2 research outputs found
Multiparameter and Parallel Optimization of ReaxFF Reactive Force Field for Modeling the Atomic Layer Deposition of Copper
No full textIn this study, we
aim to develop a ReaxFF reactive force field
for simulating the reaction mechanism of copper atomic layer deposition
(ALD). To achieve this, we optimized the Cu/C, Cu/H, and Cu/N parameters
of ReaxFF and extended the existing Cu potential to describe Cu/C/H/O/N
interactions involved in Cu ALD. The parametrization procedure was
implemented through an efficient multiparameter and parallel optimization
scheme based on the Taguchi method. Using the newly developed Cu potential,
we performed reactive molecular dynamics (RMD) simulations on an āabbreviatedā
ALD cycle using a [CuĀ(<sup><i>i</i></sup>Pr-amd)]<sub>2</sub> (<sup><i>i</i></sup>Pr-amd = <i>N</i>,<i>N</i>ā²-diisopropylacetamidinate) or CuĀ(dmap)<sub>2</sub> (dmap = dimethylamino-2-propoxide) precursor with the H radical
as a coreactant. In the first half-cycle, the [CuĀ(<sup><i>i</i></sup>Pr-amd)]<sub>2</sub> precursor is found to adsorb dissociatively
on the Cu surface as CuĀ(<sup><i>i</i></sup>Pr-amd) monomers.
During the second half-cycle, H radicals partly eliminate precursor
fragments to the gas phase, but some intermediates such as C<sub>5</sub>H<sub>12</sub>N<sub>2</sub> and C<sub>2</sub>H<sub>4</sub>N remain
on the surface and may become a source of contamination. On the other
hand, the CuĀ(dmap)<sub>2</sub> precursor dissociates into CuĀ(dmap)
and dmap on the Cu surface. The second half-cycle is initiated through
a hydrogen transfer reaction, which completely eliminates the dmap
ligands to the gas phase. In general, our RMD simulations suggest
that the surface chemistry of CuĀ(dmap)<sub>2</sub> during the ALD
is simpler and cleaner than that of [CuĀ(<sup><i>i</i></sup>Pr-amd)]<sub>2</sub>
