Hostname: page-component-7bb8b95d7b-wpx69 Total loading time: 0 Render date: 2024-09-16T07:47:57.506Z Has data issue: false hasContentIssue false
  • English
  • Français

Dopant Implantation and Activation in Polycrystalline-SiGe

Published online by Cambridge University Press:  15 February 2011

W.J. Edwards ,
Yuen-Shung Chieh ,
Samuel Lin ,
D.G. Ast ,
J.P. Krusius  and
T. I. Kamins
W.J. Edwards
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853-1501
Yuen-Shung Chieh
Affiliation:
School of Electrical Engineering, Cornell University, Ithaca, NY 14853-1501
Samuel Lin
Affiliation:
School of Electrical Engineering, Cornell University, Ithaca, NY 14853-1501
D.G. Ast
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853-1501
J.P. Krusius
Affiliation:
School of Electrical Engineering, Cornell University, Ithaca, NY 14853-1501
T. I. Kamins
Affiliation:
Hewlett-Packard, Palo Alto, CA 94303-0867
Get access

Abstract

The activation of dopants and the evolution of the microstructure of poly-SiGe films during the activation. anneal are of interest for applications such as removable diffusion sources for shallow junctions in CMOS circuit processing, low resistance contact layers and elements for thin film transistors in active matrix flat panel displays. To study these effects, 2300Å poly-SiGe films with Ge content between 20 and 48% were deposited on 600Å poly-Si seed layers by APCVD on thermally oxidized Si substrates. Growth temperatures were between 600 and 700°C. These films were then implanted with B and As at energies of 40 and 80 keV, respectively, at two different doses of 5 × 1013/cm2 and 5 × 1016/cm2. To activate the dopants, the samples were furnace annealed at temperatures from 600 to 1000°C in an N2 ambient. Additional samples were rapidly annealed at temperatures between 800 and 1050°C for times up to 120 seconds. The sheet resistance, measured using a four-point probe, of 5 × 1016 /cm2 arsenic implanted films increased by a factor of two as the Ge content in the film increased from 20 to 48%. The boron doped film, on the other hand, showed no increase in sheet resistance with Ge content. TEM showed that in all cases the grain size increased after anneal. However, the grain sizes of the annealed, arsenic doped samples were on average 5 times larger than those of the boron-doped samples with the same anneal. The sub-grain structure of these films also changed after implantation and annealing. In particular, the twin planes increased in size in boron doped samples and sub-grain twinning virtually disappeared in the arsenic doped samples. In 5 × 1016 /cm2 As implanted samples, precipitates were formed which may indicate that the As solubility limit in the films has been exceeded. These precipitates are believed to be As or Asrich and could be responsible for the sheet resistance increase with Ge fraction, since the maximum solubility for As in Ge is lower than in Si by about a factor of ten.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 343: Symposium H – Polycrystalline Thin Films - Structure, Texture, Properties and Applications , 1994 , 685
Copyright
Copyright © Materials Research Society 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

[1] Grider, D.T., Ozturk, M.C. and Wortman, J.J., 3rd Int. Symp on ULSI Science and Technology, 296, (1991).Google Scholar
[2] King, Tsu-Jae, Saraswat, K.C., Pfiester, J R., IEEE Elect. Dev. Lett. 12, 584 (1991).Google Scholar
[3] King, Tsu-Jae, Pfiester, J R., Schott, J.D., McVittie, J.T. and Saraswat, K.C., IEDM Tech. Digest, 253 (1990).Google Scholar
[4] Kamins, T.I., Polycrystalline Silicon for Integrated Circuit Applications. (Kluwer Academic Publishers, Boston, 1988), p 91.Google Scholar
[5] Trumbore, F.A., Bell System Tech. J., 39, 205 (1960).Google Scholar
[6] Kamins, T.I., Manoliu, J. and Tucker, R.N., J. Appl. Phys., 43, 83 (1972).Google Scholar