Method of forming a metal interconnect

A method of forming a metal interconnect, the method comprising:

• providing a semiconductor substrate, the semiconductor substrate comprising a conductive area, a first dielectric layer covering the semiconductor substrate and the conductive area;
• performing a photo-etching-process (PEP) on the first dielectric layer to form at least one recess in the first dielectric layer down to a surface of the conductive area;
• forming a first titanium nitride (TiN) layer and a tungsten (W) layer sequentially on surfaces of the first dielectric layer and the recess, the tungsten layer and the first titanium nitride layer being not filling the recess entirely;
• forming a second titanium nitride layer on the surface of the tungsten layer to seal an opening of the recess;
• forming a patterned photoresist layer on the surface of the second titanium nitride layer to define at least one pattern of a metal interconnect;
• performing an etching process to remove portions of the second titanium nitride layer, the tungsten layer and the first titanium nitride layer not covered by the photoresist layer to form the metal interconnect;
• removing the photoresist layer;
• and
• forming a second dielectric layer to cover the metal interconnect and the first dielectric layer.

A method of preventing residue photoresist in a metal interconnect, the method comprising:

• providing a semiconductor substrate, the semiconductor substrate comprising a conductive area, a first dielectric layer covering the semiconductor substrate and the conductive area;
• performing a photo-etching-process (PEP) on the first dielectric layer to form at least one recess in the first dielectric layer down to a surface of the conductive area;
• forming a glue layer and a tungsten (W) layer sequentially on surfaces of the first dielectric layer and the recess, the tungsten layer and the glue layer being not entirely filling the recess;
• forming a titanium nitride (TiN) layer on the surface of the tungsten layer to seal an opening of the recess;
• forming a patterned photoresist layer on the surface of the titanium nitride layer to define at least one pattern of a metal interconnect;
• performing an etching process to remove portions of the titanium nitride layer, the tungsten layer and the glue layer not covered by the photoresist layer to form the metal interconnect;
• removing the photoresist layer;
• and
• forming a second dielectric layer to cover the metal interconnect and the first dielectric layer;
• wherein the titanium nitride layer is formed by utilizing a deposition process, having a poor step coverage ability, to seal the opening of the recess so as to prevent the photoresist layer from remaining in the recess.