Sidewall inorganic passivation for dielectric etching via surface modification
A method for processing a substrate that includes: performing a cyclic process including a plurality of cycles, where the cyclic process includes, forming a carbon-containing layer over sidewalls of a recess in a Si-containing dielectric layer of the substrate, the forming including exposing the substrate disposed in a plasma processing chamber to a first plasma generated from a first gas including carbon and hydrogen, modifying a surface of the carbon-containing layer by exposing the substrate to a second plasma generated from a second gas including oxygen, and forming a passivation layer over the modified surface of the carbon-containing layer by exposing the substrate to a third gas including B, Si, or Al.
1 . A method for processing a substrate, the method comprising:
performing a cyclic process comprising a plurality of cycles, wherein one cycle of the cyclic process comprises:
forming a first carbon-containing layer over sidewalls of a recess in a Si-containing dielectric layer of the substrate, the forming comprising exposing the substrate disposed in a plasma processing chamber to a first plasma generated from a first gas comprising carbon and fluorine;
forming a second carbon-containing layer over the first carbon-containing layer, the forming comprising exposing the substrate disposed in the plasma processing chamber to a second plasma generated from a second gas comprising carbon and hydrogen, the second plasma being different from the first plasma, wherein the second carbon-containing layer has a hydrophobic surface essentially terminated with *CH groups;
modifying the hydrophobic surface of the second carbon-containing layer to become a hydrophilic surface terminated with *COH groups, the modifying comprising exposing the substrate to a third plasma generated from a third gas comprising oxygen; and
forming a passivation layer over the hydrophilic surface of the second carbon-containing layer by exposing the substrate to a fourth gas comprising B, Si, or Al.
2 . The method of claim 1 , wherein the cyclic process further comprises after forming the passivation layer, purging the plasma processing chamber with a fifth gas comprising a hydrogen-containing gas, an oxygen-containing gas, or a nitrogen-containing gas.
3 . The method of claim 2 , wherein the cyclic process further comprises after the purging modifying a surface of the passivation layer by exposing the substrate to another plasma generated from the fifth gas.
4 . The method of claim 2 , wherein the hydrogen-containing gas comprises H 2 , H 2 O, CH 4 , HBr, CH 3 F, or NH 3 , the oxygen-containing gas comprises O 2 , CO, CO 2 , or H 2 O, and the nitrogen-containing gas comprises N 2 or NH 3 .
5 . The method of claim 1 , wherein the second gas comprises hydrocarbon or hydrofluorocarbon.
6 . The method of claim 1 , wherein the third gas comprises dioxygen (O 2 ).
7 . The method of claim 1 , wherein the fourth gas comprises BCl 3 , BH 3 , BBr 3 , SiCl x H 4-x (x=0-4), Si 2 Cl x H 6-x (x=0-6), AlCl 3 , or AlF x (CH 3 ) 3-x (x=0-2).
8 . The method of claim 1 , further comprising after performing the cyclic process, vertically extending the recess into the Si-containing dielectric layer of the substrate.
9 . The method of claim 8 , wherein the recess is vertically extended by exposing the substrate to another plasma generated from a gas comprising fluorine.
10 . The method of claim 1 , wherein forming the recess further comprises using a patterned etch mask comprising carbon disposed over the Si-containing dielectric layer.
11 . The method of claim 1 , wherein the Si-containing dielectric layer comprises silicon oxide or silicon nitride.
12 . A method for processing a substrate, the method comprising:
performing a cyclic passivation process in a plasma processing chamber having a plasma electrode, the cyclic passivation process comprising a plurality of cycles, wherein a cycle of the cyclic passivation process comprises:
powering the plasma electrode to sustain a first plasma generated from a first gas comprising carbon and fluorine;
depositing a first carbonaceous layer over sidewalls of a recess in a Si-containing dielectric layer, the depositing comprising exposing the substrate to the first plasma;
powering the plasma electrode to sustain a second plasma generated from a second gas comprising carbon and hydrogen;
depositing a second carbonaceous layer over the first carbonaceous layer, the depositing of the second carbonaceous layer comprising exposing the substrate to the second plasma, the second carbonaceous layer having a different composition than the first carbonaceous layer, wherein the second carbonaceous layer has a hydrophobic surface essentially terminated with *CH groups;
oxidizing the hydrophobic surface of the second carbonaceous layer to be a hydrophilic surface terminated with *COH groups;
depositing a passivation layer over the second carbonaceous layer by exposing the substrate to a third gas comprising B, Si, or Al without powering the plasma electrode; and
purging the plasma processing chamber with a fourth gas comprising a hydrogen-containing gas, an oxygen-containing gas, or a nitrogen-containing gas.
13 . The method of claim 12 , wherein the cycle of the cyclic passivation process further comprises exposing the substrate to a plasma generated from the fourth gas by powering the plasma electrode.
14 . The method of claim 12 , wherein the third gas comprises BCl 3 , BH 3 , BBr 3 , SiCl x H 4-x (x=0-4), Si 2 Cl x H 6-x (x=0-6), AlCl 3 , or AlF x (CH 3 ) 3-x (x=0-2).
15 . The method of claim 12 , wherein the fourth gas comprises H 2 , N 2 , O 2 , CO, CO 2 , H 2 O, CH 4 , HBr, CH 3 F, or NH 3 .
16 . The method of claim 12 , further comprising:
after the cyclic passivation process, performing another anisotropic plasma etch process to extend the recess vertically, wherein the passivation layer prevents laterally etching the Si-containing dielectric layer.
17 . A method for processing a substrate, the method comprising:
performing a plurality of cycles of a cyclic etch process to form a recess in a Si-containing dielectric layer of a substrate loaded in a plasma processing chamber, the substrate comprising a patterned etch mask formed over the Si-containing dielectric layer, one of the plurality of cycles of the cyclic etch process comprising:
forming a recess in the Si-containing layer by exposing the substrate to a first plasma generated from a first gas comprising carbon and fluorine, the exposing forming a first carbonaceous layer over sidewalls of the recess;
forming a second carbonaceous layer over the first carbonaceous layer by exposing the substrate to a second plasma generated from a second gas comprising carbon and hydrogen, the second carbonaceous layer having a different composition than the first carbonaceous layer, wherein the second carbonaceous layer has a hydrophobic surface mostly terminated with *CH groups;
modifying the hydrophobic surface of the second carbonaceous layer to be a hydrophilic surface terminated with *COH groups;
depositing a passivation layer over the second carbonaceous layer by exposing the substrate to a third gas comprising B, Si, or Al;
purging the plasma processing chamber with a fourth gas comprising a hydrogen-containing gas, an oxygen-containing gas, or nitrogen-containing gas; and
extending the recess vertically by a plasma etch process, the passivation layer preventing laterally etching the Si-containing dielectric layer.
18 . The method of claim 17 , wherein modifying the surface of the second carbonaceous layer to be hydrophilic comprises introducing a hydroxyl (OH) group, a carbonyl (C═O) group, a carboxyl (COOH) group, or an amino group (NH 2 ) group to the surface of the second carbonaceous layer.
19 . The method of claim 17 , wherein the first gas comprises a fluorocarbon, the second gas comprises a hydrocarbon, and the third gas comprises BCl 3 , BH 3 , BBr 3 , SiCl x H 4-x (x=0-4), Si 2 Cl x H 6-x (x=0-6), AlCl 3 , or AlF x (CH 3 ) 3-x (x=0-2).
20 . The method of claim 17 , wherein the one of the plurality of cycles of the cyclic etch process further comprises:
modifying a surface of the passivation layer by exposing the substrate to a plasma generated from the fourth gas; and
repeating the steps of depositing the passivation layer and modifying the surface of the passivation layer.