Responding to the Challenge: Materials Design for Immersion Lithography

The performance of an experimental dry 193 nm photoresist, T83645, in dry an immersion applications is discussed. It is found that this resist exhibits good lithographic properties under both dry an immersion conditions and has no discernible impact of length and frequency of immersion. However, it still shows leaching levels in excess of the specifications set by tool vendors to prevent lens damage, and it suffers from immersion-specific, droplet-type defects related to the low receding contact angle typical of dry resists. Approaches to lower leaching are discussed, and a modified polymer design is presented that leads to materials with greatly improved contact angles, thus allowing higher scan speeds.