Abstract: A method of controlling a polishing operation includes measuring a plurality of spectra at a plurality of different positions on a substrate to provide a plurality of measured spectra. For each measured spectrum of the plurality of measured spectra, a characterizing value is generated based on the measured spectrum. For each characterizing value, a goodness of fit of the measured spectrum to another spectrum used in generating the characterizing value is determined. A wafer-level characterizing value map is generated by applying a regression to the plurality of characterizing values with the plurality of goodnesses of fit used as weighting factors in the regression. A polishing endpoint or a polishing parameter of the polishing apparatus is adjusted based on the wafer-level characterizing map, and the substrate or a subsequent substrate is polished in the polishing apparatus with the adjusted polishing endpoint or polishing parameter.

Abstract: A method of controlling a polishing system includes transporting a substrate to an in-line optical metrology system positioned in a chemical mechanical polishing system, at the in-line optical metrology system, moving a probe relative to the substrate to measure a plurality of spectra reflected from the substrate at a plurality of different positions on the substrate, for each measured spectrum of the plurality of spectra, determining a goodness of fit of the measured spectrum to a reference spectrum; and adjusting a polishing endpoint or a polishing parameter of the polishing system based on one or more characterizing values generated based on a subset of the plurality of spectra that includes only spectra of the plurality of spectra for which the goodness of fit meets a matching threshold.

Abstract: A method of controlling a polishing operation is described. A controller stores an optical model for a layer stack having a plurality of layers and a plurality of input parameters including a first parameter and a second parameter. The controller stores data defining a plurality of default values for the first parameter and measures an optical property of a substrate and generates a second value. Using the optical model and the second value and iterating over the first values, a number of reference spectra are calculated. A spectrum is measured and the measured spectrum is matched to the reference spectra and the best matched reference spectrum is determined. The first value of the best matched reference spectrum is determined and is used to adjust a polishing endpoint or a polishing parameter of a polishing apparatus.

Abstract: A method of operating a polishing system includes polishing a substrate at a polishing station, the substrate held by a carrier head during polishing, transporting the substrate to an in-sequence optical metrology system positioned between the polishing station and another polishing station or a transfer station, measuring a plurality of spectra reflected from the substrate with a probe of the optical metrology system while moving the carrier head to cause the probe to traverse a path across the substrate and while the probe remains stationary, the path across the substrate comprising either a plurality of concentric circles or a plurality of substantially radially aligned arcuate segments, and adjusting a polishing endpoint or a polishing parameter of the polishing system based on one or more characterizing values generated based on at least some of the plurality of spectra.

Abstract: A method of controlling a polishing operation includes storing an optical model for a layer stack having a plurality of layers. The optical model has a plurality of input parameters, the plurality of input parameters including a first parameter and a second parameter. The second parameter is a polarization angle or a relative contribution between two orthogonal polarizations. A spectrum reflected from the substrate is measured with an in-sequence or in-situ monitoring system to provide a measured spectrum. The optical model is fit to the measured spectrum, or a plurality of reference spectra are calculated using the optical model and a best matching reference spectrum from the plurality of reference spectra is determined.

Abstract: A polishing apparatus includes a carrier head configured to hold a wafer in a first plane, the wafer having a perimeter and a fiducial, a drive shaft having an axis perpendicular to the first plane and configured to rotate the carrier head about the axis, a light source configured to direct light onto an outer face of the wafer at a position adjacent the perimeter of the wafer; a detector configured to detect the light collected from the wafer while the drive shaft rotates the carrier head and the wafer; and a controller configured to receive a first signal indicating an angular position of the drive shaft and receive a second signal from the detector, the controller configured to determine based on the first signal and the second signal an angular position of the fiducial with respect the carrier head.

Abstract: An optical model for a layer stack has a plurality of input parameters, the plurality of input parameters defining a parameter space. A plurality of model spectra are generated by calculating a model spectrum using the optical model for each of a first plurality of different points in the parameter space. A test spectrum of a test substrate is measured. For each model spectrum of the plurality of model spectra, the test spectrum is compared to the model spectrum to determine a difference value, thereby generating a plurality of difference values. A plurality of minima in the plurality of difference values are determined. Reference spectra can be generated clustered around points in the parameter space corresponding to a local minimum from the plurality of minima, or the local minimum can be used as a seed value in fitting the optical model to a measured spectrum.

Abstract: A computer implemented method of monitoring a polishing process includes, for each sweep of a plurality of sweeps of an optical sensor across a substrate undergoing polishing, obtaining a plurality of current spectra, each current spectrum of the plurality of current spectra being a spectrum resulting from reflection of white light from the substrate, for each sweep of the plurality of sweeps, determining a difference between each current spectrum and each reference spectrum of a plurality of reference spectra to generate a plurality of differences, for each sweep of the plurality of sweeps, determining a smallest difference of the plurality of differences, thus generating a sequence of smallest difference, and determining a polishing endpoint based on the sequence of smallest differences.

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.

Abstract: An optical model for a layer stack has a plurality of input parameters, the plurality of input parameters defining a parameter space. A plurality of model spectra are generated by calculating a model spectrum using the optical model for each of a first plurality of different points in the parameter space. A test spectrum of a test substrate is measured. For each model spectrum of the plurality of model spectra, the test spectrum is compared to the model spectrum to determine a difference value, thereby generating a plurality of difference values. A plurality of minima in the plurality of difference values are determined. Reference spectra can be generated clustered around points in the parameter space corresponding to a local minimum from the plurality of minima, or the local minimum can be used as a seed value in fitting the optical model to a measured spectrum.

Abstract: A method of generating reference spectra includes polishing a first substrate in a polishing apparatus, measuring a sequence of spectra from the first substrate during polishing with an in-situ optical monitoring system, for each spectrum in the sequence of spectra, determining a best matching reference spectrum from a first plurality of first reference spectra to generate a sequence of reference spectra, calculating a value of a metric of fit of the sequence of spectra to the sequence of reference spectra, comparing the value of the metric of fit to a threshold value and determining whether to generate a second library based on the comparison, and if the second library is determined to be generated, storing the sequence of spectra as a second plurality of reference spectra.

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 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 polishing a substrate of a non-metallic layer undergoing polishing and a metal layer underlying the non-metallic layer; storing a metal reference spectrum, the metal reference spectrum being a spectrum of light reflected from a same metal material as the metal layer; measuring a sequence of raw spectra of light reflected from the substrate during polishing with an in-situ optical monitoring system; normalizing each raw spectrum in the sequence of spectra to generate a sequence of normalized spectra, of which normalizing includes a division operation where the measured spectrum is in the numerator and the metal reference spectrum is in the denominator; and determining at least one of a polishing endpoint or an adjustment for a polishing rate based on at least one normalized predetermined spectrum from the sequence of normalized spectra.

Abstract: A method of controlling polishing includes polishing a substrate, monitoring a substrate during polishing with an in-situ monitoring system, generating a sequence of values from measurements from the in-situ monitoring system, fitting a non-linear function to the sequence of values, determining a projected time at which the non-linear function reaches a target value; and determining at least one of a polishing endpoint or an adjustment for a polishing rate based on the projected time.

Abstract: A polishing apparatus includes a plurality of stations supported on a platform, the plurality of stations including at least two polishing stations and a transfer station, each polishing station including a platen to support a polishing pad, a plurality of carrier heads suspended from and movable along a track such that each polishing station is selectively positionable at the stations, and a controller configured to control motion of the carrier heads along the track such that during polishing at each polishing station only a single carrier head is positioned in the polishing station.

Abstract: A polishing apparatus includes a plurality of stations supported on a platform, the plurality of stations including at least two polishing stations and a transfer station, each polishing station including a platen to support a polishing pad, a plurality of carrier heads suspended from and movable along a track such that each polishing station is selectively positionable at the stations, and a controller configured to control motion of the carrier heads along the track such that during polishing at each polishing station only a single carrier head is positioned in the polishing station.

Abstract: A method of controlling processing of a substrate includes measuring a spectrum reflected from the substrate, for each partition of a plurality of partitions of the measured spectrum, computing a partition value based on the measured spectrum within the partition to generate a plurality of partition values, for each reference spectrum signature of a plurality of reference spectrum signatures, determining a membership function for each partition, for each partition, computing a membership value based on the membership function for the partition and the partition value for the partition to generate a plurality of groups of membership values with each group of the plurality of groups associated with a reference spectrum signature, selecting a best matching reference spectrum signature from the plurality of reference spectra signatures based on the plurality of groups of membership values, and determining a characterizing value associated with the best matching reference spectrum signature.

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 method of controlling polishing includes polishing a substrate, monitoring the substrate during polishing with an in-situ spectrographic monitoring system to generate a sequence of measured spectra, selecting less than all of the measured spectra to generate a sequence of selected spectra, generating a sequence of values from the sequence of selected spectra, and determining at least one of a polishing endpoint or an adjustment for a polishing rate based on the sequence of values.