Control and System Design for the Czochralski Crystal Growth Process

Abstract

An expanded set of control objectives is proposed for the Czochralski crystal growth process. Consideration of the thermal stress near the interface yields an operating regime specification in terms of interface shape. A lumped parameter model is used to determine the performance of alternate inputs and outputs. Based on these considerations, a new control structure is proposed to maintain crystal diameter, interface shape, and thermal gradients throughout the batch growth cycle. The performance of alternative control structures are evaluated.