TOKYO -- Hoya Corp. has said it is ready to ship samples of its extreme-ultraviolet (EUV) masks and mask blanks to photomask manufacturers and device makers.
The mask blanks are intended for EUV feasibility studies that will help the industry make progress on EUV mask inspection and metrology tools before commercial EUV mask making can begin, a Hoya spokesman said. Hoya's prototype masks have a reflection rate of 65 percent. Reflectivity is a metric that indicates the quality of the coated layers on the mask substrate.
Keeping the cost of EUV masks below $100,000 per layer is considered essential to device makers worried about the cost of upcoming EUV systems, said a lithography manager at a U.S. semiconductor maker. For EUV scanners to be sold in sufficient numbers, the cost of operation must meet the needs of DRAM and system-on-chip makers, whose products sell for lower unit prices than the average microprocessor or programmable logic device, the manager said.
Central to the mask cost equation is the ability to make defect-free mask blanks, a daunting technical challenge. EUV mask blanks have about 40 layers of silicon and molybdenum coatings. The layers must be deposited with atomic-level precision so that the EUV light is reflected from the mask accurately and with a high rate of reflectivity.
EUV mask blanks have been experimentally produced by EUV LLC (Livermore, Calif.). Japan's Mirai project has further studied the EUV mask-making challenge.
Hoya's spokesman estimated that the Tokyo company supplies 75 percent of the world's mask blanks, including 90 percent of mask blanks for the most advanced process technologies.