AVS 53rd International Symposium
    Electronic Materials and Processing Friday Sessions
       Session EM+TF-FrM

Paper EM+TF-FrM9
Controlling Interfacial Reactions between HfO@sub 2@and Si using Ultra-Thin Diffusion Barriers

Friday, November 17, 2006, 10:40 am, Room 2003

Session: High-k Dielectric & Multi-Functional Oxide Growth & Processing
Presenter: R.R. Katamreddy, University of Illinois at Chicago
Authors: R.R. Katamreddy, University of Illinois at Chicago
R. Inman, American Air Liquide
G. Jursich, American Air Liquide
A. Soulet, American Air Liquide
C.G. Takoudis, University of Illinois at Chicago
Correspondent: Click to Email
Hafnium oxide has gained considerable interest in recent years as a potential high-k dielectric material for future fabrication of complementary metal oxide semiconductor devices. One of the problems with HfO@sub 2@ is its interfacial reactivity with Si at the high temperature necessary for post deposition annealing. Our previous studies have shown that HfO@sub 2@ films on Si form silicates and silicides at the interface as low as 600 °C and this is not suitable for CMOS process integration. In this study we examine the effectiveness of ultra-thin Al@sub 2@O@sub 3@ as a HfO@sub 2@-Si diffusion barrier up to 1000 °C. Al@sub 2@O@sub 3@ has superior interface stability with Si but it also has a lower dielectric constant than HfO@sub 2@. So, to minimize reduction in overall dielectric constant of the film with this barrier layer, there is a need to understand how thin the Al@sub 2@O@sub 3@ layer can be in this system and yet still maintain its effectiveness as a barrier. Our studies have shown 0.5 nm of alumina was sufficient to prevent formation of silicates and silicides of hafnium at temperatures below 1000 °C, while thicker alumina films were required to prevent the same at 1000 °C. The ultra-thin dual layer films are prepared by sequential atomic layer deposition of Al@sub 2@O@sub 3@ and HfO@sub 2@ using tetrakis(diethylamino)hafnium and tris(diethylamino)alane as the metal oxide precursors and water vapor as the oxidizer. Nitrides and oxynitrides of silicon are some other promising diffusion barriers. Silicon nitride and oxynitride are also investigated as potential barrier layers for HfO@sub 2@-Si. After deposition, the films are subjected to high temperature annealing up to 1000 °C and the extent of interfacial reactivity is examined using Fourier transformed infrared spectroscopy, x-ray photoelectron spectroscopy, and scanning transmission electron microscopy/electron energy loss spectroscopy. An explanation of the observed behavior is also proposed for these systems.