7 July 1997 Contact holes: a challenge for signal collection efficiency and measurement algorithms
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Abstract
As critical features become smaller, metrology becomes more challenging; this is especially true of contact holes and trenches with diameters less than 0.25 micrometers . Reduced collection efficiency of secondary electrons from such contact holes can provide false edge sharpening and may interfere with obtaining critical information from the bottom of the contact hole. Whether the contact hole is open or closed is a key concern and can be determined from the waveform in many cases. This paper introduces a measure of the collection efficiency by comparing signal strength from the contact hole with a blanked beam signal and a method or determining whether the contact hole is open or closed. The collection efficiency measure can be used to determine whether information rom the bottom of the contact hole is meaningful. When found to be meaningful, the information is then evaluate to flag the contact hole's status. Results will be based on saved image analysis and lead into a discussion on the value of these parameters. Reporting collection efficiency and whether the contact hole is open or closed, along with the diameter measurement, can provide a measure of quality not yet achieved in CD metrology.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Eric P. Solecky, Eric P. Solecky, Charles N. Archie, Charles N. Archie, } "Contact holes: a challenge for signal collection efficiency and measurement algorithms", Proc. SPIE 3050, Metrology, Inspection, and Process Control for Microlithography XI, (7 July 1997); doi: 10.1117/12.275962; https://doi.org/10.1117/12.275962
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