Metal and silicon containing capping layers for interconnects
Disclosed methods cap exposed surfaces of copper lines with a layer of metal or metal-containing compound combined with silicon. In some cases, the metal or metal-containing compound forms an atomic layer. In certain embodiments, the methods involve exposing the copper surface first to a metal containing precursor to form an atomic layer of adsorbed precursor or metal atoms, which may optionally be converted to an oxide, nitride, carbide, or the like by, e.g., a pinning treatment. Subsequent exposure to a silicon-containing precursor may proceed with or without metallic atoms being converted.
1. A method of forming a capping layer on a current carrying metal line of a semiconductor device, the method comprising:
(a) delivering a metal-containing precursor to a reaction chamber holding a partially fabricated semiconductor device having an exposed surface of a metal line, wherein the metal-containing precursor adheres or bonds to the exposed surface of the metal line, wherein the metal-containing precursor comprises a first metal;
(b) delivering a silicon-containing precursor to the reaction chamber; and
(c) forming the capping layer on the metal line by allowing at least a portion of the silicon-containing precursor to interact with the exposed surface of the metal line and/or interact with the metal-containing precursor or first metal.
2. The method of claim 1 , wherein the first metal of the metal-containing precursor is different from the metal of the metal line.
3. The method of claim 1 , wherein the first metal is selected from the group consisting of aluminum, titanium, magnesium, and calcium.
4. The method of claim 1 , wherein operations (b) and (c) overlap in time.
5. The method of claim 1 , further comprising cleaning the exposed surface of the metal line prior to performing operation (a).
6. The method of claim 1 , further comprising removing an oxide from the exposed surface of the metal line prior to performing operation (a).
7. The method of claim 1 , wherein operation (a) comprises a chemical vapor deposition reaction.
8. The method of claim 1 , wherein operation (a) results in the first metal depositing on the exposed surface of the metal line.
9. The method of claim 1 , further comprising converting at least some of the metal-containing precursor or the first metal on the exposed surface of the metal line to a dielectric material.
10. The method of claim 9 , wherein the dielectric material comprises the first metal and an element selected from the group consisting of oxygen, carbon, and nitrogen.
11. The method of claim 9 , wherein converting at least some of the layer of the first metal to a dielectric material is performed prior to operation (c).
12. The method of claim 1 , wherein the metal-containing precursor is not converted to a dielectric material prior to performing operation (c).
13. The method of claim 1 , wherein the silicon containing precursor attaches to the exposed surface of the metal line in interstitial regions where the metal-containing precursor did not adhere or bond to the metal line.
14. The method of claim 1 wherein the metal line comprises copper.
15. The method of claim 1 , wherein the metal line comprises an interconnect in the semiconductor device.
16. The method of claim 1 , wherein the metal-containing precursor is selected from the group consisting of organoaluminum compounds, organomagnesium compounds, organotitanium compounds, and organocalcium compounds.
17. The method of claim 1 , wherein the silicon-containing precursor is selected from the group consisting of silanes and substituted silanes.
18. The method of claim 1 , wherein operation (c) is performed in the presence of a plasma.
19. The method of claim 1 , further comprising forming a diffusion barrier over the capping layer.
20. The method of claim 19 , wherein the diffusion barrier comprises a silicon carbide.
21. The method of claim 1 further comprising:
(i) prior to (a), applying photoresist to a workpiece;
(ii) exposing the photoresist to light;
(iii) patterning the resist and transferring a pattern to the workpiece, wherein the pattern defines locations of the metal lines; and
(iv) selectively removing the photoresist from the work piece.