Abstract: A computer-implemented method includes receiving a sequence of current spectra of reflected light from a substrate; comparing each current spectrum from the sequence of current spectra to a plurality of reference spectra from a reference spectra library to generate a sequence of best-match reference spectra; determining a goodness of fit for the sequence of best-match reference spectra; and determining at least one of whether to adjust a polishing rate or an adjustment for the polishing rate, based on the goodness of fit.

Abstract: A substrate having a plurality of zones is polished and spectra are measured. For each zone, a first linear function fits a sequence of index values associated with reference spectra that best match the measured spectra. A projected time at which a reference zone will reach the target index value is determined based on the first linear function, and for at least one adjustable zone, a polishing parameter adjustment is calculated such that the adjustable zone has closer to the target index at the projected time than without such adjustment. The adjustment is calculated based on a feedback error calculated for a previous substrate. The feedback error for a subsequent substrate is calculated based on a second linear function that fits a sequence of index values associated with reference spectra that best match spectra measured after the polishing parameter is adjusted.

Abstract: While a substrate is polished, it is also irradiated with light from a light source. A current spectrum of the light reflected from the surface of the substrate is measured. A selected peak, having a first parameter value, is identified in the current spectrum. A value of a second parameter associated with the first parameter is determined from a lookup table using a processor. Depending on the value of the second parameter, the polishing of the substrate is changed. An initial spectrum of light reflected from the substrate before the polishing of the substrate can be measured and a wavelength corresponding to a selected peak of the initial spectrum can be determined.

Abstract: A computer-implemented method includes receiving a first sequence of current spectra of reflected light from a first zone of a substrate. A second sequence of current spectra of reflected light from a second zone of the substrate is received. Each current spectrum from the first sequence of current spectra is compared to a plurality of reference spectra from a first reference spectra library to generate a first sequence of best-match reference spectra. Each current spectrum from the second sequence of current spectra is compared to a plurality of reference spectra from a second reference spectra library to generate a second sequence of best-match reference spectra. The second reference spectra library is distinct from the first reference spectra library.

Abstract: A computer-implemented method includes receiving a sequence of current spectra of reflected light from a substrate; comparing each current spectrum from the sequence of current spectra to a plurality of reference spectra from a reference spectra library to generate a sequence of best-match reference spectra; determining a goodness of fit for the sequence of best-match reference spectra; and determining at least one of whether to adjust a polishing rate or an adjustment for the polishing rate, based on the goodness of fit.

Abstract: While a substrate is polished, it is also irradiated with light from a light source. A current spectrum of the light reflected from the surface of the substrate is measured. A selected peak, having a first parameter value, is identified in the current spectrum. A value of a second parameter associated with the first parameter is determined from a lookup table using a processor. Depending on the value of the second parameter, the polishing of the substrate is changed. An initial spectrum of light reflected from the substrate before the polishing of the substrate can be measured and a wavelength corresponding to a selected peak of the initial spectrum can be determined.

Abstract: Methods, systems, and apparatus for spectrographic monitoring of a substrate during chemical mechanical polishing are described. In one aspect, a computer-implemented method includes storing a library having a plurality of reference spectra, each reference spectrum of the plurality of reference spectra having a stored associated index value, measuring a sequence of spectra in-situ during polishing to obtain measured spectra, for each measured spectrum of the sequence of spectra, finding a best matching reference spectrum to generate a sequence of best matching reference spectra, determining the associated index value for each best matching spectrum from the sequence of best matching reference spectra to generate a sequence of index values, fitting a linear function to the sequence of index values, and halting the polishing either when the linear function matches or exceeds a target index or when the associated index value from the determining step matches or exceeds the target index.

Abstract: A computer-implemented method of generating reference spectra includes polishing a plurality of set-up substrates, the plurality of set-up substrates comprising at least three set-up substrates, measuring a sequence of spectra from each of the plurality of set-up substrates during polishing with an in-situ optical monitoring system to provide a plurality of sequences of spectra, generating a plurality of sequences of potential reference spectra from the plurality of sequences of spectra, determining which sequence of potential reference spectra of the plurality of sequences provides a best match to remaining sequences of the plurality of sequences, and storing the sequence of potential reference spectra determined to provide the best match as reference spectra, and selecting and storing the sequence of potential reference spectra.

Abstract: A method of controlling the polishing of a substrate includes polishing a substrate on a first platen using a first set of parameters, obtaining first and second sequences of measured spectra from first and second regions of the substrate with an in-situ optical monitoring system, generating first and second sequences of values from the first and second sequences of measured spectra, fitting first and second linear functions to the first and second sequences of values, determining a difference between the first linear function and the second linear function, adjusting at least one parameter of the first set of parameters based on the difference, and polishing the second substrate on the first platen using the adjusted parameter.

Abstract: A substrate having a plurality of zones is polished and spectra are measured. For each zone, a first linear function fits a sequence of index values associated with reference spectra that best match the measured spectra. A projected time at which a reference zone will reach the target index value is determined based on the first linear function, and for at least one adjustable zone, a polishing parameter adjustment is calculated such that the adjustable zone has closer to the target index at the projected time than without such adjustment. The adjustment is calculated based on a feedback error calculated for a previous substrate. The feedback error for a subsequent substrate is calculated based on a second linear function that fits a sequence of index values associated with reference spectra that best match spectra measured after the polishing parameter is adjusted.

Abstract: Methods, systems, and apparatus for spectrographic monitoring of a substrate during chemical mechanical polishing are described. In one aspect, a computer-implemented method includes storing a library having a plurality of reference spectra, each reference spectrum of the plurality of reference spectra having a stored associated index value, measuring a sequence of spectra in-situ during polishing to obtain measured spectra, for each measured spectrum of the sequence of spectra, finding a best matching reference spectrum to generate a sequence of best matching reference spectra, determining the associated index value for each best matching spectrum from the sequence of best matching reference spectra to generate a sequence of index values, fitting a linear function to the sequence of index values, and halting the polishing either when the linear function matches or exceeds a target index or when the associated index value from the determining step matches or exceeds the target index.

Abstract: A method of optically monitoring a substrate during polishing includes receiving an identification of a selected spectral feature and a characteristic of the selected spectral feature to monitor during polishing, measuring a first spectrum from the substrate during polishing, the first spectrum measured within an initial time following initiation of polishing, measuring a sequence of second spectra from the substrate during polishing, the sequence of second spectra measured after the initial time, for each second spectrum in the sequence of second spectra, removing the first spectrum from the second spectrum to generate a sequence of modified third spectra, determining a value of a characteristic of the selected spectral feature for each third spectrum in the sequence of third spectra to generate a sequence of values for the characteristic, and determining a polishing endpoint or an adjustment for a polishing rate based on the sequence of values.

Abstract: A substrate having a plurality of zones is polished and spectra are measured. For each zone, a first linear function fits a sequence of index values associated with reference spectra that best match the measured spectra. A projected time at which a reference zone will reach the target index value is determined based on the first linear function, and for at least one adjustable zone, a polishing parameter adjustment is calculated such that the adjustable zone has closer to the target index at the projected time than without such adjustment. The adjustment is calculated based on a feedback error calculated for a previous substrate. The feedback error for a subsequent substrate is calculated based on a second linear function that fits a sequence of index values associated with reference spectra that best match spectra measured after the polishing parameter is adjusted.

Abstract: A method of controlling polishing includes storing a plurality libraries, each library including a plurality of reference spectra, polishing a substrate, measuring a sequence of spectra of light from the substrate during polishing, and for each measured spectrum of the sequence of spectra, finding a best matching first reference spectrum from a first library from the plurality of libraries and finding a best matching second reference spectrum from a different second library from the plurality of libraries, determining a first value associated with the best matching first reference spectrum and determining a second value from the best matching second reference spectrum, and calculating a third value from the first value and the second value to generate a sequence of calculated third values. At least one of a polishing endpoint or an adjustment for a polishing rate can be determined based on the sequence of calculated third values.

Abstract: A method of controlling polishing includes storing a library having a plurality of reference spectra, each reference spectrum of the plurality of reference spectra having a stored associated index value, polishing a substrate having a second layer overlying a first layer, measuring a sequence of spectra of light from the substrate during polishing, for each measured spectrum of the sequence of spectra, finding a best matching reference spectrum to generate a sequence of best matching reference spectra, determining the associated index value for each best matching spectrum from the sequence of best matching reference spectra to generate a sequence of index values, detecting exposure of the first layer, fitting a function to a portion of the sequence of index values corresponding to spectra measured after detection of exposure of the first layer, and determining at least one of a polishing endpoint or an adjustment for a polishing rate based on the function.

Abstract: A method of controlling polishing includes storing a library having a plurality of reference spectra, polishing a substrate, measuring a sequence of spectra of light from the substrate during polishing, for each measured spectrum of the sequence of spectra, finding a best matching reference spectrum using a matching technique other than sum of squared differences to generate a sequence of best matching reference spectra, and determining at least one of a polishing endpoint or an adjustment for a polishing rate based on the sequence of best matching reference spectra. Finding a best matching reference spectrum may include performing a cross-correlation of the measured spectrum with each of two or more of the plurality of reference spectra from the library and selecting a reference spectrum with the greatest correlation to the measured spectrum as a best matching reference spectrum.

Abstract: A method of configuring a polishing monitoring system includes receiving user input selecting a plurality of libraries, each library of the plurality of libraries comprising a plurality of reference spectra for use in matching to measured spectra during polishing, each reference spectrum of the plurality of reference spectra having an associated index value, for a first zone of a substrate, receiving user input selecting a first subset of the plurality of libraries, and for a second zone of the substrate, receiving user input selecting a second subset of the plurality of libraries.

Abstract: A method of controlling the polishing of a substrate includes polishing a substrate on a first platen using a first set of parameters, obtaining first and second sequences of measured spectra from first and second regions of the substrate with an in-situ optical monitoring system, generating first and second sequences of values from the first and second sequences of measured spectra, fitting first and second linear functions to the first and second sequences of values, determining a difference between the first linear function and the second linear function, adjusting at least one parameter of a second set of parameters based on the difference, and polishing the substrate on a second platen using the adjusted parameter.

Abstract: A method of polishing includes polishing a substrate having a second layer overlying a first layer, measuring a sequence of groups of spectra of light from the substrate while the substrate is being polished, each group of the groups of spectra including spectra from different locations on the substrate, for each group, calculating a value for a dispersion parameter of the spectra in the group to generate a sequence of dispersion values, and detecting exposure of the first layer based on the sequence of dispersion values.

Abstract: A method of polishing includes polishing a substrate, receiving an identification of a selected spectral feature to monitor during polishing, measuring a sequence of spectra of light reflected from the substrate while the substrate is being polished, determining a location value and an associated intensity value of the selected spectral feature for each of the spectra in the sequence of spectra to generate a sequence of coordinates, and determining at least one of a polishing endpoint or an adjustment for a polishing rate based on the sequence of coordinates. At least some of the spectra of the sequence differ due to material being removed during the polishing, and the coordinates are pairs of location values and associated intensity values.