Sematech touts “milestone” in EUV mask blank defect cleaning

April 17, 2007 – Sematech says its researchers at its Mask Blank Development Center (MBDC) at the U. of Albany (NY)’s College of Nanoscale Science and Engineering, have successfully detected and cleaned 10nm particles from mask blanks used in EUV lithography.

Using a combination of a Lasertec M7360 tool and an atomic force microscope (AFM), MBDC engineers were able to locate, mark and measure 10nm silicon particles intentionally deposited on a quartz mask blank, Sematech indicated in a statement. Subsequent cleaning of the mask blank utilizing a Hamatech ASC5500 tool removed all of the targeted particles, as confirmed by the AFM.

Abbas Rastegar, senior member of Sematech’s technical staff at the MBDC, noted in a statement that “this degree of precision will be necessary for EUV to be successfully implemented for the 22nm technology generation.” Michael Lercel, Sematech’s lithography director, added that higher-resolution defect-inspection tools and highly efficient cleaning techniques are still needed to ensure EUV mask blank process maturity.

Several weeks ago at this year’s SPIE, Sematech said it had achieved full cleaning of 30nm defects from the “quality area” of an EUVL mask blank, “at good removal efficiency,” and indicated it could detect <40nm mask blank defects.

A year ago Sematech’s MBDC indicated it had successfully improved its inspection capability down to 43nm defects for a fused-silica mask blank substrate, via both hardware modifications and development of complementary defect review methods that improve capture rate and reduce the false defect count of the inspection tool.


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