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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 ∼80 and ∼280 mTorr at 80 and 120 °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 ∼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 Si3N4 and other substrates. The effective activation energy for Ir film growth, with oxygen present, is 71 kJ/mol.

Platinum film growth using Pt(PF3)4 precursors was investigated. The study focused on three aspects of film growth: conformality, adhesion and selective growth. Pt(PF3)4 deposited pure Pt films over a wide range of temperatures (∼200 to 400 °C). At 200 °C, the step coverage for a via with an aspect ratio of three was poor. Lower growth temperatures showed a significant decrease in the growth rate. In addition, these films had poor adhesion to the substrate as indicated by separation between the Pt and the substrate in cross sectional scanning electron microscopy images. Oxygen addition during Pt film growth from Pt(PF3)4 improved both film conformality and adhesion. With oxygen, the step coverage on the side wall was greater than 90 % The dependence of the film growth rate on oxygen varied with the growth temperature: the growth rate decreased at 200 °C, while it changed slightly at 260 °C when oxygen was added. The substrate effect on the initial growth rate was studied on various substrates. The initial growth rate on metals is much faster than that on other substrates. The growth rate decreased on various substrates in the order of iridium > titanium nitride > barium strontium titanate > silicon nitride > silicon oxide.