• Journal of the Korean Vacuum Society
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• v.8 no.3A
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• pp.249-255
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• 1999

Deposition characteristics of Cu thin films using Ar carrier gas and $H_2$ processing gas at various working pressures and substrate temperatures were investigated. Also, effects of $H_2$ pretreatment using plasma at $200^{\circ}C$ of substrate temperature and 0.6 Torr of chamber pressure were stdied. Cu thin films were deposited on TiN/Si substrate at working pressure of 0.5~1.5 Torr, substrate temperatures of 140~$240^{\circ}C$ with (hface)Cu(tmvs). Substrates were pretreated by $H_2$ plasma, and Cu films deposited in situ using twofold shower head. The purity, electrical resistivity, thickness, surface morphology, optical properties of the deposited Cu films were measured b the AES, four point probe, stylus profiler, SEM,. and the uv-visible spectrophotometer. This study suggests that $H_2$ plasma is an effective method for enhancing deposition rate and for producing high quality copper thin films.

• ETRI Journal
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• v.19 no.1
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• pp.26-35
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• 1997

The substrate effects on solid-phase crystallization of amorphous silicon (a-Si) films deposited by low-pressure chemical vapor deposition (LPCVD) using $Si_2H_6$ gas have been extensively investigated. The a-Si films were prepared on various substrates, such as thermally oxidized Si wafer ($SiO_2$/Si), quartz and LPCVD-oxide, and annealed at 600$^{\circ}C$ in an $N_2$ ambient for crystallization. The crystallization behavior was found to be strongly dependent on the substrate even though all the silicon films were deposited in amorphous phase. It was first observed that crystallization in a-Si films deposited on the $SiO_2$/Si starts from the interface between the a-Si and the substrate, so called interface-interface-induced crystallization, while random nucleation process dominates on the other substrates. The different kinetics and mechanism of solid-phase crystallization is attributed to the structural disorderness of a-Si films, which is strongly affected by the surface roughness of the substrates.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.13-15
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• 2006

The effects of plasma treatment on the surfaces of the FR-4 (Flame Resistant-4) and copper substrates are investigated in terms of X-ray photoelectron spectroscopy (XPS), contact angle, and atomic force microscopy (AFM). The adhesion strengths of the underfills/FR-4 substrate and underfills/copper substrate are also studied. As experimental results, the plasma treatments of FR-4 and copper substrate surfaces yield several oxygen complexes in hydrophilic surfaces, which can play an important role in increasing the surface polarity, wettability, and adhesion characteristics of the underfills/substrates.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.428-435
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• 2002

Pyroelectric $Pb(Zr_{0.3}Ti_{0.7})O_3$ (PZT30/70) thin film IR detectors has been fabricated and characterised. The PZT30/70 thin film was deposited onto $Pt/Ti/Si_3N_4/SiO_2/Si$ substrate by the sol-gel process. Four different substrate conditions were studied for their effects on the pyroelectric responses of the IR detectors. The substrate conditions were the combinations of the Si etching and the Pt/Ti patterning. In the Si etched substrate, the $Si_3N_4/SiO_2$ composite layer was used as silicon etch-stop, and was used as the membrane to support the PZT pyroelectric film element as well. The measured pyroelectric current and voltage responses of detectors fabricated on the micro-machined thin $Si_3N_4/SiO_2$ membrane were two orders higher than those of the detectors on the bulk-silicon. For detectors on the membrane substrate, the Pt/Ti patterned detectors showed a 2-times higher pyroelectric response than that of not-patterned detectors. On the other hand, the pyroelectric response of the detectors on the not-etched Si substrate was almost the same, regardless of the Pt/Ti patterning. It was also found that the rise time strongly depended on the substrate thickness: the thicker the substrate was, the longer the rise-time.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.879-882
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• 1999

The effects of the substrate bias on the performance of programming erasing in p-channel flash memory cell have been investigated. It is found that applying positive substrate bias can improve the programming and erasing speed. This improvements can be explained by Substrate Current Induced Hot Electron Injection. From the results, we can confirm that BTB programming method is better in programming and erasing speed than CHE programming method.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.871-874
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• 1998

A new transmission line parameter extraction method of iC interconnects on silicon substrate is presented. To extract the acurate parameters, the silicon substrate effects were taken into account. Since the electromagnetic fields under the silicon substrate are propagated with slow wave mode, effective dielectric constant and different ground plane with the multi-layer dielectric structures were employed for inductance and capacitance matrix determination. Then accurate signal transients simulation were performed with HSPICE by using the parameters. It was shown that the simulation resutls has an excellent agreement with TDR/TDT measurements.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.320-324
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• 2015

Mutual coupling between antenna elements of a linear microstrip patch antenna array positioned along the H-plane including the effect of edge reflections is investigated. Simple formulas are presented for the estimation of the grounded dielectric substrate size with minimum mutual coupling. The substrate sizes calculated by these formulas are in good agreement with those obtained by the full-wave simulation and experimental measurement. The substrate size with minimum mutual coupling is a function of the effective dielectric constant for surface waves and the distance between the antenna centers. The substrate size with minimum mutual coupling decreases as the effective dielectric constant for surface waves on a finite grounded dielectric substrate increases.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.895-898
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• 1999

Recently, small signal modeling of CMOS device becomes more difficult because the design rule goes into deep submicron. De-embedding of substrate parameters is important in order to use CMOS devices at RF frequencies. In this paper, we suggest a new de-embedding model with refined physical meaning and accuracy. In GaAs IC’s, the substrate is almost an insulator but Si substrate has the semiconducting characteristics. It offers some troubles if it is treated like GaAs substrate. The conducting substrate is modeled with five resistances, which leads to very accurate modeling so long as the pad layout is symmetrical. Frequency range is up to 39㎓ and fitting accuracy is as small as 0.00037 on least square errors.

• Korean Journal of Materials Research
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• v.31 no.8
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• pp.439-444
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• 2021

The oxidation resistance of the diffusion aluminide bond coat (BC) is compromised largely by interdiffusion (ID) effects on coated turbine blades of aeroengines. The present study is designed to understand the influence of ID on βNiAl coatings or BC. In this regard, nickel substrate and CMSX-4 superalloy are deposited. In total, four sets of BCs are developed, i.e. pure βNiAl (on Ni substrate), simple βNiAl (on CMSX-4 substrate), Zr-βNiAl (on CMSX-4 substrate) and Pt-βNiAl (on CMSX-4 substrate). The main aim of this study is to understand the interdiffusion of Al, Zr and Pt during preparation and oxidation. In addition, the beneficial effects of both Zr and platinum are assessed. Pure βNiAl and simple βNiAl show Ni-out-diffusion, whereas for platinum inward diffusion to the substrate is noticed under vacuum treatment. Interestingly, Zr-βNiAl shows the least ID in all BCs and exhibit stability under both vacuum and oxidation treatments. However, its spallation resistance is slightly lower than that of Pt-βNiAl BC. All BCs show similar oxide growth trends, except for Zr-βNiAl, which exhibits two-stage oxidations, i.e. transient and steady-state. Moreover, it is suggested that the localized spallation in all BCs is caused by βNiAl - γ'-Ni₃Al transformation.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.2
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• pp.102-112
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• 2003

This study was carried out to research and develop a shallow green rooftop system which would require low maintenance and therefore could be used for existing rooftops. To achieve these goals, the conceptual model was induced by past studies and the experimental systems were deduced from the conceptual model. On the growth of Sedum sarmentosum grown in these rooftop systems, the effects of artificial substrate type, soil depth, and drainage type were investigated from 3 April to 11 October 2002. Artificial substrates were an alone type and a blending type. The alone type was an artificial substrate formulated by blending crushed porous glass with bark(v/v, 6:4). The blending type was formulated by blending the alone type with loam(v/v, 1:1). Soil depths were 5cm, loom, and 15cm. Drainage types were a reservoir-drainage type and a drainage type. The reservoir-drainage type could keep water and drain excessive water at the same time. The drainage type could drain excessive water but could not keep water. Covering area, total fresh and dry weight, visual quality, and water content per 1g dry matter were measured. All the variables were analyzed by correlation analysis and factor analysis. The results of the study are summarized as follows. The growth increment was higher in the blending type than in the alone type, the highest in loom soil depth and higher in the reservoir-drainage type than in the drainage type. The growth quality was higher in the blending type than in the alone type, the highest in l0cm soil depth, and higher in the drainage type than in the reservoir-drainage type. In consideration of the permissible load on the existing rooftops and the effects of the treatments on the growth increment and quality, the system should adopt the blending type in artificial substrate types, 5~10cm in soil depths, and the drainage type in drainage types. This system will be well-suited to the growth of Sedum sarmentosum, and when the artificial substrate was in field capacity, the weight will be 75~115kg/$m^2$.