Adaptive Sampling for Process Window Determination

摘要

Methods and systems for determining a process window for a process performed on a specimen are provided. In general, the embodiments preferentially sample locations in an instance of at least a portion of a device formed on a specimen at a value of a parameter of a process performed on the specimen that is closest to an edge of a determined process window for the process. If defects are detected at the sampled locations, then the sampling may be performed again but for a different instance of the device formed at a value of the parameter that is closer to nominal than the previously used value. When no defects are detected at the sampled locations, then the sampling may be ended, and the determined process window may be modified based on the value of the parameter corresponding to the instance of the device in which no defects were detected.

主权项

1. A system configured to determine a process window for a process performed on a specimen, comprising:
an output acquisition subsystem comprising at least an energy source and a detector, wherein the energy source is configured to generate energy that is directed to a specimen, and wherein the detector is configured to detect energy from the specimen and to generate output responsive to the detected energy; and one or more computer subsystems configured for:
acquiring results of an inspection of the specimen, wherein the specimen comprises multiple instances of at least a portion of a device formed thereon with different values of a parameter of a process performed on the specimen, and wherein the results of the inspection comprise information for defects detected in the multiple instances during the inspection, information for hot spots within the at least the portion of the device detected during the inspection, and information for a process window of the process determined by the inspection;selecting, based on the results of the inspection, a portion of locations within a first of the multiple instances formed on the specimen with a first of the different values that is closest to a value of the parameter at an edge of the process window;acquiring the output of the output acquisition subsystem for at least one of the locations in the portion;determining if defects are present at the at least one of the locations based on the acquired output;when one or more of the defects are determined to be present at the at least one of the locations, repeating the selecting, acquiring the output, and determining if the defects are present for another of the multiple instances formed on the specimen with another of the different values that is closer to nominal than the first of the different values; andwhen the defects are determined to be not present at the locations in the selected portion, determining a revised process window based on which of the different values corresponds to the multiple instance in which the defects were determined to be not present.