Introduction of ArF lithography has opened the era of sub-90nm patterning. Though the definable feature size was much reduced, poor etch durability and pattern collapse of ArF photoresist make it difficult to extend current patterning process into sub-80nm based on single layer resist scheme. To overcome these obstacles, some alternatives have been proposed, which are composed of thin imaging layer and mask layer with high etch resistance. One of high potential candidates is bi-layer resist (BLR) process, in which Si containing imaging layer is oxidized as a hard mask during dry development. In our previous reports, comparison of several types of bi-layer resists was discussed. Silsesquioxane (SSQ)-based bi-layer resist proved to be the most promising one with no detectable Si outgassing and high Si content. In our experiment, novel SSQ type BLR showed comparable lithographic performance to single layer resist (SLR) in terms of depth of focus (DOF), process window and critical dimension (CD) uniformity for 80-nm node line and space (L/S) patterning. 65nm 1:1 L/S pattern was also resolvable with 0.85 NA ArF scanner in bilayer resist scheme. High selectivity more than 5 was accomplished with vertical profile in the dry development and sub-70nm line patterning could be achieved with trimming technique.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.