| 摘要 |
<p>Methods and apparatuses (20, 200, 250) are provided for calibrating eddy current sensors (214). A calibration curve is formed relating thickness of a conductive layer (205) in a magnetic field to a value measured by the eddy current sensors (214) or a value derived from such measurement, such as argument of impedance. The calibration curve may be an analytic function having infinite number terms, such as trigonometric, hyperbolic, and logarithmic, or a continuous plurality of functions, such as lines. Such curves can reduce the number of wafers used in the calibration of the sensors (214) while providing higher accuracy over a larger thickness range. High accuracy allows the omission of optical sensors, and use of eddy current sensors (214) for endpoint detection, transition call detection, and closed loop control in which a process parameter is changed based on the measured magnetic flux density change in one or more processing zones.</p> |
