AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS2+EM-TuA

Paper SS2+EM-TuA8
Novel Mechanisms for Plasma Etch Front and CVD (Chemical Vapor Deposition) Growth Front Roughening

Tuesday, October 26, 1999, 4:20 pm, Room 6C

Session: Semiconductor Surface Chemistry
Presenter: Y.-P. Zhao, Rensselaer Polytechnic Institute
Authors: Y.-P. Zhao, Rensselaer Polytechnic Institute
J.T. Drotar, Rensselaer Polytechnic Institute
G.-C. Wang, Rensselaer Polytechnic Institute
T.-M. Lu, Rensselaer Polytechnic Institute
Correspondent: Click to Email
Plasma etching and chemical vapor deposition (CVD) are major tools for thin film processing in microelectronic industry. Although kinetic roughening of thin films has attracted considerable attention in recent years, very little work has been focused on the study of surface roughening mechanisms during plasma etching and chemical vapor deposition. Here, we report a novel etch front roughening phenomenon during the plasma etching of Si(100) substrates. The surface power spectrum shows an obvious wavelength selection which does not occur in conventional noise-induced roughening. The average local surface slope is almost invariant while the vertical roughness grows as a power law in time, w ~ t^@beta@, with a growth exponent @beta@ = 0.91 ± 0.03. We develop a general non-local model to describe the roughening process in plasma etching based on the gas transport kinetics for a large Knudsen number. The flux of the reactive particles redistributes according to the re-emission mechanisms that are influenced by the surrounding morphology. Our extensive numerical calculations and Monte Carlo simulations for various re-emission modes show that @alpha@ (roughness exponent) ~ @beta@ ~ z ~ 1 for plasma etching, which is consistent with our experimental results. Our calculations demonstrate that the proposed model is universal in describing the roughening of plasma etching. In addition, the reverse of this model can be used to describe CVD growth. Our Monte Carlo simulations show that @alpha@ ~ @beta@ ~ 0, z ~ 2 for CVD growth. Detailed comparisons between local and non-local dynamic growth models, as well as the growth and etching processes will also be presented. @FootnoteText@ Work supported by NSF.