Design and development of plasma enhanced chemical vapor deposition universal antireflective layer films for deep subquarter micron deep ultraviolet applications

Abstract

A dual-layer, oxynitride film stack functions as a universal antireflective layer (UARL) for patterning deep subquarter micron features on transparent dielectric films. The UARL optical constants at 248 nm are n=1.96 and k=0.3 for top layer and n=2.24 and k=1.04 for bottom layer with film thickness 360 and 650 A, respectively. The bottom UARL layer absorbs most of the incoming light, minimizing the light reflected from the underlying substrate. Therefore, the reflectance back into the photoresist is a few tenths of one percent and is independent of the substrate material’s optical properties and structures. Results of patterning 0.18 μm photoresist lines with the UARL on various Damascene film stacks show very tight critical dimension control.