Endpoint detection with light beams of different wavelengths
AssigneeApplied Materials, Inc.
InventorsBoguslaw Swedek, Andreas Norbert Wiswesser
Life of this patent
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Abstract
A chemical mechanical polishing apparatus includes two optical systems which are used serially to determine polishing endpoints. The first optical system includes a first light source to generate a first light beam which impinges on a surface of the substrate, and a first sensor to measure light reflected from the surface of the substrate to generate a measured first interference signal. The second optical system includes a second light source to generate a second light beam which impinges on a surface of the substrate and a second sensor to measure light reflected from the surface of the substrate to generate a measured second interference signal. The second light beam has a wavelength different from the first light beam.
Claims22
A chemical mechanical polishing apparatus to polish a substrate having a first surface and a second surface underlying the first surface, comprising:
- a first polishing station having a first optical system, the first optical system including a first light source to generate a first light beam to impinge the substrate as it is polished at the first polishing station, the first light beam having a first effective wavelength, and a first sensor to measure light from the first light beam that is reflected from the first and second surfaces to generate a first interference signal;
- and
- a second polishing station having a second optical system, the second optical system including a second light source to generate a second light beam to impinge on the substrate as it is polished at the second polishing station, the second light beam having a second effective wavelength that differs from the first effective wavelength, and a second sensor to measure light from the second light beam that is reflected from the first and second surfaces to generate a second interference signal;
- and
- at least one processor to determine a polishing endpoint at the first and second polishing stations from the first and second interference signals, respectively.
A method of chemical mechanical polishing, comprising:
- polishing a substrate at a first polishing station;
- generating a first interference signal by directing a first light beam having a first effective wavelength onto the substrate and measuring light from the first light beam reflected from the substrate;
- detecting a first endpoint from the first interference signal;
- after detection of the first endpoint, generating a second interference signal by directing a second light beam having a second effective wavelength onto the substrate and measuring light from the second light beam reflected from the substrate, wherein the second effective wavelength differs from the first effective wavelength;
- and
- detecting a second endpoint from the second interference signal.
A method of chemical mechanical polishing, comprising:
- polishing a first portion of a layer of a substrate;
- while polishing the first portion, generating a first interference signal by directing a first light beam having a first effective wavelength and measuring light from the first light beam reflected from the substrate;
- detecting a first intermediate polishing point from the first interference signal;
- after detection of the first intermediate polishing point, polishing a second portion of the same layer of the substrate;
- while polishing the second portion, generating a second interference signal by directing a second light beam having a second effective wavelength that differs from the first effective wavelength and measuring light from the second light beam reflected from the substrate;
- and
- detecting a polishing endpoint for the layer from the second interference signal.
Dependencies are inferred from the claim text.