7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Suppression of substrate temperatureby balanced magnetron plasma sputtering source
T. Motomura, K. Takemura, T. Nagase, N. Morita, W. Iwasaki, N. Matsuda and T. Tabaru
National Institute of Advanced Industrial Science and Technology
e-mail (speaker): t.motomura@aist.go.jp
The Magnetron sputtering deposition technique is used
as a promised tool for semiconductor manufacturing suchas seed layer depositions. Magnetron sputtering cathodeuses an 𝐸𝑧 × 𝐵𝑟 drift motion that confines plasma
particles above the target material to enhance plasma
production and target utilization efficiencies. The
commercially available magnetron cathodes haveunbalanced magnetic field lines which diverge from thetarget surface to the substrate surface to give high ion
irradiation to the target surface. Thus, in the balanced
magnetron cathodes, the substrate temperature facing thesputtering target increases above 40 ℃ because theplasmas are transported through unbalanced magnetic
field lines. Among them, we have developed a balanced
magnetron cathode to enhance the plasma production
efficiency compared with the conventional balanced
magnetron cathodes. The developed magnetron cathodehas a magnetic mirror configuration over the circularshaped target material, namely, Magnetic Mirror-typemagnetron cathode: M3C, as shown in Fig. 1.[1]The M3C has good discharge performances for the low
power density and low gas pressure operations (5 W ofinput power and 0.1 Pa of Ar gas pressure). This
presentation shows the low-temperature sputtering
performances of less than 40 ℃ by the M3C.[2] To
estimate the plasma irradiation to the substrate surface,
Langmuir probe measurements are conducted above thetarget as shown in Fig. 2. The attainable substratetemperature during the sputter deposition was verified by
the temperature indicator label (Nichiyu Giken Kogyo Co.
Ltd., Japan). Kapton tape was attached to prevent tungsten(W) film deposition on the temperature indicator labels.
We were able to suppress the temperature of the substratetemperature to the environmental temperature of less than
40℃ at a target–substrate distance of ≥50 mm with a DC

input power of ≤30 W and an Ar gas pressure of ≤0.15 Pa.
This was possible because the balanced magnetic fieldlines confined the plasmas near the sputtering target. By
enabling film deposition on low heat-resistant substrates,
this technique for suppressing the substrate temperature
can be used in various application fields such as lowtemperature sputtering deposition on a plastic mold ofsemiconductor devices, polyethylene terephthalates, andso on. We will also show examples of our metal coating
results for biomaterial surfaces.[3]Figure 1. Schematic drawing for the comparison ofFigure 2. Schematic drawing of M3C and Langmuirmagnetic field lines. Unbalanced B-field vs. balanced

probe setup. The radial and axial origins (r and z) are

B-field by M3C are shown.

the center of the target surface.

References[1] T. Motomura and T. Tabaru, AIP Adv. 7, 125225(2017).
https://doi.org/10.1063/1.5013341[2] T. Motomura, K. Takemura, T. Nagase, N. Morita andT. Tabaru, AIP Adv. 13, 025153 (2023).
https://doi.org/10.1063/5.0138840[3] K. Takemura, T. Motomura, W. Iwasaki, and N.
Matsuda, Sci. Rep. 12, 13328 (2022).
https://doi.org/10.1038/s41598-022-17562-9