AVS 52nd International Symposium
    Electronic Materials and Processing Monday Sessions
       Session EM-MoM

Paper EM-MoM10
Surface Functionalization and Interface Characterization for HfO@sub 2@ Growth by Atomic Layer Deposition

Monday, October 31, 2005, 11:20 am, Room 309

Session: Electronic Properties of High-k Dielectrics and their Interfaces
Presenter: Y. Wang, Rutgers University
Authors: Y. Wang, Rutgers University
M.-T. Ho, Rutgers University
L.S. Wielunski, Rutgers University
L.V. Goncharova, Rutgers University
T. Gustafsson, Rutgers University
Y.J. Chabal, Rutgers University
N. Moumen, Sematech
M.P. Boleslawski, Aldrich Chemical Co.
Correspondent: Click to Email
Hafnium oxide is a promising candidate to replace SiO@sub 2@ and prevent current leakage in nanoscale transistors. For fabricating ultra-thin films, atomic layer deposition (ALD) is the preferred growth method. However, formation of interfacial SiO@sub 2@ during the ALD growth significantly increases the equivalent oxide thickness (EOT), partly negating the value of high-@kappa@ dielectrics. Our approach to minimizing interfacial SiO@sub 2@ formation during HfO@sub 2@ deposition is based on surface pretreatment of H-passivated silicon surfaces with Cl@sub 2@ and NH@sub 3@, followed by studies of the effect of post annealing on the nature of the interface. Using various surface/interface analytical techniques, such as in situ infrared spectroscopy, ex situ Rutherford back scattering spectroscopy (RBS) and medium energy ion scattering spectroscopy (MEIS), we have found that surface termination/passivation by hydrogen, chlorine, or silicon nitride can effectively prevent silicon oxidation during HfO@sub 2@ ALD growth, while fostering a linear growth of HfO@sub 2@ (~0.09 nm per ALD cycle). In situ IR studies show a linear incorporation of hydroxyl within the HfO@sub 2@ film during growth, constituting a source of excess oxygen within the film. Upon annealing above 400@super o@C, interfacial SiO@sub 2@ is formed as the hydroxyl content of the film decreases down to less than 10% of the initial value. The initially amorphous HfO@sub 2@ film begins to crystallize at 500@super o@C, as reflected in the appearance of a sharper HfO@sub 2@ phonon mode (~780 cm@super -1@) and in the angular dependence in the MEIS. Preliminary electrical properties measurement indicates the leakage current of the ALD-grown HfO@sub 2@ is small on the pre-functionalized silicon substrate.