Other

Fang, Q,Zhang, JY,Wang, ZM,Wu, JX,O'Sullivan, BJ,Hurley, PK,Leedham, TL,Davies, H,Audier, MA,Jimenez, C,Senateur, JP,Boyd, IW

2003

March

Investigation of TiO2-doped HfO2 thin films deposited by photo-CVD

Validated

1

()

photo-CVD excimer lamp TiO2-doped HfO2 films high-k dielectrics CHEMICAL-VAPOR-DEPOSITION INJECTION LIQUID SOURCE DIELECTRIC-PROPERTIES PHASE-COMPOSITION PHOTOINDUCED CVD GATE DIELECTRICS OXIDES HAFNIA SUBSTITUTION ZIRCONIUM

TiO2-doped HfO2 thin films, as potential replacements for SiO2 as high-k gate dielectric material, have been grown by photo induced CVD using 222 nm excimer lamps at a temperature of 400 C. Vaporised titanium isopropoxide and hafnium (IV) tetrat-butoxide were used as the precursors. Films from approximately 45-70 nm in thickness with refractive indices from 1.850 to 2.424 were grown with various Ti:Hf ratios. The as-deposited films were found to be amorphous by X-ray diffraction when the Ti/(Ti+Hf) value was up to 33%, while the crystalline TiO2 anatase phase formed when the Ti/(Ti+Hf) was 41%. We also found that the refractive index increased sharply when the Ti/(Ti+Hf) was over 25%. Fourier transform infrared spectroscopy, XPS and TEM were also used to monitor as well as the presence of Ti, interface and microstructure of the films on Si-substrate. The effect of UV annealing on the electrical properties of these films will also be discussed. (C) 2002 Elsevier Science B.V. All rights reserved.

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PII S0040-6090(02)01221-X