METHOD AND DEVICE FOR MEASURING CONCENTRATION OF IMPURITY IN CVD MEMBRANE

摘要

PROBLEM TO BE SOLVED: To improve measurement accuracy by using a calibration curve created with membrane thickness, the concentration of impurities, and leaving time after the deposition of a CVD membrane as parameters and measuring leaving time after the formation of a CVD membrane, membrane thickness, and the concentration of impurities. SOLUTION: A measuring device is constituted of a light source 11, an interferometer 12, a sample chamber 13, a detector 14, and a computer 15. The infrared absorption spectrum of the sample chamber 13 to be reference is first measured. Next, approximately 15 types of samples each different in membrane thickness, P concentration, and B concentration with the conditions for forming CVD membranes changed, and their infrared absorption spectra are obtained. Furthermore, their infrared absorption spectra after leaving them, for example, for 30 min,, 60 min., 120 min., and 720 min. after the formation of each sample are obtained. The actual membrane thickness of the samples is measured by a light interference type membrane thickness measuring device, and the concentration of impurities is measured by an ICP. The values of measurement and the infrared absorption spectra are statistically analyzed by a PLS (Partial Leat Sqtares) method to obtain the relationship between the infrared spectra and B concentration, P concentration, membrane thickness, etc.