Endpoint detector for a chemical mechanical polishing system
First Claim
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1. An endpoint detector for a chemical mechanical polishing apparatus having a polishing surface, a positioning member for positioning a substrate in contact with the polishing surface, and a motor for creating relative movement between the polishing surface and the substrate, comprising:
- a monitor to measure the power input to the motor and generate an output signal representing the power input;
an accumulator to sum the output signal over time; and
a comparator to compare the sum to a reference value to indicate when an endpoint condition has been reached.
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Abstract
An endpoint detector for a substrate polishing apparatus integrates a signal indicative of the instantaneous material removal rate from the substrate. The signal is generated by a monitor which measures a motor parameter such as torque or current draw. The resulting sum is compared to a baseline sum known to yield the desired polishing to predict the polishing endpoint.
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Citations
15 Claims
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1. An endpoint detector for a chemical mechanical polishing apparatus having a polishing surface, a positioning member for positioning a substrate in contact with the polishing surface, and a motor for creating relative movement between the polishing surface and the substrate, comprising:
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a monitor to measure the power input to the motor and generate an output signal representing the power input; an accumulator to sum the output signal over time; and a comparator to compare the sum to a reference value to indicate when an endpoint condition has been reached. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of determining the polishing endpoint of a substrate polished on a polishing surface, wherein the polishing surface and substrate are moved with respect to one another by a motor, comprising the steps of:
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summing a condition of the motor which is indicative of the frictional load on the motor; and comparing that sum to a reference value to detect a polishing endpoint. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. An endpoint detector for a chemical mechanical polishing apparatus having a polishing surface, a positioning member for positioning the substrate in contact with the polishing surface, and a plurality of motors for creating relative movement between the polishing surface and the substrate, comprising:
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a plurality of monitors for measuring a power input to each motor and generating a plurality of output signals representing the power input to each motor; an accumulator to receive the output signals and sum the output signals over time; and a comparator to compare the sum to a reference value and indicate an endpoint condition when the reference value has been reached.
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15. An endpoint detector for a chemical mechanical polishing apparatus having a polishing surface, a positioning member for positioning the substrate in contact with the polishing surface, and a motor for creating relative movement between the polishing surface and the substrate, comprising:
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a monitor for measuring a power input to the motor and generating an output signal representing the power input; and a processor to receive the output signal and sum it over time and to compare the sum to a reference value to indicate when an endpoint condition has been reached.
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Specification