- Email: [email protected]
Effect of Sn implantation on thermal stability improvement of NiSiGe
Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
Effect of Sn implantation on thermal stability improvement of NiSiGe B. Zhang a,⇑, X. Meng a,b, Y. Ping b, W. Yu a, Z. Xue a, X. Wei a, Z. Di a, M. Zhang a, X. Wang a a b
State Key Laboratory of Functional Material for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, Shanghai 200050, China Shanghai University of Engineering Science, Shanghai 201600, China
a r t i c l e
i n f o
Article history: Received 1 October 2014 Received in revised form 2 June 2015 Accepted 15 July 2015 Available online xxxx Keywords: Germanosilicide Nickle Sn
a b s t r a c t We study the formation of nickel-germanosilicide (NiSiGe) on Sn ion pre-implanted Si0.8Ge0.2 layers. The Sn influences on NiSiGe morphology and sheet resistance are investigated at different annealing temperature. The NiSiGe films were characterized by scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS), cross-section transmission electron microscopy (XTEM), and Energy Dispersive X-ray spectrometer (EDX) techniques. It is shown that the presence of Sn atoms increases the thermal stability of NiSiGe about 150 °C. We demonstrate that the Sn atoms retard the Ni germanosilicidation rate, stabilize the NiSiGe phase, and smooth the NiSiGe/SiGe interface. Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Nickel silicide (NiSi) is considered to be the most promising material for advanced nanoscale complementary metal-oxide semiconductor (CMOS) devices because of its low resistivity, low formation temperature and low Si consumption [1,2]. The development of CMOS devices requires the introduction of new materials into the device structure. SiGe alloys are already employed in the source/drain (S/D) or channel of p-MOSFETs in order to induce strain in the channel region for increasing the hole mobility [3,4]. In this context, the formation of high quality germanosilicide/SiGe contacts represents the next advanced metallization challenge. In the ternary (Ni, Si, Ge) system, reaction behavior between Ni and SiGe is more complex, as compared to the reaction of Ni and Si [5,6]. Ge out-diffusion has been shown to be the dominant mechanism, leading to agglomeration of Ni-germanosilicides [7–10]. Substantial efforts were placed on the development of methods to improve the thermal stability and morphology of the silicide, e.g. by ion implantation [11–14]. However, little attention was devoted to the formation of NiSiGe by ion implantation. In our previous work, we reported carbon implantation could improve the NiSiGe/SiGe contact properties [15,16]. Different ion implantations may have different effects on the NiSiGe formation. In this paper, we analyze and discuss the effects of Sn ion implantation on the formation of NiSiGe on relaxed SiGe layers. The influence of Sn implantation on the thermal stability and layer morphology is primarily investigated.
Intrinsic, strain relaxed Si0.8Ge0.2 layers with thicknesses of about 800 nm were grown by reduced pressure chemical vapor deposition (RPCVD) on thick, linearly graded Si1 yGey (y < 0.2) buffer layers on Si(1 0 0) substrates. For surface protection, a 30 nm thick SiO2 layer was first deposited by plasma enhanced chemical vapor deposition. In oder to investigate the effect of different Sn doses on the formation of NiSiGe, Sn ion implantation to fluences of 1 1015 and 3 1015 ions/cm2 was performed at an energy of 70 keV which results in an ion projected range of 18 nm below the SiGe surface. Before the deposition of Ni films, the oxide layer was removed by 5% HF dip for 30 s. A Ni film with a thickness of 10 nm was deposited by electron beam evaporation at room temperature. The silicidation was performed in a rapid thermal processing (RTP) system for 30 s at temperatures ranging from 300 °C to 800 °C in N2 atmosphere. All the samples were heated from room temperature to the fixed temperature at 10 s and were cooled down to the room temperature at 120 s. The un-reacted Ni was selectively etched in H2SO4/H2O2 solution. The stoichiometry of the NiSiGe layers was investigated by RBS. The morphology and microstructure were studied by SEM and XTEM. The elements redistributions were analyzed by EDX. The sheet resistance was measured by a four-point probe system.
⇑ Corresponding author. E-mail address: [email protected] (B. Zhang).
3. Results and discussion The stoichiometry of the NiSiGe layers was investigated by RBS with 1.4 MeV He+ at a scattering angle of 170°. Fig. 1 presents the RBS spectra of NiSiGe layers formed on SiGe without and with Sn
http://dx.doi.org/10.1016/j.nimb.2015.07.075 0168-583X/Ó 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: B. Zhang et al., Effect of Sn implantation on thermal stability improvement of NiSiGe, Nucl. Instr. Meth. B (2015), http:// dx.doi.org/10.1016/j.nimb.2015.07.075
2
B. Zhang et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
implantation (a) w/o Sn and (b) 3 1015 cm 2 Sn, respectively. For low annealing temperature (400 °C), based on the RUMP program, it was simulated that the proportion of Ni and SiGe is approximately 1:1, indicating that the layer is the mono-germanosilicide phase. After high temperature (600 °C) annealing, the composition of the NiSiGe layer without Sn shows a great change indicated by the widening and lowering of the Ni signal in the RBS spectrum, which means a rough NiSiGe/SiGe interface and unhomogeous layer due to agglomeration, as shown in Fig. 1a. For Sn pre-implanted samples, the layers maintained the mono-germanesilicide phase (Fig. 1b). SEM and XTEM were employed to analyze the influence of Sn on the NiSiGe layer formation. It is found that, in the absence of Sn atoms and after annealing at 400 °C, NiSi1 xGex grains were formed at the surface as shown in Figs. 2a/3a. These grains cause a rough surface of the layer. The NiSi0.8Ge0.2 layer underneath has also a very rough interface to the Si0.8Ge0.2 substrate (see Fig. 3a). After annealing at 600 °C, the surface roughness further increases (not shown), and the NiSiGe film becomes discontinuous, resulting in an abrupt increase of the layer resistance (Fig. 5). Sn ion
implantation into the SiGe substrates reduces the roughness of both the surface and the interface of the NiSi0.8Ge0.2 layer. A low Sn ion dose of 1 1015 cm 2 is sufficient for the suppression of NiSi1 xGex grain growth, as revealed by the SEM micrograph of Fig. 2b. The layer uniformity and interface roughness are improved compared to the case of Sn absence. A high Sn dose of 3 1015 cm 2 results in a very uniform NiSi0.8Ge0.2 layer with smooth surface and interface (Figs. 2c/3b). Note that the germanosilicidation does not consume the complete Sn implanted SiGe area and, consequently, the defect region under the NiSi0.8Ge0.2 layer observed in Fig. 3b corresponds to end-of-range implantation defects. In order to get a better insight into the role of Sn on the germanosilicidation process, EDX analyses were performed. Ni, Si, Ge and Sn distributions after germanosilicidation at 400 °C with 3 1015 cm 2 Sn are plotted in Fig. 4. The Sn count is 5 times higher than the measured values for clarity. The first Sn profile peak disappears through redistributions to a more uniform profile in the NiSiGe layer, indicating Sn atoms in the NiSiGe layer may exist at grain boundaries of NiSiGe. The second peak located at
Energy (MeV) 0.8
Energy (MeV)
1.0
1.2
4000
4000 Ni
o
without Sn 400 C o without Sn 600 C
3000
0.8
1.2
o
Ni
with Sn 400 C o with Sn 600 C
3000
Si
Si
Counts
Counts
1.0
2000 Ge
2000
1000
1000
(a) 0 500
Ge
Sn
(b) 600
700
800
0 500
900
600
Channel
700
800
900
Channel
Fig. 1. RBS spectra of the NiSiGe layers formed on SiGe at different annealing temperature, (a) w/o Sn and (b) 3 1015 cm
Fig. 2. SEM images of NiSiGe layers for (a) w/o Sn, (b) 1 1015 cm
2
Sn and, (b) 3 1015 cm
Fig. 3. XTEM images of NiSiGe layers for (a) w/o Sn implantation, (b) 3 1015 cm
2
2
2
Sn.
Sn. The germanosilicidation temperature was 400 °C.
Sn. The germanosilicidation temperature was 400 °C.
Please cite this article in press as: B. Zhang et al., Effect of Sn implantation on thermal stability improvement of NiSiGe, Nucl. Instr. Meth. B (2015), http:// dx.doi.org/10.1016/j.nimb.2015.07.075
B. Zhang et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
2000
NiSiGe NiSi0.8Ge0.2
3E15 Sn 400oC
1500
Counts
NiSiGe layer increases up to 700 °C for the Sn implanted samples. It is found that the presence of Sn atoms increases the thermal stability of NiSiGe about 150 °C. We also noticed that the layer resistivity substantially increases at high Sn dose as compared to low dose or without Sn implantation between 400–500 °C, similar to NiSiGe formed on C+ implanted SiGe [15].
SiGe
Si0.8Ge0.2
Si Ni
1000
4. Conclusion
Sn X5
500
Ge
0 10
20
30
40
50
60
Position (nm) Fig. 4. EDX profiles of Ni, Si, Ge and Sn from NiSiGe layers formed at 400 °C on 3 1015 cm 2 Sn implanted SiGe substrates. The inset shows the linescan in the XTEM.
Sheet Resistance (ohms/square)
3
Acknowledgements This work is partially supported by the Natural Science Foundation of Shanghai (12ZR1453100, 14ZR1418300, 12ZR1436300), the National Natural Science Foundation of China (61306127, 61306126), the Innovation Project of Chinese Academy of Sciences (CXJJ-14-M36), and the Natural Science Foundation of Shanghai University of Engineering Science (No. 2014YYYF01).
60 w/o Sn 15 2 1 x10 /cm Sn 15 2 3 x10 /cm Sn
40
In summary, we have investigated the effect of Sn ion implantation into SiGe layers on the formation of NiSiGe layers. It is found that Sn implantation enhances the thermal stability and reduces the surface and interface roughnesses of NiSiGe layers. The presence of Sn atoms at grain boundaries and interface retards the Ni germanosilicidation rate, stabilize the NiSiGe phase and smooth the NiSiGe/SiGe interface.
References
20
0 300
400
500
600
700
800
o
Temperature ( C) Fig. 5. Sheet resistance of NiSiGe layers for different Sn doses at different annealing temperature.
the NiSiGe/SiGe interface, caused by Sn segregation during germanosilicidation. The presence of Sn at grain boundaries and the interface improves the thermal stability and reduces the interface roughness. Fig. 5 shows the sheet resistance of the NiSiGe layers formed on Sn implanted SiGe with different doses at different annealing temperature. For the Ni/SiGe system, the sheet resistance of NiSiGe films on SiGe annealed below 350 °C is much higher than that at 400 °C. This is attributed to the larger resistivity of Ni-rich germanosilicide phase formed at low annealing temperatures. The sheet resistance has the lowest value of 7 O/h in a temperature range from 350 °C to 550 °C, attributed to the mono-germanosilicide phase formation. For the high dose Sn implanted SiGe samples, NiSiGe layers with low sheet resistance were formed above 400 °C, indicating Sn atoms retard the germanosilicide phase formation. The thermal stability of the
[1] S.L. Zhang, M. Östling, Crit. Rev. Solid. State 28 (2003) 1. [2] K.D. Keyser, C.V. Bockstael, C. Detavernier, R.L. Van Meirhaeghe, J. JordanSweet, C. Lavoie, Electrochem. Solid-State Lett. 11 (2008) H266. [3] P. Packan, S. Akbar, M. Armstrong, D. Bergstrom, M. Brazier, H. Deshpande, K. Dev, G. Ding, T. Ghani, O. Golonzka, W. Han, J. He, R. Heussner, R. James, J. Jopling, C. Kenyon, S.H. Lee, M. Liu, S. Lodha, B. Mattis, A. Murthy, L. Neiberg, J. Neirynck, S. Pae, C. Parker, L. Pipes, J. Sebastian, J. Seiple, B. Sell, A. Sharma, S. Sivakumar, B. Song, A. St. Amour, K. Tone, T. Troeger, C. Weber, K. Zhang, Y. Luo, S. Natarajan, IEDM Tech. Dig. (2009) 659. [4] W. Yu, B. Zhang, Q.T. Zhao, D. Buca, J.-M. Hartmann, R. Lupták, G. Mussler, A. Fox, K.K. Bourdelle, X. Wang, S. Mantl, IEEE Electron Dev. Lett. 33 (2012) 758. [5] S.L. Zhang, Microelectron. Eng. 70 (2003) 174. [6] Q.T. Zhao, D. Buca, S. Lenk, R. Loo, M. Caymax, S. Mantl, Microelectron. Eng. 76 (2004) 285. [7] H.B. Zhao, K.L. Pey, W.K. Choi, S. Chattopadhyay, E.A. Fitzgerald, D.A. Antoniadis, P.S. Lee, J. Appl. Phys. 92 (2002) 214. [8] K.L. Pey, W.K. Choi, S. Chattopadhyay, H.B. Zhao, E.A. Fitzgerald, D.A. Antoniadis, P.S. Lee, J. Vac. Sci. Technol., B 22 (2004) 852. [9] K. Do, D. Lee, J. Kim, H. Kim, D.H. Ko, J. Electrochem. Soc. 153 (2006) J69. [10] M. Sinha, R.T.P. Lee, A. Lohani, S. Mhaisalkar, E.F. Chor, Y.C. Yeo, J. Electrochem. Soc. 156 (2009) H233. [11] O. Nakatsuka, K. Okubo, A. Sakai, M. Ogawa, Y. Yasuda, S. Zaima, Microelectron. Eng. 82 (2005) 479. [12] C.M. Hsieh, B.Y. Tsui, Y.R. Hung, Y. Yang, R. Shen, S. Cheng, T. Lin, Electrochem. Solid-State Lett. 12 (2009) H226. [13] B.Y. Tsui, C.M. Hsieh, Y.R. Hung, Y. Yang, R. Shen, S. Cheng, T. Lin, J. Electrochem. Soc. 157 (2010) H137. [14] J. Luo, Z.J. Qiu, Z. Zhang, M. Östling, S.L. Zhang, J. Vac. Sci. Technol., B 28 (2010) C1I1. [15] B. Zhang, W. Yu, Q.T. Zhao, D. Buca, B. Holländer, J.M. Hartmann, M. Zhang, X. Wang, S. Mantl, Electrochem. Solid-State Lett. 14 (2011) H261. [16] B. Zhang, W. Yu, Q.T. Zhao, D. Buca, U. Breuer, J.-M. Hartmann, B. Holländer, S. Mantl, M. Zhang, X. Wang, Nucl. Instr. Meth. B 307 (2013) 408.
Please cite this article in press as: B. Zhang et al., Effect of Sn implantation on thermal stability improvement of NiSiGe, Nucl. Instr. Meth. B (2015), http:// dx.doi.org/10.1016/j.nimb.2015.07.075
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
Effect of Sn implantation on thermal stability improvement of NiSiGe B. Zhang a,⇑, X. Meng a,b, Y. Ping b, W. Yu a, Z. Xue a, X. Wei a, Z. Di a, M. Zhang a, X. Wang a a b
State Key Laboratory of Functional Material for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, Shanghai 200050, China Shanghai University of Engineering Science, Shanghai 201600, China
a r t i c l e
i n f o
Article history: Received 1 October 2014 Received in revised form 2 June 2015 Accepted 15 July 2015 Available online xxxx Keywords: Germanosilicide Nickle Sn
a b s t r a c t We study the formation of nickel-germanosilicide (NiSiGe) on Sn ion pre-implanted Si0.8Ge0.2 layers. The Sn influences on NiSiGe morphology and sheet resistance are investigated at different annealing temperature. The NiSiGe films were characterized by scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS), cross-section transmission electron microscopy (XTEM), and Energy Dispersive X-ray spectrometer (EDX) techniques. It is shown that the presence of Sn atoms increases the thermal stability of NiSiGe about 150 °C. We demonstrate that the Sn atoms retard the Ni germanosilicidation rate, stabilize the NiSiGe phase, and smooth the NiSiGe/SiGe interface. Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Nickel silicide (NiSi) is considered to be the most promising material for advanced nanoscale complementary metal-oxide semiconductor (CMOS) devices because of its low resistivity, low formation temperature and low Si consumption [1,2]. The development of CMOS devices requires the introduction of new materials into the device structure. SiGe alloys are already employed in the source/drain (S/D) or channel of p-MOSFETs in order to induce strain in the channel region for increasing the hole mobility [3,4]. In this context, the formation of high quality germanosilicide/SiGe contacts represents the next advanced metallization challenge. In the ternary (Ni, Si, Ge) system, reaction behavior between Ni and SiGe is more complex, as compared to the reaction of Ni and Si [5,6]. Ge out-diffusion has been shown to be the dominant mechanism, leading to agglomeration of Ni-germanosilicides [7–10]. Substantial efforts were placed on the development of methods to improve the thermal stability and morphology of the silicide, e.g. by ion implantation [11–14]. However, little attention was devoted to the formation of NiSiGe by ion implantation. In our previous work, we reported carbon implantation could improve the NiSiGe/SiGe contact properties [15,16]. Different ion implantations may have different effects on the NiSiGe formation. In this paper, we analyze and discuss the effects of Sn ion implantation on the formation of NiSiGe on relaxed SiGe layers. The influence of Sn implantation on the thermal stability and layer morphology is primarily investigated.
Intrinsic, strain relaxed Si0.8Ge0.2 layers with thicknesses of about 800 nm were grown by reduced pressure chemical vapor deposition (RPCVD) on thick, linearly graded Si1 yGey (y < 0.2) buffer layers on Si(1 0 0) substrates. For surface protection, a 30 nm thick SiO2 layer was first deposited by plasma enhanced chemical vapor deposition. In oder to investigate the effect of different Sn doses on the formation of NiSiGe, Sn ion implantation to fluences of 1 1015 and 3 1015 ions/cm2 was performed at an energy of 70 keV which results in an ion projected range of 18 nm below the SiGe surface. Before the deposition of Ni films, the oxide layer was removed by 5% HF dip for 30 s. A Ni film with a thickness of 10 nm was deposited by electron beam evaporation at room temperature. The silicidation was performed in a rapid thermal processing (RTP) system for 30 s at temperatures ranging from 300 °C to 800 °C in N2 atmosphere. All the samples were heated from room temperature to the fixed temperature at 10 s and were cooled down to the room temperature at 120 s. The un-reacted Ni was selectively etched in H2SO4/H2O2 solution. The stoichiometry of the NiSiGe layers was investigated by RBS. The morphology and microstructure were studied by SEM and XTEM. The elements redistributions were analyzed by EDX. The sheet resistance was measured by a four-point probe system.
⇑ Corresponding author. E-mail address: [email protected] (B. Zhang).
3. Results and discussion The stoichiometry of the NiSiGe layers was investigated by RBS with 1.4 MeV He+ at a scattering angle of 170°. Fig. 1 presents the RBS spectra of NiSiGe layers formed on SiGe without and with Sn
http://dx.doi.org/10.1016/j.nimb.2015.07.075 0168-583X/Ó 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: B. Zhang et al., Effect of Sn implantation on thermal stability improvement of NiSiGe, Nucl. Instr. Meth. B (2015), http:// dx.doi.org/10.1016/j.nimb.2015.07.075
2
B. Zhang et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
implantation (a) w/o Sn and (b) 3 1015 cm 2 Sn, respectively. For low annealing temperature (400 °C), based on the RUMP program, it was simulated that the proportion of Ni and SiGe is approximately 1:1, indicating that the layer is the mono-germanosilicide phase. After high temperature (600 °C) annealing, the composition of the NiSiGe layer without Sn shows a great change indicated by the widening and lowering of the Ni signal in the RBS spectrum, which means a rough NiSiGe/SiGe interface and unhomogeous layer due to agglomeration, as shown in Fig. 1a. For Sn pre-implanted samples, the layers maintained the mono-germanesilicide phase (Fig. 1b). SEM and XTEM were employed to analyze the influence of Sn on the NiSiGe layer formation. It is found that, in the absence of Sn atoms and after annealing at 400 °C, NiSi1 xGex grains were formed at the surface as shown in Figs. 2a/3a. These grains cause a rough surface of the layer. The NiSi0.8Ge0.2 layer underneath has also a very rough interface to the Si0.8Ge0.2 substrate (see Fig. 3a). After annealing at 600 °C, the surface roughness further increases (not shown), and the NiSiGe film becomes discontinuous, resulting in an abrupt increase of the layer resistance (Fig. 5). Sn ion
implantation into the SiGe substrates reduces the roughness of both the surface and the interface of the NiSi0.8Ge0.2 layer. A low Sn ion dose of 1 1015 cm 2 is sufficient for the suppression of NiSi1 xGex grain growth, as revealed by the SEM micrograph of Fig. 2b. The layer uniformity and interface roughness are improved compared to the case of Sn absence. A high Sn dose of 3 1015 cm 2 results in a very uniform NiSi0.8Ge0.2 layer with smooth surface and interface (Figs. 2c/3b). Note that the germanosilicidation does not consume the complete Sn implanted SiGe area and, consequently, the defect region under the NiSi0.8Ge0.2 layer observed in Fig. 3b corresponds to end-of-range implantation defects. In order to get a better insight into the role of Sn on the germanosilicidation process, EDX analyses were performed. Ni, Si, Ge and Sn distributions after germanosilicidation at 400 °C with 3 1015 cm 2 Sn are plotted in Fig. 4. The Sn count is 5 times higher than the measured values for clarity. The first Sn profile peak disappears through redistributions to a more uniform profile in the NiSiGe layer, indicating Sn atoms in the NiSiGe layer may exist at grain boundaries of NiSiGe. The second peak located at
Energy (MeV) 0.8
Energy (MeV)
1.0
1.2
4000
4000 Ni
o
without Sn 400 C o without Sn 600 C
3000
0.8
1.2
o
Ni
with Sn 400 C o with Sn 600 C
3000
Si
Si
Counts
Counts
1.0
2000 Ge
2000
1000
1000
(a) 0 500
Ge
Sn
(b) 600
700
800
0 500
900
600
Channel
700
800
900
Channel
Fig. 1. RBS spectra of the NiSiGe layers formed on SiGe at different annealing temperature, (a) w/o Sn and (b) 3 1015 cm
Fig. 2. SEM images of NiSiGe layers for (a) w/o Sn, (b) 1 1015 cm
2
Sn and, (b) 3 1015 cm
Fig. 3. XTEM images of NiSiGe layers for (a) w/o Sn implantation, (b) 3 1015 cm
2
2
2
Sn.
Sn. The germanosilicidation temperature was 400 °C.
Sn. The germanosilicidation temperature was 400 °C.
Please cite this article in press as: B. Zhang et al., Effect of Sn implantation on thermal stability improvement of NiSiGe, Nucl. Instr. Meth. B (2015), http:// dx.doi.org/10.1016/j.nimb.2015.07.075
B. Zhang et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
2000
NiSiGe NiSi0.8Ge0.2
3E15 Sn 400oC
1500
Counts
NiSiGe layer increases up to 700 °C for the Sn implanted samples. It is found that the presence of Sn atoms increases the thermal stability of NiSiGe about 150 °C. We also noticed that the layer resistivity substantially increases at high Sn dose as compared to low dose or without Sn implantation between 400–500 °C, similar to NiSiGe formed on C+ implanted SiGe [15].
SiGe
Si0.8Ge0.2
Si Ni
1000
4. Conclusion
Sn X5
500
Ge
0 10
20
30
40
50
60
Position (nm) Fig. 4. EDX profiles of Ni, Si, Ge and Sn from NiSiGe layers formed at 400 °C on 3 1015 cm 2 Sn implanted SiGe substrates. The inset shows the linescan in the XTEM.
Sheet Resistance (ohms/square)
3
Acknowledgements This work is partially supported by the Natural Science Foundation of Shanghai (12ZR1453100, 14ZR1418300, 12ZR1436300), the National Natural Science Foundation of China (61306127, 61306126), the Innovation Project of Chinese Academy of Sciences (CXJJ-14-M36), and the Natural Science Foundation of Shanghai University of Engineering Science (No. 2014YYYF01).
60 w/o Sn 15 2 1 x10 /cm Sn 15 2 3 x10 /cm Sn
40
In summary, we have investigated the effect of Sn ion implantation into SiGe layers on the formation of NiSiGe layers. It is found that Sn implantation enhances the thermal stability and reduces the surface and interface roughnesses of NiSiGe layers. The presence of Sn atoms at grain boundaries and interface retards the Ni germanosilicidation rate, stabilize the NiSiGe phase and smooth the NiSiGe/SiGe interface.
References
20
0 300
400
500
600
700
800
o
Temperature ( C) Fig. 5. Sheet resistance of NiSiGe layers for different Sn doses at different annealing temperature.
the NiSiGe/SiGe interface, caused by Sn segregation during germanosilicidation. The presence of Sn at grain boundaries and the interface improves the thermal stability and reduces the interface roughness. Fig. 5 shows the sheet resistance of the NiSiGe layers formed on Sn implanted SiGe with different doses at different annealing temperature. For the Ni/SiGe system, the sheet resistance of NiSiGe films on SiGe annealed below 350 °C is much higher than that at 400 °C. This is attributed to the larger resistivity of Ni-rich germanosilicide phase formed at low annealing temperatures. The sheet resistance has the lowest value of 7 O/h in a temperature range from 350 °C to 550 °C, attributed to the mono-germanosilicide phase formation. For the high dose Sn implanted SiGe samples, NiSiGe layers with low sheet resistance were formed above 400 °C, indicating Sn atoms retard the germanosilicide phase formation. The thermal stability of the
[1] S.L. Zhang, M. Östling, Crit. Rev. Solid. State 28 (2003) 1. [2] K.D. Keyser, C.V. Bockstael, C. Detavernier, R.L. Van Meirhaeghe, J. JordanSweet, C. Lavoie, Electrochem. Solid-State Lett. 11 (2008) H266. [3] P. Packan, S. Akbar, M. Armstrong, D. Bergstrom, M. Brazier, H. Deshpande, K. Dev, G. Ding, T. Ghani, O. Golonzka, W. Han, J. He, R. Heussner, R. James, J. Jopling, C. Kenyon, S.H. Lee, M. Liu, S. Lodha, B. Mattis, A. Murthy, L. Neiberg, J. Neirynck, S. Pae, C. Parker, L. Pipes, J. Sebastian, J. Seiple, B. Sell, A. Sharma, S. Sivakumar, B. Song, A. St. Amour, K. Tone, T. Troeger, C. Weber, K. Zhang, Y. Luo, S. Natarajan, IEDM Tech. Dig. (2009) 659. [4] W. Yu, B. Zhang, Q.T. Zhao, D. Buca, J.-M. Hartmann, R. Lupták, G. Mussler, A. Fox, K.K. Bourdelle, X. Wang, S. Mantl, IEEE Electron Dev. Lett. 33 (2012) 758. [5] S.L. Zhang, Microelectron. Eng. 70 (2003) 174. [6] Q.T. Zhao, D. Buca, S. Lenk, R. Loo, M. Caymax, S. Mantl, Microelectron. Eng. 76 (2004) 285. [7] H.B. Zhao, K.L. Pey, W.K. Choi, S. Chattopadhyay, E.A. Fitzgerald, D.A. Antoniadis, P.S. Lee, J. Appl. Phys. 92 (2002) 214. [8] K.L. Pey, W.K. Choi, S. Chattopadhyay, H.B. Zhao, E.A. Fitzgerald, D.A. Antoniadis, P.S. Lee, J. Vac. Sci. Technol., B 22 (2004) 852. [9] K. Do, D. Lee, J. Kim, H. Kim, D.H. Ko, J. Electrochem. Soc. 153 (2006) J69. [10] M. Sinha, R.T.P. Lee, A. Lohani, S. Mhaisalkar, E.F. Chor, Y.C. Yeo, J. Electrochem. Soc. 156 (2009) H233. [11] O. Nakatsuka, K. Okubo, A. Sakai, M. Ogawa, Y. Yasuda, S. Zaima, Microelectron. Eng. 82 (2005) 479. [12] C.M. Hsieh, B.Y. Tsui, Y.R. Hung, Y. Yang, R. Shen, S. Cheng, T. Lin, Electrochem. Solid-State Lett. 12 (2009) H226. [13] B.Y. Tsui, C.M. Hsieh, Y.R. Hung, Y. Yang, R. Shen, S. Cheng, T. Lin, J. Electrochem. Soc. 157 (2010) H137. [14] J. Luo, Z.J. Qiu, Z. Zhang, M. Östling, S.L. Zhang, J. Vac. Sci. Technol., B 28 (2010) C1I1. [15] B. Zhang, W. Yu, Q.T. Zhao, D. Buca, B. Holländer, J.M. Hartmann, M. Zhang, X. Wang, S. Mantl, Electrochem. Solid-State Lett. 14 (2011) H261. [16] B. Zhang, W. Yu, Q.T. Zhao, D. Buca, U. Breuer, J.-M. Hartmann, B. Holländer, S. Mantl, M. Zhang, X. Wang, Nucl. Instr. Meth. B 307 (2013) 408.
Please cite this article in press as: B. Zhang et al., Effect of Sn implantation on thermal stability improvement of NiSiGe, Nucl. Instr. Meth. B (2015), http:// dx.doi.org/10.1016/j.nimb.2015.07.075