Dry etching mechanism of copper and magnetic materials with UV illumination

To better understand the dry etching of copper and magnetic materials with UV illumination an etch mechanism is proposed based on the subprocesses occurring in an inductively coupled plasma (ICP) reactor. The photo-dissociation of Cl2 provides chlorine-enriched environment near the surface, and UV photons enhance the surface reaction, leading to fast formation of metal chlorides on the surface with low activation energy. The overall etching process of metals with UV illumination is limited by absorption capacity of UV radiation by reaction products. The proposed etch mechanism also showed the potential gaseous etch products are CuCl, CuCl2, Cu2Cl, Cu2Cl2, Cu2Cl3, Cu3Cl2 and Cu3Cl3, while the dominant gas species are CuCl2 and Cu2Cl3 with UV illumination. The ICP etching of magnetic materials in Cl2/Ar discharges with UV illumination showed no enhancement in etch rate for NiFe, but a substantial enhancement for NiFeCo mainly due to the lower binding energy of NiFeCo relative to NiFe.