Critical dimension control for self-aligned contact patterning

A method of forming a contact pattern, the method comprising:

• providing a substrate having a substrate surface with a feature therein, the feature having sidewalls and a bottom;
• forming a conformal tungsten film in the feature, leaving a gap between the tungsten film on the sidewalls of the feature;
• filling the gap in the tungsten film with a gapfill material;
• and
• volumetrically expanding the tungsten by nitridation to grow two pillars of tungsten nitride extending above the substrate surface.

A method of forming a contact pattern, the method comprising:

• providing a substrate having a substrate surface with a feature therein, the feature having sidewalls and a bottom and a width in the range of about 10 nm to about 30 nm;
• forming a conformal tungsten film in the feature by atomic layer deposition leaving a gap between the tungsten film on the sidewalls of the feature, the conformal tungsten film having an average thickness in the range of about 2 nm to about 10 nm;
• filling the gap in the conformal tungsten film with a gapfill material comprising a dielectric;
• volumetrically expanding the tungsten by nitridation to grow two pillars of tungsten nitride straight up to extend above the substrate surface;
• removing the two pillars of tungsten nitride to leave two openings;
• and
• depositing a contact material in the openings.