Flaw Detector and Flaw Detection Method For Silicon Layer of Wafer

The present invention is achieved for the purpose of easily detecting a crack or flaw existing in the silicon layer of a wafer in a short period of time. The flaw detector thus provided includes a coil sensor placed at a predetermined distance from the surface of the silicon layer; a radiofrequency applier for applying a radiofrequency to the coil sensor; a scanner for relatively moving the silicon layer and the coil sensor with a constant distance between the surface of the silicon layer and the coil sensor; and a crack detector for detecting a crack or flaw existing in the silicon layer by detecting the change of a signal provided from the coil sensor or the change in the radiofrequency applied by the radiofrequency applier. The frequency of the radiofrequency applied by the radiofrequency applier may be set between 5 MHz and 200 MHz. This enables a flaw detection for a silicon layer which has been considered to be impossible. In the case where the silicon to be flaw-detected is low resistivity silicon, the frequency applied may be set between 0.5 MHz and 200 MHz.