Automatic selection of sample values for optical metrology

An optical metrology system comprising:

• a memory storage for storage of an optical metrology library for the system;
• and
• a processing unit to:
• provide a first library parameter space comprising a populated parameter space of a plurality of parameters for modeling of a diffracting structure using the system,
• automatically reduce, by a processing unit, the populated parameter space to produce a second library parameter space comprising a reduced populated parameter space of the plurality of parameters, wherein the reduction of the populated parameter space is based on the following:
• a recommendation of a sampling filter that includes 1) identifying correlations between two or more parameters of the plurality of parameters, 2) processing the correlated parameters using one or more algorithms, and 3) comparing such correlations,
• generate a parametrized model of the diffracting structure based on the plurality of parameters;
• and
• generate a library for the optical metrology system using the generated parameterized model of the diffracting structure and the second library parameter-dimensional space, while not using a portion of the populated parameter space that is excluded from the reduced populated parameter space,
• wherein the first library parameter space and the second library parameter space are composed of a same plurality of dimensions, each dimension associated with a different parameter of the plurality of parameters.

A non-transitory computer-readable storage medium having stored thereon data representing sequences of instructions that, when executed by a processor, cause the processor to perform operations comprising:

• providing a first library parameter space comprising a populated parameter space of a plurality of parameters for modeling of a diffracting structure using an optical metrology system;
• automatically reducing, by a processing unit, the populated parameter space to produce a second library parameter space comprising a reduced populated parameter space of the plurality of parameters, wherein the reduction of the populated parameter space is based on the following:
• recommending a sampling filter that includes 1) identifying correlations between two or more parameters of the plurality of parameters, 2) processing the correlated parameters using one or more algorithms, and 3) comparing such correlations;
• and
• generating a parameterized model of the diffracting structure based on the plurality of parameters;
• generating a library for the optical metrology system using the generated parameterized model of the diffracting structure and the second library parameter space, while not using a portion of the populated parameter space that is excluded from the reduced populated parameter space,
• wherein the first library parameter space and the second library parameter space are composed of a same plurality of dimensions, each dimension associated with a different parameter of the plurality of parameters.