1 research outputs found
Optimization of ReaxFF Reactive Force Field Parameters for Cu/Si/O Systems via Neural Network Inversion with Application to Copper Oxide Interaction with Silicon
The presence of transition metal
oxide impurities introduced
during
crystal formation or during the fabrication process may lead to a
significant yield loss in microelectronics and device manufacturing.
To enable a large-scale molecular dynamics study of the effects of
copper oxide impurities inside silicon on the structural evolution
and mechanical properties of Cu/Si/O systems, one needs to understand
the diffusional characteristics of copper and oxygen compounds next
to the silicon lattice. In this work, we introduce an accelerated
deep learning-based reactive force field parametrization platform.
In this platform, we train a deep neural network to learn the production
of ReaxFF outputs, given a set of force field parameters. Subsequently,
the trained neural network is used, as an alternative to ReaxFF, by
means of the neural network inversion algorithm to seek the inputs
to the neural network (force field parameters) that produce the experimental
and quantum mechanics reference property values of the system. We
compared the performance of the neural network inversion optimization
algorithm with that of the previously used brute force search method
by looking at the total optimization time and the total reduction
of the discrepancies between the results of molecular dynamic simulation
and the reference property values within the force field training
set. The neural network inversion algorithm significantly reduces
the average optimization time, which directly translates into less
computational resources required for the optimization process. Moreover,
we compared the quality of the force fields optimized by both algorithms
in describing the chemical properties of the Cu/O systems, including
the heat of formation and the relative phase stability. We demonstrated
that the results of the force field, optimized using the proposed
neural network inversion algorithm, align more closely with the reference
chemical properties of Cu/O systems within the force field training
set than those optimized by the brute force algorithm. We used this
platform to develop a Cu/Si/O ReaxFF reactive force field by training
on density functional theory (DFT) data, including heat of formation
values for various Cu/Si/O materials. The developed force field was
further used to perform molecular dynamics simulations on models with
up to 3542 atoms to study atomistic interactions between copper oxide
compounds and silicon by looking at the diffusional behavior of copper
and oxygen atoms adjacent to the Si substrate. We found that the temperature
substantially impacts the Cu oxide diffusion coefficient. Our simulation
results enable us to comprehensively understand the effects of oxygen
atoms on the diffusion of copper impurities into the silicon lattice.
We showed that a Cu oxide cluster shows diffusion faster than that
of a pure Cu cluster adjacent to a Si supercell. By studying the interaction
between Cu oxide and Si nanolayers at different temperatures, we observed
that at higher temperatures, oxygen atoms migrate from the initial
CuOx material to diffuse into the Si phase.
In addition, we showed that the absolute decay rate of the average
Cu–Cu bond length is directly dependent on the simulation temperature