• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.466-468
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• 2012

Amorphous InGaZnO (${\alpha}$-IGZO) thin-film transistors (TFTs) are are very promising due to their potential use in thin film electronics and display drivers [1]. However, the stability of AOS-TFTs under the various stresses has been issued for the practical AOSs applications [2]. Up to now, many researchers have studied to understand the sub-gap density of states (DOS) as the root cause of instability [3]. Nomura et al. reported that these deep defects are located in the surface layer of the ${\alpha}$-IGZO channel [4]. Also, Kim et al. reported that the interfacial traps can be affected by different RF-power during RF magnetron sputtering process [5]. It is well known that these trap states can influence on the performances and stabilities of ${\alpha}$-IGZO TFTs. Nevertheless, it has not been reported how these defect states are created during conventional RF magnetron sputtering. In general, during conventional RF magnetron sputtering process, negative oxygen ions (NOI) can be generated by electron attachment in oxygen atom near target surface and accelerated up to few hundreds eV by self-bias of RF magnetron sputter; the high energy bombardment of NOIs generates bulk defects in oxide thin films [6-10] and can change the defect states of ${\alpha}$-IGZO thin film. In this paper, we have confirmed that the NOIs accelerated by the self-bias were one of the dominant causes of instability in ${\alpha}$-IGZO TFTs when the channel layer was deposited by conventional RF magnetron sputtering system. Finally, we will introduce our novel technology named as Magnetic Field Shielded Sputtering (MFSS) process [9-10] to eliminate the NOI bombardment effects and present how much to be improved the instability of ${\alpha}$-IGZO TFTs by this new deposition method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.29-29
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• 2008

Platinum Thin films were deposited on $Al_2O_3$ by Rf magnetic Sputtering. The physical and electrical characteristics of these films were analyzed under various deposition conditions(Ar gas pressure, input power, substrate temperature.) and annealing condition. The deposition rate was increased with increasing the input power but not increased linear. In the other factor, The Pt thin films property was associated with resistance. so lower resistance had more and more good Pt thin films condition. For the purpose of this study, we will get the best Pt thin film characteristics.

• 한국재료학회지
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• 제20권12호
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• pp.629-635
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• 2010

Abstract In this study characteristics of Al-doped ZnO thin film by HIPIMS (High power impulse sputtering) are discussed. Deposition speed of HIPIMS with conventional balanced magnetic field is measured at about 3 nm/min, which is 30% of that of conventional RF sputtering process with the same working pressure. To generate additional magnetic flux and increase sputtering speed, electromagnetic coil is mounted at the back side of target. Under unbalanced magnetic flux from electromagnet with 1.5A coil current, deposition speed of AZO thin film is increased from 3 nm/min to 4.4 nm/min. This new value originates from the decline of particles near target surface due to the local magnetic flux going toward substrate from electromagnet. AZO film sputtered by HIPIMS process shows very smooth and dense film surface for which surface roughness is measured from 0.4 nm to 1 nm. There are no voids or defects in morphology of AZO films with varying of magnetic field. When coil current is increased from 0A to 1A, transmittance of AZO thin film decreases from 80% to 77%. Specific resistance is measured at about $2.9{\times}10-2\Omega{\cdot}cm$. AZO film shows C-axis oriented structure and its grain size is calculated at about 5.3 nm, which is lower than grain size in conventional sputtering.

• 한국자기학회지
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• 제11권3호
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• pp.109-113
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• 2001

Presently, an inductor adapted at MMIC (Monolithic Microwave Integrated Circuit) which is used for cellular phone or PHS operates at quasi-microwave range over 800 MHz. However, a W-CDMA (Wideband Code Division Multiple Access) will use about 2 GHz range. Therefore magnetic film device should be compatible up to 2 GHz. We have deposited Co-Pd-Al-O system film using rf sputtering method which is expected up to 2 GHz, and investigated the effect of Pd content and magnetic field annealing. When Pd composition is 19%, Hk was 118 Oe, and ${\mu}$′showed flat frequency characteristics up to 1.5 GHz. The Q factor (=${\mu}$′/${\mu}$") was 23.3 at 1 GHz, 6.7 at 1.5 GHz and 1.5 at 2 GHz, respectively. Resonance frequency was 2 GHz. Therefore Co-Pd-Al-O thin film could be used at over 1 GHz, and also expected as an inductor material for wide band CDMA type cellular phone.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 학술대회 및 기술세미나 논문집 디스플레이 광소자
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• pp.66-67
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• 2006

We studied nematic liquid crystal (NLC) alignment effect on the $SiO_x$ thin film deposited $45^{\circ}$ oblique by rf magnetic sputtering system. Pretilt angle and thermal stability characteristic as well as NLC alignment effect were investigated. A uniform liquid crystal alignment effect on the $SiO_x$ thin film was achieved and pretilt angle was about $90^{\circ}$. The thermal stability of the $SiO_x$ thin film was sustained by $200^{\circ}$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.203-203
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• 2010

Nano-crystalline Si thin films were deposited on polymer and glass by inductively coupled plasma (ICP) - assisted RF magnetron sputtering at low temperature in an argon and hydrogen atmosphere. Internal ICP coil was installed to increase hydrogen atoms dissociated by the induced magnetic field near the inlet of the working gases. The microstructure of deposited films was investigated with XRD, Raman spectroscopy and TEM. The crystalline volume fraction of the deposited films on polymer was about 70% at magnetron RF power of 600W and ICP RF power of 500W. Crystalline volume fraction was decreased slightly with increasing magnetron RF power due to thermal damage by ion bombardment. The diffraction peak consists of two peaks at $28.18^{\circ}$ and $47.10^{\circ}\;2{\theta}$ at magnetron RF power of 600W and ICP RF power of 500W, which correspond to the (111), (220) planes of crystalline Si, respectively. As magnetron power increase, (220) peak disappeared and a dominant diffraction plane was (111). In case of deposited films on glass, the diffraction peak consists of three peaks, which correspond to the (111), (220) and (311). As the substrate temperature increase, dominant diffraction plane was (220) and the thickness of incubation (amorphous) layer was decreased.

• E2M - 전기 전자와 첨단 소재
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• 제8권1호
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• pp.6-12
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• 1995

High Tc superconducting YBa$_{2}$Cu$_{3}$$O_{7-x}$ thin films were prepared on various substrates by off-axis rf magnetron sputtering method to examine the substrate effects on the film structure and its R-T characteristics. The SEM analysis showed that the surface morphology of the grown YBa$_{2}$Cu$_{3}$O.sub 7-x/, film has different characteristic structure with different substrate used. The film on (100) SrTiO$_{3}$ substrate has critical current density of 3*10$^{5}$ A/cm$^{2}$ at 77K under zero magnetic field. The X-ray diffraction measurements revealed that the films on (100) SrTiO$_{3}$ substrate have mixed a-axis and c-axis normal to the substrate surface and the films on (100) MgO and ZrO$_{2}$/sapphire substrates have c-axis normal orientation to the substrate surface. However, YBa$_{2}$Cu$_{3}$$O_{7-x}$ films on (100) sapphire substrates showed no preferential orientation.ion.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 추계학술대회 논문집
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• pp.46-46
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• 1988

Structural and magnetic properties of Co-Cr-Mo films were investigated in connection with sputtering conditions. Films were prepared using a convention RF sputtering system. X-ray diffractometry, scanning electron microscopy and transmission electron microscopy were employed to investigate structure properties. Vibrating sample magnetometry was used for coercivity and saturation magnetization measurements. Co-Cr-Mo films displayed reasonable values of perpendicular coercivity and saturation magnetization for perpendicular recording media and showed good perpendicular orientation of the hcp c-axis to the film surface. Perpendicular coercivity was strongly dependent upon substrate technique showed better c-axis orientation than hose using the stationary substrate. Co-Cr-Mo films of 2.9 at. % Mo content showed maximum perpendicular coercivity and saturation magnetization. The films deposited at lower Ar pressure showed good magnetic properties. There was no explicit relationship between the columnar structure and c-axis orientation. Co-Cr-Mo films was found to have suitable structural and magnetic properties for perpendicular recording media.

• 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.

• 한국재료학회지
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• 제8권6호
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• pp.560-564
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• 1998

RF magnetron sputtering법으로 Cr을 하지층으로 하여 CoPrCr 자성층을 성막한 후 보호층으로 $SiO_2$를 증착한 Cr/CoPtCr/$SiO_2$ 다층박막을 상온에서 제조하여 자기적 성질을 조사하였다. Cr 하지층 두께가 증가함에 따라 보자력이 증가하다가 거의 일정한 값을 얻었으며 최대 보자력값은 860 Oe였다. 보자력의 증가원인은 자성상의 면내 배향화와 자성 결정립간의 자기적인 분리에 의한다고 생각된다. 시편을 각 온도별로 열처리 함으로써 보자력이 크게 증가하였으며,$ 550^{\circ}C$에서 1시간 열처리한 박막의 보자력은 1650 Oe였다.