Process optimization for developer soluble immersion topcoat material

The 193 nm immersion lithography has been increasingly applied to the semiconductor device mass production. Topcoat material would be used in many such cases. Topcoat film can maximize the scan speed during immersion exposure step and also prevent small molecules from leaching out of resist film. However, the use of the topcoat material in the mass production affects productivity including throughput and chemical cost. To manage this problem, we attempted to improve topcoat coating process to reduce the topcoat material consumption. Using JSR NFC TCX041, the developer-soluble type topcoat material, as a model material, we examined a new coating process which introduces a pre-wet treatment using a solvent which was chosen to be appropriate for this purpose. With this new coating process, we achieved 65 percent (or more) reduction of the topcoat material consumption compared with the current standard coating process (dynamic coating). From the result of film surface observations and leaching tests, it was learned that the topcoat film properties by the new coating process are equivalent to those by the standard coating process. The process performance after development also indicated good results.