Citation

Van Dal MJH, Jawarani D, Van Berkum JGM, Kaiser M, Kittl JA, Vrancken C, De Potter M, Lauwers A, Maex K. J. Appl. Physics 2004; 96(12): 7568-7573.

Copyright

(Copyright © 2004, American Institute of Physics)

DOI

10.1063/1.1815384

PMID

unavailable

Abstract

Insight in the thermal degradation phenomena and the relation to phase transformation is presented for cobalt disilicide (CoSi 2) on narrow polysilicon lines (linewidth ranging from 30 nm to 1 μm) using electrical and morphological analysis in the temperature range 650-900°C. When polysilicon lines are scaled laterally to 30 nm, an abrupt CoSi 2 sheet resistance increase (>1000 Ω/sq) is observed, which is attributed to silicide agglomeration. At localized positions along the 30-nm Co-silicided lines, Si/silicide layer inversion is observed. At low formation temperature (650°C), no agglomeration phenomena occur, but incidentally the transition from CoSi into CoSi 2 is delayed on the 30-nm-wide polysilicon structures to such an extent that the CoSi 2 growth virtually stops. Only using nitrogen implantation through CoSi and a CoSi 2 formation temperature of 900°C, low sheet resistance values are obtained for 35-nm-wide polysilicon lines. Based on the results obtained in the present work, we propose that the abrupt increase in the CoSi 2 sheet resistance for the narrow polysilicon lines is a consequence of a decrease in the availability of nucleation sites leading to the reduction of the CoSi/CoSi 2 transformation rate, which, in turn, results in the agglomeration of Co suicide at elevated temperature. © 2004 American Institute of Physics.

Language: en

Keywords

Polycrystalline materials; Cobalt compounds; Ion implantation; Sheet resistance; Agglomeration; Nitrogen; Polysilicon; Phase transitions; Nucleation; Pyrolysis; Linewidth; Polysilicon lines; Silicon structures