EVALUATING METHOD FOR SILICON CRYSTAL

PURPOSE:To make it possible to predict the deposition of oxygen when a crystal undergoes heat treatment for forming a device by observing the incorporating form of oxygen in the crystal as the differences in physical values such as the intensities of low temperature infrared-ray absorption which appear in a specified temperature region and a wave-number region. CONSTITUTION:The intensities of a plurality of infrared-ray peaks (the intensities of the height and the area of the peak) which appear in a wave-number region of 1,110-1,220cm at temperature of 100k or lower are measured with respect to a silicon crystal incorporating impurity oxygen. Then, at least the ratio of the two absorption peak intensities among said absorption peak intensities is obtained. Then, the heat history of the silicon crystal is obtained based on the calibrating data which are obtained for the absorption peak data and the heat history data with respect to a plurality of crystals whose heat histories are known. Or the ratio between the concentrations of impurity oxygens corresponding to at least two absorption peak intensities is obtained. In this way, prediction of the amount of oxygen deposition caused by heat treatment for forming a device can be performed for the crystal whose heat history is unknown. One of the important factors of the crystal characteristics can be judged before the crystal is inputted in processing.