LONDON – Semiconductor industry consortium Sematech has announced it has made significant defect reductions in mask blanks for extreme ultraviolet (EUV) lithography, a step towards enabling high volume manufacturing at smaller geometries using the next-generation lithography.
Technologists working at Sematech's base in Albany, New York, have met the 22-nm defect requirements for EUV mask blanks, the organization said.
Sematech specifically created a mask blank defect reduction program to accelerate progress that would otherwise block the introduction of EUVL.
Following a two-year effort to improve deposition tool hardware, process parameters and substrate cleaning techniques, technologists deposited EUV multilayers with as few as eight defects per mask at 50-nm sensitivity. This result was achieved on a 40 bi-layer film stack with a ruthenium cap and measured over the mask blank quality area of 132 millimeters by 132 millimeters.
In addition, Sematech has developed a novel cleaning process to allow EUV mask blanks with less than 20 total defects at 45-nm sensitivity.
For successful introduction, integrated EUV blanks must meet a defectivity level of less than 0.003 defects per square centimeter at 25-nm sensitivity.
Stefan Wurm, Sematech's director of lithography, said in a statement that Sematech is showing EUVL is usable.
Masks have always been an issue for Xray ...oops I mean EUV litho. Really, the masks pretty much need to be perfect as far as detectable defects are concerned for high volume manufacturing. For reflective optical elements at EUV wavelengths this is both difficult and expensive to achieve. It will be a continuing issue for EUV litho despite these types of press releases.
X-ray masks will be ready before the x-ray stepper can use them. And the mask makers will have lost $$$ on their development. With all the $$$ flowing into ASML to help them with 450mm, perhaps some should dribble to maskmakers.