Carbon containing hardmask removal process using sulfur containing process gas
Apparatus, systems, and methods for conducting a hardmask (e.g., carbon containing hardmask) removal process on a workpiece are provided. In one example implementation, a process can include admitting a process gas into a plasma chamber, generating a plasma in the plasma chamber from the process gas using an inductively coupled plasma source, and exposing the carbon containing hardmask to the plasma to remove at least a portion of the carbon containing hardmask. The process gas can include a sulfur containing gas. The process gas does not include a halogen containing gas. The inductively coupled plasma source can be separated from the plasma chamber by a grounded electrostatic shield to reduce capacitive coupling between the inductively coupled plasma source and the plasma.
1. A process for etching a carbon containing hardmask on a workpiece, the process comprising:
admitting a process gas into a plasma chamber, the process gas comprising a sulfur containing gas and a passivation gas, wherein the process gas does not include a halogen containing gas;
generating a plasma in the plasma chamber from the process gas using an inductively coupled plasma source, the inductively coupled plasma source separated from the plasma chamber by a grounded electrostatic shield; and
exposing the carbon containing hardmask to the plasma to remove at least a portion of the carbon containing hardmask;
wherein the passivation gas is one or more of methane (CH 4 ), ethylene (C 2 H 4 ), ethane (C 2 H 6 ), propene (C 3 H 6 ), or propane (C 3 H 8 ).
2. The process of claim 1 , wherein the sulfur containing gas comprises carbonyl sulfide (COS), sulfur dioxide (SO 2 ), hydrogen sulfide (H 2 S), or sulfur trioxide (SO 3 ).
3. The process of claim 1 , wherein the process gas further comprises an etching gas.
4. The process of claim 3 , wherein the etching gas comprises carbon monoxide (CO), nitrogen (N 2 ), carbon dioxide (CO 2 ), oxygen (O 2 ), ozone (O 3 ), water vapor (H 2 O), hydrogen peroxide (H 2 O 2 ), nitrogen trihydride (NH 3 ), dinitrogen tetrahydride (N 2 H 4 ), hydrogen (H 2 ), or nitrogen monoxide (NO).
5. The process of claim 1 , wherein the process gas further comprises an inert gas.
6. The process of claim 5 , wherein the inert gas comprises helium (He), argon (Ar), neon (Ne), or xenon (Xe).
7. The process of claim 1 , wherein exposing the carbon containing hardmask to the plasma to remove at least the portion of the carbon containing hardmask forms a trench feature with a vertical profile.
8. The process of claim 1 , wherein exposing the carbon containing hardmask to the plasma to remove at least the portion of the carbon containing hardmask forms a trench feature with a sloped profile.
9. The process of claim 8 , wherein exposing the carbon containing hardmask to the plasma to remove at least the portion of the carbon containing hardmask forms a trench feature with a sloped profile such that a bottom critical dimension of the carbon containing hardmask is less than half of a top critical dimension of the carbon containing hardmask.
10. The process of claim 1 , wherein the grounded electrostatic shield is located between the inductively coupled plasma source and a dielectric window forming at least a portion of the plasma chamber.
11. The process of claim 1 , wherein when the inductively coupled plasma source is energized with a radio frequency (RF) source to generate the plasma, the process further comprises energizing an RF bias source.
12. The process of claim 11 , wherein a ratio between an RF source power of the RF source and a bias power of the RF bias source is in a range of about 2:1 to about 20:1.
13. The process of claim 11 , wherein the RF bias source is coupled to a workpiece support configured to support the workpiece in a processing chamber.
14. The process of claim 1 , wherein a pressure of the plasma chamber is less than about 20 mT.
15. The process of claim 1 , wherein the inductively coupled plasma source comprises a first inductive coupling element and a second inductive coupling element, the first inductive coupling element and the second inductive coupling element energized with RF energy at different RF frequencies.
16. The process of claim 1 , wherein the carbon containing hardmask is located below a dielectric hardmask on the workpiece.
17. The process of claim 16 , wherein exposing the carbon containing hardmask to the plasma to remove at least the portion of the carbon containing hardmask is performed after a dielectric hardmask etch process.
18. The process of claim 17 , further comprising conducting a strip process for removal of photoresist subsequent to the dielectric hardmask etch process.