New materials of spin-on organic hardmask for sub-70nm devices
In ArF lithography for sub-80nm L/S, amorphous carbon layer (ACL) deposition becomes an inevitable process, because thin ArF resist itself cannot provide suitable etch selectivity to sub-layers. One of the problems of the ACL hardmask is the presence of surface particles, which are more problematic in mass production. Limited capacity, high cost-of-ownership, and low process efficiency also make ACL hardmasks a dilemma, which cannot be ignored by device makers. One of the answers to these problems is using a spin-on organic hardmask (SOH) material instead of ACL hardmask. Therefore, several processes including bi-layer resist process, tri-layer resist process (TLR), and multi-layer resist process have been investigated. In this paper, we have described new SOH materials applicable to 70nm memory devices. Applications to the TLR were investigated in terms of photo property, etch property and process compatibility. Based on the test results described in this paper, our spin-on organic hardmask materials are expected to be used in mass production.
arf lithography amorphous carbon layer (acl) etch selectivity spin-on organic hardmask (soh) tri-layer resist process (tlr)