Lithography line width monitor reflecting chip-wide average feature size

DETAILED DESCRIPTION A primary object of an embodiment of the invention is to provide a method of making in-line measurements of feature sizes which are both efficient in measurement execution and simultaneously representative of feature sizes across an entire chip.
An object of an embodiment of the invention is to provide a method of making in-line measurements which does not make it very cumbersome to determine if a given measurement is within spec limits, since the spec limits may be unique for a certain reticle rather than global for a given technology.
An object of an embodiment of the invention is to provide a method of making in-line measurements that does not hinder statistical process control.
Another object of an embodiment of the invention is to provide a method of making in-line measurements that does not slow the metrology set-up.
Yet another object of an embodiment of the invention is to provide a method of making in-line measurements that is not highly inefficient for the metrology process and which does not severely restrict the metrology throughput.
Still another object of an embodiment of the invention is to provide a method of making in-line measurements which uses clear and unique labels for each feature with the critical dimension feature cluster making it easy for metrology personnel to select the appropriate feature when setting up the automated metrology job.
Another object of an embodiment of the invention is to provide a method of making in-line measurements which uses labels that make pattern recognition easy for the metrology tool, so that during automated measurements there is no risk of the metrology tool accidentally jumping to measure the wrong feature.
Yet another object of an embodiment of the present invention is to provide a method of making in-line measurements which provides increased tolerance for targeting such that the method potentially doubles the traditional article reticle specification tolerance.
Another object of an embodiment of the present invention is to provide a method of making in-line measurements which results in cost savings and improved cycle time for wafer production as fewer reticles will be rejected for out of specification critical dimensions