Iridium precursor pyrolysis and oxidation reactions and direct liquid injection chemical vapor deposition of iridium films

Pyrolysis and oxidation reactions of the iridium precursor, (methylcyclopen tadienyl)(1,5 -cyclooctadiene)iridium (I), were studied to identify the rol e of O-2 in chemical vapor deposition film growth. A toluene solution of (m ethylcyclopentadienyl)(1,5-cyclooctadiene)iridium (1) was used in a direct liquid injection chemical vapor deposition process with O-2 to deposit irid ium films on SiO2 and TiN(111) substrates. The precursor decomposition stud ies revealed O-2 decreases the reaction temperature of (methylcyclopentadie nyl)(l,5 -cyclooctadiene)iridium (1) from near 760 K to temperatures below 465 K. Oxidation of the precursor ligands acts to prevent greater than 99% of the carbon from incorporating into the deposited him, making the growth surface more reactive. The precursor and oxygen react to form CO, CO2 and H 2O. Pure iridium films were deposited on SiO2 and TiN(III) substrates at te mperatures between 550 and 625 K. Under identical conditions, the film nucl eation and coalescence rates are nearly 2 times higher on the TiN(111) subs trate with 0.22 torr O-2. The ratio of (111) to (200) X-ray diffraction int ensities resembled Ir powder for films deposited on SiO2, the same ratio wa s more than 9 times larger than that of Ir powder for Ir films produced on TiN(111). Decreasing the oxygen partial pressure from 0.66 to 0.22 torr res ulted in a 75% reduction in the film growth rate and a 40% reduction in fil m roughness. Conformal (step coverage approaching unity) iridium films were produced at 550 K in aspect ratio 1-0.25 mum vias in SiO2 and in aspect ra tio 2.5-0.35 mum vias in TIN(111). (C) 2001 Elsevier Science B,V. All right s reserved.