A silicon-added bilayer resist (SABRE) process for high-resolution optical lithography

There has been considerable recent interest in silicon-containing or silicon-receptive materials for use in improved-resolution optical and e-beam lithography. Inherent in such materials is the promise of trilayer lithographic performance in much simpler bilayer or even single-layer resist processes. Unfortunately, formulating photoresists with the necessary amount of silicon tends to dilute their performance, either by reducing their resolution or by lowering their Tg. Other approaches reverse the usual pattern polarity or are sensitive to flare light. Introduced here is a new bilayer process of positive polarity that uses conventional novolac resist materials. In this process, Silicon is added to the thin top resist layer after it is exposed and developed, with no loss in resist performance. Accordingly, we have selected the name SABRE for Silicon-Added Bilayer REsist.