AVS 49th International Symposium
    Applied Surface Science Wednesday Sessions
       Session AS-WeM

Paper AS-WeM6
Titanium Dioxide Thin Film Growth on Si(111) by Chemical Vapor Deposition of Titanium(IV) Isopropoxide

Wednesday, November 6, 2002, 10:00 am, Room C-106

Session: Optical Methods and High-k Dielectrics Characterization
Presenter: A. Sandell, Uppsala University, Sweden
Authors: A. Sandell, Uppsala University, Sweden
M.P. Andersson, Lund University, Sweden
Y. Alfredsson, Uppsala University, Sweden
M.K.-J. Johansson, Lund University, Sweden
J. Schnadt, Uppsala University, Sweden
H. Rensmo, Uppsala University, Sweden
H. Siegbahn, Uppsala University, Sweden
P. Uvdal, Lund University, Sweden
Correspondent: Click to Email
Due to its high dielectric constant, TiO@sub 2@ has been considered as a gate insulator material in Si-based MOSFETs, either in pure form or mixed with other compounds. In this contribution, I present a study of the initial stages of TiO@sub 2@ growth on Si(111)-(7x7) under ultra-high vacuum conditions using core level photoelectron spectroscopy (PES), x-ray absorption spectroscopy (XAS) and scanning tunneling microscopy (STM). The TiO@sub 2@ film was formed by means of chemical vapor deposition of titani um(IV) isopropoxide at a sample temperature of 500 C. The thickness and composition of the amorphous interface layer and its subsequent transition to crystalline anatase TiO@sub 2@ are discussed. Three different stages are identified: In the initial stag e (film thickness <1 nm), the oxygen atoms are coordinated mainly to Si atoms giving rise to Ti atoms with oxidation states lower than 4+. The next stage (<3 nm) is best described as an amorphous TiSi@sub x@O@sub y@ compound in which the oxidation state o f Ti is 4+ and the x and y values vary monotonically with the film thickness. Finally (>3 nm) a stoichiometric TiO@sub 2@ layer starts to form. The TiO@sub 2@ phase is anatase and the layer consists of largely equidimensional particles, approximately 10 nm wide. In addition, I will also broach the differences that occur upon lowering the growth temperature to 300 C and how the properties of the film can be altered by pre-oxidation of the Si(111)-(7x7) surface.