Precursor chemistry and film growth with (methylcyclopentadienyl) (1,5-cyclooctadiene)iridium

We have investigated the chemistry of the iridium precursor ((methylcyclopentadienyl) (1,5-cyclooctadiene))iridium (MeCpIrCOD) and have utilized the precursor for chemical vapor deposition (CVD) of iridium films. The vapor pressure of the precursor is $\text{∼80}$ and $\text{∼280}$ mTorr at 80 and $\text{120\hspace{0.05em}°}\mathrm{C},$ respectively. The precursor slowly dimerized at elevated temperatures (>60 °C). Pyrolysis studies revealed that the compound decomposes by breaking the methylcyclopentadienyl–Ir and cyclooctadiene–Ir bonds nearly simultaneously at temperatures above 400 °C. Iridium films grown at substrate temperatures between 250 and 400 °C were characterized by in situ x-ray photoelectron spectroscopy, x-ray diffraction, and scanning electron microscopy. Pure CVD iridium films were obtained on various substrates by codosing MeCpIrCOD with oxygen or hydrogen. Without oxygen, the metal films required higher growth temperatures and contain $\text{∼87\%}$ carbon. Oxygen also affected the film deposition rate and lowered growth temperature. X-ray diffraction analysis indicated that films grown below 270 °C are randomly oriented, while films grown at 350 °C favor the (200) orientation. Excellent step coverage has been achieved on ${\mathrm{Si}}_3{\mathrm{N}}_4$ and other substrates. The effective activation energy for Ir film growth, with oxygen present, is 71 kJ/mol.