walking load and running load is performed. The sky bridge is installed in the mid-story between two buildings and the walking load and running load induced by pedestrians are measured by load cell. LRB is modeled as a non-linear hysteresis model to accurately represent the behavior of LRB. For the serviceability evaluation of sky bridge, the acceleration responses of sky bridge are analyzed based on ISO 2631-2 and the velocity response are analyzed based on standards Bachmann &Amann. In serviceability evaluation of this sky bridge, the pedestrian can not perceive the vibration except for resonance running loads consequently. Therefore, it is concluded that this sky bridge haven't problem in the serviceability.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.243-253
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• 2008

This paper deals with the analysis, design, and implementation of a single phase AC-DC Zeta converter with high frequency transformer isolation and power factor correction(PFC) in two modes of operation, discontinuous current mode of operation(DCM), and continuous current mode of operation(CCM). A Digital Signal Processor(DSP) based implementation is carried out for validation of the Zeta converter developed design in discontinuous mode of operation. A comparison of both modes of operation is presented for a 1kW power rating from the point of view of steady state and dynamic behavior, power quality, simplicity, control technique, device rating, and converter size. The experimental results of a developed prototype of Zeta converter are presented for validation of the developed design. It is observed that CCM is most suitable for higher power applications where it requires some complex control and sensing of the additional variables.

• Journal of the Korea Society for Simulation
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• v.11 no.1
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• pp.23-30
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• 2002

An STI(Shallow Trench Isolation) by using a CMP(Chemical Mechanical Polishing) process has been one of the key issues in the device isolation[1] In this paper we fabricated N, P-MOSFEET tall analyse hump characteristics in various rounding oxdation thickness(ex : Skip, 500, 800, 1000$\AA$). As a result we found that hump occurred at STI channel edge region by field oxide recess. and boron segregation(early turn on due to boron segregatiorn at channel edge). Therefore we improved that hump occurrence by increased oxidation thickness, and control field oxide recess( 20nm), wet oxidation etch time(19HF,30sec), STI nitride wet cleaning time(99HF, 60sec+P 90min) and fate pre-oxidation cleaning time (U10min+19HF, 60sec) to prevent hump occurring at STI channel edge.

• Journal of Korean Association for Spatial Structures
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• v.19 no.2
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• pp.51-61
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• 2019

The objective of this study is to analysis the seismic response of 200m spanned honeycomb lattice domes under horizontal and up-down ground motion of El Centro earthquake. For the analysis of seismic response of the honeycomb lattice domes by rise/span ratio, the time history analysis is used for the estimation of the dynamic response. The low rise lattice dome is less deformed and less stressed than the high rise lattice dome for the earthquake ground motion. The 3-dimensional earthquake response is not significantly different the dynamic response of one directional ground motion. The earthquake response of domes with LRB isolation system is significantly reduced for the asymmetric vertical deformation and the horizontal and vertical accelerations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.119-122
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• 2003

This paper describes characteristics for insertion losses of Isolator have an effect on material parameter. One purpose of the paper is to present insertion loss on this resonator for magnetic loss, dielectric loss, magnetic field and saturation magnetization. Another is to study the effect of propeller resonator on response characteristics. In this paper, the analysis and measurement of the response characteristics were carried out for the isolator prototype. The measurement results agreed on the simulation results and acquire insertion loss $0.18\;{\sim}\;0.24dB$, return loss 27dB, isolation 27dB and bandwidth 500MHz on this condition saturation magnetization 550G, dielectric loss 0.0004, magnetic loss 20 and dielectric constant 14.