Practical Implementation of Immersion Resist Materials

摘要

Immersion lithography has gone through its first phase of introduction and acceptance as the main solution for criticallayer lithography for 45nm node and beyond. In this phase, the industry has found that immersion technology has itsown unique challenges associated with introducing water as a medium between the projection lens and wafer. Resistprocess qualification is once again under the spot light. Due to the rapid introduction of immersion technology resist suppliers did not have sufficient time toreformulate their standard ArF resist processes to be compatible with water while at the same time satisfying criticalimaging, etching and other requirements. For this reason a barrier (topcoat) had to be introduced in order to preventresist leaching as well as to produce a more desirable surface for water to glide over. Introducing a top-coat createdchallenges for all parties involved: scanner manufacturers resist vendors and the end users. Since each manufacturer hasits own unique technology for introducing immersion water, top-coat/resist processes needed not only to meet the endusers' performance criteria but also meet each scanner manufacturer's requirements. Therefore material screeningprocess and process evaluation became an important factor in immersion technology processes. Defectivity became theprimary criterion for the resist process.