Materials Challenges for sub-20nm lithography

This paper discusses the future of resist materials for sub-20nm lithography. It is my contention that polymer-bound PAG based resists will be used to 16nm node. There has been enough progress in resolution and sensitivity to justify the use of these materials. PBP resists have shown that the principal demerit of acid diffusion can be overcome through attachment of the PAG anion to the lithographic polymer. Since the introduction of this chemically amplified resist approach, we have seen steady improvement in resolution, sensitivity, and LWR. We have also seen improvement in OOB response, outgassing, and pattern collapse. There is no doubt that continuous improvement is still required for these resist systems. We believe that increasing the overall resist quantum yield for acid generation substantially improves the shot noise problem thereby leading to faster high resolution resist materials. Using a 0.30NA EUV tool with dipole, we can achieve 22nm hp resolution, with 12mJ dose, and 4.2nm LWR.