Temperature-programmed desorption study of the etching of Ni(110) with 2,4-pentanedione

Ni contamination is an increasing problem in the fabrication of thin microelectronic films on Si. In previous work, we discussed nickel removal from nickel surfaces using oxygen and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (Hhfac). In that study, Ni was etched cleanly by the precursors under net oxidizing conditions between 280 and 480 K with a maximum around 390 K. Decomposition pathways were prevalent, however, under reducing conditions. In this article we use temperature-programmed desorption to examine the use of a nonhalogenated β-diketone, 2,4-pentanedione (Hacac) and oxygen in the same process. Nonhalogenation of ligands decreases the acidity of the precursor and it is our intent to see how this affects reaction pathways, notably etching and decomposition. Ni was etched cleanly on the oxidized surface by the desorption of Ni-bis(acac) between 290 and 390 K with a maximum at 330 K. Interestingly, Ni-bis(acac) and 2,4-pentanedione desorb at lower temperatures than Ni-bis(hfac) and hexafluoropentanedione, a reversal of expectations based on volatility. Etching ceased as decomposition products formed. This was most notable above 450 K as several species including propanone, acetaldehyde, propanol and H3CCOCH2CHO (at high temperature) desorbed. The structures of decomposition products on both surfaces indicate that nickel promotes β-bond scission of the C-CH3 and C-CH/C-CH2 bonds in 2,4-pentanedione.