Contact hole shrink process with novel chemical shrink materials

Contact hole shrink process is becoming more important option for 45nm node design rules. In general, lithography of contact hole has been harder than that of line and space application due to the low contrast of incident light. The contact hole size for 45nm node device will be around 60nm and this hole size will be the limit of 193nm lithography. High NA exposure tool for 193nm lithography achieves 60nm contact hole resolution, but both under dose margin and depth of focus will be limited. This fact results in the insufficient process window of 193nm lithography. Thus some supporting process should be necessary and a chemical shrink process is one of the possible approach to resolve 60nm contact hole with appropriate process margin. The general chemical shrink process is as follows. Chemical Shrink Material (CSM) is coated on patterned photoresist, and following bake process controls chemical cross-linking reaction and forming a layer insoluble into the developer. As a result pattern size is reduced to desired CD. However current CSM has several issues: i.e. inferior etching durability of CSM than that of 193nm resist and pattern profile degradation after the process. This will be the critical problem for pattern transfer process using CSM. From this point of view, we developed a novel CSM which has good etching durability compared with 193nm resist and does not have a pattern profile degradation. This material consists of aromatic moiety to satisfy good etching durability. Also, the shrink rate and amount are not pitch dependent.