We have characterized metal-oxide-semiconductor capacitors fabricated on SF6 and SF6 + C2CIF5 reactive ion etched silicon in order to study the resulting defects at the SiSiO2 interface and in the bulk of the silicon substrate. We have used the C-V, DLTS and admittance spectroscopy techniques. The RIE induced damage reveals itself by the presence of positive charge in the oxide, by interfacial states and by two deep levels located at 300 and 335 meV above the valence band and probably related to the fluorine atoms. We have studied the effect of the chamber pressure and the plasma composition on the resulting damage. This damage turns out to be more important when the chamber pressure is low because of the higher mean free path of the plasma ions. In the case of SF6 + C2CIF5 plasma, when the C2CIF5 concentration is increased the densities of the deep levels decrease while the positive charge in the oxide and the density of interface states increase; on the other hand, the profiles of the interface states exhibit a maximum located at midgap in silicon, and is probably related to the carbon atoms. Finally, we have shown that a post-RIE thermal annealing can be used to recover partially the damaged structures. © 1993.
|Journal||Nuclear Inst. and Methods in Physics Research, B|
|Issue number||PART 2|
|Publication status||Published - 1 Jan 1993|