An apparatus capable of determining the polarity of a piezoelectric cylindrical crystal or determining the front and back side depending on the polarization direction of the wafer as a crystalline body

摘要

PROBLEM TO BE SOLVED: To provide a crystal polarity determination device which determines polarity of a piezoelectric crystal.SOLUTION: A crystal polarity determination device 100 for determining front and rear sides dependent on a polarization direction of a wafer W made of a piezoelectric crystal includes: a vibration application unit 10 which applies vibration at a prescribed frequency to the wafer W; a voltage waveform detection unit 11 which detects a waveform of a voltage generated in accordance with the vibration at the prescribed frequency; and a crystal polarity determination unit 12 which determines front and rear sides of the wafer W on the basis of comparison of a phase difference &phgr; between the waveform of the vibration and the waveform of the voltage with a preliminarily registered reference phase difference &phgr;. The voltage waveform detection unit 11 detects the waveform of the voltage by using two electrodes 3aL and 3aR arranged at two positions in a peripheral edge of the wafer W, and an electrode axis 3X defined by the two electrodes 3aL and 3aR is not perpendicular to the polarization direction of the wafer.