PSFM Frequently Asked Questions
Q: Who is using the Focus Monitor Reticle?
The PSFM reticle is employed by both lithography tool manufacturers and end users. Major chipmakers throughout the world use the PSFM reticle in a variety of applications. The PSFM Reticle is compatible with all brands of scanner and stepper-lithography equipment; data has been collected on ASML, Nikon, Canon, Ultratech Stepper and other older system brands such as SVGL and GCA.
Q: How much time can be saved using the Reticle?
When the PSFM reticle is used to determine and regularly monitor best focus, substantial savings in time can be realized vs. the OEM on-board focus methods. Since focus monitoring can be achieved by running a single wafer lot, productive lithography tool uptime is minimally affected. On-board methods generally require clearing and restarting of the integrated wafer track, which can result in hours of lost productivity. All metrology for PSFM wafers can be done using overlay tools outside of the litho cell.
Q: Which lithography systems is the PSFM reticle compatible with?
The PSFM reticle is presently used on every brand of optical stepper-lithography tool (Both step-and-repeat and step-and-scan systems) available, including; ASML, Nikon, Canon, Ultratech, SVGL,GCA/ISI. Customer-gathered data is available for most of these systems, and some published technical papers can supplied upon request through our Contact Us page
Q: Which overlay measurement tools is the PSFM Reticle compatible with?
The PSFM reticle allows data to be automatically collected and analyzed by several overlay measurement tools, including those brands from KLA-Tencor, NanoMetrics, Biorad, and IVS. Benchmark’s PSFM DATA! Focus Analysis Software, can import the standard output from these tools. If you are concerned about compatibility of your overlay tool output with PSFM please contact us.
Q: Can I use the same Focus Monitor Reticle to evaluate focus on several systems?
PSFM’s are both magnification and wavelength specific, so if you want to use them on different 4X 248nm scanners the same reticle could be used. However if the wavelength, reduction ratio or reticle physical size is different between any 2 systems under consideration then a reticle would be needed for each system. Please contact us if you are not sure.
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