IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Dielectrics Monday Sessions
       Session DI-MoA

Paper DI-MoA6
Interfacial Stability of High-k Dielectrics Deposited by Atomic Layer Chemical Vapor Deposition

Monday, October 29, 2001, 3:40 pm, Room 130

Session: High K Dielectrics I
Presenter: W. Tsai, IMEC (Intel assignee), Belgium
Authors: W. Tsai, IMEC (Intel assignee), Belgium
H. Nohira, IMEC, Belgium
R. Carter, IMEC, Belgium
M. Caymax, IMEC, Belgium
T. Conard, IMEC, Belgium
S. De Gendt, IMEC, Belgium
M.M. Heyns, IMEC, Belgium
J. Petry, IMEC, Belgium
O. Richard, IMEC, Belgium
W. Vandervorst, IMEC, Belgium
E. Young, IMEC, Belgium
C. Zhao, IMEC, Belgium
J. Maes, ASM Europe, The Netherlands
M. Tuominen, ASM Europe, The Netherlands
Correspondent: Click to Email
Control of interfacial oxide growth is critical to achieving sub 1 nm Equivalent Oxide Thickness in high k gate stacks for future generations microelectronic devices. The formation of interfacial oxide is dependent on Si surface preparations, high k dielectrics deposition, post deposition conditioning such as thermal anneal and air exposure. In this work, effect of various interfaces on initial growth of high k layers, interface stability and electrical peformance were investigated. High-k dielectrics layers are grown by Atomic Layer Chemical Vapor Deposition (ALCVD), dielectrics and interfacial layer thickness /composition were characterized by X-ray Fluorescence, X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). An initial high k dielectrics layer formation with inhibited growth was observed for both ALCVD Al2O3 and ZrO2 films, followed by a linear growth regime with a full coverage layer. For high k dielectrics deposited on Si substrates with hydrogen termination from HF dip, growth of interfacial oxide SiOx was quantified as a function of air exposure. Interfacial oxide forms due to oxygen permeation through the high k layers, either during air exposure; during thermal anneal in an oxygen ambient (>500oC) or during the ALCVD growth itself whereby the growth process itself acts as an oxygen source. The latter is observed in the case of ZrO2 where the interfacial oxide scales with ZrO2 layer thickness. In addition, an intrinsic interfacial oxide growth is observed with XPS from as-deposited high k dielectrics films. For Al2O3, an interfacial oxide of approx. 1.5 Ã… for thickness > 2 nm, reflecting the possible formation of Al-O-Si bond. Minimization of interfacial oxide growth in high k gate stacks was demonstrated with an in-situ poly-silicon cap on Al2O3 to restrict the oxygen diffusion. The stability of such capped high k/ Si interface was also shown to be intact after 1000oC RTP anneal in nitrogen.