Ion beam deposition of ruthenium thin films
Methods for forming a low resistivity ruthenium (Ru) thin film that include depositing ruthenium onto a substrate via ion beam deposition with assist ion beam in a process chamber having reactive and noble gas species therein. The substrate is at at least 250° C. A resulting thin ruthenium film has a thickness of no more than 30 nm, a resistivity less than 12 μ·cm and a crystalline structure comprising grains having a (0001) orientation. The resistivity will differ at different thickness; for example, less than 9 μΩ-cm for films of 50 nm and thicker, less than 9.5 μΩ-cm for films of 35 nm and thicker, less than 11 μΩ-cm for films of 20 nm and thicker, less than 15 μΩ-cm for films of 10 nm and thicker or less than 20 μΩ-cm for films of 2 nm and thicker. The grains have a mean grain size at least three times the film thickness.
1 . A method of forming a ruthenium film having a thickness at least 10 nm, a resistivity less than 15 μΩ-cm, and a polycrystalline structure comprising grains having a (0001) orientation, the method comprising:
depositing a ruthenium film from a ruthenium target onto a substrate via a deposition ion beam from a deposition ion source in a process chamber in the presence of one or both of a first reactive gas species and a first noble gas species, the substrate at a temperature of at least 250° C.; and
simultaneously bombarding at least some of the deposited ruthenium in the process chamber with an assist ion beam from an assist ion source in the presence of one or both of a second reactive gas species and a second noble gas species,
wherein any of the first reactive gas species, the second reactive gas species, the first noble gas species, and the second noble gas species are introduced to the process chamber by any one or more of the deposition ion source, the assist ion source, a deposition ion source neutralizer, and an assist ion source neutralizer.
2 . The method of claim 1 , wherein the depositing is in the presence of the first reactive gas species and the bombarding is in the presence of the second noble gas species.
3 . The method of claim 1 , wherein the depositing is in the presence of the first noble gas species and the bombarding is in the presence of the second reactive gas species.
4 . The method of claim 1 , wherein the depositing is in the presence of the first reactive gas species and the bombarding is in the presence of the second reactive gas species.
5 . The method of claim 1 , wherein the depositing is in the presence of the first noble gas species and the bombarding is in the presence of the second noble gas species.
6 . The method of claim 1 , wherein the depositing is in the presence of both the first reactive gas species and the first noble gas species.
7 . The method of claim 1 , wherein the bombarding is in the presence of both the second reactive gas species and the second noble gas species.
8 . The method of claim 1 , wherein the first reactive gas species is different than the second reactive gas species.
9 . The method of claim 1 , wherein the first noble gas species is different than the second noble gas species.
10 . The method of claim 1 , wherein the substrate is at a temperature of at least 300° C.
11 . The method of claim 1 , wherein the first reactive gas species and the second reactive gas species comprises at least one of oxygen, nitrogen, nitric oxide (NO), nitrogen dioxide (NO 2 ), ammonia (NH 3 ), fluorine, fluoride, and hydrogen.
12 . The method of claim 1 , wherein the first noble gas species and the second noble gas species is at least one of helium, neon, xenon, argon and krypton.
13 . The method of claim 1 , wherein the depositing the ruthenium film utilizes an ion beam having a voltage of at least 400 V and a beam current of at least 100 mA.
14 . The method of claim 1 , wherein the depositing the ruthenium film utilizes an ion beam having a voltage no greater than 2000 V and a beam current no greater than 2500 mA.
15 . The method of claim 1 , wherein the assist ion beam for simultaneously bombarding at least some of the deposited ruthenium has a voltage of 100 V to 1500 V and a beam current of 100 mA to 1500 mA.
16 . The method of claim 1 , further comprising:
prior to depositing the ruthenium film, depositing an underlayer film onto the substrate in-situ in the process chamber, and
depositing the ruthenium film on and in contact with the underlayer film.
17 . The method of claim 1 , further comprising:
after depositing the ruthenium film, depositing a capping layer on and in contact with the ruthenium film in-situ in the process chamber.
18 . A method of forming a ruthenium film having a thickness at least 10 nm, a resistivity less than 15 μΩ-cm, and a polycrystalline structure comprising grains having a (0001) orientation, the method comprising:
depositing a ruthenium film onto a substrate from a first target with a deposition ion beam in a process chamber in the presence of at least one of a first reactive gas species and a first noble gas species, the substrate at a temperature of at least 250° C.; and
simultaneously etching at least some of the deposited ruthenium in the process chamber with an assist ion beam in the presence of at least one of a second reactive gas species and a second noble gas species,
wherein any of the first reactive gas species, the second reactive gas species, the first noble gas species, and the second noble gas species are introduced to the process chamber, independently, via any one or more of the deposition ion beam, the assist ion beam, a deposition ion source neutralizer, and an assist ion source neutralizer.
19 . The method of claim 18 , further comprising:
prior to depositing the ruthenium film, depositing an underlayer film onto the substrate from a second target in the process chamber; and
after depositing the ruthenium film, depositing a capping layer onto the ruthenium film from a third target in the process chamber,
with the first target, second target, and third target all in the process chamber simultaneously.
20 . A ruthenium film comprising:
a thickness at least 10 nm,
a resistivity less than 15 μΩ-cm, and
a polycrystalline structure comprising grains having a (0001) orientation.
21 . The ruthenium film of claim 20 , wherein:
the thickness is at least 20 nm,
the resistivity is less than 11 μΩ-cm, and
the crystalline structure has at least 95% of the grains having the (0001) orientation.
22 . The ruthenium film of claim 20 , wherein:
the thickness is at least 50 nm,
the resistivity is less than 9 udμΩ-cm, and
the crystalline structure has at least 95% of the grains having the (0001) orientation.
23 . The ruthenium film of claim 20 , wherein:
the grains have a mean grain size at least three times the thickness of the ruthenium film.
24 . The ruthenium film of claim 20 , wherein:
the grains have the (0001) orientation parallel to a surface of the ruthenium film.
25 . The ruthenium film of claim 20 , wherein:
the grains have a (0001) orientation with hexagonal basal planes parallel to a surface of the ruthenium film.
26 . The ruthenium film of claim 20 , wherein:
the grains have a (0001) orientation with hexagonal c-axis planes parallel to a surface of the ruthenium film.