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 similar to 80 and similar to 280 mTorr at 80 and 120 degrees C, respectively. The precursor slowly dimerized at elevated temperatures (>60 degrees C). Pyrolysis studies revealed that the compound decomposes by breaking the methylcyclopentadienyl-Ir and cyclooctadiene-Ir bonds nearly simultaneously at temperatures above 400 degrees C. Iridium films grown at substrate temperatures between 250 and 400 degrees 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 similar to 87% carbon. Oxygen also affected the film deposition rate and lowered growth temperature. X-ray diffraction analysis indicated that films grown below 270 degrees C are randomly oriented, while films grown at 350 degrees C favor the (200) orientation. Excellent step coverage has been achieved on Si3N4 and other substrates. The effective activation energy for Ir film growth, with oxygen present, is 71 kJ/mol. (C) 2000 American Vacuum Society. [S0734-2101(00)04501-2].