• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.339-344
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• 2011

The Ohmic contact of Ti/Au metals on n-type ZnO thin film deposited on c-plane sapphire substrates by pulsed laser deposition was investigated by TLM (transfer length method) patterns. The Ti/Au metal films with thickness of 35 nm and 90 nm were deposited by electron-beam evaporator and thermal evaporator, respectively. By using the photo-lithography method, the $100{\times}100{\mu}m^2$ TLM patterns with $6{\sim}61{\mu}m$ gaps were formed. To improve the electrical properties as well as to decrease an interface states and stress between metal and semiconductor, the post-annelaing process was done in oxygen ambient by rapid thermal annealing system at temperature of $100{\sim}500^{\circ}C$ for 1 min. In this study, it appeared that the minimum specific contact resistivity shows about $1.1{\times}10^{-4}{\Omega}{\cdot}cm^2$ in $300^{\circ}C$ annealed sample, which may be originated from formation of oxygen vacancies of ZnO during an oxidation of Ti metal at the interface of Ohmic contacts.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.122-125
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• 1994

The magnetic properties of Nd-Fe-B alloys of containing 4 at.% Nd have been studied for the development of new type rare-earth magnets. The amorphous phase of a melt-spun $Nd_{4}Fe_{85.5}B_{10.5}$ alloy is transformed into the phases which have a small amount of $Nd_{2}Fe_{14}B_{1}$ in ${\alpha}-Fe$ matrix by annealing above their crystallization temperature. The addition of Mo, Nb, V or Cu to $Nd_{4}Fe_{85.5}B_{10.5}$ alloy results in the reduction of grain size and the sub¬sequent improvement of the coercivity. The coercivity of $Nd_{4}Fe_{82}B_{10}M_{3}Cu_{1}$(M = Mo, Nb, V) alloys increases in the order of M = V < Nb < Mo and shows the highest value of 2.7 kOe when M = Mo. On the other hand, the rem¬anence of these alloys shows the opposite trend and the rn>st improved value of 1.35 T is observed when M = V.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.121.1-121.1
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• 2011

현재 상용화되고 있는 단결정 실리콘 태양전지는 알루미늄 페이스트를 이용하여 후면의 전 영역에 전계를 형성한다. 최근에는 고효율을 얻기 위하여 후면에 패시베이션 효과와 장파장에 대한 반사도를 증가 시키는 SiNx막을 증착 후, 국부적으로 전계를 형성하는 국부 후면 전극(Local back surface field)기술이 연구되고 있다. 본 연구에서는 전면만 텍스쳐 된 단결정 실리콘 웨이퍼를 이용하였다. Plasma Enhanced Chemical Vapor Deposition(PECVD)를 이용하여 전,후면에 SiNx를 증착 하였고 후면의 국부적인 전극 패턴 형성을 위하여 SiNx 식각용 페이스트를 사용한 스크린 프린팅 기술을 이용하였다. 스크린 프린팅을 이용하여 패턴이 형성된 후면에 알루미늄을 인쇄 한 후 Rapid Thermal Process(RTP)를 이용하여 소성 공정 조건을 변화시켰다. 소성 조건 동안 형성되는 후면 전계층은 peak 온도와 승온속도, 냉각 속도에 따라 형상이나 특성이 변화하기 때문에 소성 조건을 변화시키며 국부적 후면 전계 형성의 최적화에 관한 연구를 수행하였다. 패이스트를 이용하여 SiNx를 식각 후 광학 현미경(Optical Microscopy)을 사용하여 SiNx의 식각 유무를 살펴보았고, RTP로 형성된 국부 전계층의 형성 두께, 주변 부분의 형상을 살피기 위해 도핑 영역을 혼합수용액으로 식각하여 주사 전자 현미경(SEM)을 이용하여 관찰 하였다. 또한 후면의 특성을 살펴보기 위해 분광 광도계(UV/VIS/NIR Spectrophotometer)를 사용하여 후면 SiNx층의 유무에 따른 반사도를 비교, 측정 하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.193-193
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• 2010

서로 다른 유전 물질을 이용하여 다층구조의 터널장벽을 이용하여 비휘발성 메모리 소자의 동작 특성 및 전하보존 특성을 향상시킬 수 있음이 보고되었다.[1-3] 본 연구에서는 $SiO_2/Si_3N_4/SiO_2$구조의 다층 구조의 터널 장벽을 이용하여 $WSi_2$ 나노 입자 비휘발성 메모리 소자를 제작하였다. P-형 Si 기판에 100 nm 두께의 Poly-Si 박막을 증착시켜 소스, 드레인 및 게이트 영역을 포토 리소그래피를 이용하여 형성하였다. $SiO_2/Si_3N_4/SiO_2$(ONO) 터널장벽은 CVD (chemical vapor deposition) 장치로 각각 2 nm, 2 nm 와 3 nm 두께로 형성하였으며, 그 위에 $WSi_2$ 박막을 3~4 nm 마그내트론 스퍼터링 방법으로 증착하였다. ONO 터널 장벽구조 위에 $WSi_2$나노입자를 형성시키기 위해, $N_2$분위기에서 급속열처리 방법을 이용하여 $900^{\circ}C$에서 1분간 열처리를 하였다. 마지막으로 20 nm 두께의 컨트롤 절연막을 초고진공 스퍼터를 이용하여 증착하고, Al 박막을 200 nm 두께로 증착하였다. 여기서. 제작된 메모리 소자의 게이트 길이와 선폭은 모두 $10\;{\mu}m$ 이다. 비휘발성 메모리 소자의 전기적 특성은 HP 4156A 반도체 파라미터 장비, Agilent 81104 A 80MHz 펄스/패턴 발생기를 이용하였다. 또한 전하 저장 터널링 메커니즘과, 전하누설의 원인을 분석하고 소자의 열적 안정성을 확인하기 위하여 $25^{\circ}C$ 에서 $125^{\circ}C$ 로 온도를 변화시켜 외부로 방출되는 전하의 활성화 에너지를 확인하여 누설근원을 확인하였다.

• Journal of the Korean Magnetics Society
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• v.9 no.3
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• pp.154-158
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• 1999

Magnetic properties and microstructure of nanocrystalline $\alpha$-(Fe, Co)-based Nd-(Fe, Co)-B-Nb-Cu alloys have been investigated. $Nd_x(Fe_{0.9}Co_{0.1})_{90-x}B_6Nb_3Cu_1$(x=2, 3, 4, 5, 6) alloys prepared by rapid solidification process show amorphous phase except the one with x=2. By a proper annealing, the amorphous in the alloy is changed to a nanocrystalline phase. It is confirmed that the nanocrystalline alloys are composed of $\alpha$-(Fe, Co) and $Nd_2(Fe, Co)_{14}B_1$ phase. The optimally annealed $Nd_3(Fe_{0.9}Co_{0.1})_87B_6Nb_3Cu_1$ alloy shows the highest remanence of 1.55 T. The coercivity increases with the increase of Nd content The maximum coercivity of 4.6 kOe is obtained from an optimally annealed $Nd_6(Fe_{0.9}Co_{0.1})_84B_6Nb_3Cu_1$ alloy, resulting in the maximum energy product of 10.6 MGOe.

• Journal of the Korean Magnetics Society
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• v.4 no.3
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• pp.226-232
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• 1994

Rapidly solidified $SmFe_{7+x}M_{x}(M=Mo,\;V,\;Ti)$ compound were found to crystallize in the ${Sm(Fe,\;M)}_{7}$ based stable magnetic phase by introducing a second transition element into the Sm-Fe binary system. The ${Sm(Fe,\;M)}_{7}$ phase exhibits the highest Curie temperatuer ($T_{c}=355^{\circ}C$) ever Known in the Sm-Fe magnetic systems with a quite high intrinsic coercivity($_{i}H_{c}=3~6\;kOe $). The ${Sm(Fe,\;M)}_{7}$ phase remains stable even after annealing if once form during the rapid solidification. The primary reason for the high coercive force is due to the fine grain size($2000~8000\;{\AA}$)of the magnetic ${Sm(Fe,\;M)}_{7}$ matrix phase, and the enhanced Curie temperature is attributed to the extended solid-solubility of the additive transition elements in Fe matrix, which leads to volume expansion of the ${Sm(Fe,\;M)}_{7}$ cell causing an enhanced coupling constant of Fe atoms.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.81-89
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• 1994

Ti film of lOnm thickness and Co film of 18nm thickness were sequentially e-heam evaporated onto Si (100) substrates. Metal deposited samples were rapidly thermal-annt.aled(KTA) in thr N1 en vironment a t $900^{\circ}C$ for 20 sec. to induce the reversal of metal bilayer, so that $CoSi_{2}$ thin films could be formed. The sheet resistance measured by the 4-point probe was 3.9 $\Omega /\square$This valur was maintained with increase in annealing time upto 150 seconds, showing high thermal stab~lity. Thc XRII spectra idrn tified the silicide film formed on the Si substrate as a $CoSi_{2}$ epitaxial layer. The SKM microgr;iphs showed smooth surface, and the cross-sectional TKM pictures revealed that the layer formed on the Si substrate were composed of two Co-Ti-Si alloy layers and 70nm thick $CoSi_{2}$ epl-layer. The AES analysis indicated that the native oxide on Si subs~rate was removed by TI ar the beginning of the RTA, and Ihcn that Co diffused to clean surface of Si substrate so that epitaxial $CoSi_{2}$ film could bt, formed. In thc rasp of KTA at $700^{\circ}C$. 20sec. followed by $900^{\circ}C$, 20sec., the thin film showed lower sheet resistance, but rough surface and interface owing to $CoSi_{2}$ crystal growth. The application scheme of this $CoSi_{2}$ epilayer to VLSI devices and the thermodynarnic/kinetic mechan~sms of the $CoSi_{2}$ epi-layer formation through the reversal of Co/Ti bdayer were discussed.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.10
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• pp.840-846
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• 1991

In case of the rapid thermal process by halogen lamps, an optical pyrometer is generally used to measure the temperature. It is, however, necessary to measure the temperature by the thermocouple when the process temperature is lower than 700$^{\circ}C$ and the correction of the temperature is required. Contact by the PdAg paste is commonly used out but in this case it is impossible to see the effect of surface states of the substrate, which is critical in the rapid thermal process. In this study, real temperature ramping speed of silicon substrates coveredwith various thin films such as SiO$_2$2, Si$_{3}N_{4}$, dopants, and conductive layers (Ti or Co) was investigated by a mechanical contact of the thermocouple. And the results were compared with the case in which the contact was made by the PdAg paste. Effect of process ambient was also studied. It was found that depending on the surface state, overshoot more than 100$^{\circ}C$ could occur. It was also found that in case of the substrate covered with conductive layers, mechanical contact might render the correct temperature.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.349-352
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• 2001

In this paper, novel device structure in order to realize ultra fast and ultra small silicon devices are investigated using ultra-high vacuum chemical vapor deposition(UHVCVD) and Excimer Laser Annealing (ELA) for ultra pn junction formation. Based on these fundamental technologies for the deep sub-micron device, high speed and low power devices can be fabricated. These junction formation technologies based on damage-free process for replacing of low energy ion implantation involve solid phase diffusion and vapor phase diffusion. As a result, ultra shallow junction depths by ELA are analyzed to 10~20 nm for arsenic dosage (2$\times$10$^{14}$ $\textrm{cm}^2$), excimer laser source(λ=248nm) is KrF, and sheet resistances are measured to 1k$\Omega$/$\square$ at junction depth of 15nm.

• Korean Journal of Materials Research
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• v.8 no.4
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• pp.323-327
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• 1998

All solid state lithium based rechargeable batteries were fabricated in a cell structure of Li/PEO-$LiCIO_4$-PC /$LIMn_2O_4$$LIMn_2O_4$ thin films were prepared by RF magnetron sputtering and the spinel structure could be obtained by Rapid Thermal Annealing (RT A) process at the temperature of around 750$750^{\circ}C$ . Room temperature cycling of this cell showed a nearly constant cell potential of 4 V( us. Li) and good reversibility.