EXPERIMENTAL METHOD TO DETERMINE AN ACCEPTABLE CONCENTRATION OF IRON IMPURITY IN HOT ZONE STRUCTURAL COMPONENTS

摘要

A technique has been developed to make measurements of iron, out diffusing from graphite parts, to lower ppbw range such as 0.002 ppbw. This method is based on the SPV method of measuring Fe in the silicon wafers exposed to samples of hot zone structural components. Not only this experimental method has been useful as an incoming quality control tool, but it has also has worked successfully as a quality assurance feedback to the crystal growth process. In addition, this technique has helped hot zone parts suppliers, in the development and improvement of purity of hot zone materials.