| 摘要 |
The present invention provides a method for monitoring a change in thickness of a conductive film brought into sliding contact with a polishing surface of a polishing pad using an eddy current sensor. The output signal of the eddy current sensor comprises two signals corresponding to a resistance component and an inductive reactance component of an impedance of an electric circuit including a coil of the eddy current sensor. The method includes acquiring the output signal of the eddy current sensor when the eddy current sensor is facing the conductive film, defining the two signals as coordinates on a coordinate system, repeating the acquiring of the output signal and the defining of the coordinates, determining a center of curvature of an arc specified by at least three sets of coordinates on the coordinate system, determining an angle of inclination of a line connecting the center of curvature and a latest one of the at least three sets of coordinates, and monitoring a change in thickness of the conductive film by monitoring a change in the angle of inclination. |
