• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.557-562
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• 2000

160nm thick amorphous Si and polycrystalline Si were each deposited on to 10nm thick SiO$_2$, Co monolayer and Co/Ti bilayer were sequentially evaporated to form Co-polycide. Then MOS capacitors were fabricated by BF$_2$ ion-implantation. The characteristics of the fabricated capacitor samples depending upon the drive-in annel conductions were measured to study the effects of thermal stability of CoSi$_2$and dopant redistribution on electrical properties of Co-polycide gates. Results for capacitors using Co/Ti bilayer and drive-in annealed at 80$0^{\circ}C$ for 20~40sec. showed excellent C-V characteristics of gate electrode.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.499-504
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• 1998

For the formation of cobalt polycide gate electrode, CoSi, was grown on columnar poly-Si, granular poly-Si or amorphous Si by depositing either Co monolayer or Co/Ti bilayer and its thermal stability was compared to study effects of the substrate crystallinity and the silicide formation method. When specimens were rapidly heat-treated at 90$0^{\circ}C$ up to 600 seconds, using amorphous Si or Co/Ti on all substrates improved the thermal stability. This was attributed to the uniform chemical composition of initial CoSi, and its smooth interface with the substrates, induced by smooth and clean Si surface and delayed Co diffusion. The main factors determining the thermal stability were found to be composition uniformity and smooth interface of $CoSi_2$, intially formed at the early stage of the heat-treatment.

• Korean Journal of Materials Research
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• v.10 no.11
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• pp.738-741
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• 2000

Univorm epitaxial $CoSi_2$layers have been grown in situ on a (100) Si substrate at temperatures near$ 600^{\circ}C$ by reactive chemical vapor deposition of cyclopentadienyl dicarbonyl cobalt, (Co(η(sup)5-C(sub)5H(sub)5) ($CO_2$). The growth kinetics of an epitaxial $CoSi_2$layer on al Si(100) substrate was investigated at temperatures ranging from 575 to $650^{\circ}C$. In initial deposition stage, plate-like discrete $CoSi_2$spikes were nucleated along the <111> directions in (100) Si substrate with a twinned structure. The discrete $CoSi_2$plates with both {111} and (100) planes grew into an epitaxial layer with a flat interface on (100) Si. For epitaxial $CoSi_2$growth on (100) Si, the activation energy of the parabolic growth was found to be 2.82 eV. The growth rate seems to be controlled by the diffusion of Co through the $CoSi_2$layer.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.2
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• pp.68-76
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• 1992

Concurrent Junction process (simultaneous formation of a silicide and a junction on the implanted substrate) by Rapid Thermal Annealig has been investigated. Electrical and material properties of CoSi$_2$ films were analyzed with Alpha Step, 4-point probe, X-ray diffraction(XRD) and Scanning Electron Microscope(SEM). And CoSi$_2$ junctions were examined with Spreading Resistance probe in order to see the redistribution of electrically activated dopants and determined the junction depth. Two step annealing process, which was 80$0^{\circ}C$ for 30sec and 100$0^{\circ}C$ for 30sec in NS12T ambient was employed to form CoSi$_2$ and shallow junctions. Resistivity of CoSi$_2$ was turned out to be 11-15${\mu}$cm and shallow junctions less than 0.1$\mu$m were successfully formed by the process. It was found that the dopant concentration at CoSi$_2$/Si interface increased as decreasing the thickness of Co films in case of $p^{+}/n$ and $n^{+}/p$ junctions while the junction depth decreased as increasing CoSiS12T thickness in case of $p^{+}/n$ junction.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.83-83
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• 2012

금속 실리사이드는 낮은 비저항, 실리콘과의 좋은 호환성 등으로 배선 contact 물질로 널리 연구되고 있다. 특히 $CoSi_2$는 선폭의 축소와 관계없이 일정하고 낮은 비저항과 열적 안정성이 우수한 특성 등으로 배선 contact 물질로 활발히 연구되고 있다. 금속 실리사이드를 실리콘 평면기판에 형성시키는 방법으로는 열처리를 통한 금속박막과 실리콘 기판 사이에 확산작용을 이용한 SALICIDE (self-algined silicide) 기술이 대표적이며 CoSi2도 이와 같은 방법으로 형성할 수 있다. Co 박막을 증착하는 방법에는 물리적 기상증착법 (PVD)과 유기금속 화학 증착법 등이 보고되어있지만 최근 급격하게 진행 중인 소자구조의 나노화 및 고 단차화에 따라 기존의 증착 기술은 낮은 단차 피복성으로 인하여 한계에 부딪힐 것으로 예상되고 있다. ALD(atomic layer deposition)는 뛰어난 단차 피복성을 가지고 원자단위 두께조절이 용이하여 나노 영역에서의 증착 방법으로 지대한 관심을 받고 있다. 앞선 연구에서 본 연구진은 CoCp2 전구체과 $NH_3$ plasma를 사용하여 Plasma enhanced ALD (PE-ALD)를 이용한 고 순도 저 저항 Co 박막 증착 공정을 개발 하고 이를 SALICIDE 공정에 적용하여 $CoSi_2$ 형성 연구를 보고한 바 있다. 하지만 이 연구에서 PE-ALD Co 박막은 플라즈마 고유의 성질로 인하여 단차 피복성의 한계를 보였다. 이번 연구에서 본 연구진은 Co(AMD)2 전구체와 $NH_3$, $H_2$, $NH_3$ plasma를 반응 기체로 사용하여 Thermal ALD(Th-ALD) Co 및 PE-ALD Co 박막을 증착 하였다. 고 단차 Co 박막의 증착을 위하여 Th-ALD 공정에 초점을 맞추어 Co 박막의 특성을 분석하였으며, Th-ALD 및 PE-ALD 공정으로 증착된 Co 박막의 단차를 비교하였다. 연구 결과 Th-ALD Co 박막은 95% 이상의 높은 단차 피복성을 가져 PE-ALD Co 박막의 단차 피복성에 비해 크게 향상되었음을 확인하였다. 추가적으로, Th-ALD Co 박막에 고 단차 박막의 증착이 가능한 Th-ALD Ru을 capping layer로 이용하여 CoSi2 형성을 확인하였고, 기존의 PVD Ti capping layer와 비교하였다. 이번 연구에서 Co 박막 및 $CoSi_2$ 의 특성 분석을 위하여 X선 반사율 분석법 (XRR), X선 광전자 분광법 (XPS), X선 회절 분석법 (XRD), 주사 전자 현미경 (SEM), 주사 투과 전자 현미경 (STEM) 등을 사용하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.764-768
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• 2002

Characteristics of ohmic Co/Si/Co contacts to n-type 4H-SiC are investigated systematically. The ohmic contacts were formed by annealing Co/Si/Co sputtered sequentially. The annealings were performed at $800^{\circ}C$ using RTP in vacuum ambient and $Ar:H_2$(9:1) ambient, respectively. The specific contact resistivity$(\rho_c)$, sheet resistance$(R_s)$, contact resistance$(R_c)$, transfer length$(L_T)$ were calculated from resistance$(R_T)$ versus contact spacing(d) measurements obtained from TLM(transmission line method) structure. While the resulting measurement values of sample annealed at vacuum ambient were $\rho_c=1.0{\tiimes}10^{-5}{\Omega}cm^2$, $R_c=20{\Omega}$ and $L_T$ = 6.0 those of sample annealed at $Ar:H_2$(9:1) ambient were $\rho_c=4.0{\tiimes}10^{-6}{\Omega}cm^2$, $R_c=4.0{\Omega}$ and $L_T$ = 2.0. The physical properties of contacts were examined using XRD and AES. The results showed that cobalt silicide was formed on SiC and Co was migrated into SiC.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.3
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• pp.1-7
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• 2003

The crystallized stable cobalt silicide$(CoSi_2)$ films were prepared on $poly-Si/SiO_2/Si$substrates for the application of inkjet printing head as a heating element with omega shape. The structural images and temperature resistance coefficient were investigated. The value of temperature resistance coefficient of the heating element was found to be about $0.0014/^{\circ}C$. The maximum power of the heating element was 2 W at the applied voltage of 2 V, 10 kHz in frequency and $1{\mu}s$ in pulse width. From the investigation of fatigue property according to the repeated applied voltages, there was no drastic changes in the resistances of heating element under the condition of $10^8$ pulsed cycles at below 15 V biased voltage. In contrast, the resistance of heating element was greatly increased at $10^6$ pulsed cycles when the heating element was operated at 17 V.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.641-646
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• 2001

The $CoSi_2$ layers have been in-situ grown on undoped poly-Si by the reactive chemical vapor deposition of $Co({\Eta}^5-C_5H_5)(CO)_2$ at $650^{\circ}C$ and their thermal stabilities have been investigated in the temperature range of 800 to $1000^{\circ}C$. The $CoSi_2$ layer grown by the in-situ method had grains with large area of (111) plane, while grains with little area of (111) plane appeared on the $CoSi_2$ layer grown by the conventional two-step method where $CoSi_2$ formed first and transformed to $CoSi_2$. The thermal stability of the $CoSi_2$ layer grown by the in- situ process was improved by more than $100^{\circ}C$ higher than that of the $CoSi_2$ layer grown by the conventional two-step process. The $CoSi_2$ layer grown in situ on a large-grained Poly-Si was stable up to $950^{\circ}C$. The effect of stability improvement by the in situ growth was more pronounced when the grain sizes of the poly-Si substrate were small. The improved thermal stability of the in-situ grown $CoSi_2$ layer could be mainly due to the formation of a uniform $CoSi_2$ layer with the $CoSi_2$ grains, which are in the form of epitaxial-like growth on the each poly-Si grains, causing a reduction of the interfacial energy of the system.