SEMATECH researchers have made a breakthrough in reducing tool-generated defects from multi-layer deposition of mask blanks used for extreme ultraviolet lithography (EUVL). The breakthrough brings EUVL technology a step closer to high-volume manufacturing. SEMATECH is an international consortium of leading semiconductor device, equipment, and materials manufacturers.
SEMATECH researchers deposited EUV multilayers with as few as eight defects per mask at 50nm sensitivity (SiO2 equivalent), which includes six substrate defects, one handling defect and one defect from the multi-layer deposition process. This result was achieved on a 40 bi-layer film stack with an Ru cap and measured over the mask blank quality area of 132 x 132 mm2.
SEMATECH has also developed cleaning processes that improve substrate cleaning yield on quality substrates, yielding an integrated process capable of manufacturing EUV mask blanks with less than 20 total defects at 45nm sensitivity. SEMATECH’s achievements in mask defect reduction and increase in yield for high quality blanks are attributed to a significant improvement in substrate cleaning, handling, and deposition.
Defects are generally formed by decoration of substrate defects by the multilayer deposition process and, to a lesser extent, by the deposition process itself and have prevented the quality of mask blanks from keeping pace with roadmap requirements for the production of pilot line and high-volume manufacturing EUV reticles. Reducing the defects in the extreme ultraviolet (EUV) mask blank multilayer deposition system is one of the most critical technology gaps the industry needs to address to enable cost effective insertion of this technology at the 22nm half-pitch. For successful introduction, integrated EUV blanks must meet a defectivity level of less than 0.003 defects/cm2 at 25 nm sensitivity.
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