Patent ID: 9632061
Date: 2017-04-25
CPC Classifications: B24B,G01N,H01L

Claim:
1. An eddy current sensor disposed near a metal film or a conductive film formed on a substrate to detect an eddy current generated in the metal film or the conductive film, said eddy current sensor comprising: a plurality of detection coils comprising an inner detection coil and an outer detection coil spaced from each other, said outer detection coil being configured to surround said inner detection coil; and a plurality of exciting coils comprising an inner exciting coil and an outer exciting coil spaced from each other, said outer exciting coil being configured to surround said inner exciting coil; wherein said plurality of detection coils are configured to detect respective eddy currents generated in the metal film or the conductive film; and wherein each of said plurality of exciting coils is connected to an AC signal source and configured to generate an eddy current in the metal film or the conductive film.