Other

Anh The Ngo

Cuong Duy Le

A method and system for identifying thicknesses of inspection samples, such as semiconductor wafers is presented. The method and system includes a probe housing, comprising an eddy current sense coil and a linear motion controller, and a computer that controls the linear motion controller and the eddy current sense coil. The computer may be configured to identify a thickness of the inspection sample by a method comprising the generation of a natural intercepting curve based on resistance and reactance measurements of at least two data points. Then, a plurality of corresponding resistance and reactance measurements of a location on the inspection sample is obtained with the eddy current sensor, where the eddy current sensor makes a first measurement at a first distance from the inspection sample, and makes each of the remaining plurality of measurements at a distance that is incrementally further away from the inspection surface. Next, an inspection sample curve is generated based on the plurality of corresponding resistance and reactance measurements obtained from the inspection sample. An intersection point between the natural intercepting curve and the inspection sample curve is also generated. A vector impedance for each of the at least two data points, and the intersection point, is calculated to identify a closest two data points that the intersection point is positioned. Then, the thickness of the identified location of the inspection sample is calculated by performing an interpolation between the closest two data points.

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Anh The Ngo