Lithographic feasibility of escap beyond quarter micron

A production-worthy deep UV resist system built on the ESCAP platform is described. The resist consists of a thermally and hydrolytically stable resin and acid generator and thus can be heated at high temperatures for free volume reduction, which provides stabilization toward airborne base contamination. The film densification in conjunction with the use of a bulky acid reduces acid diffusion during postexposure bake, contributing to high lithographic performance. Robust 0.25 Jim process latitudes have been demonstrated. Furthermore, the resist has produced excellent 175 nm line/space images with a depth-of-focus of 0.3 u,m on a KrF excimer laser stepper with a numerical aperture of 0.60, indicating that the resist allows the use of the current exposure tool in the early 1 Gbit generation. 01996 TAPJ.