Abstract
A quarter micron lithography (0.25-0.2μm) required for 256M DRAM fabrication is discussed. KrF excimer laser lithography combined with a phase-shifting mask (PSM), optics innovation such as an annular illumination technology, chemically amplified resist material, and resist process improvement will make possible the fabrication of a 0.25μm pattern. Reflection type system with an ArF excimer laser source is attractive for an about 0.2μm pattern fabrication. Electron beam (EB) lithography is especially important for 256M DRAM class reticle production. EB direct writing has become an important technology for the device development stage. X- ray lithography might be the next generation technology for a less than 0.2μm region.
