Characterization of cobalt annealed on silicon-germanium epilayers

Lin, F.; Sarcona, G.; Hatalis, Miltiadis K.; Cserhati, A.; Austin, Eva; Greve, David W.

doi:10.1016/0040-6090(94)90158-9

Cited by 29 publications

(12 citation statements)

References 30 publications

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“…8 Other work where Pt or N was added to the CoSi 2 showed an improvement in morphological stability of the film at high temperature. 9 Others have studied the effect of additional elements through silicide formation on alloyed substrates (SiGe) [10][11][12][13] or through the use of interlayers or capping layers. [14][15][16][17][18] A recent extensive study of the addition of metal elements to the Co-Si system was also performed using metal interlayers or capping layers in which arguments pertaining to nucleation barriers and mediated epitaxy are well developed.…”

Section: Introductionmentioning

confidence: 99%

Effects of alloying elements on cobalt silicide formation

Lavoie

Cabral

d’Heurle

et al. 2002

Journal of Elec Materi

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Alloying elements can substantially affect the formation of cobalt silicide. A comprehensive study of phase formation was performed on 23 Co alloys with alloying element concentrations ranging from 1 at.% up to 20 at.%. Using insitu characterization techniques in which x-ray diffraction (XRD) and elasticlight scattering are monitored simultaneously, we follow the formation of the silicide phases and the associated variation in surface roughness in real time during rapid thermal annealing. For pure Co silicide, we detect the formation of all stable silicide phases (Co 2 Si, CoSi, and CoSi 2 ) as well as abnormal grain growth in the Co film and thermal degradation of the silicide layer at high temperatures. The effect of the various additives on phase formation was determined. The roughness of the interface was also measured using grazing incidence x-ray reflectivity (GIXR). We show that by selecting an alloy with a specific composition, we can change the phase-formation temperatures and modify the final CoSi 2 film texture and roughness.* Each Co-alloy layer contained an equivalent of 8 nm of pure Co. These films were capped with 20 nm of TiN without an air break.

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Section: Introductionmentioning

confidence: 99%

Effects of alloying elements on cobalt silicide formation

Lavoie

Cabral

d’Heurle

et al. 2002

Journal of Elec Materi

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“…9,10,20,21 For the ternary phase diagram of the Co-Si-Ge system, a miscible ternary compound, Co(Si 1Ϫy Ge y ) (yϽ0.67), is observed after low-temperature furnace annealing with temperature ranging from 400 to 700°C, which is based on cubic CoSi structure. 22 However, the crystal structures of CoSi 2 ͑i.e., cubic CaF 2 structure͒ and CoGe 2 ͑i.e., orthorhombic structure͒ are different, and the reaction between Co and Si is more favored than the Co-Ge one.…”

Section: Introductionmentioning

confidence: 99%

Study on Ge/Si ratio, silicidation, and strain relaxation of high temperature sputtered Co/Si1−xGex structures

Huang

Chen

Chang

et al. 2000

Journal of Applied Physics

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Articles you may be interested inPlastic relaxation of solid GeSi solutions grown by molecular-beam epitaxy on the low temperature Si(100) buffer layerAs the transistors continue to scale down, the characteristics of high-temperature-sputtered Co/Si 1Ϫx Ge x junction have received lots of attention because of its potential applications to heterojunction bipolar transistors. In this study, we have fabricated Co/Si 1Ϫx Ge x junction using room-temperature and high-temperature ͑i.e., at 450°C͒ sputtered Co on top of strained Si 0.86 Ge 0.14 and Si 0.91 Ge 0.09 layers prepared by ultrahigh vacuum chemical molecular epitaxy. The relative composition of Ge in Ge-rich Si 1Ϫz Ge z precipitate and the solid solution of ternary phase silicide of Co-Si-Ge system were compared between room-temperature and high-temperature sputtered samples. We found that the high-temperature-sputtered samples are more effective in inhibiting lattice relaxation, which would be beneficial for manufacturing metal silicide/Si 1Ϫx Ge x structure devices. Mechanisms were proposed to explain the large difference between the room-temperature and high-temperature sputtered samples. It is believed that the mixed Co-Si-Ge solution on high-temperature-sputtered samples is responsible for the different silicidation behaviors.

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“…1 Perhaps even more significant, Si 1−x Ge x /Si heterostructures are being considered for raised source and drain structures in integrated circuits. There have been several efforts to evaluate a number of metal silicide contact systems to Si 1−x Ge x alloys by using metals such as Co, [6][7][8][9][10][11][12][13][14] Ni, 15 Pd, 16,17 Pt, 16,18 Ti, [8][9][10][19][20][21] W, 22 and Zr. There have been several efforts to evaluate a number of metal silicide contact systems to Si 1−x Ge x alloys by using metals such as Co, [6][7][8][9][10][11][12][13][14] Ni, 15 Pd, 16,17 Pt, 16,18 Ti, [8][9][10][19][20][21] W, 22 and Zr.…”

Section: Introductionmentioning

confidence: 99%

Germanium segregation in the Co/SiGe/Si(001) thin film system

et al. 1999

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Cobalt disilicide contacts to silicon–germanium alloys were formed by direct deposition of pure cobalt metal onto silicon–germanium films on Si(001) substrates. Segregation of germanium was observed during the reaction of the cobalt with the silicon–germanium alloy. The nature of the Ge segregation was studied by transmission electron microscopy, energy dispersive spectroscopy, and x-ray diffraction. In the case of cobalt films deposited onto strained silicon–germanium films, the Ge segregation was discovered to be in the form of Ge-enriched Si1−xGex regions found at the surface of the film surrounding CoSi and CoSi2 grains. In the case of cobalt films deposited onto relaxed silicon–germanium films, the Ge segregation was dependent on formation of CoSi2. In samples annealed below 800 °C, where CoSi was the dominant silicide phase, the Ge segregation was similar in form to the strained Si1−xGex case. In samples annealed above 800 °C, where CoSi2 was the dominant silicide phase, the Ge segregation was also in the form of tetrahedron-shaped, Ge-enriched, silicon–germanium precipitates, which formed at the substrate/silicon– germanium film interface and grew into the Si substrate. A possible mechanism for the formation of these precipitates is presented based on vacancy generation during the silicidation reaction coupled with an increased driving force for Ge diffusion due to silicon depletion in the alloy layer.

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Characterization of cobalt annealed on silicon-germanium epilayers

Cited by 29 publications

References 30 publications

Effects of alloying elements on cobalt silicide formation

Effects of alloying elements on cobalt silicide formation

Study on Ge/Si ratio, silicidation, and strain relaxation of high temperature sputtered Co/Si1−xGex structures

Germanium segregation in the Co/SiGe/Si(001) thin film system

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