The self-aligned silicide (salicide) process has been used for gate, source, and drain contact metallization in microelectronics devices. Among leading silicides, $CoSi_{2}$ is the most promising due to its low resistivity and line-width-independent sheet resistance. Epitaxial $CoSi_{2}$ layers, rat...
The self-aligned silicide (salicide) process has been used for gate, source, and drain contact metallization in microelectronics devices. Among leading silicides, $CoSi_{2}$ is the most promising due to its low resistivity and line-width-independent sheet resistance. Epitaxial $CoSi_{2}$ layers, rather than polycrystalline $CoSi_{2}$ layers, are of special interest because of their better thermal stability and shallow junction formation using a silicide-as-doping-source (SADS) process. Due to its small lattice mismatch (-1.2\%) with respect to Si and similar crystal structure ($CaF_{2}$ structure), $CoSi_{2}$ can be epitaxially grown on Si substrates. Several growth techniques such as titanium interlayer-mediated epitaxy, oxide-mediated epitaxy, Co-C alloy epitaxy and reactive chemical-vapor-deposition epitaxy (RCVDE) have been introduced to produce $CoSi_{2}$/Si heteroepitaxy structure. In salicide process, silicides are grown on heavily doped source/drain regions and polycrystalline silicon gates. Little data is available on the effect of dopants during the growth of $CoSi_{2}$. \\ Therefore, the growth behavior and mechanism of epitaxial $CoSi_{2}$ layers on heavily arsenic-doped Si and boron-doped Si by metal-organic chemical-vapor deposition (MOCVD) have been investigated in comparison with undoped Si. Futhermore, the electrical characteristics of cobalt silicided junctions also have been studied. In the initial deposition stage by in-situ growth, the discrete $CoSi_{2}$ plates on heavily As-doped Si were grown with much deeper penetration depth and had a higher density of type-B $CoSi_{2}$, compared to plates on undoped Si. A thicker $CoSi_{2}$ layer was necessary for an epitaxial layer with uniform thickness on heavily As-doped Si. From the analyses of the X-ray rocking curve and residual stress, it showed that the As atoms in $CoSi_{2}$ reduced the lattice mismatch between Si and $CoSi_{2}$ and reduced lattice strain. The difference of growth behavior between heavily As-doped Si and undoped Si was attributed to the difference of strain energy during nucleation and growth of the epitaxial $CoSi_{2}$. The formation of $CoSi_{2}$ by annealing Co-C film reduced the effect of heavy arsenic doping in the growth behavior of $CoSi_{2}$ layer. In the initial deposition stage by in-situ growth, the discrete $CoSi_{2}$ plates on heavily B-doped Si were grown with a deeper penetration depth and had a higher density of type-B $CoSi_{2}$, compared to plates on undoped Si. However, the effect of heavy boron doping was small in growth behavior of epitaxial $CoSi_{2}$ layer on heavily B-doped Si. \\ The leakage current characteristics of cobalt silicided junctions also have been studied. The leakage current of pn junction diode was very high when the in-situ grown $CoSi_{2}$ was used. The main path of leakage current was the edge of active region. The leakage current of pn junction diode was drastically improved when the $CoSi_{2}$ was formed by annealing the Co-C film. The leakage current of silicided junction diode was slightly decreased by additional annealing at 850$^{\circ}$C in $N_{2}$ for 30 sec. The $CoSi_{2}$ layers have been in-situ grown on undoped poly-Si by MOCVD and their thermal stabilities have been investigated. The thermal stability of the $CoSi_{2}$ layer grown by the in-situ process was improved by 100$^{\circ}$C over than that of the $CoSi_{2}$ layer grown by the conventional two-step process. 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.
The self-aligned silicide (salicide) process has been used for gate, source, and drain contact metallization in microelectronics devices. Among leading silicides, $CoSi_{2}$ is the most promising due to its low resistivity and line-width-independent sheet resistance. Epitaxial $CoSi_{2}$ layers, rather than polycrystalline $CoSi_{2}$ layers, are of special interest because of their better thermal stability and shallow junction formation using a silicide-as-doping-source (SADS) process. Due to its small lattice mismatch (-1.2\%) with respect to Si and similar crystal structure ($CaF_{2}$ structure), $CoSi_{2}$ can be epitaxially grown on Si substrates. Several growth techniques such as titanium interlayer-mediated epitaxy, oxide-mediated epitaxy, Co-C alloy epitaxy and reactive chemical-vapor-deposition epitaxy (RCVDE) have been introduced to produce $CoSi_{2}$/Si heteroepitaxy structure. In salicide process, silicides are grown on heavily doped source/drain regions and polycrystalline silicon gates. Little data is available on the effect of dopants during the growth of $CoSi_{2}$. \\ Therefore, the growth behavior and mechanism of epitaxial $CoSi_{2}$ layers on heavily arsenic-doped Si and boron-doped Si by metal-organic chemical-vapor deposition (MOCVD) have been investigated in comparison with undoped Si. Futhermore, the electrical characteristics of cobalt silicided junctions also have been studied. In the initial deposition stage by in-situ growth, the discrete $CoSi_{2}$ plates on heavily As-doped Si were grown with much deeper penetration depth and had a higher density of type-B $CoSi_{2}$, compared to plates on undoped Si. A thicker $CoSi_{2}$ layer was necessary for an epitaxial layer with uniform thickness on heavily As-doped Si. From the analyses of the X-ray rocking curve and residual stress, it showed that the As atoms in $CoSi_{2}$ reduced the lattice mismatch between Si and $CoSi_{2}$ and reduced lattice strain. The difference of growth behavior between heavily As-doped Si and undoped Si was attributed to the difference of strain energy during nucleation and growth of the epitaxial $CoSi_{2}$. The formation of $CoSi_{2}$ by annealing Co-C film reduced the effect of heavy arsenic doping in the growth behavior of $CoSi_{2}$ layer. In the initial deposition stage by in-situ growth, the discrete $CoSi_{2}$ plates on heavily B-doped Si were grown with a deeper penetration depth and had a higher density of type-B $CoSi_{2}$, compared to plates on undoped Si. However, the effect of heavy boron doping was small in growth behavior of epitaxial $CoSi_{2}$ layer on heavily B-doped Si. \\ The leakage current characteristics of cobalt silicided junctions also have been studied. The leakage current of pn junction diode was very high when the in-situ grown $CoSi_{2}$ was used. The main path of leakage current was the edge of active region. The leakage current of pn junction diode was drastically improved when the $CoSi_{2}$ was formed by annealing the Co-C film. The leakage current of silicided junction diode was slightly decreased by additional annealing at 850$^{\circ}$C in $N_{2}$ for 30 sec. The $CoSi_{2}$ layers have been in-situ grown on undoped poly-Si by MOCVD and their thermal stabilities have been investigated. The thermal stability of the $CoSi_{2}$ layer grown by the in-situ process was improved by 100$^{\circ}$C over than that of the $CoSi_{2}$ layer grown by the conventional two-step process. 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.
주제어
#cobalt silicide MOCVD epitaxial growth leakage current 코발트 실리사이드 heavily doped Si 금속유기화학기상증착법 에피 성장 누설 전류
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