AVS 45th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoA

Paper TF-MoA1
Computer Simulation Modeling of Sculptured Thin Films

Monday, November 2, 1998, 2:00 pm, Room 310

Session: Mechanical Properties of Thin Films
Presenter: V.C. Venugopal, Pennsylvania State University
Authors: V.C. Venugopal, Pennsylvania State University
R. Messier, Pennsylvania State University
Correspondent: Click to Email
Sculptured Thin Films (STFs) are characterized by free standing columns whose shape can be engineered as desired. Films with S-shaped, C-shaped, helicoidal or chevronic columns have been grown. Low adatom mobility and self-shadowing effects are critical for the growth of such films. To aid characterization of STFs theoretically, the growth of STFs is simulated using a simple ballistic aggregation deposition model assuming a high sticking coefficient, negligible relaxations, and low substrate temperatures. Substrate manipulations and complex substrate topographies are investigated. Clustering is found at the 1-3 nm level and is related to the larger column sizes which result from competitive growth evolution. A 3-D model of a growing STF is built up. The model structures are directly correlated to our experimental results in the relations between the incoming vapor angle @chi@@sub v@, and the resulting morphology column angle @chi@@sub m@. The final simulated structure is being used to develop mechanical models of STFs. Mechanical strength and elastic moduli can be determined at several different continuum levels and verified experimentally to develop a reliable model. Residual stress fields and other mechanical characteristics can also be studied. Using acoustic wave propagation principles, the maximum theoretical strength of these films can be determined and verified experimentally. Initial results of such models developed are presented.