Impact of the Ge Content on the Bandgap-Narrowing Induced Leakage Current of Recessed $\hbox{Si}{1 - x}\hbox{Ge}{x}$ Source/Drain Junctions (original) (raw)

Abstract

The purpose of this paper is to evaluate the impact of process-induced stress on the generation current of fully strained Si 1−x Ge x source/drain junctions. The Ge content of the compressively strained SiGe epitaxial layer plays a key role in the tensile stress levels present in the underlying Si substrate. Current-voltage (I-V ) measurements were employed to further investigate the leakage current enhancement due to the stressinduced bandgap narrowing in the Si depletion region, when no extended defects are formed. An empirical approach is proposed to describe the Ge content dependence of the bandgap-shrinkageinduced leakage current. An increase of the intrinsic carrier concentration as a function of the stress mismatch is observed. Moreover, the role of the epilayer thickness in the generation current is also discussed.

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References (26)

  1. M. L. Lee, E. A. Fitzgerald, M. T. Bulsara, M. T. Currie, and A. Lochtefeld, "Strained Si, SiGe, and Ge channels for high-mobility metal-oxide-semiconductor field-effect transistors," J. Appl. Phys., vol. 97, no. 1, pp. 011 101-1-011 101-27, 2005.
  2. L. Washington, F. Nouri, S. Thirupapuliyur, G. Eneman, P. Verheyen, V. Moroz, L. Smith, X. Xu, M. Kawaguchi, T. Huang, K. Ahmed, M. Balseanu, L.-Q. Xia, M. Shen, Y. Kim, R. Rooyackers, K. De Meyer, and R. Schreutelkamp, "pMOSFET with 200% mobility enhancement induced by multiple stressors," IEEE Electron Device Lett., vol. 27, no. 6, pp. 511-513, Jun. 2006.
  3. E. Simoen, M. B. Gonzalez, G. Eneman, P. Verheyen, A. Benedetti, H. Bender, R. Loo, and C. Claeys, "Germanium content dependence of the leakage current of recessed SiGe source/drain junctions," J. Mater. Sci., Mater. Electron., vol. 18, no. 7, pp. 787-791, 2007.
  4. C. Claeys, M. B. Gonzalez, G. Eneman, P. Verheyen, H. Bender, R. Schreutelkamp, L. Washington, F. Nouri, and E. Simoen, "Leakage current control in recessed SiGe source/drain junctions," J. Electrochem. Soc., vol. 154, no. 9, pp. H814-H821, 2007.
  5. E. Simoen, M. B. Gonzalez, B. Vissouvanadin, M. K. Chowdhury, P. Verheyen, A. Hikavyy, R. Loo, C. Claeys, V. Machkaoutsan, P. Tomasini, S. Thomas, J. P. Lu, J. W. Weijtmans, and R. Wise, "Factors influencing the leakage current in embedded SiGe source/drain junctions," IEEE Trans. Electron Devices, vol. 55, no. 3, pp. 925-930, 2008.
  6. G. Eneman, E. Simoen, R. Delhougne, P. Verheyen, R. Loo, and K. De Meyer, "Influence of dislocations in strained Si/relaxed SiGe layers on n + /p -junctions in a metal-oxide-semiconductor field-effect transis- tor technology," Appl. Phys. Lett., vol. 87, no. 19, pp. 192 112-1-192 112- 3, 2005.
  7. L. M. Giovane, H.-C. Luan, A. A. Agarwal, and L. C. Kimerling, "Corre- lation between leakage current density and threading dislocation density in SiGe p-i-n diodes grown on relaxed graded buffer layers," Appl. Phys. Lett., vol. 78, no. 4, pp. 541-543, 2001.
  8. P. Smeys, P. B. Griffin, Z. U. Rek, I. De Wolf, and K. C. Saraswat, "The influence of oxidation-induced stress on the generation current and its impact on scaled device performance," in IEDM Tech. Dig., 1996, pp. 709-712.
  9. J. Vanhellemont, E. Simoen, A. Kaniava, M. Libezny, and C. Claeys, "Im- pact of oxygen related extended defects on silicon diode characteristics," J. Appl. Phys., vol. 77, no. 11, pp. 5669-5676, 1995.
  10. A. Czerwinski, E. Simoen, C. Claeys, K. Klima, D. Tomaszewski, J. Gibki, and J. Katcki, "Optimized diode analysis of electrical Si substrate properties," J. Electrochem. Soc., vol. 145, no. 6, pp. 2107-2112, 1998.
  11. Y. C. Yeo and J. Sun, "Finite-element study of strain distribution in transistor with silicon-germanium source and drain regions," Appl. Phys. Lett., vol. 86, no. 2, pp. 023 103-1-023 103-3, 2005.
  12. R. Hull, "Misfit strain accommodation in SiGe heterostructures," in Germanium Silicon: Physics and Materials, ser. Semiconductor and Semimetals Series, vol. 56, R. Hull and J. C. Bean, Eds. San Diego, CA: Academic, 1998, pp. 102-167.
  13. S. C. Jain and W. Hayes, "Structure, properties and applications of Ge xSi1-x strained layers and superlattices," Semicond. Sci. Technol., vol. 6, no. 7, pp. 547-576, 1991.
  14. L. A. Zepeda-Ruiz, D. Maroudas, and W. H. Weinberg, "Theoretical study of the energetics, strain fields, and semicoherent interface structures in layer-by-layer semiconductor heteroepitaxy," J. Appl. Phys., vol. 85, no. 7, pp. 3677-3695, 1999.
  15. I. De Wolf, J. Vanhellemont, A. Romano-Rodriguez, H. Norström, and H. E. Maes, "Micro-Raman study of stress distribution in local isolation structures and correlation with transmission electron microscopy," J. Appl. Phys., vol. 71, no. 2, pp. 898-906, 1992.
  16. S. M. Hu, "Film-edge-induced stress in substrates," J. Appl. Phys., vol. 50, no. 7, pp. 4661-4666, 1979.
  17. S. C. Jain, A. H. Harker, A. Atkinson, and K. Pinardi, "Edge-induced stress and strain in stripe films and substrates: A two-dimensional finite element calculation," J. Appl. Phys., vol. 78, no. 3, pp. 1630-1637, 1995.
  18. TSUPREM4 User Manual of Version A-2007.12, Synopsys, Inc., Mountain View, CA, Dec. 2007.
  19. F. La Via and E. Rimini, "Electrical characterization of ultra-shallow junctions formed by diffusion from a CoSi 2 layer," IEEE Trans. Electron Devices, vol. 44, no. 4, pp. 526-534, Apr. 1997.
  20. J. Oh, P. Majhi, H. Lee, O. Yoo, S. Banerjee, C. Y. Kang, J. W. Yang, R. Harris, H. H. Tseng, and R. Jammy, "Improved electrical characteris- tics of Ge-on-Si field-effect transistors with controlled Ge epitaxial layer thickness on Si substrates," IEEE Electron Device Lett., vol. 28, no. 11, pp. 1044-1046, Nov. 2007.
  21. M. A. Green, "Intrinsic concentration, effective densities of states, and effective mass in silicon," J. Appl. Phys., vol. 67, no. 6, pp. 2944-2954, 1990.
  22. S. Richard, N. Cavassilas, F. Aniel, and G. Fishman, "Strained silicon on SiGe: Temperature dependence of carrier effective masses," J. Appl. Phys., vol. 94, no. 8, pp. 5088-5094, 2003.
  23. J. J. Wortman, J. R. Hauser, and R. M. Burger, "Effect of mechanical stress on p-n junction device characteristics," J. Appl. Phys., vol. 35, no. 7, pp. 2122-2131, 1964.
  24. J. J. Wortman and J. R. Hauser, "Effect of mechanical stress on p-n junction device characteristics. II. Generation-recombination current," J. Appl. Phys., vol. 37, no. 9, pp. 3527-3530, 1966.
  25. Y. Sun, S. E. Thompson, and T. Nishida, "Physics of strain effects in semiconductors and metal-oxide-semiconductor field-effect transistors," J. Appl. Phys., vol. 101, no. 10, pp. 104 503-1-104 503-22, 2007.
  26. J. D. Cressler and G. Niu, Silicon-Germanium Heterojunction Bipolar Transistors. Norwood, MA: Artech House, 2003. Mireia Bargallo Gonzalez received the M.S. de- gree in physics from the University of Barcelona, Barcelona, Spain. She is currently working toward the Ph.D. degree on the topic of defect assessment in semiconductor materials and devices at the Electri- cal Engineering Department, Katholieke Universiteit Leuven, Leuven, Belgium. She is doing her Doctoral research at the Interuni- versity Microelectronics Center (IMEC), Leuven. Her current research interests include the field of device physics and strain engineering. Eddy Simoen received the M.S. degree in physics engineering and the Ph.D. degree in engineering from the University of Gent, Gent, Belgium, in 1980 and 1985, respectively. His doctoral thesis was