AVS 49th International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuA

Paper TF-TuA10
Room Temperature NH@sub 3@-Catalyzed SiO@sub 2@ Atomic Layer Deposition Using Sequential Exposures of TEOS and H@sub 2@O

Tuesday, November 5, 2002, 5:00 pm, Room C-101

Session: Atomic Layer Deposition - Oxides
Presenter: J.D. Ferguson, University of Colorado
Authors: J.D. Ferguson, University of Colorado
S.M. George, University of Colorado
Correspondent: Click to Email
The atomic layer deposition of SiO@sub 2@ has employed SiCl@sub 4@ and H@sub 2@O and required high temperatures and long exposure times. Amine catalysts have been shown to reduce the exposure lengths, lower the growth temperature to 300 K and increase the SiO@sub 2@ growth rate. However, the reaction product, HCl, readily reacts with the amine catalysts to form a salt. The salt formation problem can be avoided using organometallic silicon precursors. NH@sub 3@-catalyzed SiO@sub 2@ ALD was accomplished using tetraethoxysilane (TEOS) based upon the following AB reaction sequence: A) SiOH* + Si(OCH@sub 2@CH@sub 3@)@sub 4@ --> SiOSi(OCH@sub 2@CH@sub 3@)@sub 3@* + CH@sub 3@CH@sub 2@OH B) Si(OCH@sub 2@CH@sub 3@)* + H@sub 2@O --> SiOH* + CH@sub 3@CH@sub 2@OH SiO@sub 2@ films were grown on high surface area ZrO@sub 2@ and BaTiO@sub 3@ particles using alternating exposures of TEOS and H@sub 2@O at 300 K with NH@sub 3@ as the catalyst. The sequential surface chemistry was monitored in a vacuum chamber using in situ transmission FTIR spectroscopy. The particles initially contained OH* surface species that were converted to Si(OCH@sub 2@CH@sub 3@)@sub x@* species by the first TEOS/NH@sub 3@ exposure. The subsequent H@sub 2@O/NH@sub 3@ exposure converted the Si(OCH@sub 2@CH@sub 3@)* species to SiOH* species. Alternating TEOS/NH@sub 3@ and H@sub 2@O/NH@sub 3@ exposures yielded Si(OCH@sub 2@CH@sub 3@)@sub x@* and SiOH* species, respectively, that sequentially deposit silicon and oxygen with atomic layer control. The repetition of the TEOS and H@sub 2@O exposures in an ABAB... reaction sequence led to the appearance of bulk SiO@sub 2@ vibrational modes that increased with the number of AB reaction cycles. After SiO@sub 2@ deposition, the ZrO@sub 2@ and BaTiO@sub 3@ particles were examined using transmission electron microscopy (TEM). The TEM images revealed extremely uniform and conformal SiO@sub 2@ films on both types of particles and growth rates of ~0.7 Å per AB cycle.