Advantages over Other Methods

• The PSFM reticle provides data over several points within a single field. A real-time snapshot of focus is gathered.
• The PSFM is compatible with all widely used overlay measurement tools, thus allowing automated collection of focus data.
  • Operator interpretation is eliminated, thus increasing repeatability of the data, and reducing the time required for evaluation and characterization..
• PSFM reticles are available for all existing optical scanner and stepper lithography tools, including the latest 193 immersion scanners.
  •  Allows data to be readily evaluated across a variety of models, manufacturers, reduction ratios and lens types.
• The reticle allows rapid characterization of several types of focus errors, to evaluate the effects of the stepper lens, autofocus and autoleveling subsystems and wafer chuck flatness, The PSFM reticle has also been used to identify process-induced focus errors.