By Cameron Chai
Novellus Systems has introduced a ceramic hard mask (CHM) materials that find applications in sub-22nm patterning. The hard mask material is deposited with the help of the company’s VECTOR plasma-enhanced chemical vapor deposition (PECVD) platform and they permit controlled dopant incorporation into silicon carbide and silicon nitride films of the company.
Typically dry etch rates and CMP rates of ceramic hard mask films
Hard mask films must have a high etch selectivity relative to inter-level dielectric (ILD) material, have good compatibility with lithography, and should be removable without causing any damage to the ILD layer. Titanium nitride (TiN) can be used as a hard mask film as it has a high etch selectivity. However, there are integration problems associated with these films at lower dimensions below sub-22nm technology.
The CHM materials are distinctly more advantageous than the TiN hard masks. The removal of these films is performed using chemical mechanical polishing (CMP). The CHM film eliminates the line bending issues and offers efficient etch selectivity to ultra-low k. The dielectric etchers of the fab’s production flow can be used to etch these films without using additional metal etchers. The etch by-products of CHM materials can be managed without stringent queue time controls thereby enhancing the manufacturability. These films offer low tensile, high modulus and low etch rates when compared to the TiN hard masks.
Sesha Varadarajan, Novellus’ senior vice president, said that the opportunity for new materials is increased by introducing porous ULK materials in sub-28nm technologies. She added on that the integration concerns related with metal hard masks are resolved with the introduction of this new technology, and the PECVD deposition techniques used are cost effective. She also stated that these CHM films are a good substitute the TiN hard masks.