• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.64-65
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• 2005

The structural and electrical properties of the films are investigated as a function of nitrogen/argon ratio at room temperature and at various deposition temperatures. The phase changes as $Ta_2N$ or TaN in the films were observed as nitrogen/argon ratio increases from 3% to 25%. The phase changes were associated with a change in the resistivity and TCR (temperature coefficient of resistance) of the films. TCR values of the films deposited at room temperature and different nitrogen contents were negative, and strongly decreased with the increase in nitrogen/argon ratio. The Ta2N films deposited at nitrogen/argon ratio of 3% show improved TCR values and thermal stability with increasing deposition temperature. The $Ta_2N$ films grown at nitrogen/argon ratio of 3% and the temperature of $200^{\circ}C$ showed a TCR value of -47 $ppm/^{\circ}C$, which is close to near-zero TCR in the range of deposition temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.19-19
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• 2009

TiNxOy/TiNx multilayer thin films with a high resistance (~ k$Omega$) were deposited on SiO2/Si substrates at room temperature by sputtering. The TiNx thin films show island and smooth surface morphology in samples prepared by dc and rf magnetron sputtering, respectively. TiNxOy/TiNx multilayer has been developed to control temperature coefficient of resistance (TCR) by the incorporation of TiNx layer (positive TCR) inserted into TiNxOy layers(negative TCR). Electrical and structural properties of sputtered TiNxOy/TiNx multilayer films were investigated as a function of annealing temperature. In order to achieve a stable high resistivity, multilayer films were annealed at various temperatures in oxygen ambient. Samples annealed at 700 oC for 1 min exhibit a good TCR value and a stable high resistivity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1399-1401
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• 2001

We studied on structure and resistivity, temperature coefficient of resistance (TCR) of NiCr and NiCr-N thin resistor films prepared by do reactive magnetron sputtering of NiCr target. It is found that while pure NiCr films are polycrystalline, an addition of nitrogen (N2/(Ar+N2) ratios are between 10% and 70%) into the film is changed into amorphous structure and sheet resistance of films is increased. Measurement temperatures of TCR are ratios of $5^{\circ}C$ per 15min from $25^{\circ}C$ to $130^{\circ}C$. TCR for an as-deposited NiCr-N thin film is varied from positive to negative.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.337-338
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• 2006

The 200 nm thick-NiCr films grew on $SiO_2$/Si substrates at various deposition temperatures by a dc magnetron co-sputtering technique were characterized for the variation of film texture. The resistivity of the films decreases with increasing deposition temperature and temperature coefficient of electrical resistance (TCR) varies from negative value to a positive one with increasing deposition temperature. The NiCr films deposited at $300^{\circ}C$ exhibit 4 ppm/K being near zero TCR, resulting in TCR suitable for $\pi$-type attenuator applications.

• 한국진공학회지
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• 제6권1호
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• pp.77-84
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• 1997

DC Magnetron Sputtering 방법으로 원기둥형 Alumina기판(직경 4mm, 길이 11mm) 상에 부(-)의 TCR특성의 TaN0.1(부도체)와 정(+)의 TCR특성의 Cr(금속)박막두께를 적절히 조절하므로써 초정밀 저항기를 제조하였다. 그리고 면저항(Rs)을 1k$\Omega$/수준으로 높이고 보 호막을 형성키 위하여 상부에 $Ta_2O_5$막을 입형 $Ta_2O_5/TaN_{0.1}/Cr/Al_2O_3$(substrate)의 다층 박 막저항체를 제조하였다. 적절한 조건(기판온도, $N_2$(g), Ar(g)의 유속 등)으로 상기 다층박막 내 각 막의 두께를 약10,100과 500nm두께로 증착했을 때, $Rs\approx 1k\Omega/\Box$와 $TCR\approx 20$\pm 5ppm/^{\circ}C$ 의 초정밀 저항체가 제조되었다.

• 한국재료학회지
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• 제26권6호
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• pp.293-297
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• 2016

Ni-C composite films were prepared by co-deposition using a combined technique of plasma CVD and ion beam sputtering deposition. Depending on the deposition conditions, Ni-C thin films manifested three kinds of microstructure: (1) nanocrystallites of non-equilibrium carbide of nickel, (2) amorphous Ni-C film, and (3) granular Ni-C film. The electrical resistivity was also found to vary from about $10^2{\mu}{\Omega}cm$ for the carbide films to about $10^4{\mu}{\Omega}cm$ for the amorphous Ni-C films. The Ni-C films deposited at ambient temperatures showed very low TCR values compared with that of metallic nickel film, and all the films showed ohmic characterization, even those in the amorphous state with very high resistivity. The TCR value decreased slightly with increasing of the flow rate of $CH_4$. For the films deposited at $200^{\circ}C$, TCR decreased with increasing $CH_4$ flow rate; especially, it changed sign from positive to negative at a $CH_4$ flow rate of 0.35 sccm. By increasing the $CH_4$ flow rate, the amorphous component in the film increased; thus, the portion of $Ni_3C$ grains separated from each other became larger, and the contribution to electrical conductivity due to thermally activated tunneling became dominant. This also accounts for the sign change of TCR when the filme was deposited at higher flow rate of $CH_4$. The microstructures of the Ni-C films deposited in these ways range from amorphous Ni-C alloy to granular structures with $Ni_3C$ nanocrystallites. These films are characterized by high resistivity and low TCR values; the electrical properties can be adjusted over a wide range by controlling the microstructures and compositions of the films.

• 대한금속재료학회지
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• 제47권9호
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• pp.591-596
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• 2009

$TiN_xO_y/TiN_x$ multi-layer thin films with a high resistance(${\sim}k{\Omega}$) were deposited on $SiO_2/Si$ substrates at room temperature by sputtering. The $TiN_x$ thin films show island and smooth surface morphology in samples prepared by ${\alpha}$ and RF magnetron sputtering, respectively. $TiN_xO_y/TiN_x$ multi-layer in has been developed to control temperature coefficient of resistance(TCR) by the incorporation of $TiN_x$ layer(positive TCR) inserted into $TiN_xO_y$ layers(negative TCR). Electrical and structural properties of sputtered $TiN_xO_y/TiN_x$ multi-layer films were investigated as a function of annealing temperature. In order to achieve a stable high resistivity, multi-layer films were annealed at various temperatures in oxygen ambient. Samples annealed at $700^{\circ}C$ for 1 min exhibited good TCR value of approximately $-54 ppm/^{\circ}C$ and a stable high resistivity around $20k{\Omega}/sq$. with good reversibility.

• IMMUNE NETWORK
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• 제2권2호
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• pp.72-78
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• 2002

Background: The precise mechanism by which CTLA-4 regulates T cell immune responses is still not fully understood. Previously we proposed that CTLA-4 could downregulate T cell function by modulating a signaling cascade initiated from the T cell receptor complex. The evidence for this notion comes from our findings that CTLA-4 associated with the T cell receptor zeta (TCR zeta) chain, and hence regulated TCR zeta phosphorylation by co-associated SHP-2 tyrosine phosphatase (1). In this report, we investigated whether any other signaling molecules could be involved in the CTLA-4 signaling pathway. Methods: We have taken biochemical approaches, such as immunoprecipitation followed by autoradiography or immunoblotting, to identify the molecules associated with CTLA-4. To perform these assays, we used activated primary T cells and ectopically transfected 293 cells. Various truncation mutants of CTLA-4 were used to map the interaction site on CTLA-4. Results: We found that in addition to TCR zeta and SHP-2, a recently cloned small adaptor molecule, SAP (SLAM-associated protein), was also able to associate with CTLA-4. We identified the domain of SAP association in CTLA-4 being a motif involving GVYVKM. This motif has been previously found to bind SHP-2 through its phosphorylated tyrosine interaction with SH-2 domain of SHP-2. Indeed, co-expression of SAP and SHP-2 reduced their binding to CTLA-4 significantly, suggesting that SAP and SHP-2 compete for the common binding site, GVYVKM. Thus, by blocking SHP-2 recruitment SAP could function as a negative regulator of CTLA-4. Conclusion: Taken together, our data suggest the existence of complicate signaling cascade in regulating CTLA-4 function, and further provide evidence that SAP can act either as a positive or negative regulator depending on the nature of the associating receptors.

• 전자공학회논문지A
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• 제29A권11호
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• pp.84-90
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• 1992

The dependence of electrical characteristics of RuO$_2$-based thick film resistors on the RuO$_2$ contents, glass composition variation and the firing temperatures was measured. The sheet resistance of resistors decreased as the contents of RuO$_2$ increased and at firing temperatures higher than C, the sheet resistance increased as the firing temperature increased. In case of using lead borosilicate glass-containing $Bi_{2}O_{3}$, the sheet resistance decreased as the contents of $Bi_{2}O_{3}$ increased. TCR changes from negative to positive values as RuO$_2$ contents increased and from positive to negative values as the firing temperature increased. TCR increased to positive values as $Bi_{2}O_{3}$ increased in the glass.

• 한국세라믹학회지
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• 제12권1호
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• pp.5-11
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• 1975

Thick film resistor paste was made utilizing oxide materials such as SnO, SnO＋Sb2O3, and SnO＋Zn. The oxide materials were mixed respectively with Q-12 glass powder and finally suspended in ethyl cellulose dissolved in ethyl cellosolve. Thick film resistor was made by screen printing the paste on the alumina substrate and firing it at a suitable temperature. Among thick films made from the resistor paste, the thick film containing 85% SnO and fired at $600^{\circ}C$ demonstrated the finest electrical properties showing 10 K ohm in sheet resistance, 110 ppm/$^{\circ}C$ in TCR. In general, TCR of the thick films made from the oxide-mixture paste is good in linearity, therefore it is suggested the oxide-mixture paste is utilized as the negative thermistor.