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 m icroelectronic films on Si. In previous work, we discussed nickel remo val from nickel surfaces using oxygen and 1,1,1,5,5,5-hexafluoro-2,4-p entanedione (Hhfac). In that study, Ni was etched cleanly by the precu rsors under net oxidizing conditions between 280 and 480 K with a maxi mum around 390 K. Decomposition pathways were prevalent, however, unde r reducing conditions. In this article we use temperature-programmed d esorption to examine the use of a nonhalogenated beta-diketone, 2,4-pe ntanedione (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 decomposi tion. 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. Interes tingly, Ni-bis(acac) and 2,4-pentanedione desorb at lower temperatures than Ni-bis(hfac) and hexafluoropentanedione, a reversal of expectati ons based on volatility. Etching ceased as decomposition products form ed. This was most notable above 450 K as several species including pro panone, acetaldehyde, propanol and H3CCOCH2CHO (at high temperature) d esorbed. The structures of decomposition products on both surfaces ind icate that nickel promotes beta-bond scission of the C-CH3 and C-CH/C- CH2 bonds in 2,4-pentanedione. (C) 1998 American Vacuum Society. [S073 4-2101(98)04404-2].