Endpoint method using peak location of spectra contour plots versus time
First Claim
1. A computer program product, tangibly embodied on a computer readable medium, comprising instructions to:
- receive an identification of a selected spectral feature, a characteristic of the selected spectral feature to monitor during polishing, an expected initial value for the characteristic and a target difference for the characteristic;
receiving measurements of a sequence of spectra of light reflected from a substrate while the substrate is being polished, at least some of the spectra of the sequence differing due to material being removed during the polishing;
determine a value of the characteristic of the selected spectral feature for each of the spectra in the sequence of spectra to generate a sequence of values for the characteristic;
calculate an actual initial value of the characteristic from the sequence of values;
calculate a first difference between the actual initial value and the expected initial value;
generate a weighted combination of the first difference and the target difference; and
determine at least one of a polishing endpoint or an adjustment for a polishing rate based on the weighted combination.
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Accused Products
Abstract
In one aspect, a method of polishing includes polishing a substrate, and receiving an identification of a selected spectral feature and a characteristic of the selected spectral feature to monitor during polishing. The method includes measuring a sequence of spectra of light reflected from the substrate while the substrate is being polished, where at least some of the spectra of the sequence differ due to material being removed during the polishing. The method of polishing includes determining a value of a characteristic of the selected spectral feature for each of the spectra in the sequence of spectra to generate a sequence of values for the characteristic, fitting a function to the sequence of values, and determining either a polishing endpoint or an adjustment for a polishing rate based on the function.
92 Citations
16 Claims
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1. A computer program product, tangibly embodied on a computer readable medium, comprising instructions to:
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receive an identification of a selected spectral feature, a characteristic of the selected spectral feature to monitor during polishing, an expected initial value for the characteristic and a target difference for the characteristic; receiving measurements of a sequence of spectra of light reflected from a substrate while the substrate is being polished, at least some of the spectra of the sequence differing due to material being removed during the polishing; determine a value of the characteristic of the selected spectral feature for each of the spectra in the sequence of spectra to generate a sequence of values for the characteristic; calculate an actual initial value of the characteristic from the sequence of values; calculate a first difference between the actual initial value and the expected initial value; generate a weighted combination of the first difference and the target difference; and determine at least one of a polishing endpoint or an adjustment for a polishing rate based on the weighted combination. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of polishing, comprising:
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polishing a substrate; receiving an identification of a selected spectral feature, a characteristic of the selected spectral feature to monitor during polishing, an expected initial value for the characteristic and a target difference for the characteristic; measuring a sequence of spectra of light reflected from a substrate while the substrate is being polished, at least some of the spectra of the sequence differing due to material being removed during the polishing; determining a value of the characteristic of the selected spectral feature for each of the spectra in the sequence of spectra to generate a sequence of values for the characteristic; calculating an actual initial value of the characteristic from the sequence of values; calculating a first difference between the actual initial value and the expected initial value; generating a weighted combination of the first difference and the target difference; and determining at least one of a polishing endpoint or an adjustment for a polishing rate based on the weighted combination. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification