Contact Shrinkage Techniques for 157-nm Lithography

摘要

The development of a process for contact hole tends to be overdue although priority is generally given to the development of line and space patterns. The size of a contact hole pattern in 45 nm node will be about 60 nm. 157-nm lithography will be applied to 45 nm node. The depth of focus is critical issue. Then we evaluated three types of contact hole shrinkage techniques such as Thermal Flow, SAFIER~(TM) and RELACS~(TM) for 157-nm lithography. A resist which was consisted of a polymer with fluoride on a side chain was used. The shrinkage temperature was optimized by applying contact hole shrinkage processes to patterns formed by 193-nm lithography. It was made clear that Thermal Flow process was not practical in the view point of extremely high shrinkage temperature. On the other hand, hole size was reduced by about 20 nm in the case of SAFIER~(TM) and RELACS~(TM) at controllable temperature. It is an advantage of SAFIER~(TM) process that hole size is changed with shrinkage bake temperature. In RELACS~(TM) process, small mixing temperature dependence of critical dimension (CD) is advantageous. Also in 157-nm lithography, it was shown that the shrinkage techniques such as SAFIER~(TM) and RELACS~(TM) are possible, and the about 75nm hole pattern was formed.