• 한국전기전자재료학회논문지
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• 제31권1호
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• pp.6-10
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• 2018

Ni germanide (NiGe) is a promising alloy material with small contact resistance at the source/drain (S/D) of Ge MOSFETs. However, it is necessary to reduce the specific contact resistance between NiGe and the doped Ge S/D region in high-performance MOSFETs. In this study, a novel method is proposed to reduce the specific contact resistance between NiGe and p-type Ge (p-Ge) using a Tb interlayer. The specific contact resistance between NiGe and p-Ge was successfully decreased with the introduction of the Tb interlayer. To investigate the mechanism behind the reduction in the specific contact resistance, the elemental distribution and crystalline structure of NiGe were analyzed using secondary ion mass spectroscopy and X-ray diffraction. It is likely that the reduction in specific contact resistance was caused by an increase in the concentration of boron in the space between NiGe and p-Ge due to the influence of the Tb interlayer.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권2호
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• pp.277-282
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• 2017

Nickel germanide (NiGe) is one of the most promising alloy materials for source/drain (S/D) of Ge MOSFETs. However, NiGe has limited thermal stability up to $450^{\circ}C$ which is a challenge for fabrication of Ge MOSFETs. In this paper, a novel method is proposed to improve the thermal stability of NiGe using Co interlayer. As a result, we found that the thermal stability of NiGe was improved from $450^{\circ}C$ to $570^{\circ}C$ by using the proposed Co interlayer. Furthermore, we found that current-voltage (I-V) characteristic was improved a little by using Co/Ni/TiN structure after post-annealing. Therefore, NiGe formed by the proposed Co interlayer that is, Co/Ni/TiN structure, is a promising technology for S/D contact of Ge MOSFETs.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.391-394
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• 2004

In this study, highly thermal stable Ni Germanosilicide has been utilized using NiPt alloy and novel NiPt/Co/TiN tri-layer. And, the Ni Germanosilicide Properties were characterized according to different Ge ratio (x) in $Si_{l-x}Ge_x$ for the next generation CMOS application. The sheet resistance of Ni Germanosilicide utilizing pure-Ni increased dramatically after the post-silicidation annealing at $600^{\circ}C$ for 30 min. Moreover, more degradation was found as the Ge fraction increases. However, using the proposed NiPt/Co/TiN tri-layer, low temperature silicidation and wide range of RTP process window were achieved as well as the improvement of the thermal stability according to different Ge fractions by the subsequent Co and TiN capping layer above NiPt on the $Si_{l-x}Ge_x$. Therefore, highly thermal immune Ni Germanosilicide up to $600^{\circ}C$ for 30 min is utilized using the NiPt/Co/TiN tri-layer promising for future SiGe based ULSI technology.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.138-138
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• 2008

Ti capping layer를 이용하여 NiGe의 열적 안정성을 향상시키는 연구를 수행하였다. N-type Ge(100) 기판에 30nm 두께의 Ni과 30nm 두께의 Ti capping layer를 E-beam evaporator를 이용하여 증착하고 $300^{\circ}C$에서 $700^{\circ}C$ 까지 30초간 $N_2$ 분위기에서 급속 열처리하여 Ni-Germanide를 형성하였다. XRD의 결과로부터 Ti capping layer 유무에 상관없이, 전 온도 범위에 걸쳐 NiGe 상이 형성된 것을 관찰할 수 있었다. 급속 열처리 온도에 따른 면저항 값을 측정한 경우, $300^{\circ}C$에서 $600^{\circ}C$까지의 열처리 온도 범위에서는 모든 시편들이 비슷한 면저항 값을 보인 반면, 열처리 온도가 $700^{\circ}C$ 이상에서는 Ti capping layer가 있는 시편이 Ti capping layer가 없는 시편보다 낮은 면저항 값을 갖는 것을 확인할 수 있었다. 이는 고온 열처리 시 Ti capping layer에 있는 Ti가 기판 방향으로 확산하여 NiGe grain boundary에 segregation 되고 그로 인하여 NiGe의 grain boundary 움직임을 억제하여 agglomeration 현상을 효과적으로 방지하였기 때문에 나타난 현상으로 사료된다.

• Applied Microscopy
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• 제45권1호
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• pp.16-22
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• 2015

The reaction kinetics of the growth of Ni germanide in the Ni/Zr-interlayer/Ge system was investigated using isothermal in situ annealing at three different temperatures in a transmission electron microscope. The growth rate of Ni germanide in the Ni/Zr-interlayer/Ge system was determined to be diffusion controlled and depended on the square root of the time, with the activation energy of $1.04P{\pm}0.04eV$. For the Ni/Zr-interlayer/Ge system, no intermediate or intermixing layer between the Zr-interlayer and Ge substrate was formed, and thus the Ni germanide was formed and grew uniformly due to Ni diffusion through the diffusion path created in the amorphous Zr-interlayer during the annealing process in the absence of any intermetallic compounds. The reaction kinetics in the Ni/Zr-interlayer/Ge system was affected only by the Zr-interlayer.

• 한국전기전자재료학회논문지
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• 제21권8호
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• pp.733-737
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• 2008

In this paper, Ni-Co alloy was used to improve thermal stability of Ni Germanide. It was found that uniform germanide is obtained on epitaxial Ge-on-Si substrate by employing Ni-Co alloy. Moreover, neither agglomeration nor penetration is observed during post-germanidation annealing process. The thermal stability of Ni germanide using Ni-Co alloy is improved due to the less agglomeration of Germanide. Therefore, the proposed Ni-Co alloy is promising for highly thermal immune Ni germanide for nano scale Ge-MOSFETs technology.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권2호
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• pp.210-214
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• 2016

In this paper, the decrease in the contact resistance of Ni germanide/Ge contact was studied as a function of the thickness of the antimony (Sb) interlayer for high performance Ge MOSFETs. Sb layers with various thickness of 2, 5, 8 and 12 nm were deposited by RF-Magnetron sputter on n-type Ge on Si wafers, followed by in situ deposition of 15nm-thick Ni film. The contact resistance of samples with the Sb interlayer was lower than that of the reference sample without the Sb interlayer. We found that the Sb interlayer can lower the contact resistance of Ni germanide/Ge contact but the reduction of contact resistance becomes saturated as the Sb interlayer thickness increases. The proposed method is useful for high performance n-channel Ge MOSFETs.

• 한국자기학회지
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• 제23권4호
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• pp.117-121
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• 2013

본 연구에서는 대표적인 강자성 금속인 Fe에 비자성 원소가 치환된 비교적 단순한 B2 구조의 FeX(X = Al, Si, Ni, Ga, Ge, Sn) 합금의 자기변형계수를 제일원리계산으로 수행하여 Fe 기반 합금이 희토류 원소 기반 자기변형 물질인 Terfenol을 대체할 수 있는 가능성을 탐색하였다. 계산방법으로 자성 연구에 가장 적합한 것으로 알려져 있는 총퍼텐셜 선형보강 평면파(Full-potential Linearized Augmented Plane Wave; FLAPW) 방법을 사용하였으며 일반화 물매근사(generalized gradient approximation: GGA)을 도입하여 전자 상호간의 교환-상관 퍼텐셜을 기술하였다. B2 구조의 FeX(X = Al, Si, Ni, Ga, Ge, Sn)의 합금들 중에 FeSi와 FeGe은 비자성 상태가, 그 외 나머지 합금은 강자성 상태가 안정된 것으로 계산되었다. FeAl, FeNi, FeGa, FeSn의 자기변형계수 는 각각 -5, +6, -84, -522ppm으로 계산되어 FeSn은 큰 자기변형을 가질 수도 있음을 예측하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 추계학술발표강연 및 논문개요집
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• pp.151-151
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• 1998

• 한국재료학회지
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• 제29권7호
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• pp.451-455
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• 2019

The electromagnetic and thermal properties of a heavy fermion $CeNi_2Ge_2$ are investigated using first-principle methods with local density approximation (LDA) and fully relativistic approaches. The Ce f-bands are located near the Fermi energy $E_F$ and hybridized with the Ni-3d states. This hybridization plays important roles in the characteristics of this material. The fully relativistic approach shows that the 4f states split into $4f_{7/2}$ and $4f_{5/2}$ states due to spin-orbit coupling effects. It can be found that within the LDA calculation, the density of states near the Fermi level are mainly of Ce-derived 4f states. The Ni-derived 3d states have high peaks around -1.7eV and spreaded over wide range around the Fermi level. The calculated magnetic of $CeNi_2Ge_2$ with LDA method does not match with that of experimental result because of strong correlation interaction between electrons in f orbitals. The calculations show that the specific heat coefficient underestimates the experimental value by a factor of 19.1. The discrepancy between the band calculation and experiment for specific heat coefficient is attributed to the formation of a quasiparticle. Because of the volume contraction, the exchange interaction between the f states and the conduction electrons is large in $CeNi_2Ge_2$, which increases the quasiparticle mass. This will result in the enhancement of the specific hear coefficient.