A. Paccagnella, A.C. Callegari, et al.
Applied Physics Letters
Interface reactions in Si/SiO x(N y)/ZrO 2 and Si/SiO x(N y)/ZrO 2/poly-Si gate stacks have been studied by high-resolution transmission electron microscopy. In the case of an uncapped stack ZrSi and ZrSi 2 phases form during an ultrahigh vacuum anneal at temperatures above 900°C. Both phases show an island-type growth with an epitaxial relationship with Si (100). Gate dielectric stacks with a poly-Si cap are found to be thermally unstable at T=1000°C, so that the reaction is initiated at the ZrO 2/poly-Si interface. Here a different reaction mechanism is identified, which involves the reduction of ZrO 2 and the growth of a bottom interfacial layer between ZrO x and Si. Replacement of the bottom SiO 2 layer by an ultrathin Si oxinitride does not completely suppress these interfacial reactions at T≥1000°C. We suggest that control of the poly-Si/ZrO 2 interfacial reactions may be an important factor in modifying the thermal stability of a stack. These results shed a new light on understanding the material challenges involved in the integration of ZrO 2 for the next generation of complementary metal-oxide-semiconductor technologies. © 2002 American Institute of Physics.
A. Paccagnella, A.C. Callegari, et al.
Applied Physics Letters
Z. Ren, M.V. Fischetti, et al.
IEDM 2003
J.Z. Sun, W.J. Gallagher, et al.
Applied Physics Letters
D. Singh, P. Solomon, et al.
IEDM 2004