Eddy current end-point detection device and method

Abstract

The invention discloses an eddy current end-point detection device comprises multiple resonant circuits connected in series, each resonant circuit generating a set frequency; a magnetic core, inductors of all the resonant circuits being wound around the magnetic core; according to a thickness threshold of a metal film, the corresponding resonant circuit being selected to generate a target frequency, which is applied to a surface of the metal film; a detection unit, configured to acquire first voltage signals of two terminals all the resonant circuits connected in series and second voltage signals of two terminals of any resonant circuits; and a processing unit, configured to calculate the thickness of the metal film according to the detection voltage signals acquired by the detection unit. The invention further discloses an eddy current end-point detection method.

1 . An eddy current end-point detection device, comprising:
 multiple resonant circuits connected in series, each resonant circuit generating a set frequency;   a magnetic core, inductors of all the resonant circuits being wound around the magnetic core;   according to a thickness threshold of a metal film, the corresponding resonant circuit being selected to generate a target frequency, the target frequency is applied to a surface of the metal film;   a detection unit, configured to acquire first voltage signals of two terminals of all the resonant circuits connected in series and second voltage signals of two terminals of any of the resonant circuits; and   a processing unit, calculates to acquire a thickness of the metal film according to detection voltage signals acquired by the detection unit.   
     
     
         2 . The eddy current end-point detection device according to  claim 1 , wherein the processing unit converts current amplitude and phase signals received by the detection unit into direct-current voltage signals and then performs analog-to-digital conversion to convert the direct-current voltage signals into film thickness signals corresponding to the metal film. 
     
     
         3 . The eddy current end-point detection device according to  claim 1 , wherein the processing unit performs differentiation on the first voltage signals and the second voltage signals to convert the first voltage signals and the second voltage signals into direct-current voltage signals and then performs analog-to-digital conversion to convert the direct-current voltage signals into the thickness of the corresponding metal film. 
     
     
         4 . The eddy current end-point detection device according to  claim 1 , wherein a resonant frequency generated by the resonant circuits is 0.1-3 MHz. 
     
     
         5 . An eddy current end-point detection method, comprising following steps:
 connecting multiple resonant circuits in series, and winding inductors of the multiple resonant circuits around a same magnetic core;   selecting a target frequency according to a current thickness threshold of a detected metal film;   selecting, according to the target frequency, the resonant circuit that outputs a set frequency, and applying the set frequency to a surface of the metal film;   acquiring, by a detection unit, first voltage signals of two terminals of all the resonant circuits connected in series and second voltage signals of two terminals of any of the resonant circuits; and   calculating, by a processing unit, a thickness of the metal film according to changes of detection voltage signals acquired by the detection unit.   
     
     
         6 . The eddy current end-point detection method according to  claim 5 , wherein the processing unit converts current amplitude and phase signals received by the detection unit into direct-current voltage signals and then performs analog-to-digital conversion to convert the direct-current voltage signals into film thickness signals corresponding to the metal film. 
     
     
         7 . The eddy current end-point detection method according to  claim 5 , wherein the processing unit performs differentiation on the first voltage signals and the second voltage signals to convert the first voltage signals and the second voltage signals into direct-current voltage signals and then performs analog-to-digital conversion to convert the direct-current voltage signals into the thickness of the corresponding metal film. 
     
     
         8 . The eddy current end-point detection method according to  claim 5 , wherein further comprising a following step: when the thickness of the metal film falls within a set threshold, selecting a target frequency, wherein the target frequency corresponds to the another resonant circuit. 
     
     
         9 . The eddy current end-point detection method according to  claim 5 , wherein when the thickness of the polished metal film exceeds a thickness detection range of the current target frequency, the current target frequency is switched to a target frequency corresponding to the thickness until the thickness of the metal film reaches a target thickness, and then the target frequency will not be changed.