AVS 50th International Symposium
    Manufacturing Science and Technology Tuesday Sessions
       Session MS-TuP

Paper MS-TuP4
Progress toward Spatially Programmable CVD

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: J. Choo, University of Maryland
Authors: J. Choo, University of Maryland
L. Henn-Lecordier, University of Maryland
Y. Liu, University of Maryland
R.A. Adomaitis, University of Maryland
G.W. Rubloff, University of Maryland
Correspondent: Click to Email
A preliminary sequence of experimental tests performed to obtain engineering performance data for the Programmable CVD reactor system, together with simulation-based analysis of these data, will be described in this paper. The Programmable Reactor system was developed to improve across wafer sensing and control of reactant gas composition; to demonstrate this concept, a 3-segment prototype reactor was constructed by modifying a commercial tungsten CVD cluster tool. The key design features of the prototype system include a segmented showerhead assembly which allows control of precursor gas composition to each segment, a reversed flow of residual gas up through the showerhead to reduce inter-segment gas transport, and in-situ residual gas sampling tubes within each segment. These modifications constitute a major evolution in actuator and sampling capabilities relative to conventional CVD designs. To assess the ability of the prototype system to control gas composition across the wafer surface, a sequence of experiments was performed in which the spacing between the showerhead assembly and wafer surface was varied; pure Ar, WF6, and H2 was fed to each of the 3 segments in each test. Visual observations of the deposition patterns demonstrate sharp hexagonal deposition patterns corresponding to the shape of the showerhead segments for the close-spaced experiments; the pattern becomes more diffused as spacing is increased due to increased across-wafer diffusion. Surface resistance measurements reveal the thickest deposition directly under the WF6-fed segment and measurable deposition under Ar and H2 fed segments; simulation analysis of transport within the 1D segments will show that there is significant back-diffusion down each segment from a common exhaust volume, accounting for the observed deposition patterns.