Endpoint detection with light beams of different wavelengths
AssigneeApplied Materials, Inc.
InventorsBoguslaw Swedek, Andreas Norbert Wiswesser
Life of this patent
Estimating the term…
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.
Claims23
A chemical mechanical polishing apparatus to polish a layer of a substrate, comprising:
- a first polishing station;
- a 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 layer to generate a first intensity signal;
- a second polishing station;
- a 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 layer to generate a second intensity signal;
- and
- at least one processor to determine an intermediate polishing point at the first polishing station from the first intensity signal and a polishing endpoint at the second polishing station from the second intensity signal.
A method of chemical mechanical polishing, comprising:
- polishing a substrate at a first polishing station;
- generating a first intensity 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 a layer in the substrate;
- detecting an intermediate polishing point from the first intensity signal;
- after detection of the intermediate polishing point, generating a second intensity 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 layer of the substrate, wherein the second effective wavelength differs from the first effective wavelength;
- and
- detecting a polishing endpoint from the second intensity signal.
Dependencies are inferred from the claim text.