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The crystallinity and wet etching behaviors of ultrathin (<10 nm) HfO2 films grown by metal organic chemical vapor deposition (MOCVD) were examined as a function of deposition temperature, film thickness, and post-deposition annealing. Films 3 nm in thickness deposited at 400 or 500 oC were amorphous as-deposited and slowly etchable in aqueous HF; after annealing at 700 oC, the same films showed some nanocrystallinity and were impervious to HF. However, thicker films grown under the same conditions showed significant crystallinity and were impervious to HF even as-deposited. These observations, in combination with measurements on various samples etched back by an Ar+ ion damage/wet etch process, suggest a film structure comprising an initially amorphous near-interface region capped with a HF-resistant crystalline upper layer. It was found that the initially amorphous near-interface region (the bottom 1-3 nm) of films grown at 500 oC can be induced to at least partially crystallize as the upper part of the film starts becoming crystalline as-deposited, but that this near-interface region remains at least partially amorphous after annealing at 700 oC.
By: Katherine L. Saenger, Cyril Cabral, Jr., Paul C. Jamison, Edward Preisler, Andrew J. Kellock
Published in: MRS Symposia Proceedings Series, volume 786, (no ), pages 153-8 in 2004
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