Corrosion at the grain boundary and a fluorine-related passivation layer on etched Al-Cu (1%) alloy surfaces

After etching Al-Cu alloy films using SiCl4/Cl2He/ CHF3 mixed gas plasma, t he corrosion phenomenon at the grain boundary of the etched surface and a p assivation layer on the etched surface with an SF6 plasma treatment subsequ ent to the etching were studied. In Al-Cu alloy system, corrosion occurs ra pidly on the etched surface by residual chlorine atoms, and it occurs domin antly at the grain boundaries rather than the crystalline surfaces. To prev ent corrosion, the SF6 gas plasma treatment subsequent to etching was carri ed out. The passivation layer is composed of fluorine-related compounds on the etched.41-Cu surface after the SF6 treatment, and it suppresses effecti vely corrosion on the surface as the SF6 treatment pressure increases. Corr osion could be suppressed successfully with the SF6 treatment at a total pr essure of 300 mTorr: To investigate the reason why corrosion could be suppr essed with the SF6 treatment, behaviors of chlorine and fluorine were studi ed by various analysis techniques, It was also found that the residual chlo rine incorporated at the grain boundary of the etched surface accelerates c orrosion and could not be re moved after the SF6 plasma treatment.