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Proceedings Paper

Process Modeling With Inhomogeneous Thin Films
Author(s): R Machorro; H A Macleod; M R Jacobson
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Paper Abstract

Designers of optical multilayer coatings commonly assume that the individual layers will be ideally homogeneous and isotropic. In practice, it is very difficult to control the conditions involved in the complex evaporation process sufficiently to produce such ideal films. Clearly, changes in process parameters, such as evaporation rate, chamber pressure, and substrate temperature, affect the microstructure of the growing film, frequently producing inhomogeneity in structure or composition. In many cases, these effects are interdependent, further complicating the situation. However, this process can be simulated on powerful, interactive, and accessible microcomputers. In this work, we present such a model and apply it to estimate the influence of an inhomogeneous layer on multilayer performance. Presently, the program simulates film growth, thermal expansion and contraction, and thickness monitoring procedures, and includes the effects of uncertainty in these parameters or noise. Although the model is being developed to cover very general cases, we restrict the present discussion to isotropic and nondispersive quarterwave layers to understand the particular effects of inhomogeneity. We studied several coating designs and related results and tolerances to variations in evaporation conditions. The model is composed of several modular subprograms, is written in Fortran, and is executed on an IBM-PC with 640 K of memory. The results can be presented in graphic form on a monochrome monitor. We are currently installing and implementing color capability to improve the clarity of the multidimensional output.

Paper Details

Date Published: 23 December 1986
PDF: 10 pages
Proc. SPIE 0678, Optical Thin Films II: New Developments, (23 December 1986); doi: 10.1117/12.939542
Show Author Affiliations
R Machorro, University of Arizona (United States)
H A Macleod, University of Arizona (United States)
M R Jacobson, University of Arizona (United States)

Published in SPIE Proceedings Vol. 0678:
Optical Thin Films II: New Developments
Richard Ian Seddon, Editor(s)

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