J. Semicond. > 2016, Volume 37 > Issue 10 > 102001
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SEMICONDUCTOR PHYSICS

Electrical properties of sub-100 nm SiGe nanowires

B. Hamawandi1, M. Noroozi1, G. Jayakumar2, A. Ergül1, 3, K. Zahmatkesh1, M. S. Toprak1 and H. H. Radamson2

+ Author Affiliations

 Corresponding author: M. Noroozi, Email:

DOI: 10.1088/1674-4926/37/10/102001

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Abstract: In this study, the electrical properties of SiGe nanowires in terms of process and fabrication integrity, measurement reliability, width scaling, and doping levels were investigated. Nanowires were fabricated on SiGe-on oxide (SGOI) wafers with thickness of 52 nm and Ge content of 47%. The first group of SiGe wires was initially formed by using conventional I-line lithography and then their size was longitudinally reduced by cutting with a focused ion beam (FIB) to any desired nanometer range down to 60 nm. The other nanowire group was manufactured directly to a chosen nanometer level by using sidewall transfer lithography (STL). It has been shown that the FIB fabrication process allows manipulation of the line width and doping level of nanowires using Ga atoms. The resistance of wires thinned by FIB was 10 times lower than STL wires which shows the possible dependency of electrical behavior on fabrication method.

Key words: SiGe, FIB, STL, pattern transfer lithography, nanowires



[1]
Noroozi M, Hamawandi B, Toprak M S, et al. Fabrication and thermoelectric characterization of GeSn nanowires. IEEE ULIS 2014 15th Int Conf Ultim Integr Silicon, 2014: 125 http://cn.bing.com/academic/profile?id=2052429245&encoded=0&v=paper_preview&mkt=zh-cn
[2]
Boukai A I, Bunimovich Y, Tahir-Kheli J, et al. Silicon nanowires as efficient thermoelectric materials. Nature, 2008, 451: 168 doi: 10.1038/nature06458
[3]
Jayakumar G, Garidis K, Hellstrom P E, et al. Fabrication and characterization of silicon nanowires using STL for biosensing applications. IEEE 2014 15th Int Conf Ultim Integr Silicon, 2014: 109 http://cn.bing.com/academic/profile?id=2152858635&encoded=0&v=paper_preview&mkt=zh-cn
[4]
Noroozi M, Ergul A, Abedin A, et al. Fabrications of size-controlled SiGe nanowires using I-line lithography and focused ion beam technique. ECS Trans, 2014, 64: 167 http://cn.bing.com/academic/profile?id=2004258090&encoded=0&v=paper_preview&mkt=zh-cn
[5]
Martinez J A, Provencio P P, Picraux S T, et al. Enhanced thermoelectric figure of merit in SiGe alloy nanowires by boundary and hole-phonon scattering. J Appl Phys, 2011, 110: 074317 doi: 10.1063/1.3647575
[6]
Halstedt J, Hellstro P E, Zhang Z, et al. A robust spacer gate process for deca-nanometer high-frequency MOSFETs. Microelectron Eng, 2006, 83: 434 doi: 10.1016/j.mee.2005.11.008
[7]
Burchhart T, Zeiner C, Lugstein A, et al. Tuning the electrical performance of Ge nanowire MOSFETs by focused ion beam implantation. Nanotechnology, 2011, 22: 035201 doi: 10.1088/0957-4484/22/3/035201
[8]
Gnaser H, Brodyanski A, Reuscher B. Focused ion beam implantation of Ga in Si and Ge: fluence-dependent retention and surface morphology. Surf Interface Anal, 2008, 40: 1415 doi: 10.1002/sia.v40:11
[9]
Hållstedt J, Hellström P E, Radamson H H. Sidewall transfer lithography for reliable fabrication of nanowires and deca-nanometer MOSFETs. Thin Solid Films, 2008, 517: 117 doi: 10.1016/j.tsf.2008.08.134
[10]
Jayakumar G, Asadollahi A, Hellström P E, et al. Silicon nanowires integrated with CMOS circuits for biosensing application. Solid State Electron, 2014, 98: 26 doi: 10.1016/j.sse.2014.04.005
[11]
Koleśnik-Gray M M, Lutz T, Collins G, et al. Contact resistivity and suppression of Fermi level pinning in side-contacted germanium nanowires. Appl Phys Lett, 2013, 103: 2013 http://cn.bing.com/academic/profile?id=1977154259&encoded=0&v=paper_preview&mkt=zh-cn
[12]
Wu X, Kulkarni J S, Collins G, et al. Synthesis and electrical and mechanical properties of silicon and germanium nanowires. Chem Mater, 2008, 20: 5954 doi: 10.1021/cm801104s
[13]
Bergin S M, Chen Y H, Rathmell A R, et al. The effect of nanowire length and diameter on the properties of transparent, conducting nanowire films. Nanoscale, 2012, 4: 1996 doi: 10.1039/c2nr30126a
[14]
Nur O, Willander M, Radamson H H, et al. Strain characterization of CoSi2/n-Si0.9Ge0.1/p-Si heterostructures. Appl Phys Lett, 1994, 64: 440 doi: 10.1063/1.111122
[15]
Haållstedt J, Blomqvist M, Persson P O, et al. The effect of carbon and germanium on phase transformation of nickel on Si1-x-yGexCy epitaxial layers. J Appl Phys, 2004, 95: 2397 doi: 10.1063/1.1645996
[16]
Bearden J A. X-ray wavelengths. Rev Mod Phys, 1967, 39: 78 doi: 10.1103/RevModPhys.39.78
Fig. 1.  A schematic of the condensation process to manufacture SGOI.

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Fig. 2.  HRRLMs around (004) reflection of (a) as-grown Si0.74Ge0.26/Si layers and (b) condensed Si0.53Ge0.47 layer on SOI wafer.

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Fig. 3.  SEM top view of SiGe NWs before and after FIB treatment.

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Fig. 4.  (a) The starting substrate is a condensed SGOI wafer with SiGe device layer of thickness 52 nm. (b) Deposition of a stack of SiO2 (40 nm)/a-Si(100 nm)/SiN layer (40 nm). (c) Definition of NWs pattern using I-line lithography. (d) Using resist as a mask, SiN is dry etched in CHF3/CF4 precursors. (e) After stripping the resist in O2 plasma, SiN is used as a mask to etch the a-Si in Cl2/HBr plasma. (f) The SiN mask is selectively removed in H3PO4 solution and 60 nm SiN spacer (same thickness as desired final SiGe NWs dimension) is deposited using the PECVD technique. (g) Selective dry etching of SiN to form spacers along the sidewall. (h) Selective wet-etch of the a-Si in tetra-methylammonium-hydroxide (TMAH) with respect to SiN spacer and underlying SiO2. (i) Dry-etch of underlying oxide and SiGe layer in CHF3/O2 and Cl2/HBr plasma respectively. (k) Finally, SiN and SiO2 hard mask are stripped using 5% HF to form SiGe NWs.

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Fig. 5.  SEM micrograph of 60 nm SiGe NWs formed by STL method.

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Fig. 6.  The resistance behavior of NWs for frequent I-V measurements.

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Fig. 7.  (a) Resistance values verses 1/width of the SiGe NWs downscaled by FIB when the B doping in original SGOI wafer was 1017 cm3. (b) Highly doped SiGe 1019 cm-3 extracted from Reference [4].

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Fig. 8.  (a) EDX spectrum of Ge, in SiGe NW, before and after FIB process revealing Ga implantation. (b) Line scan of FIB processed NW showing the presence of Ga ions in the NW.

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Table 1.   Comparison of the resistance value for the 60 nm wide SiGe NWs fabricated by STL and FIB methods.
[1]
Noroozi M, Hamawandi B, Toprak M S, et al. Fabrication and thermoelectric characterization of GeSn nanowires. IEEE ULIS 2014 15th Int Conf Ultim Integr Silicon, 2014: 125 http://cn.bing.com/academic/profile?id=2052429245&encoded=0&v=paper_preview&mkt=zh-cn
[2]
Boukai A I, Bunimovich Y, Tahir-Kheli J, et al. Silicon nanowires as efficient thermoelectric materials. Nature, 2008, 451: 168 doi: 10.1038/nature06458
[3]
Jayakumar G, Garidis K, Hellstrom P E, et al. Fabrication and characterization of silicon nanowires using STL for biosensing applications. IEEE 2014 15th Int Conf Ultim Integr Silicon, 2014: 109 http://cn.bing.com/academic/profile?id=2152858635&encoded=0&v=paper_preview&mkt=zh-cn
[4]
Noroozi M, Ergul A, Abedin A, et al. Fabrications of size-controlled SiGe nanowires using I-line lithography and focused ion beam technique. ECS Trans, 2014, 64: 167 http://cn.bing.com/academic/profile?id=2004258090&encoded=0&v=paper_preview&mkt=zh-cn
[5]
Martinez J A, Provencio P P, Picraux S T, et al. Enhanced thermoelectric figure of merit in SiGe alloy nanowires by boundary and hole-phonon scattering. J Appl Phys, 2011, 110: 074317 doi: 10.1063/1.3647575
[6]
Halstedt J, Hellstro P E, Zhang Z, et al. A robust spacer gate process for deca-nanometer high-frequency MOSFETs. Microelectron Eng, 2006, 83: 434 doi: 10.1016/j.mee.2005.11.008
[7]
Burchhart T, Zeiner C, Lugstein A, et al. Tuning the electrical performance of Ge nanowire MOSFETs by focused ion beam implantation. Nanotechnology, 2011, 22: 035201 doi: 10.1088/0957-4484/22/3/035201
[8]
Gnaser H, Brodyanski A, Reuscher B. Focused ion beam implantation of Ga in Si and Ge: fluence-dependent retention and surface morphology. Surf Interface Anal, 2008, 40: 1415 doi: 10.1002/sia.v40:11
[9]
Hållstedt J, Hellström P E, Radamson H H. Sidewall transfer lithography for reliable fabrication of nanowires and deca-nanometer MOSFETs. Thin Solid Films, 2008, 517: 117 doi: 10.1016/j.tsf.2008.08.134
[10]
Jayakumar G, Asadollahi A, Hellström P E, et al. Silicon nanowires integrated with CMOS circuits for biosensing application. Solid State Electron, 2014, 98: 26 doi: 10.1016/j.sse.2014.04.005
[11]
Koleśnik-Gray M M, Lutz T, Collins G, et al. Contact resistivity and suppression of Fermi level pinning in side-contacted germanium nanowires. Appl Phys Lett, 2013, 103: 2013 http://cn.bing.com/academic/profile?id=1977154259&encoded=0&v=paper_preview&mkt=zh-cn
[12]
Wu X, Kulkarni J S, Collins G, et al. Synthesis and electrical and mechanical properties of silicon and germanium nanowires. Chem Mater, 2008, 20: 5954 doi: 10.1021/cm801104s
[13]
Bergin S M, Chen Y H, Rathmell A R, et al. The effect of nanowire length and diameter on the properties of transparent, conducting nanowire films. Nanoscale, 2012, 4: 1996 doi: 10.1039/c2nr30126a
[14]
Nur O, Willander M, Radamson H H, et al. Strain characterization of CoSi2/n-Si0.9Ge0.1/p-Si heterostructures. Appl Phys Lett, 1994, 64: 440 doi: 10.1063/1.111122
[15]
Haållstedt J, Blomqvist M, Persson P O, et al. The effect of carbon and germanium on phase transformation of nickel on Si1-x-yGexCy epitaxial layers. J Appl Phys, 2004, 95: 2397 doi: 10.1063/1.1645996
[16]
Bearden J A. X-ray wavelengths. Rev Mod Phys, 1967, 39: 78 doi: 10.1103/RevModPhys.39.78

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    Received: 16 February 2016 Revised: 11 May 2016 Online: Published: 01 October 2016

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      Article Navigation >  Journal of Semiconductors  > 2016  >  37(10): 102001
      B. Hamawandi, M. Noroozi, G. Jayakumar, A. Ergül, K. Zahmatkesh, M. S. Toprak, H. H. Radamson. Electrical properties of sub-100 nm SiGe nanowires[J]. Journal of Semiconductors, 2016, 37(10): 102001. doi: 10.1088/1674-4926/37/10/102001 ****B. Hamawandi, M. Noroozi, G. Jayakumar, A. Ergül, K. Zahmatkesh, M. S. Toprak, H. H. Radamson. Electrical properties of sub-100 nm SiGe nanowires[J]. J. Semicond., 2016, 37(10): 102001. doi: 10.1088/1674-4926/37/10/102001.
      Citation:
      B. Hamawandi, M. Noroozi, G. Jayakumar, A. Ergül, K. Zahmatkesh, M. S. Toprak, H. H. Radamson. Electrical properties of sub-100 nm SiGe nanowires[J]. Journal of Semiconductors, 2016, 37(10): 102001. doi: 10.1088/1674-4926/37/10/102001 ****
      B. Hamawandi, M. Noroozi, G. Jayakumar, A. Ergül, K. Zahmatkesh, M. S. Toprak, H. H. Radamson. Electrical properties of sub-100 nm SiGe nanowires[J]. J. Semicond., 2016, 37(10): 102001. doi: 10.1088/1674-4926/37/10/102001.
      shu

      Electrical properties of sub-100 nm SiGe nanowires

      DOI: 10.1088/1674-4926/37/10/102001
      • 1.

        Functional Materials Division, Department of Materials and Nano Physics, KTH Royal Institute of Technology, Electrum 229, SE-164 40 Kista, Sweden

      • 2.

        Department of Integrated Devices and Circuits, KTH Royal Institute of Technology, Electrum 229, SE-164 40 Kista, Sweden

      • 3.

        Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA

      Funds:

      Swedish Foundation for Strategic Research “SSF” EM-011-0002

      Scientific and Technological Research Council of Turkey TÜBİTAK

      Project support by the Swedish Foundation for Strategic Research “SSF” (No. EM-011-0002) and the Scientific and Technological Research Council of Turkey (No. TÜBİTAK).

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