METHOD FOR EVALUATING OXYGEN PRECIPITATION DEFECT DENSITY OF SILICON WATER

摘要

PURPOSE: To grasp an oxygen precipitation defect (BMD) density in a silicon wafer in which a high density BMD has occurred, accurately through a convenient method. CONSTITUTION: A large number of silicon wafers having BMD are prepared and the minority carrier diffusion length thereof is measured by SPV method. The BMD density is also measured by infrared tomography. The measurements are distributed substantially along a line B, as shown on the drawing, which implies a relationship between the minority carrier diffusion length and the BMD density obtained by infrared tomography. A constant A is determined from the drawing. The minority carrier diffusion length L of an objective wafer is measured by SPV method and expressed in terms of the BMD density using a formula A×L<-2> . This method can determine the BMD density accurately in a short time. Since the objective wafer is not cleft, in-plane distribution of the BMD density can also be determined easily.