AVS 64th International Symposium & Exhibition
    Thin Films Division Tuesday Sessions
       Session TF-TuA

Paper TF-TuA7
Direct Measurements of Half-Cycle Reaction Heats during Atomic Layer Deposition Provide Mechanistic Insights

Tuesday, October 31, 2017, 4:20 pm, Room 20

Session: ALD Precursors and Surface Reactions
Presenter: Charles T. Campbell, University of Washington
Authors: C. Campbell, University of Washington
J. Lownsbury, University of Washington
K.S. Kim, Argonne National Laboratory
A.B.F. Martinson, Argonne National Laboratory
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We introduce here a new high-temperature adsorption calorimeter that approaches the ideal limit of a heat detector whereby the signal at any time is proportional to the heat power being delivered to the sample, and prove its sensitivity for measuring pulse-to-pulse heats of half-reactions during atomic layer deposition (ALD) at 400 K. The heat dynamics of amorphous Al2O3 growth via sequential self-limiting surface reaction of trimethylaluminum (TMA) and H2O is clearly resolved. Calibration enables quantitation of the exothermic TMA and H2O half-reactions with high precision, -343 kJ/mol TMA and -251 kJ/mol H2O, respectively. A time resolution better than 1 millisecond is demonstrated, allowing for the deconvolution of at least two distinct surface reactions during TMA micro-dosing. It is further demonstrated that this method can provide the heat of reaction versus extent of reaction during each precursor’s half-reaction, thus providing even richer mechanistic information on the surface processes involved. The broad applicability of this novel calorimeter is demonstrated through excellent signal-to-noise ratios of less exothermic ALD half-reactions to produce TiO2 and MnO.