Experimental thermodynamics for the evaluation of ALD growth processes

The development of an ALD process, which is based on the sequential self-limiting surface reactions from generally two gaseous precursors, requires knowledge of the reactions mechanisms. Most of the studies of ALD modeling have been focused on the surface reactions. However, the most common use of organometallic molecule as gaseous precursors which are generally thermally unstable at temperatures close to the deposition one requires also an understanding of the gas-phase chemical reactions, as for the usual CVD processes. This presentation describes specific examples of the application of mass spectrometry to the determination of the thermal stability and behavior of organometallic precursors used for the ALD deposition of TaN and ZrO2 ultra thin layers.