Strain-controlled boron and nitrogen doping of amorphous carbon layers for hard mask applications

Nitrogen- and boron-doped amorphous carbon layers (ACLs) were grown by plasma- enhanced chemical vapor deposition (PECVD) on a Si substrate and characterized by Raman and X-ray photoelectron spectroscopy (XPS) techniques. Increasing doping levels resulted in a shift in the Raman G-peak of the doped ALCs, indicating a change in bond lengths upon doping. The XPS N1s and B1s spectra revealed the presence of different types of N-related (involving pyridinic, pyrrolinic, and graphitic N) and B-related (corresponding to BC₂O and [Formula presented] species) bonds in the N- and B-doped ACLs, with N and B doping levels ranging from 2.03 to 3.94 at.% and from 1.44 to 10.4 at.%, respectively. These results suggest that the dry etch resistance of the present ACLs was enhanced by B doping and negatively affected by N doping. Density functional theory calculations highlighted the strengthening of [Formula presented] bonds induced by B doping and their corresponding weakening caused by N doping as possible explanations for the effects of doping on the dry etching characteristics of the ACLs.