Method of fabricating semiconductor device
View Patent ↗After low dielectric constant films are formed on a wiring, hardmasks are formed on the low dielectric constant films. A resistmask is formed on the hardmasks. Via holes are formed in the low dielectric constant films using the resistmask. Ashing the resistmask is performed. During this process, a protection film is formed by sticking a sputtered material generated from the resistmask at least onto side surfaces of the via holes. Thereafter, the via holes are extended to the wiring, and a conductive material is buried into the via holes.
1. A method of fabricating a semiconductor device, comprising:
forming an inorganic low dielectric constant film over a wiring;
forming a hardmask over the inorganic low dielectric constant film;
forming a resistmask over the hardmask;
forming an opening in the inorganic low dielectric constant film using the resistmask;
ashing the resistmask with forming a protection film by sticking a sputtered material generated from the resistmask at least onto a side surface of the opening by using O 2 plasma;
extending the opening to the wiring; and
burying a conductive material in the opening,
wherein ashing the resistmask includes applying a substrate voltage of less than or equal to −300 V to a substrate above which the inorganic low dielectric constant film is formed.
2. The method of fabricating a semiconductor device according to claim 1 wherein, as the opening, a via hole in a dual damascene method is formed.
3. The method of fabricating a semiconductor device according to claim 1 wherein ashing the resistmask includes sputter-etching the resistmask.
4. The method of fabricating a semiconductor device according to claim 1 further comprising, between ashing the resistmask and extending the opening to the wiring, sticking onto the protection film a sputtered material generated from the hardmask by sputter-etching the hardmask during over-ashing the resistmask.
5. The method of fabricating a semiconductor device according to claim 1 wherein, as the hardmask, one selected from the group consisting of a SiN-based film, a SiC-based film, a SiOC-based film, a C-based film, a Ta-based film, and a Ti-based film is used.
6. The method of fabricating a semiconductor device according to claim 1 further comprising, between forming the protection film and extending the opening to the wiring:
forming a second resistmask over the hardmask;
patterning the hardmask using the second resistmask;
ashing the second resistmask with sticking a sputtered material generated from the second resistmask at least onto the side surface of the opening; and
forming a second opening in the inorganic low dielectric constant film using the hardmask.
7. The method of fabricating a semiconductor device according to claim 6 wherein, as the second opening, a wiring trench in a dual damascene method is formed.
8. A method of fabricating a semiconductor device comprising:
forming an inorganic low dielectric constant film over a wiring;
forming a hardmask over the inorganic low dielectric constant film;
forming a resistmask over the hardmask;
forming an opening in the inorganic low dielectric constant film using the resistmask;
ashing the resistmask;
forming a protection film by sticking a sputtered material generated from the hardmask by sputter-etching the hardmask during over-ashing the resistmask at least onto a side surface of the opening by using O 2 plasma;
extending the opening to the wiring; and
burying a conductive material in the opening,
wherein ashing the resistmask includes applying a substrate voltage of less than or equal to −300 V to a substrate above which the inorganic low dielectric constant film is formed.
9. The method of fabricating a semiconductor device according to claim 8 wherein, as the opening, a via hole in a dual damascene method is formed.
10. The method of fabricating a semiconductor device according to claim 8 further comprising, between forming the protection film and extending the opening to the wiring:
forming a second resistmask over the hardmask;
patterning the hardmask using the second resistmask;
ashing the second resistmask with sticking a sputtered material generated from the second resistmask at least onto the side surface of the opening; and
forming a second opening in the inorganic low dielectric constant film using the hardmask.
11. The method of fabricating a semiconductor device according to claim 10 wherein, as the second opening, a wiring trench in a dual damascene method is formed.
12. The method of fabricating a semiconductor device according to claim 10 wherein, in ashing the resistmask, one selected from a group consisting of an oxygen plasma, an ammonia plasma, and a hydrogen plasma is used as an ashing plasma.
13. A method of fabricating a semiconductor device comprising:
forming an inorganic low dielectric constant film over a wiring;
forming a hardmask over the inorganic low dielectric constant film;
forming a first resistmask over the hardmask;
forming a first opening in the inorganic low dielectric constant film using the first resistmask;
ashing the first resistmask;
forming a second resistmask over the hardmask;
patterning the hardmask using the second resistmask;
ashing the second resistmask with forming a protection film by sticking a sputtered material generated from the second resistmask at least onto a side surface of the first opening by using O 2 plasma;
forming a second opening in the inorganic low dielectric constant film using the hardmask;
extending the first opening to the wiring; and
burying a conductive material in the first and second openings,
wherein ashing either or both of the resistmask includes applying a substrate voltage of less than or equal to −300 V to a substrate above which the inorganic low dielectric constant film is formed.
14. The method of fabricating a semiconductor device according to claim 13 wherein, as the first opening, a via hole in a dual damascene method is formed, and as the second opening, a wiring trench in the dual damascene method is formed.
15. The method of fabricating a semiconductor device according to claim 13 wherein ashing the second resistmask includes sputter-etching the second resistmask.
16. The method of fabricating a semiconductor device according to claim 13 further comprising, between ashing the second resistmask and forming the second opening, over-ashing the second resistmask on a condition where a substrate voltage applied to a substrate above which the inorganic low dielectric constant film is formed is set to be weaker than when the second resistmask is ashed.
17. The method of fabricating a semiconductor device according to claim 13 wherein, in ashing the second resistmask, one selected from a group consisting of an oxygen plasma, an ammonia plasma, and a hydrogen plasma is used as an ashing plasma.