• 한국전기전자재료학회논문지
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• 제13권5호
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• pp.444-450
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• 2000

We prepared Co-Cr thin film for perpendicular magnetic recording media with facing targets sputtering system(FTS system) which can deposit a high quality thin film in plasma-free state and wide range of working pressure. The effect of sputtering conditions(argon gas pressure and substrate temperature) on the magnetic and the crystallographic characteristic of Co-Cr thin film was investigated. And the variation of perpendicular coercivity with the variation of film thickness was studied. As a result we obtained the high perpendicular coercivity of 1900Oe and the good dispersion angle of c-axis($\Delta$$\theta$$_{50}$) of 5$^{\circ}$on the film thickness of 100nm for the promising recording layer of perpendicular magnetic recording media.c recording media.a.

• 대한금속재료학회지
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• 제50권3호
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• pp.248-255
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• 2012

AlN thin films containing various amounts of Co, AlN-Co, and Al-Co alloy particles were prepared using a two-facing-target type dc reactive sputtering (TFTS) system. The as-deposited films exhibited the variable nature expected from an AlN-rich phase, and an amorphous-like phase, depending on the Co content in the films. Specific favorable microstructures were prepared by optimizing annealing conditions. Those microstructures and their magnetic properties and resistivity were investigated. As-deposited films showed very small saturation magnetization and an amorphous-like structure. However, when annealed, the as-deposited amorphous-like phase decomposes into phases of AlN, Co and Al-Co. These annealing induced changes in the microstructure improve the magnetization and resistivity of the films. Further improvement of soft magnetic properties could lead to the material being used for high density magnetic recording head material.

• 한국자기학회지
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• 제8권5호
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• pp.261-269
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• 1998

스퍼터링 중 500~600 Oe의 자기장을 인가한 상태에서 제조된 비정징 Sm-Fe 합금 박막에서 6$\times$104 J/m3 크기의 유도자기이방성이 형성되었다. 자장 증착에 이해유도자기이방성이 형성된 합금 박막은 이방성이 형성되지 않은 합금 박막에 비해 자구 구조에 무관한 "포화" 자기변형은 유사하지만, 측정 방향에 따른 자기변형의 이방성 비는 최대 35 정도로서 매우 크게 증가하였다. 이는 자기변형 박막의 디바이스 응용시 성능을 크게 향상시키므로, 실용적인 측면에서 매우 중요하다. 스퍼터링 중 자기장을 인가하지 않고 통상의 마그네트론 스퍼터링에 의해 제조된 비정질 Sm-Fe 합금 박막을 넓은 조성 범위에 걸쳐서 체계적으로 소자한 결과, 이러한 합금 박막에서도 미약하나마 스퍼터링 중의 누설 자계에 의해 증착 도중 유도자기이방성이 형성되는 것을 관찰하였으며, 최대의 유도자기이방성은 Sm 함량 25~30 원자%에서 얻어졌다. 또한 본 합금 박막의 유도자기이방성은 자장 중 열처리에 의해서도 형성되는 것을 관찰하였는데, 형성된 이방성의 크기는 자장 증착에 의해 제조된 시료보다 매우 작게 나타났다. 이는 자장 증착의 경우 원자의 표면 확산을 통한 원자의 이동에 의해 유도자기이방성이 형성되나, 증착 후 자장 열처리에 의한 경우는 체적 확산에 의해 유도자기이방성이 형성되기 때문으로 생각된다.때문으로 생각된다.

• 한국자기학회지
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• 제6권4호
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• pp.235-241
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• 1996

수직자기 기록매체를 위해 스퍼터링법으로 Co/Pd 및 Co/Pt 다층막을 형성하였으며 Pd 및 Pt 바닥층의 증착 압력이 다층막의 자화거동 및 보자력에 미치는 영향에 대해 연구하였다. Co/Pd 다층막의 경우 보자력이 바닥층의 증착 압력에 매우 민감하여 바닥층 증착압력만을 조절함으로써 보자력을 크게 증가시킬 수 있었으나 Co/Pt 경우 바닥층의 증착압력 조절에 의한 보자력 증대효과는 미미하였다. 바닥층의 종류 및 증착압력에 따른 다층막의 보자력 변화를 바닥층의 표면 거칠기 및 다층막 증착착시의 계면상태 변화의 측면에서 설명할 수 있었으며 이는 바닥층의 증착압력의 증가에 따른 다층막의 수직이방성 에너지 감소 및 자화반전 기구의 변화와도 연관시킬 수 있었다. 다층막의 Kerr 회전각은 바닥층의 종류 및 증착압력에는 거의 의존하지 않는 것으로 나타났다.

• 한국재료학회지
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• 제9권4호
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• pp.341-344
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• 1999

We reported compositional separation(CS) into Co-enriched and Cri-enriched components inside the grains of Co-Cr based thin films prepared by rf sputtering. CS strongly depends on the sputtering conditions of substrate temperature and target composition. Tuning the microstructure of the Co-Cr films is important in order to employ the CS for high-density magnetic recording. We investigated the origin of CS from thermodynamic viewpoint. We employ a spinodal decomposition-like model to describe the origin of the CS in Co-Cr films. We consider the total free energy of the Co-Cr films as the sum of several free energies of; 1) thermodynamic mixing entropy of a binary solid solution, 2) magnetic ordering interaction(MOI) energy below the Curie temperature, and 3) excess interaction energy(XS) caused by the sputtering process as a function of temperature and composition. Those energies distorted the total free energy like the spinodal decomposition and caused the compositionally separated fine microstructure inside the grains. If the second derivative of the total free energy with respect to Cr composition becomes negative at a given substrate temperature, we may observe a metastable compositional separation inside the Co-Cr alloy films. We expect to exploit the microstructure of CS for ultra-high density magnetic recording.

• 한국전기전자재료학회논문지
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• 제14권1호
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• pp.74-83
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• 2001

In this study, the optimum structure of a magnetic thin film inductor was designed for application of DC-DC converters. The Ni$\sub$81/Fe$\sub$19/ (at%) alloy was selected as a high-frequency($\geq$MHz) magnetic thin film magnetron sputtering system. As-deposited NiFe thin films show similar magnetic properties compared to bulk NiFe alloys, indicating that they have a good film quality. The optimum design of dolenoid-type magnetic thin film inductors was performed utilizing a Maxwell computer simulator (Ansoftt HFSS V7.0 for PC) and parameters obtained from the magnetic properties of magnetic core materials selected. The high-frequency characteristics of the inductance(L) and quality factor(Q) obtained for the designed inductors through simulation agreed well with those obtained by theoretical calculations, confirming that the simulated result is realistic. The optimum structure of high-performance (Q$\geq$60, L = 1${\mu}$H, efficiency $\geq$90%), high-frequency ($\geq$5MHz), and solenoid-type magnetic thin film inductors was designed successfully.

• 한국자기학회지
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• 제3권4호
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• pp.320-324
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• 1993

스퍼터된 자기기록매체 Co-10at%Cr-2at%Mo/Cr 자성박막의 제조조건이 미세구조와 자기적특성에 미치는 영향을 조사하였다. 기판의 온도는 상온-$250^{\circ}C$로 하였으며 Cr하지층과 CoCrMo층의 두께는 각각 $1000-2500\AA$, $300-800\AA$이었다. CoCrMo층의 두께가 $500{\AA}-800{\AA}$ 증가함에 따라 결정립은 미세화 되었으며 균일한 조직을 나타냈다. 보자력은 기판의 온도, CoCrMo자성층, Cr하지층의 두께 를 증가시켰을때 향상되었다. 기판온도가 $250^{\circ}C$, 자성층의 두께가 $700\AA$, Cr 하지층의 두께가 $1000\AA$일때 880 Oe의 보자력을 나타냈다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.288-289
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• 2011

Indium Tin Oxide (ITO) is a typical highly Transparent Conductive Oxide (TCO) currently used as a transparent electrode material. Most widely used deposition method is the sputtering process for ITO film deposition because it has a high deposition rate, allows accurate control of the film thickness and easy deposition process and high electrical/optical properties. However, to apply high quality ITO thin film in a flexible microelectronic device using a plastic substrate, conventional DC magnetron sputtering (DMS) processed ITO thin film is not suitable because it needs a high temperature thermal annealing process to obtain high optical transmittance and low resistivity, while the generally plastic substrates has low glass transition temperatures. In the room temperature sputtering process, the electrical property degradation of ITO thin film is caused by negative oxygen ions effect. This high energy negative oxygen ions(about over 100eV) can be critical physical bombardment damages against the formation of the ITO thin film, and this damage does not recover in the room temperature process that does not offer thermal annealing. Hence new ITO deposition process that can provide the high electrical/optical properties of the ITO film at room temperature is needed. To solve these limitations we develop the Magnetic Field Shielded Sputtering (MFSS) system. The MFSS is based on DMS and it has the plasma limiter, which compose the permanent magnet array (Fig.1). During the ITO thin film deposition in the MFSS process, the electrons in the plasma are trapped by the magnetic field at the plasma limiters. The plasma limiter, which has a negative potential in the MFSS process, prevents to the damage by negative oxygen ions bombardment, and increases the heat(-) up effect by the Ar ions in the bulk plasma. Fig. 2. shows the electrical properties of the MFSS ITO thin film and DMS ITO thin film at room temperature. With the increase of the sputtering pressure, the resistivity of DMS ITO increases. On the other hand, the resistivity of the MFSS ITO slightly increases and becomes lower than that of the DMS ITO at all sputtering pressures. The lowest resistivity of the DMS ITO is $1.0{\times}10-3{\Omega}{\cdot}cm$ and that of the MFSS ITO is $4.5{\times}10-4{\Omega}{\cdot}cm$. This resistivity difference is caused by the carrier mobility. The carrier mobility of the MFSS ITO is 40 $cm^2/V{\cdot}s$, which is significantly higher than that of the DMS ITO (10 $cm^2/V{\cdot}s$). The low resistivity and high carrier mobility of the MFSS ITO are due to the magnetic field shielded effect. In addition, although not shown in this paper, the roughness of the MFSS ITO thin film is lower than that of the DMS ITO thin film, and TEM, XRD and XPS analysis of the MFSS ITO show the nano-crystalline structure. As a result, the MFSS process can effectively prevent to the high energy negative oxygen ions bombardment and supply activation energies by accelerating Ar ions in the plasma; therefore, high quality ITO can be deposited at room temperature.

• 한국전기전자재료학회논문지
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• 제15권3호
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• pp.281-286
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• 2002

In odder to investigate the magnetic properties of CoCr-based bilayered thin films on kind of underlayer, we introduced amorphous Si layer to Co-Cr(-Ta) magnetic layer as underlayer. First, we prepared CoCr and CoCrTa single layer using the Facing Targets Sputtering system to investigate theirs properties. It was revealed that with increasing the film thickness of CoCr, CoCrTa single layer, crystalline orientation and perpendicular coercivity was improved. The CoCrTa thin film showed bettor crystalline and magnetic characteristics than CoCr thin film. As a result of investigating magnetic properties of CoCr and CoCrTa magnetic layer on introducing the Si underlayer, perpendicular coercivity and saturation magnetization of CoCr/Si and CoCrTa/Si bilayered thin film were decreased due to the increased grain size and diffusion of Si atoms to magnetic layer. And they showed constant with increasing the film thickness of Si thin film. However, in case of CoCrTa/Si bilayered thin film, in-plane coercivity was controlled low at about 250Oe. The c-axis orientations of CoCr/si and CoCrTa/Si bilayered thin film showed a good crystalline characteristics as about $2^{\circ}$.

• Journal of Magnetics
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• 제8권4호
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• pp.146-148
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• 2003

Multilayered films of Co/Pd have been studied as a candidate material for a high density perpendicular recording medium due to higher anisotropy energy. However, high exchange coupling among grains results in large transition noise. To reduce the exchange coupling and grain size, addition of 3rd elements and physical separation of grains have been attempted. In the present paper, effects of sputtering pressure, Co sublayer thickness and Pd underlayer thickness on magnetic properties and microstructures were studied. It was found that by increasing sputtering pressure from 5 mTorr to 25 mTorr, Ms decreased to one half and coercivity increased more than 5000 Oe. The increase of the coercivity is associated with physical separation of grains by high pressure sputtering. Ms per volume of Co for Co/Pd multilayered film deposited at 25 mTorr shows continuous decrease with increasing Co sublayer thickness. This was related to void formation and intermixing of Co/Pd interface. Also, effect of Pd underlayer thickness on magnetic properties will be discussed.