AVS 52nd International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM-TuP

Paper EM-TuP2
Production of a Hafnium Silicate Dielectric Layer For Use As a Gate Oxide by Solid-State Reaction

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Electronic Materials and Processing Poster Session
Presenter: H.T. Johnson-Steigelman, University of Wisconsin-Milwaukee
Authors: H.T. Johnson-Steigelman, University of Wisconsin-Milwaukee
S.S. Parihar, University of Wisconsin-Milwaukee
A.V. Brinck, University of Wisconsin-Milwaukee
P.F. Lyman, University of Wisconsin-Milwaukee
Correspondent: Click to Email
The formation of hafnium silicate films (HfSi@sub x@O@sub y@) for use as gate oxides with large dielectric constant by solid state reaction of Hf metal and high quality thermal oxide and native oxide SiO@sub 2@/Si(001) substrates was investigated using LEED, XPS, and AFM. Thin, fully reacted silicate films could be formed, and were thermally stable in vacuum to temperatures in excess of 800°C. Spectroscopic evidence indicates that the interface between a hafnium silicate layer and the silicon substrate was stable against SiO@sub 2@ formation. The observed binding energy (BE) shift provides evidence that the hafnium silicate/Si interface will be stable against interfacial SiO@sub 2@ formation (as predicted by Hubbard and Schlom@footnote 1@). The thermodynamic driving force for interfacial SiO@sub 2@ formation when most oxides are placed in contact with Si is the large heat of formation of the SiO@sub 2@ phase. While Si is rather electro-positive, Hf is even more electropositive, and HfO@sub 2@ has a higher heat of formation than does SiO@sub 2@. The shift of the Si oxide XPS feature to shallower BE indicates@footnote 2@ that Hf donates charge to the SiO@sub 2@ complexes in the newly formed silicate compound. This shift, therefore, corroborates that Hf is able to reduce SiO@sub 2@; conversely, Si will be unable to reduce HfO@sub 2@, and interfacial SiO@sub 2@ formation will be thermodynamically unfavorable. The morphology of the surface was determined by AFM to be smooth and featureless on the length scale of hundreds of nanometers. LEED results show the surface to be amorphous and free of pinholes. @FootnoteText@ @footnote 1@ K.J. Hubbard, D.G. Schlom: J. Mater. Res. 11, 2757 (1996).@footnote 2@ T.L. Barr: Crit. Rev. Anal. Chem. 22, 115 (1991).