7 July 1997 Alternative method for monitoring an in-line CD SEM
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Semiconductor manufacturers must ensure that their in-line critical dimension scanning electron microscopes (CD-SEMs) are providing precise and reliable data on a daily basis. As with other process equipment, tool stability and production worthiness is determined by a daily qualification procedure that involves measuring a reference, etched wafer's linewidth and comparing those results to a set target mean. However, repeated exposure to a SEM creates an unacceptable increase in the measured feature's CD. This increase can be disruptive to tool qualification, requires the introduction of new reference wafers, and ultimately limits the tool's availability to production. A new method for daily qualification using a rotating daily job scheme has been developed and employed for monitoring multiple systems at Motorola MOS-13/APRDL. This new procedure allows for better statistical process control, increase the reference wafer's useful life, and provides an easier method of monitoring the tool throughout its lifetime.
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Pedro P. Herrera, Pedro P. Herrera, Susan A. Dick, Susan A. Dick, John A. Allgair, John A. Allgair, } "Alternative method for monitoring an in-line CD SEM", Proc. SPIE 3050, Metrology, Inspection, and Process Control for Microlithography XI, (7 July 1997); doi: 10.1117/12.275948; https://doi.org/10.1117/12.275948

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