Characterization of Binary and Attenuated Phase Shift Mask Blanksfor 32nm Mask Fabrication

摘要

During the development of optical lithography extensions for 32nm, both binary and attenuated phase shift ReticleEnhancement Technologies (RETs) were evaluated. The mask blank has a very strong influence on the minimum featuresize and critical dimension (CD) performance that can be achieved on the finished reticle and can have a significantimpact on the ultimate wafer lithographic performance. Development of a suitable high resolution binary mask makingprocess was particularly challenging. Standard chrome on glass (COG) binary blanks with 70 nm thick chrome filmswere unable to support the required minimum feature size, linearity, and through pitch requirements. Two alternativemask blank configurations were evaluated for use in building high resolution binary masks: a binary (BIN) mask blankbased on the standard attenuated PSM blank and an Opaque MoSi on Glass (OMOG) mask blank consisting of a newly-developed opaque MoSi [1]. Data comparing the total process bias, minimum feature size, CD uniformity, linearity,through pitch, etch loading effects, flatness, film stress, cleaning durability and radiation durability performance of thedifferent binary and attenuated PSM mask blanks are reported. The results show that the new OMOG binary blank offerssignificant mask performance benefits relative to the other binary and attenuated PSM mask blanks. The new OMOGblank was the opaque mask blank candidate most capable of meeting 32nm binary mask fabrication requirements..