In-situ method and apparatus for end point detection in chemical mechanical polishing
AssigneesASML US, Inc., Massashusetts Institute of Technology
InventorsNannaji Saka, Jamie Nam, Hilario L. Oh
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Abstract
A method and apparatus for providing in-situ monitoring of the removal of materials in localized regions on a semiconductor wafer or substrate during chemical mechanical polishing (CMP) is provided. In particular, the method and apparatus of the present invention provides for detecting the differences in reflectance between the different materials within certain localized regions or zones on the surface of the wafer. The differences in reflectance are used to indicate the rate or progression of material removal in each of the certain localized zones.
Claims17
A chemical mechanical polishing (CMP) apparatus comprising:
- a rotating polishing platen having a first diameter,
- a wafer carrier for holding a wafer in cooperative relationship with said rotating platen, said wafer carrier having multiple chambers that allow for independently varying pressure within the chambers that urge against the wafer at corresponding multiple localized zones on the wafer,
- at least one window formed in said polishing platen whereby said window is periodically scanned across a wafer,
- an optical detection system carried on said platen for transmitting light through said window and receiving light reflected from the wafer through said window as it rotates past the wafer, to detect the reflectance of materials on the surface of the wafer at the multiple localized zones, and
- a controller, which receives reflectance signals representing the reflectance of materials on the surface of the wafer at the multiple localized zones from the optical detection system, and said controller is configured to process said reflectance signals to determine the state of polishing within each of the localized regions, and to selectively vary the pressure independently within each of the multiple chambers responsive to said state of polishing determination.
A method of chemical mechanical polishing (CMP) of a semiconductor wafer, comprising the steps of:
- providing a CMP machine which includes apolishing pad and awafer carrier having multiple chambers that allow for independently varying pressure within the chambers that urge against a wafer at corresponding localized zones on the wafer;
- measuring the reflectance of the surface of the wafer during polishing at each of the localized zones on the wafer;
- processing the reflectance data to determine the state of polishing within each of the localized zones;
- and
- independently adjusting the pressure within any one of the chambers responsive to the state of polishing within each of the corresponding localized zones.
Dependencies are inferred from the claim text.