Plasma etching of Cu-containing layers
A method and apparatus are provided for plasma etching of Cu-containing layers in semiconductor devices using an aluminum source in the presence of a halogen-containing plasma. The aluminum source reacts with halogenated Cu-containing surfaces and forms volatile etch products that allows for anisotropic etching of Cu-containing layers using conventional plasma etching tools.
1. A method of processing a copper-containing layer in a plasma etcher, the method comprising:
providing a copper-containing layer overlying a substrate;
introducing a process gas;
forming a plasma from said process gas;
introducing from a common source an aluminum-containing material into the plasma etcher from an ex situ commercially available gaseous source of aluminum by separate injection from the common source of the aluminum-containing material both into a plasma processing region proximate the substrate and into an exterior region removed from the substrate; and
etching said copper-containing layer by exposing said copper-containing layer to said plasma and said aluminum-containing material, wherein said process gas reacts with said copper-containing layer.
2. The method according to claim 1 , wherein said aluminum-containing material comprises an amine alane gas.
3. The method according to claim 1 , wherein said aluminum-containing materials comprises a trialkyl aluminum gas.
4. The method according to claim 1 , wherein said aluminum-containing materials comprises a dialkyl aluminum hydride gas.
5. The method according to claim 1 wherein said substrate is maintained at a temperature below 200° C.
6. The method according to claim 1 wherein said substrate is maintained at a temperature below 150° C.
7. The method according to claim 1 wherein said substrate is maintained at a temperature below 100° C.
8. The method according to claim 1 , wherein said copper-containing layer comprises at least one of a pure Cu layer and an Al—Cu alloy.
9. The method according to claim 1 , wherein said process gas comprises a chlorine-containing gas.
10. The method according to claim 9 , wherein said chlorine-containing gas comprises at least one of Cl 2 , HCl, BCl 3 , SiCl 4 , CHCl 3 , CCl 4 , and aluminum chloride.
11. The method according to claim 1 , wherein said process gas further comprises an inert gas.
12. The method according to claim 11 , wherein said inert gas comprises at, least one of argon, helium, krypton, xenon, and nitrogen.
13. The method according to claim 1 , wherein said aluminum-containing material comprises an aluminum halide gas.
14. The method according to claim 13 , further comprising introducing at least one of argon, helium, krypton, xenon, and nitrogen.
15. The method according to claim 13 , wherein a flowrate of the aluminum halide is less than 1000 sccm.
16. The method according to claim 13 , wherein the aluminum halide gas comprises an aluminum halide gas in plasma form.
17. The method according to claim 13 , wherein said aluminum halide gas comprises an aluminum chloride gas.
18. The method according to claim 17 , wherein a flowrate of the aluminum chloride is less than 1000 sccm.
19. The method according to claim 17 , wherein the step of etching comprises etching said copper-containing layer using the aluminum chloride gas in gaseous form.