• 한국표면공학회지
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• 제44권4호
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• pp.137-143
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• 2011

The internal stress and magnetic properties (coercivity and squareness) of Ni-Fe nano thin film synthesized by electrodeposition method were studied as a function of acidic chloride bath conditions (composition and temperature) and current density. Fe deposition patterns were different depending on the temperature of the solution, the stress of film decreased with increasing the solution temperature, and the depending on the amount of Fe deposition showed a parabolic shape. The grain size of film was inversely proportional to stress of thin film. The internal stress of thin film and magnetic properties were deeply relevant, and the stress of thin film had a relationship with bath conditions and grain size of the thin film surface.

• 한국전기전자재료학회논문지
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• 제16권2호
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• pp.138-143
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• 2003

A double spiral thin-film inductor with a NiFe magnetic core is integrated with DC-DC converter IC. The NiFe core is deposited on a polyimide film as the thinckness of NiFe is 2.5~3.5 ${\mu}$m. Then, copper conductor line is deposited on the NiFe core with double spiral structure. Process integration is performed by sequential processes of etching the polyimide film deposited both top and bottom of the NiFe core and electroplation copper conductor line from exposed metal pad of the DC-DC converter IC. Process integration is simplified by elimination planarization process for top core because the proposed thin-film inductor has a bottom NiFe core only. Inductor of the fabricated monolithic DC-DC converter IC is 0.53 ${\mu}$H when the area of converter IC and thin-film inductor are 5X5$\textrm{mm}^2$ and 3.5X2.5$\textrm{mm}^2$, respectively. The efficiency is 72% when input voltage and output voltage are 3.5 V and 6 V, respectively at the operation frequency of 8 MHz.

• 한국표면공학회지
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• 제43권5호
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• pp.243-247
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• 2010

The micro Vickers hardness and internal stress of Ni-Fe metal thin film synthesized by electrodeposition method at $25^{\circ}C$ were studied as a function of bath composition, and surface microstructure and atomic compositions of thin films were investigated by SEM and EDS. And the shape change of $200\;{\AA}$ Ni-Fe nanowires made using anodic aluminum oxide(AAO) templates by electrodeposition method were observed by SEM as a function of ultrasonic treatment time and bath composition. The Fe deposition contents on the substrate non-linearly increased with Fe ion concentration over total metal ion concentration. In case of low Fe contents film, the grain size is smaller and denser than high Fe contents deposited films, and the micro Vickers hardness increased with Fe contents of electrodeposited films. These results affected the shape change of nanowire after ultrasonic treatments.

• 한국자기학회지
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• 제15권5호
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• pp.265-269
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• 2005

강자성 공명 측정을 통하여 다양한 층 구성을 갖는 교환 바이어스 박막들의 교환 결합 특성에 대해 연구하였다. 공명자기장의 각도의존 실험을 통하여 일축방향이방성 자기장과 일축이방성 자기장을 구하여 분석하였다. NiFe 단일 박막과 비교하여 교환 바이어스된 NiFe/IrMn, IrMn/NiFe/IrMn, NiFe/IrMn/CoFe 박막들은 큰 일축방향이방성 자기장을 나타내었으며, 일축이방성 자기장 또한 큰 값을 나타내었다. 그러나 NiFe/Cu/IrMn의 경우, Cu의 두께가 두꺼울 때는 매우 작은 일축방향이방성 자기장을 나타내었으며, NiFe 단일 박막과 비슷한 크기의 일축이방성 자기장을 나타내었다. NiFe/IrMn/CoFe 박막의 경우 NiFe와 CoFe 강자성층들에 의해 두 개의 공명 자기장이 나타났다. 그 외에 공명 자기장의 선폭에 관한 분석이 교환 바이어스 특성과 연관하여 논의되어졌다.

• 한국재료학회지
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• 제28권10호
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• pp.595-600
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• 2018

This study investigates the microstructural properties of CoCrFeMnNi high entropy alloy (HEA) oxynitride thin film. The HEA oxynitride thin film is grown by the magnetron sputtering method using nitrogen and oxygen gases. The grown CoCrFeMnNi HEA film shows a microstructure with nanocrystalline regions of 5~20 nm in the amorphous region, which is confirmed by high-resolution transmission electron microscopy (HR-TEM). From the TEM electron diffraction pattern analysis crystal structure is determined to be a face centered cubic (FCC) structure with a lattice constant of 0.491 nm, which is larger than that of CoCrFeMnNi HEA. The HEA oxynitride film shows a single phase in which constituting elements are distributed homogeneously as confirmed by element mapping using a Cs-corrected scanning TEM (STEM). Mechanical properties of the CoCrFeMnNi HEA oxynitride thin film are addressed by a nano indentation method, and a hardness of 8.13 GPa and a Young's modulus of 157.3 GPa are obtained. The observed high hardness value is thought to be the result of hardening due to the nanocrystalline microstructure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.71-71
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• 2009

This paper describes a simple, on-chip CMOS compatible the thin-film inductor applied for the dc-dc converters. A fully CMOS-compatible thin-film inductor with a bottom NiFe core is integrated with the DC-DC converter circuit on the same chip. By eliminating ineffective top magnetic layer, very simple process integration was achieved. Fabricated monolithic thin film inductor showed fairly high inductance of 2.2 ${\mu}H$ and Q factor of 11.2 at 5MHz. When the DC-DC converter operated at $V_{in}=3.3V$ and 5MHz frequency, it showed output voltage $V_{out}=8.0V$, and corresponding power efficiency was 85%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.185-188
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• 2000

Crystal orientation of Ni$_{18}$ $Fe_{19}$ thin films prepared by facing targets sputtering system was investigated. FTS system can deposit a high quality thin film and control deposition conditions in wide range. T he crystallographic characteristics of Ni$_{18}$ $Fe_{19}$ thin films on variation of thickness and substrate tempera ture was investigated by XRD and AFM. As a result, we obtained Ni$_{18}$ $Fe_{19}$ thin films prepared at subst rate temperature room temperature, thickness 160nm and over revealed good crystal orientation to [111] direction.irection.

• 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.

• 한국결정성장학회지
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• 제20권5호
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• pp.216-220
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• 2010

Si(100) wafer와 $SiO_2$/Si(100) 웨이퍼에 증착된 NiFe 합금 박막의 결정상과 자기적 특성을 비교하고자 동시 스퍼터링법을 이용하여 두 기판 위에 150 nm의 박막을 제조하여 그의 상변화와 자기적 특성을 XRD, FE-SEM, VSM으로 비교하였다. 두 기판 위에 증착된 NiFe 박막은 BCC상으로 증착되었으나 $400^{\circ}C$에서 2시간 열처리를 한 결과 BCC에서 FCC로의 상전이가 일어나는 것을 관찰 할 수 있었으며 Si(100) wafer위에 증착된 박막에서는 $500^{\circ}C$에서 열처리 후에도 BCC와 FCC가 혼재하여 나타나는 것을 알 수 있었다. $450^{\circ}C$에서 열처리 하였을 때 각형비가 가장 높았으며 포화자화는 0.0118 emu로 나타나고 있었다. $500^{\circ}C$ 이상의 온도에서는 상전이로 인해 포화자화가 급격히 감소하는 것을 볼 수 있었다.

• ETRI Journal
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• 제25권4호
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• pp.270-273
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• 2003

This paper presents a simple process to integrate thin-film inductors with a bottom NiFe magnetic core. NiFe thin films with a thickness of 2 to 3${\mu}m$ were deposited by sputtering. A polyimide buffer layer and shadow mask were used to relax the stress of the NiFe films. The fabricated double spiral thin-film inductor showed an inductance of 0.49${\mu}H$ and a Q factor of 4.8 at 8 MHz. The DC-DC converter with the monolithically integrated thin-film inductor showed comparable performances to those with sandwiched magnetic layers. We simplified the integration process by eliminating the planarization process for the top magnetic core. The efficiency of the DC-DC converter with the monolithic thin-film inductor was 72% when the input voltage and output voltage were 3.5 V and 6 V, respectively, at an operating frequency of 8 MHz.