Kinetics and nucleation model of the C49 to C54 phase transformation in TiSi2 thin films on deep-sub-micron <i>n</i>+ type polycrystalline silicon lines

Kittl, J. A.; Prinslow, Douglas A.; Apte, Pushkar P.; Pas, M. F.

doi:10.1063/1.115135

Cited by 105 publications

(41 citation statements)

References 10 publications

(31 reference statements)

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“…The limiting factor for both Ti and Co was the inability to form the low resistivity phases, which grow by a nucleation controlled process, in small structures for which the nucleation density was not high enough to result in sufficient number of nuclei per structure [1,2,4,8]. The growth of NiSi and PtSi, in contrast, is diffusion limited (or interface limited).…”

Section: Introductionmentioning

confidence: 93%

“…Silicides have been used in self-aligned (SALICIDE) processes for several generations of complementary metal-oxide semiconductor (CMOS) devices, to reduce the sheet resistance and provide stable Ohmic contacts with low contact resistivity on gate and source/drain (S/D) areas [1][2][3][4][5][6][7][8][9][10][11][12][13]. One of the key considerations that were taken into account for SALICIDE processes through the different technology generations was the ability to silicide small structures of critical dimensions for the corresponding technology node, achieving low sheet resistance.…”

Section: Introductionmentioning

confidence: 99%

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Silicides and germanides for nano-CMOS applications

Kittl

Opsomer

Torregiani

et al. 2008

Materials Science and Engineering: B

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Silicides and germanides for nano-CMOS applications

Kittl

Opsomer

Torregiani

et al. 2008

Materials Science and Engineering: B

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“…[1][2][3][4][5][6][7] Silicides can significantly reduce the contact resistance of the gate electrode and the source/drain regions as compared to nonsilicided structures. In particular, titanium disilicide (TiSi 2 ) has been used extensively as a contact material in ultra-large-scale integration technology because of its low electrical resistivity and good thermal stability.…”

Section: Introductionmentioning

confidence: 99%

“…2,3 TiSi 2 is a polymorphic material and may exist either as a high resistivity (ϳ60-90 ⍀cm) base-centered orthorhombic C49 phase or a low resistivity (ϳ15-20 ⍀cm) face-centered orthorhombic C54 phase. [2][3][4] When titanium reacts with silicon, the high resistivity C49 phase forms at temperatures ranging between 550 and 650°C and then transforms into the low resistivity C54 phase at annealing temperatures greater than 650°C. The C49 structure usually forms first due to a lower barrier to nucleation that has been attributed to a lower surface energy of this phase.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the subsequent transformation from the C49 to the C54 phase is limited by a low driving force and a high activation energy. 3,4 Currently, a two-step anneal process is employed for the silicidation of titanium. The first rapid thermal anneal (RTA) step is to achieve the C49 TiSi 2 phase, and the second step is to form the low resistivity C54 TiSi 2 .…”

mentioning

confidence: 99%

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Laser-induced titanium disilicide formation for submicron technologies

Chong

Pey

Wee

et al. 2001

Journal of Elec Materi

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A great deal of studies on thin-film silicides have been conducted over the past 15 years due to their applications in the fabrication of complementary metal oxide semiconductor devices. 1-7 Silicides can significantly reduce the contact resistance of the gate electrode and the source/drain regions as compared to nonsilicided structures. In particular, titanium disilicide (TiSi 2 ) has been used extensively as a contact material in ultra-large-scale integration technology because of its low electrical resistivity and good thermal stability. 2,3 TiSi 2 is a polymorphic material and may exist either as a high resistivity (ϳ60-90 ⍀cm) base-centered orthorhombic C49 phase or a low resistivity (ϳ15-20 ⍀cm) face-centered orthorhombic C54 phase. 2-4 When titanium reacts with silicon, the high resistivity C49 phase forms at temperatures ranging between 550 and 650°C and then transforms into the low resistivity C54 phase at annealing temperatures greater than 650°C. The C49 structure usually forms first due to a lower barrier to nucleation that has been attributed to a lower surface energy of this phase. On the other hand, the subsequent transformation from the C49 to the C54 phase is limited by a low driving force and a high activation energy. 3,4 Currently, a two-step anneal process is employed for the silicidation of titanium. The first rapid thermal anneal (RTA) step is to achieve the C49 TiSi 2 phase, and the second step is to form the low resistivity C54 TiSi 2 . However, as the width of the polysilicon line decreases to sub-0.25 m, conversion of C49 TiSi 2 to C54 phase becomes increasingly difficult. This is because the C49 to C54 phase transformation nucleates only at locations where three C49 grains intersect and the number of such intersection points (triple grain boundaries) is reduced as the gate length/polysilicon linewidth decreases. 5-7 As a consequence, the TiSi 2 films will be composed of a mixture of C49 and C54 phase and have a higher resistivity than if they are completely in the C54 phase. The need to completely form the C54 phase in submicron structures has encouraged numerous efforts to increase the density of C54 nucleation sites. They include rapid thermal processing, refractory metal ion implantation, and preamorphization of the silicon substrate prior to titanium deposition. [6][7][8] Pulsed laser beams are known to offer the advantage of rapidly heating and cooling localized areas near the top surface regions, while the underlying substrate remains at a much lower temperature. 9,10 Currently, a two-step anneal is employed for the formation of titanium selfaligned silicide (Salicide). The first rapid thermal anneal (RTA) step is to achieve the C49 TiSi 2 phase, and the second step is to form the low resistivity C54 phase. However, as the width of the polysilicon line decreases, conversion of C49 to C54 TiSi 2 becomes increasingly difficult. This is because the C49 to C54 phase transformation nucleates only at locations where three C49 grains intersect and the number of such intersection points i...

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An optimized sample preparation approach for atomic resolution in situ studies of thin films

Moatti

Sachan

Prater

et al. 2018

Microscopy Res & Technique

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This work provides the details of a simple and reliable method with less damage to prepare electron transparent samples for in situ studies in scanning/transmission electron microscopy. In this study, we use epitaxial VO 2 thin films grown on c-Al 2 O 3 by pulsed laser deposition, which have a monoclinic-rutile transition at~68 C. We employ an approach combining conventional mechanical wedge-polishing and Focused Ion beam to prepare the electron transparent samples of epitaxial VO 2 thin films. The samples are first mechanically wedge-polished and ion-milled to be electron transparent. Subsequently, the thin region of VO 2 films are separated from the rest of the polished sample using a focused ion beam and transferred to the in situ electron microscopy test stage. As a critical step, carbon nanotubes are used as connectors to the manipulator needle for a soft transfer process. This is done to avoid shattering of the brittle substrate film on the in situ sample support stage during the transfer process. We finally present the atomically resolved structural transition in VO 2 films using this technique. This approach significantly increases the success rate of high-quality sample preparation with less damage for in situ studies of thin films and reduces the cost and instrumental/user errors associated with other techniques.The present work highlights a novel, simple, reliable approach with reduced damage to make electron transparent samples for atomic-scale insights of temperature-dependent transitions in epitaxial thin film heterostructures using in situ TEM studies. K E Y W O R D Sin situ FIB sample preparation, in situ heating, scanning transmission electron microscopy, structural transition, VO 2 thin films

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Kinetics and nucleation model of the C49 to C54 phase transformation in TiSi2 thin films on deep-sub-micron n+ type polycrystalline silicon lines

Cited by 105 publications

References 10 publications

Silicides and germanides for nano-CMOS applications

Silicides and germanides for nano-CMOS applications

Laser-induced titanium disilicide formation for submicron technologies

An optimized sample preparation approach for atomic resolution in situ studies of thin films

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