Photomask process development for next generation lithography

Abstract

For the coming technology nodes, lithography options that use 1X masks are becoming practical candidates. Especially the nano-imprint lithography (NIL) is expected as one of the candidates for 32nm node and below, because of its potential low lithography cost. Naturally, 1X masks require features finer than those on today's 4X masks, and for mask making this means a big and hard technology jump. From the mask making point of view, even the 1X mask is still a candidate, it would be a technology driver in terms of patterning process development for the coming nodes. In this paper, we focused on the NIL mold (or mask) making evaluation. Among the important factors dominating the resolution of the mask making process, we studied particularly on the resist and the dry etch. We found that with tools currently used in the commercial mask shops today, and by modification of resists, we could achieve 30nm isolated spaces and 50nm dense lines and holes. We also discuss about our initial results of mask EB writing method evaluation. We found that, to improve the resolution further, the implementation of high resolution EB tools into the mask manufacturing line is inevitable to made molds for 32nm or 22nm technology nodes.