Eddy current monitoring system and data reduction protocol for Czochralski silicon crystal growth

Abstract

A computer controlled eddy current system for the in situ monitoring of Czochralski silicon crystal growth is introduced. A scheme to reduce eddy current sensor data to temperature values and thermal profiles in the growing crystal is presented. The principle of eddy current testing involves the behavior of electromagnetic radiation penetrating the silicon crystal and its subsequent reflection. This behavior is outlined by Maxwell's equations, and it is the solution of the electromagnetic field boundary-value problem that relates voltage measurements from the eddy current probe to the changing electrical conductivity of the crystal. Due to a strong temperature dependence of the electrical conductivity in solid silicon, it is then possible to determine thermal profiles within the growing crystal.