ECMP system
First Claim
1. A method of IR correction for use in an ECMP cell having, within an electrolyte, at least a working electrode, a counter electrode, and a reference electrode adjacent to the working electrode, the method comprising:
- measuring a voltage transient between the reference electrode and the working electrode resulting from application of a substantially square step function test signal to the ECMP cell;
deriving from the voltage transient a measure of the resistive impedance of the ECMP circuit between and including the working electrode and the reference electrode; and
subsequently using the measure of resistive impedance to derive an IR correction to the measured voltage between the working electrode and the reference electrode.
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Accused Products
Abstract
An improved electrochemical IR calculation and correction system allows for the precise measurement and control of the interfacial voltage drop at an electrode double layer. In an exemplary use of the invention, this improved IR correction ability allows ECMP to be used for precise surface polishing that would otherwise be impractical with ECMP. The system according to an embodiment of the invention comprises a working electrode, a counter electrode, and a reference electrode. An electrical perturbation is applied to the system and a unique IR calculation circuit is used to determine the IR drop. In an embodiment of the invention applicable to ECMP, an IR correction is provided such that the polishing at the surface of interest is precisely controlled despite the IR drop in the system.
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Citations
27 Claims
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1. A method of IR correction for use in an ECMP cell having, within an electrolyte, at least a working electrode, a counter electrode, and a reference electrode adjacent to the working electrode, the method comprising:
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measuring a voltage transient between the reference electrode and the working electrode resulting from application of a substantially square step function test signal to the ECMP cell;
deriving from the voltage transient a measure of the resistive impedance of the ECMP circuit between and including the working electrode and the reference electrode; and
subsequently using the measure of resistive impedance to derive an IR correction to the measured voltage between the working electrode and the reference electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A computer-readable medium having stored thereon computer-executable instructions for performing a method of IR correction for use in an ECMP cell having, within an electrolyte, at least a working electrode, a counter electrode, and a reference electrode adjacent to the working electrode, the method comprising:
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measuring a voltage transient between the reference electrode and the working electrode resulting from application of a substantially square step function test signal to the ECMP cell;
deriving from the voltage transient a measure of the resistive impedance of the ECMP circuit between and including the working electrode and the reference electrode; and
subsequently using the measure of resistive impedance to derive an IR correction to the measured voltage between the working electrode and the reference electrode. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. An IR corrected ECMP system comprising:
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an ECMP cell comprising a working electrode, a counter electrode, a reference electrode, and an electrolyte, each of the electrodes being in contact with the electrolyte;
a potentiostat for supplying current and voltage to the ECMP cell via the counter electrode to accomplish a polishing process, the potentiostat having an input and an output;
a current limiter placed in series between the potentiostat output and the counter electrode to current limit a signal at the potentiostat output prior to application of the signal to the counter electrode; and
an IR correction circuit for calculating an unwanted IR contribution to a voltage drop between the reference electrode and the working electrode by causing the potentiostat to emit one or more transient current spikes that are limited by the current limiter to form a substantially square current step function to be applied to the counter electrode, and observing the transient response of the voltage between the reference electrode and the working electrode. - View Dependent Claims (20, 21, 22)
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23. A method of IR correction for use in an electrochemical cell having, within an electrolyte, at least a working electrode, a counter electrode, and a reference electrode adjacent to the working electrode, the method comprising:
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applying a substantially square step function test signal to the electrochemical cell;
measuring a voltage transient between the reference electrode and the working electrode resulting from the application of the test signal, the test signal having a start point, wherein the measurement of the voltage transient comprises measuring the voltage between the reference electrode and the working electrode at three times prior to the test signal start point and at three times subsequent to the test signal start point;
deriving an extrapolated time-based voltage curve based on the measurements taken subsequent to the test signal start point;
deriving from the time-based voltage curve a measure of the resistive impedance of the electrochemical cell circuit between and including the working electrode and the reference electrode; and
subsequently using the measure of resistive impedance to derive an IR correction to the measured voltage between the working electrode and the reference electrode. - View Dependent Claims (24, 25, 26, 27)
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Specification