Development of next generation EUV mask blanks

The first generation of EUV masks, largely based on Tantalum, were a key enabler for the success of EUV lithography. Continuous improvements in defectivity, zero phase defects are now realized and EUV reflectivity has allowed use of the 3nm node. Beyond this node, further advances in blank materials are required and similar to optical imaging, the use of resolution enhancement techniques are necessary; referred to as low-n blanks for EUV imaging. Key aspects include imaging performance, defects, durability and mask manufacturability, and involve refined absorbers and capping layers. In this paper, we overview our effort to design and accomplish the EUV blanks design that meets criteria from industry. We will also describe the challenges for next generation EUV blanks.