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US 7,409,260 B2Granted
Substrate thickness measuring during polishing
AssigneeApplied Materials, Inc.
InventorsJeffrey Drue David, Dominic J. Benvegnu, Harry Q. Lee, Boguslaw A. Swedek, Lakshmanan Karuppiah
Life of this patent
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Abstract
A method for determining a polishing endpoint includes obtaining spectra from different zones on a substrate during different times in a polishing sequence, matching the spectra with indexes in a library and using the indexes to determining a polishing rate for each of the different zones from the indexes. An adjusted polishing rate can be determined for one of the zones, which causes the substrate to have a desired profile when the polishing end time is reached.
Claims19
A computer-implemented method, comprising:
- obtaining a first spectrum of reflected light from a first zone on a substrate and a second spectrum from a second zone on the substrate during a polishing sequence;
- comparing the first spectrum and the second spectrum to a spectra library to determine a first index for the first spectrum and a second index for the second spectrum;
- obtaining a third spectrum of reflected light from the first zone and a fourth spectrum from the second zone at a different time during the polishing sequence;
- comparing the third spectrum and the fourth spectrum to the library to determine a third index for the third spectrum and a fourth index for the fourth spectrum;
- determining a first polishing rate at the first zone from the first index and the third index and a second polishing rate at the second zone from the second index and the fourth index;
- and
- based on the first polishing rate, the second polishing rate, a first target relative thickness for the first zone and a second target relative thickness for the second zone, determining an adjusted polishing rate for the second zone to cause the second zone to be polished to the second target relative thickness at substantially the same time as the first zone is polished to the first target relative thickness.
4 more elements
A method of monitoring a chemical mechanical polishing process, comprising:
- directing a multi-wavelength light beam onto a substrate undergoing a polishing sequence and measuring a first spectrum of light reflected from the substrate;
- causing the light beam to move in a path across the substrate surface;
- after causing the light beam to move, directing the multi-wavelength light beam onto the substrate during the polishing sequence and measuring a second spectrum of light reflected from the substrate;
- repeating the steps of directing the multi-wavelength light beam, causing the light beam to move in a path and after causing the light beam to move, directing the multi-wavelength light beam at a different time during the polishing sequence to measure a third spectrum of reflected light and a fourth spectrum of reflected light from the substrate;
- determining a radial position on the substrate for each of the spectral measurements;
- sorting the spectral measurements into a plurality of radial ranges according to the radial positions, wherein the first spectrum and the third spectrum correspond to a first radial range and the second spectrum and fourth spectrum correspond to a second radial range of the plurality of radial ranges;
- comparing the spectral measurements to a spectra library to determine a first index for the first spectrum, a second index for the second spectrum, a third index for the third spectrum and a fourth index for the fourth spectrum;
- determining a first polishing rate at the first radial range from the indices corresponding to the first radial range and a second polishing rate at the second radial range from the indices corresponding to the second radial range;
- and
- based on the first polishing rate, the second polishing rate, a first target relative thickness for the first radial range and a second target relative thickness for the second radial range, determining an adjusted polishing rate for the second radial range to cause the second radial range to be polished to the second target relative thickness at substantially the same time as the first radial range is polished to the first target relative thickness.
7 more elements
Dependencies are inferred from the claim text.