Porous Ultra Low K deposited by PECVD:
From deposition to material properties
V. Jousseaume1, L. Favennec2, A. Zenasni1, O. Gourhant2
1
2
CEA/LETI, 17 rue des Martyrs - 38054 Grenoble Cedex 9, France.
STMicroelectronics, 850 rue Jean Monnet - 38920 Crolles, France.
.
A new challenge for semiconductor industry is to reach low permittivity (k<2.4) required for
advanced microelectronic interconnections. Porosity introduction in an a-SiOCH matrix is the
main research field investigated. Several synthesis ways were used to deposit these a-SiOCH
layers by spin-coating: using a template approach, using a foaming technique or using
nanocluster silica precursors. In this work, the transfer of these different concepts by using
PECVD is discussed. A special attention concerns the porogen approach which consists on
the co-deposition of a matrix precursor and a sacrificial organic porogen followed by a posttreatment to remove the organic porogen phase and create porosity in the film. The impact of
deposition process and curing on basic film properties such as chemical composition and
skeleton crosslinking, dielectric constant, porosity, pore size and pore size distribution are
studied. The limits/differences of PECVD approaches in comparison to spin-coating ones are
discussed.