Post-etch treatment of plasma-etched feature surfaces to prevent corrosion

DETAILED DESCRIPTION We have discovered a post-etch treatment for plasma-etched, metal-comprising feature surfaces which significantly reduces or eliminates surface corrosion of the etched feature.
As a part of the post etch treatment, we have determined that it is particularly important to prevent the formation of moisture on the surface of the feature surface prior to an affirmative treatment to remove corrosion-causing contaminants from the feature surface.
The moisture forms an acid upon contact with several of the corrosion-causing contaminants.
Presence of the acid both enables side reactions which increase the number of modes of corrosion as well as increases the rate of corrosion in many instances.
Avoidance of moisture formation is assisted by use of a high vacuum, use of an inert, moisture-free purge gas, and by maintaining the substrate at a sufficiently high temperature to volatilize moisture.
We have also discovered that if moisture does form on the feature surface prior to an affirmative treatment to remove corrosion-causing contaminants, it is very important to avoid contact of the feature surface with pollutants present in the ambient surrounding the etched feature surface.
The use of a high vacuum ambient is helpful; the use of an inert purge gas which constantly sweeps the feature surface to prevent pollutants resident in the process environment from contacting the etched surface is also helpful.
The avoidance of feature surface contact by pollutants increases the amount of time permissible between the end of the etch step and the beginning of the affirmative post-etch treatment, all other factors held constant.
The post-etch treatment which utilizes a plasma includes exposure of the etched, metal-comprising feature surface to sufficient hydrogen which is in a kinetic state permitting reaction with residual halogen-comprising residues on the etched copper surface, while maintaining the etched feature surface at a temperature which supports volatilization of the byproducts of the reaction between the active hydrogen species and the halogen-comprising residues