• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1581-1584
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• 2008

In dual-polycide-gate structure with butting contact, net doping concentration of polysilicon was decreased due to overlap between $n^+$ and $p^+$ and lateral dopant diffusion in silicide/polysilicon layers. The generation of parasitic Schottky diode in butting contact region is attributed both to the $CoSi_2$-loss due to $CoSi_2$ agglomeration and to the decrease in net doping concentration of polysilicon layer. Parasitic Schottky diode reduces noise margin of sense amplifier in DDI DRAM, which causes column fail. The column fail could be reduced by physical isolation of $n^+/p^+$ polysilicon junction or suppressing $CoSi_2$ agglomeration by using nitrogen implantation into $p^+$ polysilicon before $CoSi_2$ formation.

• 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.13 no.1
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• pp.1-5
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• 2003

Uniform polycrystalline $CoSi_2$layers have been grown in situ on a polycrystalline Si substrate at temperature near $625^{\circ}C$ by reactive chemical vapor deposition of cyclopentadienyl dicarbonyl cobalt, Co(η$^{5}$ -C$_{5}$ H$_{5}$ )(CO)$_2$. The growth behavior and thermal stability of $CoSi_2$layer grown on polycrystalline Si substrates were investigated. The plate-like CoSi$_2$was initially formed with either (111), (220) or (311) interface on polycrystalline Si substrate. As deposition time was increasing, a uniform epitaxial $CoSi_2$layer was grown from the discrete $CoSi_2$plate, where the orientation of the$ CoSi_2$layer is same as the orientation of polycrystalline Si grain. The interface between $CoSi_2$layer and polycrystalline Si substrate was always (111) coherent. The growth of the uniform $CoSi_2$layer had a parabolic relationship with the deposition time. Therefore we confirmed that the growth of $CoSi_2$layer was controlled by diffusion of cobalt. The thermal stability of $CoSi_2$layer on small grain-sized polycrystalline Si substrate has been investigated using sheet resistance measurement at temperature from $600^{\circ}C$ to $900^{\circ}C$. The $CoSi_2$layer was degraded at $900^{\circ}C$. Inserting a TiN interlayer between polycrystalline Si and $_CoSi2$layers improved the thermal stability of $CoSi_2$layer up to $900^{\circ}C$ due to the suppression of the Co diffusion.