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Thermal stability of nickel silicide on silicon on insulator (SOI) material
Materials Science and Engineering B 114–115 (2004) 228–231
Thermal stability of nickel silicide on silicon on insulator (SOI) material B. Cafraa , A. Albertia,∗ , L. Ottavianoa , C. Bongiornoa , G. Manninoa , T. Kammlerb , T. Feudelb b
a CNR-IMM Sezione Catania, Stradale Primosole 50, Catania 95121, Italy AMD Saxony LLC & Co. KG, Wilschdorfer Landstrasse 101, Dresden, Germany
Abstract The growth of Ni monosilicide layers on As doped silicon on insulator (SOI) substrates has been studied in the temperature range between 450 and 950 ◦ C. Sheet resistance measurements (Rs ) and X-ray diffraction (XRD) analyses have shown a remarkable improvement of the thermal stability mainly due to the use of spike annealing processes. TEM analyses have indicated that NiSi film maintains a columnar structure and a flat interface with the substrate as the temperature increases up to 900 ◦ C. Above this temperature, morphological and structural changes like agglomeration phenomena, hole formation and nucleation of the silicon rich phase, have caused an abrupt increase of the sheet resistance of the layer. © 2004 Elsevier B.V. All rights reserved. Keywords: Nickel silicide; Silicidation; Thermal stability; Spike annealing; Silicon on insulator
1. Introduction A low resistivity Ni monosilicide layer is an attractive alternative to the silicides currently used to contact source, drain and gates of CMOS devices, i.e. TiSi2 and CoSi2 . Advantages of this material reside in a low silicon consumption during silicidation, low thermal budget for formation and high conductivity even on narrow lines. Because of these advantages Ni reaction has been extensively studied in recent years and it has been found that the low resistivity NiSi silicide is the stable phase for temperatures ranging from 400 to 700–800 ◦ C for both undoped, As and B doped Si substrates [1–4]. Yun et al. [5] give also evidence of the structural degradation of the NiSi layer at a quite low temperature (650 ◦ C). More recently, it has been shown that the use of interlayers like Pt, Co or Ir can shift the nucleation of the disilicide phase, which is less conductive [6,7], at higher temperature. Increasing interest in thin (<100 nm) silicon on insulator (SOI) substrates [8] makes necessary a detailed study, both morphological and electrical, of the interaction between metal and ∗
Corresponding author. E-mail address: [email protected] (A. Alberti).
0921-5107/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2004.07.020
SOI. Degradation in contact resistance and device performance can in fact occur if, during the silicidation process, part of the formed silicide reaches the buried oxide. It is also important to understand the role of the buried oxide on the structural properties of the silicide and on its evolution during annealing. In this respect a lack of data in the literature has been noticed, with only an earlier work on nickel disilicide films formed on SIMOX substrate, published by Yang et al. [9], that discussed the barrier role to the buried oxide as it prevents Ni diffusion into the silicon substrate resulting in a uniform silicide layer. In the present work electrical and morphological results for Ni silicidation on As doped SOI substrates are investigated. Instead of a conventional two-step rapid thermal treatments (RTP) [2,4], Ni monosilicide formation has been performed by means of spike annealing thermal processes and its thermal stability has been investigated over a wide range of temperatures (450–950 ◦ C). 2. Experimental SOI wafers doped with arsenic to a dose of 2 × 1015 atoms/cm2 have been used as a substrate. After a stan-
B. Cafra et al. / Materials Science and Engineering B 114–115 (2004) 228–231
229
Fig. 1. Normalised sheet resistance changes as a function of annealing temperature. The stability window extends to 900 ◦ C.
dard cleaning treatments and the dopant activation process, Ni films, 14 nm thick, have been deposited on SOI. The metaldeposited wafers were cut into 2 cm × 2 cm pieces and subjected to spike annealing processes in a flowing N2 ambient. Sheet resistance has been measured before and after spike annealing processes. Nickel silicide phases have been identified by grazing incidence X-ray diffraction analyses. Morphology and interfacial properties of the silicides were characterised by transmission electron microscopy (TEM) operating at 200 kV.
3. Results The ratio of the sheet resistance after annealing to the as deposited value, that was 24 square, is plotted as a function of temperature in Fig. 1. The data are the mean values over a number of silicidation processes, that have been done in order to test the reproducibility of the process; the error bars represent the mean square root of the values collected on different samples over an area of 2 cm × 2 cm and they result negligible for all data except for 950 ◦ C. In the range from 450 to 850 ◦ C, the normalised resistance maintains an almost constant value of 0.5. At 900 ◦ C the resistance slightly decreases to a value of 0.3, whilst, at 950 ◦ C, it raises up to 2.62. Variations found in the resistance vs temperature curve have been associated, by means of X-ray diffraction analyses (XRD), to the occurrence of Ni–Si reactions. Phases identification after 450, 900 and 950 ◦ C annealing processes are shown in Fig. 2. At 450 ◦ C NiSi was formed by Ni diffusion towards the Si substrate [10]. The corresponding XRD diffraction pattern has three peaks at 31.66◦ , 36.19◦ and 37.55◦ which have been attributed to the diffraction of the NiSi (0 1 1), (1 1 1) and (2 0 1) planes, respectively. The more intense peak (38 counts per second) has been detected at 2θ = 45.85◦ and has been attributed to NiSi (1 1 2) planes. Additional NiSi contributions come from (2 1 1) and (1 0 3) planes. In the range between 2θ = 53◦ and 2θ = 58◦ , a NiSi peak region has been detected, due to the overlap of a number of adjacent peaks, while a single peak has been found at 2θ = 62.5◦ and attributed to NiSi (4 2 3) planes. With increasing the annealing temperature from 450 to 900 ◦ C, the (2 0 1) and (4 2 3) peaks disappeare whilst the remaining ones become more intense. Among these, NiSi
Fig. 2. XRD diffraction patterns showing phases and grain orientation for Ni silicides at 450, 900 and 950 ◦ C. Note that NiSi2 starts appearing at 950 ◦ C.
(1 1 2) double its intensity. All the NiSi peaks detected at 900 ◦ C still persist at 950 ◦ C with the difference that a weak contribution from the silicon rich phase starts appearing at 2θ = 28.49◦ , due to NiSi2 (1 1 1) planes. The position of the NiSi diffraction peaks have been compared as a function of the annealing temperature and the differences related to the (0 1 1), (1 1 2) and (2 1 1) planes have been listed in Table 1. It should be noted that the peak position shifts towards lower angles as the temperature increases and, consequently, the interplanar distances increase at higher temperatures. Such an issue suggests that NiSi grains formeded at high temperature are strained. From the peak positions the lattice parameter of the orthorhombic NiSi phase have been calculated. At 900 ◦ C we have found: a = 5.261, b = 3.225 and c = 5.581, with a and Table 1 Comparison of XRD peak positions of Ni monosilicide at various annealing temperature (0 1 1)
(1 1 2)
(◦ )
d (nm)
2θ
(◦ )
d (nm)
2θ (◦ )
d (nm)
31.66 31.65 31.62
0.2823 0.2824 0.2827
45.89 45.89 45.85
0.1975 0.1975 0.1977
47.38 47.23 47.18
0.1917 0.1922 0.1924
2θ 450 ◦ C
900 ◦ C 950 ◦ C
(2 1 1)
230
B. Cafra et al. / Materials Science and Engineering B 114–115 (2004) 228–231
c that increase by 0.53 and 1.37%, and b that decreases by 1.01% with respect to the room temperature lattice parameter of the Joint Committee on Powder Diffraction Standards (JCPDS) [11]. Peak shift and variation in the lattice parameters for Ni monosilicide on poly-Si substrate were reported by several authors [1,12–14] and related to the anisotropy in the thermal expansion coefficients along the different axis. Our results are in agreement with this behaviour. The electrical and diffraction data have indicated that NiSi is the stable phase that defines the range of electrical stability in the resistance curve. NiSi thermal stability is remarkably enhanced by using spike annealing, with respect to the conventional RTA processes, being extendible, from the high temperature side, up to 900 ◦ C. In this respect, the role of SOI, compared to the case of using a conventional silicon substrate, is not excluded. This study is still under investigation. The NiSi2 phase starts nucleating at 950 ◦ C, but NiSi still remains the dominant. The presence of such a small amount of NiSi2 cannot fully explain the increase by a factor of 5 in the sheet resistance observed at 950 ◦ C (Fig. 1). If NiSi phase had totally converted into the silicon rich phase, sheet resistance would have increased by a factor of three. To check whether this variation has additionally been caused by morphological degradations, TEM analyses were done. The silicide which reacted in the range from 450 to 900 ◦ C is a continuous film with a columnar structure and an interface with silicon quite flat. Cross-sectional TEM images of samples reacted at 450 and 900 ◦ C are shown in Fig. 3. The sample annealed at 450 ◦ C (Fig. 3a) has a three-layer structure in which an intermediate layer, of amorphous contrast, is located between two different Ni-containing layers. The layer at the surface has a mean thickness of 8 nm and is probably a nickel layer. The intermediate layer is 2 nm thick and has a uniform distribution along the sample. EFTEM analysis (not shown), have demonstrated this amorphous layer to be a silicon oxide film, probably present at the Si/Ni interface before the thermal treatments and not fully removed by the
Fig. 3. Cross-sectional TEM micrograph of NiSi films grown on SOI substrate at 450 ◦ C (a) and at 900 ◦ C (b).
cleaning procedure. The Ni silicide at the interface with silicon has a uniform thickness of 15 nm. The sample reacted at higher temperatures does not have the oxide film as intermediate layer due to the fact that all the Ni atoms have diffused through this and have reacted with silicon. The Ni monosilicide formed at 900 ◦ C is shown in Fig. 3b. It has an average thickness of 25 nm and a surface almost flat. A boundary between two adjacent silicide grains is also visible on the left side of Fig. 3b. Dramatic morphological changes occur at an annealing temperature of 950 ◦ C (Fig. 4), consisting in silicide agglomeration, roughening of the interface and silicon hole formation. With respect to the case at the immediately lower temperature, the presence of big silicon holes has dramatically reduced the current flow, being possible only by means of percolation paths, and this causes the sheet resistance to abruptly increase (Fig. 1). Additionally, NiSi grains growth has occurred, as it is shown by the plan view analysis of Fig. 4. The grains have a long and narrow shape and, in some cases, they constitute separate islands. It has been calculated that approximately the 60% of sample surface is covered by silicide grains, while in the remaining part, silicon from the substrate has appeared at the sample surface. The corresponding electron diffraction pattern, shown on the inset of Fig. 4 exhibits arcs of diffraction rings corresponding to (1 0 2) and (2 0 2) crystallographic plans. Together with the arcs, additional spots are present. These spots refer to plains in Bragg conditions that identify the (2 3 1) zone axis of the NiSi phase. This evidence supports the fact that at high temperature (950 ◦ C) the phase transition does not occur significantly.
Fig. 4. Plan view TEM analysis of the sample reacted at 950 ◦ C. White regions are exposed Si areas. The silicide has agglomerated and exhibits a dark contrast. The corresponding diffraction pattern, shown on the inset, indicates that the agglomerated silicide is NiSi.
B. Cafra et al. / Materials Science and Engineering B 114–115 (2004) 228–231
4. Conclusion Formation and thermal stability of nickel monosilicide was studied on As doped SOI substrate as a function of spike annealing temperature. Four point probe resistance measurements, supported by XRD diffraction, indicate that Ni monosilicide on SOI substrate is the phase in equilibrium with silicon in a temperature range from 450 to 900 ◦ C, so that the thermal stability window is considerably extended with respect to the conventional RTA processes. Degradation phenomena and contribution from NiSi2 phase have indeed been delayed to 950 ◦ C.
Acknowledgement This work has been partially supported by EU grant IST2001-32061 (IMPULSE project).
References [1] C. Lavoie, F.M. d’Heurle, C. Detavernier, C. Cabral Jr., Microelectron. Eng. 79 (2003) 144.
231
[2] J.A. Kittl, A. Lauwers, O. Chamirian, M. Van Dal, A. Akheyar, M. De Potter, R. Lindsay, K. Maex, Microelectron. Eng. 70 (2003) 158–165. [3] O. Chamirian, J.A. Kittl, A. Lauwers, O. Richard, M. Van Dal, K. Maex, Microelectron. Eng. 70 (2003) 201–208. [4] A. Lauwers, A. Steegen, M. de Potter, R. Lindsay, A. Satta, H. Bender, K. Maex, J. Vac. Sci. Technol. B 19 (6) (2001) 2026. [5] J. Yun, H.-H. Ji, S.-Y. Oh, M.-S. Bae, H.-J. Lee, B.-F. Huang, Y.-G. Kim, J.-S. Wang, N.-G. Sung, S.-B. Hu, J.-G. Lee, S.-H. Park, H.-S. Lee, W.-J. Ho, D.-B. Kim, H.-D. Lee, Electrochem. Solid State Lett. 7 (4) (2004) 83–85. [6] J.F. Liu, H.B. Chen, J.Y. Feng, J. Zhu, Appl. Phys. Lett. 77 (2000) 2177. [7] J.-S. Maa, Y. Ono, D.J. Tweet, F. Zhang, S.T. Hsu, J. Vac. Sci. Technol. A 19 (4) (2001) 1595. [8] G.K. Celler, S. Cristoloveneau, J. Appl. Phys. 93 (2003) 4955. [9] H. Yang, R.F. Pinizzotto, L. Luo, F. Namavar, Appl. Phys. Lett. 62 (1993) 2694. [10] J.P. Gambino, E.G. Colgan, Mater. Chem. Phys. 52 (1999) 96. [11] Joint Committee on Powder Diffraction Standards 38-0844. [12] D.F. Wilson, O.B. Cavin, Scr. Metall. Mater. 26 (1992) 85. [13] C. Detavernier, C. Lavoie, F.M. d’Heurle, J. Appl. Phys. 93 (2003) 2510. [14] M.K. Rabadanov, M.B. Ataev, Inorg. Mater. (Transl. Neorg. Mater.) 38 (2002) 120.
Thermal stability of nickel silicide on silicon on insulator (SOI) material B. Cafraa , A. Albertia,∗ , L. Ottavianoa , C. Bongiornoa , G. Manninoa , T. Kammlerb , T. Feudelb b
a CNR-IMM Sezione Catania, Stradale Primosole 50, Catania 95121, Italy AMD Saxony LLC & Co. KG, Wilschdorfer Landstrasse 101, Dresden, Germany
Abstract The growth of Ni monosilicide layers on As doped silicon on insulator (SOI) substrates has been studied in the temperature range between 450 and 950 ◦ C. Sheet resistance measurements (Rs ) and X-ray diffraction (XRD) analyses have shown a remarkable improvement of the thermal stability mainly due to the use of spike annealing processes. TEM analyses have indicated that NiSi film maintains a columnar structure and a flat interface with the substrate as the temperature increases up to 900 ◦ C. Above this temperature, morphological and structural changes like agglomeration phenomena, hole formation and nucleation of the silicon rich phase, have caused an abrupt increase of the sheet resistance of the layer. © 2004 Elsevier B.V. All rights reserved. Keywords: Nickel silicide; Silicidation; Thermal stability; Spike annealing; Silicon on insulator
1. Introduction A low resistivity Ni monosilicide layer is an attractive alternative to the silicides currently used to contact source, drain and gates of CMOS devices, i.e. TiSi2 and CoSi2 . Advantages of this material reside in a low silicon consumption during silicidation, low thermal budget for formation and high conductivity even on narrow lines. Because of these advantages Ni reaction has been extensively studied in recent years and it has been found that the low resistivity NiSi silicide is the stable phase for temperatures ranging from 400 to 700–800 ◦ C for both undoped, As and B doped Si substrates [1–4]. Yun et al. [5] give also evidence of the structural degradation of the NiSi layer at a quite low temperature (650 ◦ C). More recently, it has been shown that the use of interlayers like Pt, Co or Ir can shift the nucleation of the disilicide phase, which is less conductive [6,7], at higher temperature. Increasing interest in thin (<100 nm) silicon on insulator (SOI) substrates [8] makes necessary a detailed study, both morphological and electrical, of the interaction between metal and ∗
Corresponding author. E-mail address: [email protected] (A. Alberti).
0921-5107/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2004.07.020
SOI. Degradation in contact resistance and device performance can in fact occur if, during the silicidation process, part of the formed silicide reaches the buried oxide. It is also important to understand the role of the buried oxide on the structural properties of the silicide and on its evolution during annealing. In this respect a lack of data in the literature has been noticed, with only an earlier work on nickel disilicide films formed on SIMOX substrate, published by Yang et al. [9], that discussed the barrier role to the buried oxide as it prevents Ni diffusion into the silicon substrate resulting in a uniform silicide layer. In the present work electrical and morphological results for Ni silicidation on As doped SOI substrates are investigated. Instead of a conventional two-step rapid thermal treatments (RTP) [2,4], Ni monosilicide formation has been performed by means of spike annealing thermal processes and its thermal stability has been investigated over a wide range of temperatures (450–950 ◦ C). 2. Experimental SOI wafers doped with arsenic to a dose of 2 × 1015 atoms/cm2 have been used as a substrate. After a stan-
B. Cafra et al. / Materials Science and Engineering B 114–115 (2004) 228–231
229
Fig. 1. Normalised sheet resistance changes as a function of annealing temperature. The stability window extends to 900 ◦ C.
dard cleaning treatments and the dopant activation process, Ni films, 14 nm thick, have been deposited on SOI. The metaldeposited wafers were cut into 2 cm × 2 cm pieces and subjected to spike annealing processes in a flowing N2 ambient. Sheet resistance has been measured before and after spike annealing processes. Nickel silicide phases have been identified by grazing incidence X-ray diffraction analyses. Morphology and interfacial properties of the silicides were characterised by transmission electron microscopy (TEM) operating at 200 kV.
3. Results The ratio of the sheet resistance after annealing to the as deposited value, that was 24 square, is plotted as a function of temperature in Fig. 1. The data are the mean values over a number of silicidation processes, that have been done in order to test the reproducibility of the process; the error bars represent the mean square root of the values collected on different samples over an area of 2 cm × 2 cm and they result negligible for all data except for 950 ◦ C. In the range from 450 to 850 ◦ C, the normalised resistance maintains an almost constant value of 0.5. At 900 ◦ C the resistance slightly decreases to a value of 0.3, whilst, at 950 ◦ C, it raises up to 2.62. Variations found in the resistance vs temperature curve have been associated, by means of X-ray diffraction analyses (XRD), to the occurrence of Ni–Si reactions. Phases identification after 450, 900 and 950 ◦ C annealing processes are shown in Fig. 2. At 450 ◦ C NiSi was formed by Ni diffusion towards the Si substrate [10]. The corresponding XRD diffraction pattern has three peaks at 31.66◦ , 36.19◦ and 37.55◦ which have been attributed to the diffraction of the NiSi (0 1 1), (1 1 1) and (2 0 1) planes, respectively. The more intense peak (38 counts per second) has been detected at 2θ = 45.85◦ and has been attributed to NiSi (1 1 2) planes. Additional NiSi contributions come from (2 1 1) and (1 0 3) planes. In the range between 2θ = 53◦ and 2θ = 58◦ , a NiSi peak region has been detected, due to the overlap of a number of adjacent peaks, while a single peak has been found at 2θ = 62.5◦ and attributed to NiSi (4 2 3) planes. With increasing the annealing temperature from 450 to 900 ◦ C, the (2 0 1) and (4 2 3) peaks disappeare whilst the remaining ones become more intense. Among these, NiSi
Fig. 2. XRD diffraction patterns showing phases and grain orientation for Ni silicides at 450, 900 and 950 ◦ C. Note that NiSi2 starts appearing at 950 ◦ C.
(1 1 2) double its intensity. All the NiSi peaks detected at 900 ◦ C still persist at 950 ◦ C with the difference that a weak contribution from the silicon rich phase starts appearing at 2θ = 28.49◦ , due to NiSi2 (1 1 1) planes. The position of the NiSi diffraction peaks have been compared as a function of the annealing temperature and the differences related to the (0 1 1), (1 1 2) and (2 1 1) planes have been listed in Table 1. It should be noted that the peak position shifts towards lower angles as the temperature increases and, consequently, the interplanar distances increase at higher temperatures. Such an issue suggests that NiSi grains formeded at high temperature are strained. From the peak positions the lattice parameter of the orthorhombic NiSi phase have been calculated. At 900 ◦ C we have found: a = 5.261, b = 3.225 and c = 5.581, with a and Table 1 Comparison of XRD peak positions of Ni monosilicide at various annealing temperature (0 1 1)
(1 1 2)
(◦ )
d (nm)
2θ
(◦ )
d (nm)
2θ (◦ )
d (nm)
31.66 31.65 31.62
0.2823 0.2824 0.2827
45.89 45.89 45.85
0.1975 0.1975 0.1977
47.38 47.23 47.18
0.1917 0.1922 0.1924
2θ 450 ◦ C
900 ◦ C 950 ◦ C
(2 1 1)
230
B. Cafra et al. / Materials Science and Engineering B 114–115 (2004) 228–231
c that increase by 0.53 and 1.37%, and b that decreases by 1.01% with respect to the room temperature lattice parameter of the Joint Committee on Powder Diffraction Standards (JCPDS) [11]. Peak shift and variation in the lattice parameters for Ni monosilicide on poly-Si substrate were reported by several authors [1,12–14] and related to the anisotropy in the thermal expansion coefficients along the different axis. Our results are in agreement with this behaviour. The electrical and diffraction data have indicated that NiSi is the stable phase that defines the range of electrical stability in the resistance curve. NiSi thermal stability is remarkably enhanced by using spike annealing, with respect to the conventional RTA processes, being extendible, from the high temperature side, up to 900 ◦ C. In this respect, the role of SOI, compared to the case of using a conventional silicon substrate, is not excluded. This study is still under investigation. The NiSi2 phase starts nucleating at 950 ◦ C, but NiSi still remains the dominant. The presence of such a small amount of NiSi2 cannot fully explain the increase by a factor of 5 in the sheet resistance observed at 950 ◦ C (Fig. 1). If NiSi phase had totally converted into the silicon rich phase, sheet resistance would have increased by a factor of three. To check whether this variation has additionally been caused by morphological degradations, TEM analyses were done. The silicide which reacted in the range from 450 to 900 ◦ C is a continuous film with a columnar structure and an interface with silicon quite flat. Cross-sectional TEM images of samples reacted at 450 and 900 ◦ C are shown in Fig. 3. The sample annealed at 450 ◦ C (Fig. 3a) has a three-layer structure in which an intermediate layer, of amorphous contrast, is located between two different Ni-containing layers. The layer at the surface has a mean thickness of 8 nm and is probably a nickel layer. The intermediate layer is 2 nm thick and has a uniform distribution along the sample. EFTEM analysis (not shown), have demonstrated this amorphous layer to be a silicon oxide film, probably present at the Si/Ni interface before the thermal treatments and not fully removed by the
Fig. 3. Cross-sectional TEM micrograph of NiSi films grown on SOI substrate at 450 ◦ C (a) and at 900 ◦ C (b).
cleaning procedure. The Ni silicide at the interface with silicon has a uniform thickness of 15 nm. The sample reacted at higher temperatures does not have the oxide film as intermediate layer due to the fact that all the Ni atoms have diffused through this and have reacted with silicon. The Ni monosilicide formed at 900 ◦ C is shown in Fig. 3b. It has an average thickness of 25 nm and a surface almost flat. A boundary between two adjacent silicide grains is also visible on the left side of Fig. 3b. Dramatic morphological changes occur at an annealing temperature of 950 ◦ C (Fig. 4), consisting in silicide agglomeration, roughening of the interface and silicon hole formation. With respect to the case at the immediately lower temperature, the presence of big silicon holes has dramatically reduced the current flow, being possible only by means of percolation paths, and this causes the sheet resistance to abruptly increase (Fig. 1). Additionally, NiSi grains growth has occurred, as it is shown by the plan view analysis of Fig. 4. The grains have a long and narrow shape and, in some cases, they constitute separate islands. It has been calculated that approximately the 60% of sample surface is covered by silicide grains, while in the remaining part, silicon from the substrate has appeared at the sample surface. The corresponding electron diffraction pattern, shown on the inset of Fig. 4 exhibits arcs of diffraction rings corresponding to (1 0 2) and (2 0 2) crystallographic plans. Together with the arcs, additional spots are present. These spots refer to plains in Bragg conditions that identify the (2 3 1) zone axis of the NiSi phase. This evidence supports the fact that at high temperature (950 ◦ C) the phase transition does not occur significantly.
Fig. 4. Plan view TEM analysis of the sample reacted at 950 ◦ C. White regions are exposed Si areas. The silicide has agglomerated and exhibits a dark contrast. The corresponding diffraction pattern, shown on the inset, indicates that the agglomerated silicide is NiSi.
B. Cafra et al. / Materials Science and Engineering B 114–115 (2004) 228–231
4. Conclusion Formation and thermal stability of nickel monosilicide was studied on As doped SOI substrate as a function of spike annealing temperature. Four point probe resistance measurements, supported by XRD diffraction, indicate that Ni monosilicide on SOI substrate is the phase in equilibrium with silicon in a temperature range from 450 to 900 ◦ C, so that the thermal stability window is considerably extended with respect to the conventional RTA processes. Degradation phenomena and contribution from NiSi2 phase have indeed been delayed to 950 ◦ C.
Acknowledgement This work has been partially supported by EU grant IST2001-32061 (IMPULSE project).
References [1] C. Lavoie, F.M. d’Heurle, C. Detavernier, C. Cabral Jr., Microelectron. Eng. 79 (2003) 144.
231
[2] J.A. Kittl, A. Lauwers, O. Chamirian, M. Van Dal, A. Akheyar, M. De Potter, R. Lindsay, K. Maex, Microelectron. Eng. 70 (2003) 158–165. [3] O. Chamirian, J.A. Kittl, A. Lauwers, O. Richard, M. Van Dal, K. Maex, Microelectron. Eng. 70 (2003) 201–208. [4] A. Lauwers, A. Steegen, M. de Potter, R. Lindsay, A. Satta, H. Bender, K. Maex, J. Vac. Sci. Technol. B 19 (6) (2001) 2026. [5] J. Yun, H.-H. Ji, S.-Y. Oh, M.-S. Bae, H.-J. Lee, B.-F. Huang, Y.-G. Kim, J.-S. Wang, N.-G. Sung, S.-B. Hu, J.-G. Lee, S.-H. Park, H.-S. Lee, W.-J. Ho, D.-B. Kim, H.-D. Lee, Electrochem. Solid State Lett. 7 (4) (2004) 83–85. [6] J.F. Liu, H.B. Chen, J.Y. Feng, J. Zhu, Appl. Phys. Lett. 77 (2000) 2177. [7] J.-S. Maa, Y. Ono, D.J. Tweet, F. Zhang, S.T. Hsu, J. Vac. Sci. Technol. A 19 (4) (2001) 1595. [8] G.K. Celler, S. Cristoloveneau, J. Appl. Phys. 93 (2003) 4955. [9] H. Yang, R.F. Pinizzotto, L. Luo, F. Namavar, Appl. Phys. Lett. 62 (1993) 2694. [10] J.P. Gambino, E.G. Colgan, Mater. Chem. Phys. 52 (1999) 96. [11] Joint Committee on Powder Diffraction Standards 38-0844. [12] D.F. Wilson, O.B. Cavin, Scr. Metall. Mater. 26 (1992) 85. [13] C. Detavernier, C. Lavoie, F.M. d’Heurle, J. Appl. Phys. 93 (2003) 2510. [14] M.K. Rabadanov, M.B. Ataev, Inorg. Mater. (Transl. Neorg. Mater.) 38 (2002) 120.