Influence of Target-Substrate Distance on the Transport Process of Sputtered Atoms: MC-MD Multiscale Coupling Simulation

Abstract

A Monte Carlo (MC) and molecular dynamics (MD) coupling simulation scheme for sputtered particle transport was first proposed in this work. In this scheme, the MC method was utilized to model the free-flight process of sputtered atoms, while the MD model was adopted to simulate the collision between the sputtered atom and background gas atom so as to self-consistently calculate the post-collision velocity of the sputtered atom. The reliability of the MD collision model has been verified by comparing the computation results of the MD model and of an analytical model. This MC-MD coupling simulation scheme was used to investigate the influence of target-substrate distance on the transport characteristic parameters of sputtered Cu atoms during magnetron sputtering discharge. As the target-substrate distance increased from 30 to 150 mm, the peak energy of the incident energy distribution of deposited Cu atoms decreased from 2 to 1 eV due to the gradual thermalization of sputtered atoms. The distribution of differential deposition rate in unit solid angle firstly became more forward-peaked and then reversely approached the cosine distribution, which was agreed with the existing experimental observations. This work is expected to provide a more realistic simulation scheme for sputtered particle transport, which can be further combined with the MD simulation of sputtered film growth to explore the influence mechanism of process parameters on the properties of sputtered film.

Matrix-formation dynamics dictate methyl nitrite conformer abundance

“…95 This is corroborated by Zhu et al, using a MC-MD coupling method to show that the surface morphology was almost flat when Cu atoms were deposited with incident angles less than 45°. 96 Based on these two model studies depicting the growth of an atomic species deposited onto a flat surface, in combination with earlier simulations by Cruz and Lopez that used classical MD simulations to depict the slow-deposition of Ar at 10 K, we do not expect significant differences in the surface morphologies of the atomic matrices in this study (Ar and Xe) when the deposition angle is changed.…”

Evolution Mechanism of Sputtered Film Uniformity with the Erosion Groove Size: Integrated Simulation and Experiment

“…The emission azimuth angles of sputtered atoms, due to symmetry, were supposed to be distributed uniformly between 0 and 2π. After that, the transport processes of sputtered atoms could be modeled using the coupled MC-MD method, whose simulation procedures were introduced in our previous paper [24]. Ultimately, the deposition density distributions of 2-inch target sputtering and 4-inch target sputtering can be calculated, respectively.…”

“…As the sputtering pressure is 0.5 Pa, the mean free paths of sputtered atoms with 2 eV and 30 eV kinetic energy are 41.6 mm and 113.7 mm, respectively, and the percentage of these sputtered Cu atoms is around 70% [24]. This suggests that, at a target-substrate distance of 30 mm, most of the sputtered atoms undergo no collision before they arrive at the substrate surface.…”

“…In most MC simulations, the post-collision flight angles of colliding particles are approximately calculated based on the assumption that the argon atom is at rest before the collision [15][16][17][18][19][20][21][22], since the accurate calculation of the scattering angle requires complex coordinate transformations [23]. In this context, a coupled MC-MD method was developed to simulate the transport processes of sputtered particles [24], in which the velocities of colliding particles after collisions were calculated using the MD method. Furthermore, the initial emission positions of sputtered particles are determined by the ionization density distribution near the target surface during magnetron sputtering discharge [25].…”

On the Microcrystal Structure of Sputtered Cu Films Deposited on Si(100) Surfaces: Experiment and Integrated Multiscale Simulation

“…In this work, sputtered Cu/Si thin films were experimentally prepared at different sputtering pressures and characterized using X-ray diffraction (XRD) and an atomic force microscope (AFM). Simultaneously, the transport processes of sputtered Cu atoms in the argon gas and the deposition processes of sputtered Cu atoms on the Si(100) substrate under different sputtering pressures were successively simulated using MC–MD coupling simulation [ 20 ] and MD simulation. The evolution mechanism of the microcrystal structure of the sputtered Cu film with the sputtering pressure was investigated based on the simulation results of this integrated multiscale simulation of combined transport and deposition processes.…”