Optimization of hardmask for dual anti-reflection layers

The continuous shrinkage of critical dimensions has driven ArF lithography to resolve very small features and ever thinner resist films to prevent pattern collapse. Also importance of hardmask technology is becoming increasingly evident as the demand for both the critical dimension control and sufficient thickness of etch mask. We have developed a silicon based hardmask prepared by plasma-enhanced chemical vapor deposition (PECVD) to match organic anti-reflective coating (ARC). The ordinary single dielectric ARC or organic ARC is very sensitivity to the substrate topology. Dual ARC (dielectric ARC + organic ARC) perform a less CD variation than single ARC. In addition, this material can serve as an effective hardmask etch barrier during the plasma etch. The most advantage of Dual ARC is that we have good critical dimension uniformity (CDU) regardless of substrate thickness variation.