Integrated endpoint detection system with optical and eddy current monitoring
AssigneeApplied Materials, Inc.
InventorsBoguslaw A. Swedek, Manoocher Birang, Nils Johansson
Life of this patent
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Abstract
A chemical mechanical polishing apparatus and method can use an eddy current monitoring system and an optical monitoring system. Signals from the monitoring systems can be combined on an output line and extracted by a computer. A thickness of a polishing pad can be calculated. The eddy current monitoring system and optical monitoring system can measure substantially the same location on the substrate.
Claims20
An apparatus for chemical mechanical polishing, comprising:
- a platen to support a polishing surface;
- an eddy current monitoring system positioned in the platen to generate a first signal;
- an optical monitoring system positioned in the platen to generate a second signal;
- circuitry in the platen to combine the first and second signals into a third signal on an output line;
- and
- a computer to receive the third signal on the output line and extract the first and second signals.
A method of determining the thickness of a polishing pad, comprising:
- positioning a substrate having a conductive layer disposed thereon in contact with a polishing surface of a polishing pad;
- generating an alternating magnetic field from an inductor to induce eddy currents in the conductive layer;
- measuring a strength of the magnetic field;
- and
- calculating a thickness of the polishing pad from at least the strength of the magnetic field.
A method of measuring a thickness of a conductive layer on a substrate during chemical mechanical polishing, comprising:
- positioning a substrate having a conductive layer disposed thereon in contact with a polishing surface of a polishing pad;
- creating relative motion between the substrate and the polishing pad to polish the substrate;
- driving an inductor with a drive signal to generate an alternating magnetic field that induces eddy currents in the conductive layer;
- measuring a strength of the magnetic field and a phase difference between the magnetic field and the drive signal;
- calculating a correction factor based on the strength of the magnetic field;
- and
- calculating a thickness of the conductive layer from the phase difference and the correction factor.
A chemical mechanical polishing apparatus, comprising:
- a polishing surface;
- a carrier head to hold a substrate having a conductive layer disposed thereon in contact with the polishing surface;
- a motor to create relative motion between the substrate and the polishing surface;
- an eddy current monitoring system including an inductor and a current source to drive the inductor to generate an alternating magnetic field that induces eddy currents in the conductive layer;
- a sensor to measure a strength of the magnetic field and a phase difference between the magnetic field and the drive signal;
- and
- a computer configured to calculate a correction factor based on the strength of the magnetic field and calculate a thickness of the conductive layer from the phase difference and the correction factor.
An apparatus for chemical mechanical polishing, comprising:
- a platen to support a polishing surface;
- a carrier head to hold a substrate;
- an eddy current monitoring system to generate a first signal during polishing, the eddy current monitoring system including an inductor to generate a magnetic field that extends to a first region of the substrate;
- an optical monitoring system positioned to generate a second signal during polishing, the optical monitoring system including a light source, the light source positioned and oriented to direct a light beam to a spot in the first region of the substrate so that the eddy current monitoring system and optical monitoring system measure substantially the same location on the substrate.
Dependencies are inferred from the claim text.