Automatic wavelength or angle pruning for optical metrology

A non-transitory machine-accessible storage medium having instructions stored thereon which when executed cause a data processing system to perform a method of automatic wavelength or angle pruning for optical metrology, the method comprising:

• determining a model of a target microelectronic structure including at least a first geometric parameter and a second geometric parameter of the target microelectronic structure that is different than the first geometric parameter;
• designing and generating a dataset that includes:
• 1) a first set of datapoints for a set of wavelengths or a set of angles, wherein the first set of datapoints for the set of wavelengths or the set of angles are derived from a set of values for the first geometric parameter, and
• 2) a second set of datapoints for the set of wavelengths or the set of angles, wherein the second set of datapoints for the set of wavelengths or the set of angles are derived from a set of values for the second geometric parameter;
• storing the dataset in a computer memory;
• performing with a processor an analysis of the dataset for the model including:
• applying an outlier detection technology on the dataset, and
• identifying any datapoints outliers within the first and second sets of datapoints for the set of wavelengths or the set of angles of the dataset;
• if any datapoint outliers are identified in the analysis of the dataset of the model,
• removing any wavelengths or angles corresponding to the datapoint outliers from the set of wavelengths or the set of angles to produce a subset of wavelengths or a subset of angles,
• generating a modified dataset that includes
• 1) a first set of datapoints for the subset of wavelengths or the subset of angles, wherein the first set of datapoints for the subset of wavelengths or the subset of angles are derived from the first set of values for the first geometric parameter, and
• 2) a second set of datapoints for the subset of wavelengths or the subset of angles, wherein the second set of datapoints for the subset of wavelengths or the
• subset of angles are derived from the second set of values for the second geometric parameter, and
• storing the modified dataset in the computer memory;
• and
• performing optical metrology of the target structure with an optical metrology system using the modified stored dataset of the model to measure a diffraction signal,
• wherein the first geometric parameter and the second geometric parameter are each one of a height (HT), a middle critical dimension (MCD), a top critical dimension (TCD), or a sidewall angle (SWA).

A system comprising:

• an optical metrology system configured to determine one or more process parameters of a target structure, the optical metrology system comprising:
• a beam source and detector configured to measure a diffraction signal of the target structure;
• a processor configured to process measurement data;
• and
• a computer memory to store data;
• wherein the optical metrology system is configured to provide automatic wavelength or angle pruning for optical metrology, including:
• determining a model of the target structure including at least a first geometric parameter and a second geometric parameter of the target structure, wherein the second geometric parameter is different than the first geometric parameter;
• designing and generating a dataset that includes:
• 1) a first set of datapoints for a set of wavelengths or a set of angles, wherein the first set of datapoints for the set of wavelengths or the set of angles are derived from a set of values for the first geometric parameter, and
• 2) a second set of datapoints for the set of wavelengths or a set of angles, wherein the second set of datapoints for the set of wavelengths or the set of angles are derived from a set of values for the second geometric parameter;
• storing the dataset in the computer memory;
• performing with the processor an analysis of the dataset for the model including:
• applying an outlier detection technology on the dataset, and
• identifying any datapoint outliers within the first and second sets of datapoints for the set of wavelengths or the set of angles of the dataset;
• if any datapoint outliers are identified in the analysis of the dataset of the model,
• removing any wavelengths or angles corresponding to the datapoint outliers from the set of wavelengths or the set of angles to produce a subset of wavelengths or a subset of angles,
• generating a modified dataset that includes:
• 1) a first set of datapoints for the subset of wavelengths or the subset of angles, wherein the first set of datapoints for the subset of wavelengths or the subset of angles are derived from the first set of values for the first geometric parameter, and
• 2) a second set of datapoints for the subset of wavelengths or the subset of angles, wherein the second set of datapoints for the subset of wavelengths or the subset of angles are derived from the second set of values for the second geometric parameter, and
• storing the modified dataset in the computer memory, and
• performing optical metrology of the target structure using the modified stored dataset of the model to measure a diffraction signal,
• wherein the first geometric parameter and the second geometric parameter are each one of a height (HT), a middle critical dimension (MCD), a top critical dimension (TCD), or a sidewall angle (SWA).