Reactivity of deposited byproducts generated from ZrO2 atomic layer deposition

- Strategies were developed for the characterization of unknown reactive byproducts formed during ALD manufacturing processes.
- Byproducts from ZrO2 ALD processes were studied to understand their thermal instability and possible chemical constituents.
- The byproducts generated using TEMAZ as a precursor present significant thermal and pressure hazards.
- The TEMAZ byproducts are likely comprised of a mixture of several organic compounds and a zirconium coordination complex.

In semiconductor manufacturing processes, certain reactive byproducts are known to deposit in the post-process piping and exhaust systems due to the use of extremely reactive chemistries, presenting a significant safety risk. An experimental strategy was developed to evaluate unknown byproducts formed from ZrO2 atomic layer deposition (ALD). Two byproducts were analyzed for this study. These byproducts were generated from the full-scale manufacturing processes using tetrakis (ethylmethylamino)zirconium (TEMAZ) or tris(dimethylamino) (cyclopentadienyl) zirconium (TDCZ) as zirconium precursors. Differential scanning calorimetry and Multiple Mode Calorimetry were first used to characterize the reactivity hazards of the two byproducts. The onset temperature and reaction energy were quantified from both thermal analytical methods. Thermal analysis of the TEMAZ byproduct shows the sample presents significant thermal and pressure hazards, and thus, may lead to an explosion. For the TDCZ byproduct, the risk of a thermal runaway/explosion is low due to its slow kinetics, despite its potential in releasing energy and gases. Subsequently, a series of solid-phase characterization methods, including scanning electron microscopy, electron dispersive x-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), were employed to achieve a thorough understanding of the TEMAZ byproduct, because of its high reactivity. In order to understand the exothermic reactions, the initial byproduct samples were pre-heated and quenched from specific temperatures. These quenched samples were characterized using appropriate analytical methods. Results show that the TEMAZ byproduct is likely to be a mixture of several organic compounds and a zirconium coordination complex. Upon heating, the organic compounds decomposed at a lower temperature range, accompanied by a complete mass loss, whereas the decomposition of the zirconium coordination complex occurred at higher temperatures, resulting in the formation of tetragonal zirconia crystal.