AVS 51st International Symposium
    Thin Films Monday Sessions
       Session TF-MoM

Paper TF-MoM11
Radical-Enhanced Atomic Layer Deposition of Pure and Erbium-Doped Y@sub 2@O@sub 3@ Thin Films

Monday, November 15, 2004, 11:40 am, Room 303C

Session: ALD and Applications
Presenter: J.P. Chang, University of California, Los Angeles
Authors: T.T. Van, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
The deposition of pure and Er-doped yttrium oxide thin films, using radical-enhanced ALD (RE-ALD), was investigated in this work. Yttrium oxide can be used as a high dielectric constant material, or as a waveguide material due to its high refractive index and compatibility with high concentration doping of optically active Er@super 3+@ ions. The Y@sub 2@O@sub 3@ films were deposited on Si using alternating pulses of Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)yttrium(III) precursor, or Y(TMHD)@sub 3@, and O radicals. Erbium dopants were incorporated by introducing Er(TMHD)@sub 3@ after every ten ALD cycles of Y@sub 2@O@sub 3@. To assess the feasibility of RE-ALD, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to determine the chemical composition and distribution, crystallinity, surface morphology, and step coverage of the deposited films. Well-controlled RE-ALD of pure Y@sub 2@O@sub 3@ and Er@sub 2@O@sub 3@ were achieved with both precursors and O radicals. With reactant pulse time ratio of 1:1, stoichiometric films were deposited with minimal carbon incorporation. The ALD window for both materials ranged from 200 to 300°C. Above 300°C, the precursors decomposed, causing significant carbon incorporation into the films. AFM analysis yields a root mean square roughness of less than 5Å for films below 110Å. Conformal deposition of Y@sub 2@O@sub 3@ was achieved over 0.5-µm features with an aspect ratio of 4, determined by cross-sectional SEM. The Er@super 3+@ doping concentration was effectively controlled by varying the ratio of Y@sub 2@O@sub 3@:Er@sub 2@O@sub 3@ cycles. For example, up to 8 at.% of Er@super 3+@ concentration was achieved at 300°C with alternating 10 cycles of Y@sub 2@O@sub 3@ and 5 cycles of Er@sub 2@O@sub 3@. These results indicate that RE-ALD is a viable technique for doping and depositing metal oxide thin films.