Method for fabricating air gap for semiconductor device

A method for fabricating an interconnect structure in a semiconductor device, comprising:

• forming a dielectric layer on a substrate;
• forming a masking layer on the dielectric layer, comprising at least one opening to expose the dielectric layer;
• etching the exposed dielectric layer to transfer the opening into the dielectric layer;
• performing a plasma stripping process to remove the masking layer, such that a damaged sidewall portion of the dielectric layer surrounding the opening therein is formed;
• filling the opening in the dielectric layer with a conductive element;
• removing the damaged sidewall portion of the dielectric layer to form a gap between the dielectric layer and the conductive element, wherein metal ion impurities from removal of the damaged sidewall portion of the dielectric layer are formed on the conductive element;
• and
• removing the metal ion impurities.

A method for fabricating an interconnect structure in a semiconductor device, comprising:

• forming a dielectric layer on a substrate;
• forming a masking layer on the dielectric layer, comprising at least one opening to expose the dielectric layer;
• etching the exposed dielectric layer to transfer the opening into the dielectric layer;
• performing a plasma stripping process to remove the masking layer, such that a damaged sidewall portion of the dielectric layer surrounding the opening therein is formed;
• filling the opening in the dielectric layer with a conductive element;
• removing the damaged sidewall portion of the dielectric layer to form a gap between the dielectric layer and the conductive element, wherein metal ion impurities and particles from removal of the damaged sidewall portion of the dielectric layer are formed on the conductive element;
• and
• removing the metal ion impurities and the particles by brush scrubbing using a citric acid solution.