| 摘要 |
PURPOSE:To determine the damage strength effectively, by measuring the lifetime at a corresponding point on the surface and back of a wafer after the wafer with a distortion on the back undergoes an oxidation processing. CONSTITUTION:After the oxidation heat treatment of a wafer, the lifetime at a corresponding point of the surface and back of the wafer is measured with a laser light and a microwave in combination of the irradiating direction. As a result, there is a difference generated in the lifetime between the surface and the back and the difference changes corresponding to variations in the damage strength. Thus, the damage strength can be obtained from the ratio of the lifetime by previously determining the relationship between the ratio of the lifetime and the damage strength. Moreover, this allows the surface and back of the same wafer to be used for the measurement of the lifetime, thereby eliminating the need for preparing other wafers the same in the kind as that to be measured.
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