METHODS FOR ETCHING A DIELECTRIC BARRIER LAYER WITH HIGH SELECTIVITY

Abstract

Methods for etching a dielectric barrier layer with high selectivity to a dielectric bulk insulating layer are provided. In one embodiment, the method includes providing a substrate having a portion of a dielectric barrier layer exposed through a dielectric bulk insulating layer in a reactor, flowing a gas mixture containing H2 gas, fluorine containing gas, at least an insert gas into the reactor, and etching the exposed portion of the dielectric barrier layer selectively to the dielectric bulk insulating layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.

FIGS. 1A-1D are sectional views of exemplary interconnect structures;

FIG. 2 is a schematic cross-sectional view of a plasma reactor used according to one embodiment of the invention;

FIG. 3 is a flow diagram of one embodiment of a dielectric barrier layer removal process on an interconnect structure according to one embodiment of the invention; and

FIGS. 4A-4B are sectional views of one embodiment of an interconnect structure having an exposed dielectric barrier layer disposed on a substrate.

Claims

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 having a dielectric constant less than 5.5 exposed through a dielectric bulk insulating layer in a reactor;forming a plasma from a gas mixture containing at least H2 gas in the reactor; andetching the exposed portion of the dielectric barrier layer selectively to the dielectric bulk insulating layer with the plasma formed in the reactor, wherein the selectivity is at least 5.

2. The method of claim 1, wherein the gas mixture from which the plasma is formed further comprises: a fluorine containing gas.

3. The method of claim 1, wherein the gas mixture from which the plasma is formed further comprises: at least one insert gas.

4. The method of claim 1, wherein the dielectric barrier layer selectively to the dielectric bulk insulating layer is 15.

5. The method of claim 1, wherein the step of 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; andapplying a plasma power between about 100 Watts to about 800 Watts.

6. The method of claim 2, wherein the fluorine containing gas is at least one of CH2F2, CHF3, CH3F, C2F6, CF4 or C3F8.

7. The method of claim 3, wherein the insert gas is at least one of Ar, O2, CO, NO, N2O, He or N2.

8. The method of claim 1, wherein the dielectric insulating layer has a dielectric constant less then 4.

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

10. The method of claim 1, further comprising: removing the exposed dielectric barrier layer; andexposing an underlying conductive layer disposed below the dielectric barrier layer on the substrate.

11. A method for etching a dielectric barrier layer in an interconnect structure, comprising: providing a substrate having a portion of a dielectric barrier layer having a dielectric constant less than 5.5 exposed through a dielectric bulk insulating layer having a dielectric constant less then 4 in a reactor;flowing a gas mixture containing H2 gas and a fluorine containing gas into the reactor;etching the exposed portion of the dielectric barrier layer in a presence of a plasma formed from the gas mixture; andexposing an underlying conductive layer disposed below the dielectric barrier layer on the substrate.

12. The method of claim 11, wherein the fluorine containing gas is at least one of CH2F2, CHF3, CH3F, C2F6, CF4 and C3F8.

13. The method of claim 12, wherein the gas mixture further comprises: an insert gas selected from a group consisting of Ar, O2, CO, NO, N2O, He and N2.

14. The method of claim 11, wherein the step of 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; andapplying a plasma at between about 100 Watts to about 800 Watts.

15. The method of claim 11, wherein the dielectric barrier layer is a carbon containing silicon film.

16. 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 having a dielectric constant less then 4 in a reactor, wherein the dielectric barrier layer is a carbon containing silicon film;flowing a gas mixture containing H2 gas and a fluorine containing gas into the reactor; andforming a plasma from the gas mixture in the reactor; andetching the exposed portion of the dielectric barrier layer selectively to the dielectric bulk insulating layer with the plasma formed in the reactor, wherein the selectivity is at least 5.

17. The method of claim 16, wherein the step of flowing a gas mixture further comprises: flowing the H2 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 CH2F2, CHF3, CH3F, C2F6, CF4 and C3F8; andflowing 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, O2, CO, NO, N2O, He and N2.

18. The method of claim 16, wherein the step of flowing the gas mixture 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; andapplying a plasma at between about 100 Watts to about 800 Watts.