Metal capping process and processing platform thereof
Before depositing a metal capping layer on a metal interconnect in a damascene structure, a remote plasma is used to reduce native oxide formed on the metal interconnect. Accordingly, a remote plasma reducing chamber is integrated in a processing platform for depositing a metal capping layer.
1. A method of forming a metal capping layer on a metal interconnect, the method comprising:
embedding a copper interconnect in a substrate;
degassing the copper interconnect and the substrate under a non-oxidative gas at a pressure of 10 −3 -10 −8 Torr to decrease a thickness of a native oxide layer formed on the copper interconnect;
reducing the native oxide layer by a remote plasma generated by a reducing gas containing hydrogen; and
forming a cobalt capping layer on the copper interconnect.
2. The method of claim 1 , wherein the reducing gas is hydrogen gas or ammonium gas.
3. The method of claim 2 , wherein a plasma density of the remote plasma is 10 6 -10 13 cm −3 .
4. The method of claim 2 , wherein the reducing step is performed at a pressure of 10-1000 mTorr.
5. The method of claim 2 , wherein the reducing step is performed at a temperature of 25-400° C.
6. The method of claim 2 , wherein the reducing step is performed for 10 seconds to 10 minutes.
7. The method of claim 1 , wherein the cobalt layer is formed by a selective deposition method.
8. The method of claim 1 , wherein degassing the copper interconnect and the substrate is at a temperature of 200-400° C.
9. The method of claim 1 , wherein the non-oxidative gas is argon or hydrogen.
10. A method of forming a metal capping layer on metal interconnects, the method comprising:
embedding metal interconnects in a wafer;
degassing the wafer and the metal interconnects to decrease a thickness of native oxide formed on the metal interconnects under a non-oxidative gas at a pressure of 10 −3 -10 −8 Torr in a degassing chamber;
reducing the native oxide by a remote plasma in a remote plasma reducing chamber of a processing platform; and
depositing a metal capping layer on the reduced metal interconnects in a chemical vapor deposition chamber of the processing platform.
11. The method of claim 10 , wherein a source gas of the remote plasma is hydrogen or ammonium.
12. The method of claim 11 , wherein a plasma density of the remote plasma is 10 6 -10 13 cm −3 .
13. The method of claim 11 , wherein the reducing step is performed at a pressure of 10-1000 mTorr.
14. The method of claim 11 , wherein the reducing step is performed at a temperature of 25-400° C.
15. The method of claim 11 , wherein the reducing step is performed for 10 seconds to 10 minutes.
16. The method of claim 10 , wherein the metal interconnects are made from copper.
17. The method of claim 16 , wherein the metal capping layer is a cobalt layer.
18. The method of claim 17 , wherein the cobalt layer is formed by a selective deposition method.
19. The method of claim 10 , wherein the non-oxidative gas is argon or hydrogen.
20. The method of claim 10 , wherein degassing the wafer and the metal interconnects at a temperature of 200-400° C.