Pursuit of Lower Critical Dimensional Uniformity in EUV Resists

This paper describes Dow’s efforts toward improved Critical Dimensional Uniformity (CDU) in EUV resists. Many non-material related factors contribute to good CDU, such as aerial image quality. We have focused on fundamental resist properties like intrinsic dissolution contrast and we have found that the photo-decomposable base (PDB) concept can be successfully employed. With the use of a PDB, we can reduce CDU variation at lower exposure energies. For sensitivity, we have focused on more efficient EUV photon capture through increased EUV absorption, as well as more highly efficient PAGs for greater acid generating efficiency. The formulation concepts will be confirmed using Prolith stochastic resist modeling. For the 26nm hp contact holes, we observe excellent overall process window with over 280nm depth of focus for a 10% exposure latitude Process window. The 1σ CDU is 1.1 nm. We also obtain 20nm hp contact resolution in one of our new EUV resists.