Method of treating inlaid copper for improved capping layer adhesion without damaging porous low-k materials
View Patent ↗An exposed surface of inlaid Cu is plasma treated for improved capping layer adhesion while controlling plasma conditions to avoid damaging porous low-k materials. Embodiments include forming a dual damascene opening in a porous dielectric material having a dielectric constant (k) of up to 2.4, e.g., 2.0 to 2.2, filling the opening with Cu, conducting CMP, plasma treating the exposed Cu surface in NH 3 or H 2 at a low power, e.g., 75 to 125 watts, for a short period of time, e.g., 2 to 8 seconds, without etching the porous low-k material and depositing a capping layer, e.g., silicon nitride or silicon carbide.
1. A method of fabricating a semiconductor device, the method comprising:
forming an opening in an upper surface of a porous low-k dielectric layer;
filling the opening with copper (Cu) or a Cu alloy;
conducting chemical-mechanical polishing (CMP) leaving this upper surface of the Cu or Cu alloy exposed; and
treating the upper surface of the Cu or Cu alloy with a plasma while controlling plasma conditions to avoid etching the upper surface of the porous low-k material.
2. The method according to claim 1 , further comprising depositing a capping layer on the treated upper surface of the Cu or Cu alloy.
3. The method according to claim 2 , comprising depositing silicon nitride or silicon carbide as the capping layer.
4. The method according to claim 1 , comprising treating the upper surface of the Cu or Cu alloy in an ammonia (NH 3 ) or hydrogen (H 2 ) plasma.
5. The method according to claim 4 , comprising treating the upper surface of the Cu or Cu alloy with the plasma at a power of 75 to 125 watts.
6. The method according to claim 5 , comprising treating the upper surface of the Cu or Cu alloy with the plasma for 2 to 8 seconds.
7. The method according to claim 4 , comprising treating the upper surface of the Cu or Cu alloy with a plasma for 2 to 8 seconds.
8. The method according to claim 4 , comprising treating the upper surface of the Cu or Cu alloy with an NH 3 plasma at:
an NH 3 flow rate of 100 to 700 sccm;
a nitrogen (N 2 ) flow rate of 2,000 to 9,000 sccm;
a power of 35 to 125 watts;
a pressure of 4.0 to 5.2 torr; and
a temperature of 300° C. to 400° C.; for 2 to 8 seconds.
9. The method according to claim 4 , comprising treating the upper surface of the Cu or Cu alloy with an H 2 plasma at:
a H 2 flow rate of 100 to 400 sccm;
an N 2 flow rate of 200 to 8,000 sccm;
a power of 75 to 125 watts;
a pressure of 4.0 to 5.2 torr; and
a temperature of 300° C. to 400° C.; for 2 to 8 seconds.
10. The method according to claim 4 , comprising forming the opening in a dielectric layer having a dielectric constant (k) up to 2.4.
11. The method according to claim 10 , comprising forming the opening in a dielectric layer having a k value of 2.0 to 2.2.
12. The method according to claim 4 , comprising forming the opening as a dual damascene opening.
13. The method according to claim 1 , comprising depositing a barrier metal layer lining the opening before filling the opening with the Cu or the Cu alloy.
14. The method according to claim 13 , comprising depositing tantalum, tantalum nitride, or a composite of tantalum nitride and alpha (α)-tantalum, as the barrier metal layer.
15. A method of fabricating a semiconductor device, the method comprising:
forming a dual damascene opening in an upper surface of a porous dielectric layer having a dielectric constant (k) up to 2.4;
depositing a barrier metal layer lining the opening;
filling the opening with copper (Cu) or a Cu alloy;
conducting chemical-mechanical polishing (CMP) leaving an upper surface of the Cu or Cu alloy exposed;
treating the exposed upper surface of the Cu or Cu alloy in an ammonia (NH 3 ) or a hydrogen (H 2 ) plasma at a power of 75 to 125 watts for 2 to 8 seconds; and
depositing a capping layer.
16. The method according to claim 15 , comprising treating the exposed upper surface of the Cu or Cu alloy in the plasma at:
an NH 3 flow rate of 100 to 700 sccm;
a nitrogen (N 2 ) flow rate of 2,000 to 9,000 sccm;
a pressure of 4.0 to 5.2 torr; and
at a temperature of 300° C. to 400° C.
17. The method according to claim 15 , comprising treating the exposed upper surface of the Cu or Cu alloy with the plasma at:
a H 2 flow rate of 100 to 400 sccm;
a nitrogen (N 2 ) flow rate of 200 to 8,000 sccm;
a pressure of 4.0 to 5.2 torr; and
a temperature of 300° C. to 400° C.
18. The method according to claim 15 , comprising forming the opening in a dielectric layer have a k value of 2.0 to 2.2.
19. A method according to claim 15 , comprising depositing silicon nitride or silicon carbide as the capping layer.
20. The method according to claim 15 , comprising depositing a layer of tantalum, tantalum nitride, or a composite of tantalum nitride and alpha (α)-tantalum, as the barrier metal layer.