• E2M - 전기 전자와 첨단 소재
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• 제10권7호
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• pp.645-650
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• 1997

We manufactured CoNbZr/Cu/CoNbZr multi-layer films by rf magnetron sputtering methods and formed the patterns on the deposited multi-layer films. In this study, we fabricated a new etchant for forming the patterns by the wet etching with etchant and we searched for the best etching conditions and the etchant composition. Cu was etched selectively independent on the concentration of iron chloride solution, but amorphous CoNbZr thin film did not. The etchant was achieved by iron chloride solution(17.5 mol%) mixed with HF (20 mol%) during 150 sec, which etched CoNbZr/Cu/CoNbZr multi-layer films at the same time. Also, the etchant etched CoNbZr/Cu/CoNbZr multi-layer films by the three-step. It was shown that the cross-section had the isotropic structure and excellent etching characteristics with the above etchant.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.141-145
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• 1997

스퍼터링법으로 제조한 CoNbZr/Cu/CoNbZr 다층막에 대해 습식 식각법으로 패턴을 형성하기 위해 새로운 식각 용액을 제조하여 이 용액의 최적의 식각 조건에 대해 연구하였다. 염기성 수용액은 농도에 관계없이 Cu만을 선택적으로 식각하며 CoNbZr 비정질 박막은 식각하지 않았다. 그러나, 본 연구에서 제조 한 17.5 mol%의 염기성 수용액에 HF를 20 mol% 혼합한 식각 용액으로 CoNbZr/Cu/CoNbZr 다층막을 동시에 식각할 수 있었다. 또한 이 식각 용액은 CoNbZr/Cu/CoNbZr 다층막을 3단계로 식각하고 식각된 단면은 이방성 구조를 가지며, 매우 우수한 식각 특성을 나타내었다.

• Journal of Magnetics
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• 제9권1호
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• pp.13-16
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• 2004

Magnetic tunnel junctions (MTJs) comprising amorphous CoNbZr layers have been investigated. $Co_{85.5}Nb_8Zr_{6.5}$(in at. %) layers were employed to substitute the traditionally used Ta layers with an emphasis given on under-standing underlayer effect. The typical junction structure was $SiO_2/CoNbZr$ or Ta 2/CoFe 8/IrMn 7.5/CoFe 3/Al 1.6 + oxidation/CoFe 3/CoNbZr or Ta 2 (nm). For both as-deposited state and after annealing, the CoNbZr-underlayered structure showed superior surface smoothness up to the tunnel barrier than Ta-underlayerd one (rms roughness of 0.16 vs. 0.34 nm). CoNbZr-based MTJs was proven beneficial for increasing thermal stability and increasing $V_h$ (the bias voltage where MR ratio becomes half) characteristics than Ta-based MTJs. This is because the CoNbZr-based junctions offer smoother interface structure than the Ta-based one.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1968-1970
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• 1999

본 연구에서는 RF 마그네트론 스퍼터링법으로 CoNbZrPd 비정질 연자성 박막을 제조하여 Pd의 첨가 효과와 자장중 열처리에 의한 특성 변화에 대해 연구하였다. Pd가 4.34 at% 첨가된 $Co_{87.56}Nb_{6.45}Zr_{1.65}Pd_{4.34}$ 박막은 비정질 구조이며 Pd 첨가에 의해 보자력은 0.54 Oe으로 감소하였으며, 이방성 자계는 10.45 Oe로 Pd를 첨가하지 않은 CoNbZr 비정질 박막 보다 특성이 향상되었다. $Co_{87.56}Nb_{6.45}Zr_{1.65}Pd_{4.34}$ 비정질 박막은 $400^{\circ}C$까지 비정질 상을 유지하고 있지만, 연자기 특성이 열화되어 보자력이 증가하고 이방성자계가 급격히 감소하였지만, 포화 자화는 크게 변화지 않았다.

• 한국자기학회지
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• 제13권5호
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• pp.198-203
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• 2003

경자성박막을 이용한 자기임피던스센서의 바이어스 자계 인가의 유용성을 알아보기 위해서, SmCo 경자성박막의 조성에 따른 자기적 특성과 이 박막이 아몰퍼스 CoZrNb 연자성박막에 미치는 바이어스 효과에 대하여 조사하였다. 아몰퍼스상을 가지는 SmCo 경자성박막의 포화자화는 Sm 조성이 증가함에 따라 감소하였으며, 보자력은 Sm 조성의 증가에 따라 증가하다가 28 at% 부근에서 약 500 Oe를 나타낸 후 다시 감소하였다. SmCo 박막에 의해서 발생된 바이어스 자계가 CoZrNb 박막에 미치는 효과는 자화곡선과 투자율의 측정, 그리고 자구관찰을 통하여 조사되었다. MI센서로 사용이 가능한 3${\times}$0.5 $\textrm{mm}^2$ 크기의 박막시료에 있어서, 약 60 Oe의 바이어스 자계가 얻어졌으며, 센서의 감도를 최적화하기에 충분한 바이어스 자계를 경자성박막을 이용하여 발생시킬 수 있음을 입증하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.778-781
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• 2002

MI(Magneto-Impedance) sensor which is made by thin films has significantly high detecting sensitivity in weak magnetic field. It also has a merit to be able to build in the low power system. Its structure is simple, which makes it easier to prepare a miniature. In this study, its magnetic permeability and anisotropy field$(H_k)$ as a function of a thickness of sputtered amorphous CoZrNb films with zero-magnetostriction and excellent soft magnetic property are investigated. In order to make a uniaxial anisotropy, film was subjected to the post annealing in a static magnetic field with 1KOe intensity at 250, 300, and $320^{\circ}C}$ respectively for 2 hours. Anisotropy field$(H_k)$ of film is measured by using a MH loop tracer. Its magnetic permeability of a film is measured over the frequency range from 1 MHz to 750MHz. It has shown that the magnetic permeability of amorphous CoZrNb film is decreased due to the skin effect with increasing a thickness of the CoZrNb film, and hence its driving frequency is lowered. And, it was examined on the permeability and impedance to fabricate the MI sensor which acts at a low frequency by thickening a CoZrNb film relatively.

• 한국자기학회지
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• 제1권2호
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• pp.31-36
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• 1991

스퍼터링에 의해 형성된 비정질 Co/sub 87/Zr/sub 4/Nb/sub 9/ 박막을 TEM과 EDS로 분석하여 박막의 구조적 그리고 저성적 불균일성을 관찰하였다. 특히 기판 bias를 가한 상태에서 제조된 박막을 회전 자장 열처리했을 때는 Co-rich 지역과 (Zrnb) oxied-rich 지역의 조대한 조직으로 분리되었으며, 이러한 박 막의 자기적 특성은 'ultra-soft'한 성질을 나타내었다. Ulta-soft함 박막은 H/sub c/=0.18 Oe, H/sub k/ = 0.55 Oe, M/sub r//M/sub s/=0.75의 자기적 특성과 overdamping된 고주파특성, 그리고 외부자계에 대한 자화율 변화곡선이 가역적이고 연속적이라는 특이한 현상을 보인다. 조성적으로 불균일한 박막의 ultra-soft 한 특성은 Co-rich 입자들이 exchange coupling energy와 magnetostatic coupling energy를 최소화 하기 위해 만드는 vortex형의 자화분포로써 설명되었다. 즉 vortex 는 여러개의 co-rich 입자들로 형성 되어있는 것으로 추정되며, 수평, 수직방향으로의 반자장 계수(demagnetizing factor)가 각각 flux closure 와 flux reversal에 의해 무시되기 때문에 vortex로 부터 CoZrNb 박막의 ultra-soft 특성을 설명할 수 있었다.

• 한국전기전자재료학회논문지
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• 제11권6호
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• pp.486-492
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• 1998

The amorphous Co-based magnetic films have a large saturation flux density, a low coercive force, and a zero magnetostriction constant. Therefore, they have been studied for application to magnetic recoding heads and micro magnetic devices. However, it was found that the magnetic anisotropy was changed for each film fabrication processes. In this study, we investigated how to control the anisotropy of sputtered amorphous $Co_{89}Nb{8.5}Zr{2.5}$ films. After deposition, the rotational field annealing ant the uniaxial field annealing were performed under the magnetic field of 1.5 kOe. the annealing was done at the temperature range from 400 to $600^{\circ}C$ for one hour. As-deposited amorphous $Co_{89}Nb{8.5}Zr{2.5}$ thin film had saturation magnetization ($4\piM_5$) of 0.8 T, coercive force($_IH_C$) of 1.5 Oe, and anisotropy field($H_k$) of 11 Oe. The amorphous $Co_{89}Nb{8.5}Zr{2.5}$ thin films annealed by rotational field annealing at $500^{\circ}C$ for one hour was found to be isotropy, and $4\piM_5$ of 0.9 T was obtained from these films, Also, the magnetic anisotropy of as-deposited films could be controlled by uniaxial field annealing at $400^{\circ}C$ for one hour. Anisotropy field($H_k$) of 17 Oe and $4\piM_5$ of 1.0 T were obtained by this method.

• Journal of Magnetics
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• 제2권3호
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• pp.96-100
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• 1997

A spin valve structure of NiO(40 nm)/Co(2 nm)/Cu(2.6 nm)/Co(x nm)/Ta(5 nm) has been investigated for the application of magnetic random access memory (MRAM). The spin valve structure exhibited very large difference in the coercivities between pinned and free layers, a relatively high GMR ratio, and a low free layer coercivity. The spin valves were prepared by sputtering and were characterized by dc 4-point probe, and VSM. The spin valves with combined free layer exhibited a maximun GMR ratio of 10.4% with a free layer coercivity of about 82 Oe. The spin valves with a single 10 nm thick a-CoNbZr free layer exhibited a GMR ratio of about 4.3% with a free layer coercivity of about 12 Oe. The GMR ratio of the spin valves increased by addition of Co between Cu and a-CoNbZr. It has been confirmed that the coercivity of free layer can be decreased by increasing the thickness of a-CoNbZr. It has been confirmed that the coercivity of free layer can be decreased by increasing the thickness of a-CoNbZr layer without losing the GMR ratio substantially, which was mainly due to high resistivity of the amorphous "layers".

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 춘계연구발표회 논문개요집
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• pp.48-49
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• 2000