Nonlinear model-based control of the Czochralski process IV: Feedforward control and its interpretation from the crystal grower's view

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

Abstract

The paper proposes a model-based feedforward control for the Czochralski crystal growth process. It completes the system for nonlinear model-based control presented by the authors in previous publications. From a system theoretical point of view such a feedforward control requires a dynamic lumped parameter model of the hydrodynamical–geometrical as well as of the thermal subsystem of the process. For the heater feedforward control one lacks the latter one with the necessary accuracy. A static approach circumventing this problem is presented here, based on a mathematical description regarding the most important qualitative dependencies between relative changes of manipulated and controlled variables during growth. In combination with feedback control, high precision tracking of the most important system variables, crystal diameter and crystal growth rate, is ensured. Additionally, a comprehensive discussion of the dependencies of the heater feedforward control on technological parameters, growth regimes and crystal shapes is given

Details

Original languageGerman
Pages (from-to)210-222
Number of pages12
JournalJournal of Crystal Growth
Publication statusPublished - 2014
Peer-reviewedYes

External IDs

Scopus 84905976295