Patent ID: 8037761

Claim:
A device for quantitatively evaluating atomic vacancy existing in a silicon wafer, which comprises: means for applying an external magnetic field to a silicon sample cut out from a given site of a silicon wafer, means for cooling the silicon sample to a temperature region of not higher than 50 K, means for oscillating an ultrasonic pulse to the surface of the silicon sample and propagating the oscillated ultrasonic pulse into the silicon sample and detecting a change of sound velocity in the propagated ultrasonic pulse, wherein a thin-film transducer having properties capable of following an expansion of the silicon sample associated with a temperature drop at the above temperature region and substantially aligning C-axis in a given direction is directly formed on the surface of the silicon sample; wherein the thin-film transducer has a C-axis inclined at an angle of 5-60° with respect to the surface of the silicon sample, and measures at least a transverse wave component among a vertical wave component and a transverse wave component propagated and detected in the silicon sample.