Characterization of the manufacturability of ultrathin resist

A study was conducted to explore the manufacturability of ultrathin resist by focusing on two key issues, defects and etch resistance. Defects in ultrathin resist were characterized by optical inspection and scanning electron microscopy reviews. A number of representative defect types in the ultrathin resist/hardmask process were identified. With process optimization, defect density in ultrathin resist was reduced to levels that are comparable to that of a baseline 0.5 μm thick resist process on nontopographic wafers. Etch resistance sufficient for patterning metal–oxide–semiconductor transistor gate film stacks was demonstrated for a 100–150 nm thick resist layer.