Control of the Czochralski crystal growth process is presently limited by the absence of an adequate transfer-function model of growth dynamics. Such a model would allow the development of more efficient control algorithms, and would lead to increased production of high-quality crystals. It would also help to give a greater understanding of the mechanisms of the growth process under a variety of ambient conditions. The approach used in this paper is to fit a high-order difference equation to the measured crystal weight signal, while modulating the heater power by a deterministic signal. Low-order modelling techniques are then used to extract the dominant transfer-function terms which represent the dynamic crystal growth characteristics.
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