Techniques for processing photoresist features using ions
A method of treating a substrate includes directing first ions over a first range of angles to one or more photoresist features disposed on the substrate, the first ions effective to generate an altered layer in the one or more photoresist features, the altered surface layer encapsulating an inner portion of the one or more photoresist features, and directing second ions different from the first ions over a second range of angles to the one or more photoresist features, the second ions effective to generate gaseous species in the inner regions of the one or more photoresist features.
1. A method of treating a substrate, comprising:
directing first ions over a first range of angles to one or more photoresist features disposed on the substrate, the first ions effective to generate an altered layer in a surface region of the one or more photoresist features, the altered layer encapsulating an inner portion of the one or more photoresist features; and
directing second ions different from the first ions over a second range of angles to the one or more photoresist features, the second ions effective to generate gaseous species in the inner regions of the one or more photoresist features.
2. The method of claim 1 , the first angular range comprising a same angular range as the second angular range.
3. The method of claim 1 , the first angular range comprising a wider angular range than the second angular range.
4. The method of claim 1 , the first ions comprising a first ion energy, and the second ions comprising a second ion energy different from the first ion energy.
5. The method of claim 1 , the first ions comprising one or more of Ar, Xe, N 2 , O 2 , F 2 , NF 3 , and PF 3 and the second ions comprising one or more of He, Ne, and H 2 .
6. The method of claim 1 , comprising directing the second ions subsequently to the first ions.
7. The method of claim 1 , further comprising:
establishing a substrate temperature at a first temperature greater than room temperature before or during the directing first ions; and
reducing the substrate temperature to a second substrate temperature after the directing the second ions.
8. The method of claim 1 , comprising:
directing the first ions and second ions simultaneously to the substrate during a first period; and
directing only the second ions to the substrate during a second period subsequent to the first period.
9. The method of claim 8 , the first ions comprising one or more of Ar, NH 3 , CH 4 , Ne, and the second ions comprising one or more of He and H 2 .
10. The method of claim 1 , further comprising:
forming the first ions and the second ions from a common precursor gas; and
directing the first ions and second ions simultaneously to the substrate.
11. The method of claim 1 , further comprising, after the directing the first and second ions, directing third ions at an angle of incidence generally perpendicular to a plane of the substrate.
12. The method of claim 11 , the third ions comprising a third ion energy greater than a first ion energy of the first ions and a second ion energy of the second ions.
13. The method of claim 1 , the photoresist comprising a polymer material that generates the gaseous species at least in part as hydrogen gas.
14. The method of claim 1 , wherein diffusivity of the gaseous species through the altered layer is less than diffusivity of the gaseous species through the inner region.
15. A method of reducing roughness in patterned photoresist layers on a substrate, comprising:
directing first ions over a first range of angles to one or more photoresist features disposed on the substrate, the first ions effective to generate an altered layer in the one or more photoresist features, the altered layer forming an encapsulating layer that surrounds an inner portion of the one or more photoresist features; and
after the directing the first ions, directing second ions different from the first ions over a second range of angles different from the first range of angles to the one or more photoresist features, the second ions effective to generate gaseous species in the inner regions of the one or more photoresist features.
16. The method of claim 15 , the first angular range comprising a wider angular range than the second angular range.
17. The method of claim 15 , the first ions comprising a first ion energy, and the second ions comprising a second ion energy different from the first ion energy.
18. The method of claim 15 , further comprising, after the directing the first and second ions, directing third ions at an angle of incidence generally perpendicular to a plane of the substrate, the third ions comprising a third ion energy greater than a first ion energy of the first ions and a second ion energy of the second ions.
19. The method of claim 15 , the photoresist comprising a polymer material that generates the gaseous species at least in part as hydrogen gas, wherein the altered layer comprises a carbon rich composition as compared to composition of the inner portion of the photoresist features.
20. The method of claim 15 , wherein the directing the first ions and second ions comprises:
generating a plasma having a plasma sheath; and
modifying a shape of a boundary between the plasma and the plasma sheath with a plasma sheath modifier so that a portion of the boundary facing a front surface of the substrate is not parallel to a plane defined by the front surface.