The surface chemistry of 1,1,1-trifluoro-2,4-pentanedione on clean and oxygen pre-covered Cu(210): A comparison with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione and 2,4-pentanedione surface chemistry on the same surfaces

• Published in: Surface science 1999-01, Vol.419 (2), p.97-103
• Main Authors: Nigg, H.Lee, Ford, Laura P, Masel, R.I
• Format: Article
• Language: English
• Subjects: Applied sciences; Copper; Cross-disciplinary physics: materials science; rheology; Etching; Exact sciences and technology; Materials science; Metals. Metallurgy; Physics; Surface chemical reaction; Surface cleaning, etching, patterning; Surface treatments; Temperature programmed desorption
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(98)00745-6

In the recent literature there has been some interest in the use of diones as metal etchants during wafer cleaning and metal patterning. In previous work we found that trifluoro-2,4-pentanedione was a better etchant for nickel than either hexafluoro-2,4-pentanedione or 2,4-pentanedione. In this paper we examine the decomposition of trifluoro-2,4-pentanedione on copper and etching of copper with the same compound. We find that trifluoro-2,4-pentanedione is not a good etchant for copper, even though trifluoro-2,4-pentanedione is a good etchant for nickel. Trifluoro-2,4-pentanedione decomposes via a β-scission process beginning at about 300 K on copper. While we did observe a tiny amount of etching as evidenced by a tiny Cu(CF 3COCHCOCH 3) 2 peak at 380 K, the etching rate was more than an order of magnitude smaller than that observed with hexafluoro-2,4-pentanedione. These results show that copper is more reactive than nickel for trifluoro-2,4-pentanedione decomposition, even though nickel is usually more reactive than copper for carbon–carbon bond scission processes.