Development of Cu Etching Using O2 Cluster Ion Beam under Acetic Acid Gas Atmosphere

Cu etching was carried out at a low substrate temperature using a gas cluster ion beam (GCIB) under an acetic acid gas atmosphere. A very shallow Cu surface was oxidized by O 2 -GCIB irradiation. Reactions between copper oxide and acetic acid occurred, and the reaction products were desorbed by loca...

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Bibliographic Details
Published inJpn J Appl Phys Vol. 51; no. 8; pp. 08HA02 - 08HA02-5
Main Authors Suda, Takanori, Toyoda, Noriaki, Hara, Ken-ichi, Yamada, Isao
Format Journal Article
LanguageEnglish
Published The Japan Society of Applied Physics 25.08.2012
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Summary:Cu etching was carried out at a low substrate temperature using a gas cluster ion beam (GCIB) under an acetic acid gas atmosphere. A very shallow Cu surface was oxidized by O 2 -GCIB irradiation. Reactions between copper oxide and acetic acid occurred, and the reaction products were desorbed by local heating owing to the O 2 -GCIB irradiation. Thus, Cu etching at a low substrate temperature (${<}60$ °C) was achieved. By introducing acetic acid gas during O 2 -GCIB irradiation, the etching depth of Cu became almost 29 times higher than the depth achieved when the etching was carried out using O 2 -GCIB alone at an acceleration voltage of 5 kV. In addition to the etching of Cu, there was no surface roughening after O 2 -GCIB irradiation under acetic acid atmosphere.
Bibliography:(a) Schematic diagram of the GCIB apparatus with CH 3 COOH supply and (b) model of Cu etching by O 2 -GCIB irradiation with acetic acid vapor. Etching depth of Cu using O 2 -GCIB as a function of the partial pressure of CH 3 COOH. Acceleration voltage dependence of etching depths of Cu with irradiation of O 2 -GCIB, Ar-GCIB, and O 2 + at room temperature. The enhancement factor, which is defined as the ratio of the etching depth of Cu using O 2 -GCIB with acetic acid to that using O 2 -GCIB alone, is also shown. AFM images of Cu surface polished by CMP (a), after O 2 + irradiation (b), and after O 2 -GCIB irradiation with acetic acid (c). Cu 2p 3/2 XPS spectra on copper specimens after irradiation using O 2 -GCIB alone (a) and after irradiation using O 2 -GCIB with acetic acid (b). Cu O 1s XPS spectra on Cu after irradiation by O 2 -GCIB alone (c), and irradiation of O 2 -GCIB with acetic acid (d). Cu 2p 3/2 XPS spectra of sputtered particles by O 2 -GCIB alone (a) and O 2 -GCIB with acetic acid (b) and angular distributions of Cu atoms sputtered by O 2 -GCIB both without and with acetic acid (c).
ISSN:0021-4922
1347-4065
DOI:10.1143/JJAP.51.08HA02