AVS 47th International Symposium
    Thin Films Monday Sessions
       Session TF-MoA

Paper TF-MoA1
The Effect of Atomic Layer CVD Flow Parameters on the Growth Orientation of AlN Thin Films

Monday, October 2, 2000, 2:00 pm, Room 203

Session: Atomic Layer Chemical Vapor Deposition II
Presenter: J.N. Kidder, University of Washington
Authors: J.N. Kidder, University of Washington
J.W. Rogers, University of Washington
T.P. Pearsall, University of Washington
Correspondent: Click to Email
We have observed a strong dependence of growth orientation on reactant pulse length in an atomic layer CVD of AlN. The AlN thin films were deposited on Al@sub2@O@sub3@ and Si substrates at 523-723 K and 25 Torr using an amine-alane Al source. The Al precursor, dimethylethylamine alane (DMEAA) and ammonia were delivered to the growth surface in separate steps. Strict self-limited adsorption did not occur for the DMEAA at these process conditions but a kinetic barrier to rapid decomposition of DMEAA coupled with process flow control provided a means to generate film formation through a sequence of adsorption/reaction steps. We observed that film microstructure was strongly dependent on ALCVD pulse lengths and substrate temperature. By this process, crystalline AlN films were deposited at temperatures as low as 573 K. AlN films deposited on Si(100), Si(111), Al@sub2@O@sub3@(00.1) tended to show a preferred orientation with the AlN{00.1} planes aligned parallel to the substrate surface. AlN{11.0}oriented growth was observed on Al@sub2@O@sub3@(01.2)substrates. The growth orientation was strongly dependent on the pulse length and substrate temperature. Both random and well-oriented films were deposited on Al@sub2@O@sub3@(00.1). By varying the reactant flow sequence the growth orientation on Al@sub2@O@sub3@(01.2) could be controlled to be either AlN{00.1} or AlN{11.0}oriented. X-ray four circle diffractometry scans showed in-plane orientations associated with epitaxial alignment for films deposited at temperatures as low as 673 K. These results illustrate the potential for using sequential reactant delivery in CVD to tailor the microstructure of thin film materials.