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

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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.