AVS 50th International Symposium
    Applied Surface Science Wednesday Sessions
       Session AS-WeM

Paper AS-WeM4
High-k Al@sub 2@O@sub 3@-HfO@sub 2@ Layers for CMOS Applications Studied by XPS and ToF-SIMS

Wednesday, November 5, 2003, 9:20 am, Room 324/325

Session: High-K Materials Interface Analysis
Presenter: R.G. Vitchev, Facultes Universitaires Notre-Dame de la Paix, Belgium
Authors: R.G. Vitchev, Facultes Universitaires Notre-Dame de la Paix, Belgium
L. Houssiau, Facultes Universitaires Notre-Dame de la Paix, Belgium
J.J. Pireaux, Facultes Universitaires Notre-Dame de la Paix, Belgium
Correspondent: Click to Email
High-k metallic oxides are considered as promising candidates to replace SiO@sub2@ as a gate dielectric in the future CMOS devices. Al@sub 2@O@sub 3@-HfO@sub 2@ mixed oxide layers deposited by Atomic Layer Chemical Vapor Deposition on differently pretreated silicon wafers (0.5 nm and 1 nm SiO@sub 2@ grown by rapid thermal oxidation as well as HF-last Si surface) were characterized by single- and two emission angle XPS and by ToF-SIMS dual beam depth profiling (250 eV Xe@super +@ and Cs@super +@ sputtering beam, 15 keV Ga@super +@ analysis beam). The composition and the depth distribution of constituent elements were measured for mixed oxide layers deposited with different number of cycles (and hence with different thickness) and different Hf/Al cycle ratios. It was found that the Hf/Al content ratio for the thinnest films was much higher than for the thicker films with the same cycle ratio. The surface region of the thicker films was enriched in Al (and depleted in Hf) indicating a preferential deposition of HfO@sub 2@ at the film/silicon interface. The depth distribution of impurities was also measured and compared. The interfacial SiO@sub 2@ layer thickness was determined as well as the oxidation state of Si atoms in it. Changes of the interfacial SiO@sub 2@ layer thickness and chemistry after prolonged air exposure were followed. Work performed under EU-CUHKO project.