Applied Physics A

, Volume 40, Issue 2, pp 101–107 | Cite as

Two-dimensional phosphorus diffusion for soft drains in silicon MOS transistors

  • F. Lau
  • U. Gösele
Contributed Papers


Phosphorus has a considerably less steep concentration profile than arsenic. Therefore phosphorus is considered as an alternative dopand for soft drain concepts in future MOS devices. In-diffusion of phosphorus starting from a high surface concentration generatesexcess point defects which diffuse into the depth of the crystal and lead to a tail in the phosphorus concentration profile by considerably enhancing the phosphorus diffusion in this region. It is also well known that the interface between silicon and a non growing oxide acts as a sink for excess point defects. Since source/drain areas of MOS transistors are surrounded by gate and isolation oxides, the question arises how the resulting excess point defect distribution may influence the lateral and vertical diffusion profile of phosphorus and hence the channel length and the junction depth of the source/drain region in a MOS device. We extended the one-dimensional Fair-Tsai model of phosphorus diffusion into two dimensions and incorporated that the interface between silicon and a gate oxide acts as a sink for excess point defects and modifies their distribution. The appropriate code was implemented in the two-dimensional process simulation program LADIS. Based on this extended model two-dimensional simulations of phosphorus drains have been performed and compared to experimental results and to results from other numerical models. It turns out that the presence of the gate oxide reduces the tail in the phosphorus concentration profile, considerably in lateral direction and less pronounced in vertical direction. Limitations of the model will be discussed in detail.


61.70 66.30 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    S. Ogura, P.J. Tsang, W.W. Walker, D.L. Chritchlow, J.F. Shepard: IEEE J. SC-15, 424 (1980)Google Scholar
  2. 2.
    S.M. Hu:Atomic Diffusion in Semiconductors, ed. by D. Shaw (Plenum, New York 1973) p. 217CrossRefGoogle Scholar
  3. 3.
    A.F.W. Willoughby:Impurity Doping Processes in Silicon, ed. by F.F.Y. Wang (North-Holland, New York 1981) p. 1CrossRefGoogle Scholar
  4. 4.
    W. Frank, U. Gösele, H. Mehrer, A. Seeger:Diffusion in Crystalline Solids, ed. by G.E. Murch, A.S. Nowick (Academic, New York 1984) pp. 110–116Google Scholar
  5. 5.
    R.B. Fair, J.C.C. Tsai: J. Electrochem. Soc.124, 1107 (1977)CrossRefGoogle Scholar
  6. 6.
    M. Yoshida: Jpn. J. Appl. Phys.22, 1404 (1983)ADSCrossRefGoogle Scholar
  7. 7.
    D. Mathoit, J.C. Pfister: J. Appl. Phys.53, 3053 (1982)ADSCrossRefGoogle Scholar
  8. 8.
    H.F. Schaake: J. Appl. Phys.55, 1208 (1984)ADSCrossRefGoogle Scholar
  9. 9.
    H. Strunk, U. Gösele, B.O. Kolbesen: Appl. Phys. Lett.34, 530 (1979)ADSCrossRefGoogle Scholar
  10. 10.
    R.M. Harris, D.A. Antoniadis: Appl. Phys. Lett.43, 937 (1983)ADSCrossRefGoogle Scholar
  11. 11.
    P. Fahey, R.W. Dutton, S.M. Hu: Appl. Phys. Lett.44, 777 (1984)ADSCrossRefGoogle Scholar
  12. 12.
    C.P. Ho, J.D. Plummer, S.E. Hansen, R.W. Dutton: IEEE Trans. ED-30, 1438 (1983)ADSCrossRefGoogle Scholar
  13. 13.
    A.M. Lin, R.W. Dutton, D.A. Antoniadis: Appl. Phys. Lett.35, 799 (1979)ADSCrossRefGoogle Scholar
  14. 14.
    M. Hamasaki: Solid State Electronics25, 1 (1982)ADSCrossRefGoogle Scholar
  15. 15.
    R. Tielert: IEEE Trans. ED-27, 1479 (1980)ADSCrossRefGoogle Scholar
  16. 16.
    K. Taniguchi, D.A. Antoniadis, Y. Matsushita: Appl. Phys. Lett.42, 961 (1983)ADSCrossRefGoogle Scholar
  17. 17.
    Y.-S. Shin, C.-K. Kim: IEEE Trans. ED-31, 797 (1984)CrossRefGoogle Scholar
  18. 18.
    T.Y. Tan, U. Gösele: Appl. Phys. A37, 1 (1985)ADSCrossRefGoogle Scholar
  19. 19.
    P.B. Griffin, P.M. Fahey, J.D. Plummer, R.W. Dutton: Appl. Phys. Lett.47, 319 (1985)ADSCrossRefGoogle Scholar
  20. 20.
    K. Taniguchi, D.A. Antoniadis: Appl. Phys. Lett.46, 944 (1985)ADSCrossRefGoogle Scholar
  21. 21.
    B.R. Penumalli: IEEE Trans. ED-30, 986 (1983)CrossRefGoogle Scholar
  22. 22.
    K. Taniguchi, M. Kashigawi, H. Iwai: IEEE Trans. ED-28, 574 (1981)CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • F. Lau
    • 1
  • U. Gösele
    • 1
  1. 1.Corporate Research and Development MicroelectronicsSiemens AGMünchen 83Fed. Rep. Germany

Personalised recommendations