Automated calibration methodology for VUV metrology system
First Claim
1. A method of evaluating an optical metrology tool, comprising:
- utilizing an optical tool characterization pad for use in assisting in the evaluation of an optical metrology tool;
providing multiple characterization sites of a similar characterization structure upon the characterization pad; and
designating at least some of the characterization sites as either acceptable for use or not, wherein based upon the designation, after the designation at least some of the characterization sites are not utilized for evaluation of the optical metrology tool.
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Abstract
A calibration pad having multiple calibration sites is provided. A particular calibration site may be utilized until that particular site has been determined to have become unacceptable for further use, for example from contamination, in which case the calibration processes may then move to use a different calibration site(s) on the calibration pad(s). A variety of techniques may be utilized to provide the determination that a site is no longer acceptable for use. Movement may thus occur over time from site to site for use in a calibration process. A variety of criteria may be established to determine when to move to another site. Though the designation of a site as “bad” may be based upon measured reflectance data, other criteria may also be used. For example, the number of times a site has been exposed to light may be the criteria for designating a site as bad. Alternatively the cumulative exposure of a site may be the criteria. Further, the plurality of calibration sites that are provided on the single calibration pad may be pre-evaluated so as to initially screen out unacceptable calibration sites prior to use. The techniques provided may be utilized in calibration processes which utilize a single calibration sample or processes which require a plurality of calibration samples.
99 Citations
24 Claims
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1. A method of evaluating an optical metrology tool, comprising:
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utilizing an optical tool characterization pad for use in assisting in the evaluation of an optical metrology tool; providing multiple characterization sites of a similar characterization structure upon the characterization pad; and designating at least some of the characterization sites as either acceptable for use or not, wherein based upon the designation, after the designation at least some of the characterization sites are not utilized for evaluation of the optical metrology tool. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of calibrating an optical metrology tool, comprising:
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providing a calibration pad for use in a calibration process of the optical metrology tool; partitioning the calibration pad into a plurality of calibration sites, the calibration sites having similar calibration structures; utilizing a first calibration site of the calibration pad for calibrating the optical metrology tool; detecting that the first calibration site does not satisfy a criteria for use of the first calibration site; and switching from use of the first calibration site to use of a second calibration of the calibration pad for calibrating the optical metrology tool based upon the detection of the first calibration site not satisfying the criteria. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A pad for use in characterizing an optical metrology tool, comprising:
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a first region of the pad at which optical measurements may be obtained, the first region comprising characterization structures constructed to be used for characterizing the optical metrology tool; a plurality of sub-regions of the pad, the sub-regions being a plurality of characterization sites which are sized such that separate optical measurements may be obtained from different ones of the characterization sites so that at least some of the characterization sites may be designated unacceptable for use in the characterization of the optical metrology tool while still allowing use of other of the characterization sites for characterizing the optical metrology tool. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification