Critical dimension control for self-aligned contact patterning
Processing methods to create self-aligned contacts are described. A conformal liner can be deposited in a feature in a substrate surface leaving a gap between the walls of the liner. A tungsten film can be deposited in the gap of the liner and volumetrically expanded. The expanded film can be removed and replaced with a contact material to a make a contact. In some embodiments, a conformal tungsten film can be formed in the feature leaving a gap between the walls. A dielectric can be deposited in the gap and the conformal tungsten film can be volumetrically expanded to grow two pillars. The pillars can be removed and replaced with a contact material to make two contacts.
1. A method of forming a contact pattern, the method comprising:
providing a substrate having a substrate surface with a feature, the feature having sidewalls and a bottom;
forming a conformal liner in the feature, leaving a gap between the conformal liner on the sidewalls of the feature;
filling the gap between the sidewalls of the conformal liner with tungsten; and
volumetrically expanding the tungsten by nitridation to grow a pillar of tungsten nitride extending above the substrate surface.
2. The method of claim 1 , wherein the tungsten is deposited by atomic layer deposition.
3. The method of claim 1 , wherein volumetrically expanding the tungsten grows a pillar of tungsten nitride straight up to extend above the substrate surface.
4. The method of claim 1 , wherein the gap between the sidewalls of the conformal liner has a width less than or equal to about 10 nm.
5. The method of claim 1 , wherein the conformal liner comprises a low-k dielectric.
6. The method of claim 5 , wherein the conformal liner comprises multiple layers, wherein at least one layer is a low-k dielectric.
7. The method of claim 6 , wherein at least one layer of the multiple layers comprises TaN.
8. The method of claim 5 , wherein the low-k dielectric comprises one or more of SiN, SiCN, SiO 2 , TiN, TaN, TiSiN, Si or C.
9. The method of claim 1 , wherein the conformal liner has an average thickness in the range of about 2 nm to about 15 nm.
10. The method of claim 9 , wherein the feature has a width in the range of about 15 nm to about 40 nm and the conformal liner has an average thickness sufficient to form a gap in the conformal liner with a width in the range of about 5 nm to about 15 nm.
11. The method of claim 1 , further comprising removing the tungsten nitride pillar to leave an opening and depositing a contact material in the opening.
12. 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.
13. The method of claim 12 , further comprising removing the pillars to leave two openings and depositing a contact material in the openings.
14. The method of claim 12 , wherein the conformal tungsten film is formed by atomic layer deposition.
15. The method of claim 12 , wherein volumetrically expanding the tungsten grows pillars of tungsten nitride straight up to extend above the substrate surface.
16. The method of claim 12 , wherein the conformal tungsten film has an average thickness in the range of about 2 nm to about 10 nm.
17. The method of claim 12 , wherein the conformal tungsten film has an average thickness in the range of about 2 nm to about 5 nm and the conformal tungsten film is substantially continuous.
18. The method of claim 12 , wherein the gapfill material comprises a dielectric.
19. The method of claim 12 , wherein the feature has a width in the range of about 10 nm to about 30 nm.
20. 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.