Silicon ribbon growth dendrite thickness control system

摘要

A method and system for controlling the thickness of a pair of dendrites in a dendritic silicon web growth process to improve dendritic silicon web production. An image of each dendrite in a web emerging from a silicon melt in a furnace is produced by a pair of cameras focused on the dendrite pair. The dendrite images are digitized, the average thickness of the dendrites is calculated, and compared to set point parameters. The average difference between the dendrite thicknesses and the set point parameters is used to control the overall furnace temperature, while the differences between the thickness of each pair are used to control the lateral temperature distribution in the furnace in order to maintain the dendrite thickness within predetermined limits. The method can be used in a closed loop configuration to automatically control the furnace temperature and lateral temperature distribution; or in an open loop configuration to provide visible feedback information to an operator who manually adjusts the furnace temperature conditions.