In situ Reaction Mechanism Studies on Atomic Layer Deposition of Ir and IrO2 from Ir(acac)3

Reaction mechanisms in three atomic layer deposition (ALD) processes using Ir(acac)(3) as a precursor were studied: Ir(acac)(3)-O-2 process at 300 degrees C for Ir deposition, Ir(acac)(3)-O-3 process at 195 degrees C for IrO2 deposition, and Ir(acac)(3)-O-3-H-2 process at 195 degrees C for Ir deposition. Reactions were studied in situ with a quadrupole mass spectrometer (QMS) and a quartz crystal microbalance (QCM). The byproducts in all processes were CO2 and H2O. Only in the Ir(acac)(3)-O-2 process these were partially released during the Ir(acac)(3) pulse (14% of CO2 and 57% of H2O as compared to a complete ALD cycle). To explain this, some oxygen atoms were concluded to chemisorb on the surface during the O-2 pulse. In the other two processes, the adsorption of Ir(acac)(3) appeared to be molecular on a plain surface of the film material.