SAN FRANCISCO—Novellus Systems Inc. said Wednesday (Nov. 9) it has developed new ceramic hard mask (CHM) materials for use in sub-22-nm patterning applications.
Deposited using Novellus' Vector plasma-enhanced chemical vapor deposition (PECVD) platform, the new materials allow for the controlled incorporation of dopants into the company's family of silicon carbide and silicon nitride films, Novellus (San Jose, Calif.) said.
Hard mask films are often used as an aid in patterning applications for back-end-of-line (BEOL) inter-level dielectric (ILD) materials. These hard mask films should have a high etch selectivity with respect to the ILD material, be compatible with basic lithography processes and be capable of removal without damaging the underlying ILD layer.
Titanium nitride (TiN), which has a high etch selectivity with respect to ILD, is typically used as a metallic hard mask. But, according to Novellus, as device dimensions shrink below the sub-22-nm technology node, there is a series of integration challenges associated with using this film. These range from high compressive stress, which causes the mechanically weak, ultra-low k ILD to deform (resulting in pattern distortion) to compatibility issues with the polymer formed to protect the ULK sidewall during the etch process, according to Novellus.
Novellus said its CHM materials, in contrast, present several advantages compared to TiN hard masks.
In addition to productivity advantages afforded by ceramic hard masks, the films demonstrate excellent technical performance, according to Novellus.
"The introduction of porous ULK materials in sub-28-nm technologies brings new challenges that present opportunities for novel materials," said Sesha Varadarajan, senior vice president of Novellus' PECVD business unit. "Ceramic hard mask materials deposited on the Vector platform represent a replacement candidate for the TiN hard mask."