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 H 2 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.

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 H 2  gas in the reactor; and   etching 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; and   applying 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 CH 2 F 2 , CHF 3 , CH 3 F, C 2 F 6 , CF 4  or C 3 F 8 . 
   
   
       7 . The method of  claim 3 , wherein the insert gas is at least one of Ar, O 2 , CO, NO, N 2 O, He or N 2 . 
   
   
       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; and   exposing 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 H 2  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; and   exposing 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 CH 2 F 2 , CHF 3 , CH 3 F, C 2 F 6 , CF 4  and C 3 F 8 . 
   
   
       13 . The method of  claim 12 , wherein the gas mixture further comprises:
 an insert gas selected from a group consisting of Ar, O 2 , CO, NO, N 2 O, He and N 2 .   
   
   
       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; and   applying 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 H 2  gas and a fluorine containing gas into the reactor; and   forming a plasma from the gas mixture in the reactor; and   etching 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 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 .   
   
   
       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; and   applying a plasma at between about 100 Watts to about 800 Watts.