Novolak resin for ultrafast high-resolution positive i-line photoresist compositions

An improved process for isolation of novolak resins from phenol-formaldehyde condensation products has been developed. The process results in resins having low polydispersity and higher photospeed while typical phenol/formaldehyde resin syntheses generate a broad distribution of molecular weight fragments with a wide polydispersity. The novolak resins were characterized by NMR and GPC and were formulated to obtain ultra fast high resolution i-line photoresists. The characteristics of the resins and their effect on lithographic properties as i-line photoresist compositions will be discussed in this paper.