Sematech, Albany, N.Y., announces that its researchers have reached a significant milestone in reducing to zero the defects generated by tools from the multi-layer deposition of mask blanks for extreme ultraviolet lithography. These results were achieved on a 40 bi-layer Si/Mo film stack, and were measured over the entire mask blank quality area of 132×132 mm2.
Following a four-year effort to improve deposition tool hardware, process parameters, and substrate cleaning techniques, technologists at Sematech have, for the first time, deposited EUV multilayers with zero defects per mask at 100nm sensitivity (SiO2 equivalent).
In addition, by subtracting out incoming substrate defects, Sematech has demonstrated that the multilayer deposition process itself can achieve zero defects down to 50nm sensitivity. Coupled with novel improvements to the mask substrate cleaning process to remove incoming defects, this represents the capability to extend EUV to future nodes by eliminating smaller “killer” defects. It is also a step to reducing smaller defects (which can be mitigated) to a level where improved yield and mask cost make EUV a more cost-effective HVM technology.
