Structure and process for W contacts
Structures and processes include a single metallization step for forming a metal nitride liner layer suitable for contact formation. The structure and processes generally includes forming a nitrogen-enriched surface in a deposited metal liner layer or forming a nitrogen-enriched surface in the dielectric material prior to deposition of the metal liner layer. In this manner, nitridization of the metal occurs upon deposition of nitrogen ions into the metal liner layer and/or as a function of additional conventional processing in fabricating the integrated circuit such that the deposited nitrogen ions diffuse into at least a portion of the metal liner layer. As a consequence, only a single metal layer deposition step is needed to form the metal liner layer.
1. A method for forming an integrated circuit comprising:
providing a patterned substrate comprising a contact hole in a dielectric layer, wherein the contact hole includes sidewalls formed of the dielectric layer and a bottom surface defined by a source/drain region or a metal gate;
generating nitrogen ions from a nitrogen containing gas selected from the group consisting of nitrogen (N 2 ) and ammonia (NH 3 );
exposing the substrate including the dielectric layer to form a nitrogen enriched dielectric layer at about a surface of the dielectric layer;
conformally depositing a single metal liner layer onto the patterned substrate and forming a metal nitride at an interface between the single metal liner layer and the nitrogen enriched dielectric layer and into at least a portion of the metal liner layer;
depositing a tungsten metal into the contact hole, wherein the tungsten metal is in direct contact with the nitrogen enriched metal liner layer; and
removing regions of the tungsten metal and regions of the metal nitride on a top surface of the dielectric layer such that the tungsten metal is coplanar to the top surface of the dielectric layer.
2. The method of claim 1 , wherein generating the nitrogen ions from the nitrogen containing gas comprises exposing the energy source effective to generate the nitrogen ions from the nitrogen containing gas.
3. The method of claim 1 , wherein the energy source is a plasma energy source.
4. The method of claim 1 , wherein the energy source is thermal energy source.
5. The method of claim 1 , wherein the metal liner layer is formed of a metal selected from the group consisting of tantalum (Ta), titanium (Ti), ruthenium (Ru), iridium (Ir) tungsten (W), Co (cobalt) and mixtures thereof.
6. The method of claim 1 , further comprising selectively removing the nitrogen from a bottom surface of the contact hole prior to depositing the single metal liner layer, wherein the single metal liner layer is in direct contact with the bottom surface of the contact hole such that the metal liner layer contacts the source/drain regions or the metal gate and is free of nitrogen enrichment.
7. The method of claim 1 , wherein removing regions of the tungsten metal and regions of the metal nitride on a top surface of the dielectric layer comprises a chemical mechanical polishing process.
8. The method of claim 1 , wherein removing regions of the tungsten metal and regions of the metal nitride on a top surface of the dielectric layer comprises a blanket reactive ion etch process.