AVS 50th International Symposium
    Thin Films Monday Sessions
       Session TF-MoM

Paper TF-MoM11
Atomic Layer Deposition on Fine Particles

Monday, November 3, 2003, 11:40 am, Room 329

Session: Atomic Layer Deposition
Presenter: S.M. George, University of Colorado
Authors: J.D. Ferguson, University of Colorado
A.W. Weimer, University of Colorado
S.M. George, University of Colorado
Correspondent: Click to Email
Because of the self-limiting nature of the sequential surface reactions in atomic layer deposition (ALD), atomic layer controlled and conformal films can be deposited on fine particles. Our recent work has investigated coatings on BaTiO@sub 3@ particles that are used to fabricate multilayer capacitors. SiO@sub 2@ has been coated on BaTiO@sub 3@ particles using NH@sub 3@-catalyzed SiO@sub 2@ ALD with tetraethoxysilane (TEOS) and H@sub 2@O as the reactants. ZnO has been coated on BaTiO@sub 3@ particles using ZnO ALD with diethylzinc (DEZ) and H@sub 2@O as the reactants. The ALD surface chemistry has been investigated using Fourier transform infrared (FTIR) spectroscopy. The FTIR studies observe the exchange of surface species as expected from the surface chemistry. In addition, the growth of the bulk SiO@sub 2@ and ZnO films versus number of reactant cycles is also observed in the FTIR spectra. Further confirmation of the SiO@sub 2@ ALD and ZnO ALD is obtained from transmission electron microscopy (TEM) analysis of the BaTiO@sub 3@ particles. The TEM analysis reveals conformal SiO@sub 2@ films with a SiO@sub 2@ growth rate of 0.7 Å per TEOS/H@sub 2@O reaction cycle at 300 K. TEM measurements also observe conformal ZnO films with a ZnO growth rate of 2.2 Å per DEZ/H@sub 2@O reaction cycle at 450 K. Additional FTIR and TEM studies have explored Al@sub 2@O@sub 3@ ALD on polyethylene (PE) particles at 350 K using trimethylaluminum (TMA) and H@sub 2@O as the reactants. The deposition of inorganic oxides on polymers may be important as gas diffusion barriers for packaging applications. The FTIR investigations observe the exchange of surface species during Al@sub 2@O@sub 3@ ALD and the growth of Al@sub 2@O@sub 3@ bulk features. The TEM measurements reveal a conformal Al@sub 2@O@sub 3@ film on the surface of the PE particles. ALD on large quantities of fine particles will be demonstrated using fluidized particle bed ALD reactors.