Cyclic plasma etching of carbon-containing materials

1. A method for processing a substrate, the method comprising:

performing a cyclic process comprising a plurality of cycles, wherein the cyclic process comprises:

forming, in a plasma processing chamber, a passivation layer over sidewalls of a recess in a carbon-containing layer, by

exposing the substrate to a first gas comprising boron, silicon, or aluminum, the carbon-containing layer being disposed over a substrate,

purging the plasma processing chamber with a second gas comprising a hydrogen-containing gas, an oxygen-containing gas, or nitrogen-containing gas, and

exposing the substrate to a plasma generated from the second gas,

wherein each cycle of the plurality of cycles extends the recess vertically into the carbon-containing layer.

2. The method of claim 1 , wherein the cyclic process further comprises:

extending the recess in the carbon-containing layer with a second plasma generated from a third gas comprising an oxygen-containing gas, a sulfur-containing gas, a nitrogen containing gas, or a hydrogen-containing gas.

3. The method of claim 2 , further comprising, after exposing a major surface of the substrate, repeating the exposing the substrate to a first gas, purging the plasma processing chamber, and exposing the substrate to a plasma to extend the passivation layer to the substrate.

4. The method of claim 1 , further comprising:

before forming the passivation layer, forming the recess by performing an anisotropic plasma etch process by using an etch mask comprising a patterned mask layer over the carbon-containing layer, the substrate comprising the carbon-containing layer and the patterned mask layer.

5. The method of claim 4 , wherein the patterned mask layer comprises silicon nitride, silicon oxide (SiO2), or silicon oxynitride (SiON).

6. The method of claim 4 , wherein the anisotropic plasma etch process is performed with an etch gas comprises an oxygen-containing gas, a sulfur-containing gas, a nitrogen containing gas, or a hydrogen-containing gas.

7. The method of claim 1 , wherein the carbon-containing layer comprises amorphous carbon.

8. The method of claim 1 , further comprising forming the carbon-containing layer over the substrate by coating a spin-on carbon hard mask (SOH) material or a silicon-containing anti-reflective coating film (SiARC).

9. The method of claim 1 , wherein the first gas comprises BCl3, BH3, BBr3, SiClxH4-x (x=0-4), Si2ClxH6-x (x=0-6), AlCl3, or AlFx(CH3)3-x (x=0-2).

10. The method of claim 1 , wherein the hydrogen-containing gas comprises H2, H2O, CH4, HBr, CH3F, CH4, HBr, CH3F, or NH3, the oxygen-containing gas comprises O2, CO, CO2, or H2O, and the nitrogen-containing gas comprises N2 or NH3.

11. A method for processing a substrate, the method comprising:

performing a cyclic passivation process in a plasma processing chamber having a plasma source, the cyclic passivation process comprising a plurality of cycles, wherein a cycle of the cyclic passivation process comprises:

forming a passivation layer by

exposing the substrate to a first gas comprising boron, silicon, or aluminum without powering the plasma source, the substrate comprising a carbon-containing layer, the first gas interacting with the carbon-containing layer to form the passivation layer,

purging the plasma processing chamber with a second gas comprising hydrogen, and

exposing the substrate to a plasma generated from the second gas by powering the plasma source.

12. The method of claim 11 , wherein the first gas comprises BCl3, BH3, BBr3, SiClxH4-x (x=0-4), Si2ClxH6-x (x=0-6), AlCl3, or AlFx(CH3)3-x (x=0-2).

13. The method of claim 11 , wherein the second gas comprises H2, N2, O2, CO, CO2, H2O, CH4, HBr, CH3F, NH3, CH4, HBr, CH3F, H2O, or NH3.

14. The method of claim 11 , further comprising

performing an anisotropic plasma etch process to pattern the carbon-containing layer using an etch gas comprising an oxygen-containing gas, a sulfur-containing gas, a nitrogen containing gas, or a hydrogen-containing gas, wherein the pattern comprises a vertical recess in the carbon-containing layer.

15. The method of claim 11 , wherein the cycle of the cyclic passivation process further comprises:

purging the plasma processing chamber with a third gas; and

exposing the substrate to a third plasma of a third gas, wherein the third gas comprises H2, N2, CH4, HBr, CH3F, H2O, O2, or NH3, the third gas being different from the second gas.

16. 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 carbon-containing layer of a substrate loaded in a process chamber, each cycle comprising:

forming a passivation layer from the carbon-containing layer by

exposing the substrate to a plasma formed from a first gas comprising a hydrogen-containing gas,

after turning OFF power to the plasma, purging the process chamber with a second gas comprising boron and a halogen, and

purging the process chamber with the first gas and turning ON power to the plasma.

17. The method of claim 16 , wherein a cycle of the plurality of cycles further comprises extending the recess by performing a first plasma etch process to anisotropically remove the carbon-containing layer exposed by a first etch mask.

18. The method of claim 17 , further comprising, after the cyclic etch process, performing a second plasma etch process to anisotropically remove an underlying layer using the carbon-containing layer as a second etch mask.

19. The method of claim 18 , the underlying layer comprises oxide, silicon oxide (SiO2), silicon nitride, silicon oxynitride (SiON), silicon carbide, titanium nitride, or tantalum nitride.

20. The method of claim 16 , the recess has an aspect ratio between 5 and 100 after performing the plurality of cycles.