|TUPA01||Oxygen-Free Titanium Thin Film as a New Nonevaporable Getter with an Activation Temperature as Low as 185 °C||119|
Funding: This work was partly supported by JSPS KAKENHI (17K05067, 19K05280) and TIA-Kakehashi (TK19-035, TK20-026). The XPS measurements were performed under the Photon Factory proposal (2018S2-005).
Although nonevaporable getter (NEG) pumps are widely used in synchrotron radiation facilities, pure metal Titanium (Ti) has not been used as a NEG because the activation temperature of a Ti thin film deposited by DC magnetron sputtering was reported to be 350-400 °C*. Recently Miyazawa et al. found that high-purity Ti deposited under ultra-high vacuum (UHV) followed by N2 introduction works as a NEG with an activation temperature of 185 °C**,***. Since the concentration of impurities such as O, C, and N in the Ti thin film prepared by this method is 0.05% or less, we named this as oxygen-free Ti. In this study, we evaluated the pumping properties of oxygen-free Ti thin films after high-purity N2 introduction by total and partial pressure measurements. A vacuum vessel with oxygen-free Ti deposited on the inner walls was found to pump H2, H2O, O2, CO and CO2 even after 30 cycles of high purity N2 introduction, air exposure, pumping, and baking at 185 °C. Furthermore, we analyzed the oxygen-free Ti thin films after high-purity N2 or air introduction by synchrotron radiation X-ray photoelectron spectroscopy. The results show that more TiN was formed when high-purity N2 was introduced after oxygen-free Ti deposition. High purity of the Ti thin film and TiN formation on the surface seem to be responsible for the reduced activation temperature as low as 185 °C.
*C. Benvenuti et al., J. Vac. Sci. Technol. A 16, 148 (1998).
**T. Miyazawa et al., Vac. Surf. Sci. 61, 227 (2018).
***KEK, patent pending, WO2018097325 (Nov. 28, 2017).
|DOI •||reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2020-TUPA01|
|About •||paper received ※ 30 July 2021 paper accepted ※ 14 October 2021 issue date ※ 01 November 2021|
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