Methods for etching a dielectric barrier layer with high selectivity

1. A method for etching a dielectric barrier layer in an interconnect structure, comprising:

providing a substrate having a portion of a dielectric barrier layer exposed through a dielectric bulk insulating layer in an etch reactor, wherein the dielectric barrier layer is a nitrogen doped carbon containing silicon film (SiCN);

flowing a gas mixture containing at least H 2 gas into the etch reactor; and

etching the exposed portion of the SiCN dielectric barrier layer selectively to the dielectric bulk insulating layer in the presence of a plasma formed from the gas mixture.

2. The method of claim 1 , wherein the flowing the gas mixture further comprises:

flowing a fluorine containing gas accompanying with the H 2 gas into the etch reactor.

3. The method of claim 1 , wherein the flowing the gas mixture further comprises:

flowing at least one insert gas into the etch reactor.

4. The method of claim 1 , wherein the flowing the gas mixture further comprises:

flowing the H 2 at a flow rate between at 5 sccm to about 100 sccm.

5. The method of claim 1 , wherein the etching further comprises:

maintaining a process pressure at between about 10 mTorr to about 200 mTorr;

controlling substrate temperature between about 0 degrees Celsius to about 50 degrees Celsius; and

applying a plasma power between about 100 Watts to about 800 Watts.

6. The method of claim 1 , wherein the SiCN dielectric barrier layer has a dielectric constant less than 5.5, and the dielectric bulk insulating layer has a dielectric constant less then 4.

7. The method of claim 1 , wherein the dielectric bulk layer is a carbon containing silicon oxide film.

8. The method of claim 1 , further comprising:

removing the exposed SiCN dielectric barrier layer; and

exposing an underlying conductive layer disposed below the SiCN dielectric barrier layer on the substrate.

9. The method of claim 2 , wherein the flowing a fluorine containing gas further comprises:

flowing the fluorine containing gas at a flow rate between at about 0 sccm to about 80 sccm.

10. The method of claim 2 , wherein the fluorine containing gas is selected from a group consisting of CH 2 F 2 , CHF 3 , CH 3 F, C 2 F 6 , CF 4 and C 3 F 8 .

11. The method of claim 3 , wherein the flowing an insert gas further comprises:

flowing the insert gas at a rate between at 50 sccm to about 500 sccm.

12. The method of claim 3 , wherein the insert gas is selected from a group consisting of Ar, O 2 , CO, NO, N 2 O, He and N 2 .

13. A method for etching a dielectric barrier layer in an interconnect structure, comprising:

providing a substrate having a portion of a dielectric barrier layer exposed through a dielectric bulk insulating layer in an etch reactor, wherein the dielectric barrier layer is a nitrogen doped carbon containing silicon film (SiCN);

flowing a gas mixture containing H 2 gas and a fluorine containing gas into the etch reactor; and

etching the exposed portion of the SiCN dielectric barrier layer selectively to the dielectric bulk insulating layer in a presence of a plasma formed from the gas mixture.

14. The method of claim 13 , wherein the flowing the gas mixture further comprises:

flowing the hydrogen gas (H 2 ) at a flow rate between at about 5 sccm to about 100 sccm; and

flowing fluorine containing gas at a flow rate between at about 0 sccm to about 80 sccm.

15. The method of claim 13 , wherein the flowing the gas mixture further comprises:

flowing at least one insert gas into the etch reactor, wherein the insert gas is flowed at a flow rate between at about 50 sccm to about 500 sccm.

16. The method of claim 13 , wherein the fluorine containing gas is selected from a group consisting of CH 2 F 2 , CHF 3 , CH 3 F, C 2 F 6 , CF 4 and C 3 F 8 .

17. The method of claim 13 , wherein the flowing a gas mixture further comprises:

maintaining a process pressure at between about 10 mTorr to about 200 mTorr;

controlling substrate temperature between about 0 degree Celsius to about 50 degree Celsius; and

applying a plasma at between about 100 Watts to about 800 Watts.

18. The method of claim 13 , wherein the SiCN dielectric barrier layer has a dielectric constant less than 5.5.

19. The method of claim 15 , wherein the insert gas is selected from a group consisting of Ar, O 2 , CO, NO, N 2 O, He and N 2 .

20. A method for etching a dielectric barrier layer in an interconnect structure, comprising:

providing a substrate having a portion of a dielectric barrier layer exposed through a dielectric bulk insulating layer in an etch reactor, wherein the dielectric barrier layer is a nitrogen doped carbon containing silicon film (SiCN) and the dielectric bulk insulating layer is a carbon containing silicon oxide film;

controlling the substrate temperature between about 0 degrees Celsius to about 50 degrees Celsius;

flowing a gas mixture containing H 2 gas, a fluorine containing gas and at least one insert gas into the etch reactor; and

etching the exposed portion of the dielectric barrier layer selectively to the dielectric bulk insulating layer in the presence of a plasma formed from the gas mixture.

21. The method of claim 20 , wherein the flowing a gas mixture further comprises:

flowing the H 2 gas at a flow rate between about 5 sccm to about 100 sccm;

flowing the fluorine containing gas at a rate between about 0 sccm to about 80 sccm, wherein the fluorine containing gas is selected from a group consisting of CH 2 F 2 , CHF 3 , CH 3 F, C 2 F 6 , CF 4 and C 3 F 8 ; and

flowing the insert gas at a flow rate between about 50 sccm to 500 sccm, wherein the insert gas is selected from a group consisting Ar, O 2 , CO, NO, N 2 O, He and N 2 .

22. The method of claim 20 , wherein the flowing the gas mixture further comprises:

maintaining a process pressure at between about 10 mTorr to about 200 mTorr;

and

applying a plasma at between about 100 Watts to about 800 Watts.