A Monte Carlo simulation of the metal flux from a small scale rotating cylindrical magnetron is presented. The model describes the sputtered particles trajectories through the gas in a user definable 3D set-up. The ejection positions of the sputtered particles are generated according to the simulated ion current density on the target. The thermal motion of the background gas is included, with collisions modelled based on either quantum chemical or screened Coulomb interaction potentials. Experimental characterization of the metal flux was performed for Cu, Al and Ti targets at a range of argon pressures (0.3-1 Pa) by measuring deposition rate distributions. A comparison with preliminary simulations showed the importance of a correct description of the nascent angular distribution of the sputtered particles. Therefore, this distribution was not considered as given by sputter simulation or analytical formula, but was instead reconstructed from the low pressure experimental deposition profiles. The typical heart-like shaped emission observed at low energy sputtering was found and a comparison was made with results from binary collision approximation modelling. The spatial, pressure and material dependence of the metal flux in the chamber was then simulated and found to be in good agreement with the experiment.

https://iopscience.iop.org/article/10.1088/0022-3727/41/20/205307/pdf

The metal flux from a rotating cylindrical magnetron : a Monte Carlo simulation

Comparative study on structure and internal stress in tin-doped indium oxide and indium-zinc oxide films deposited by r.f. magnetron sputtering

The Monte Carlo technique has been used to simulate the thermalization of sputtered atoms in the filling or background gas within a planar sputtering discharge. The model uses Thompson’s theoretical distribution of the energy of atoms sputtered from the cathode surface together with an approximation to the 6–12 Lennard–Jones potential to describe collisions between sputtered atoms and background gas atoms. The diffusion of the thermalized atoms is included explicitly in the Monte Carlo calculations. The velocity distribution of sputtered atoms between the cathode and substrate is calculated, from which their average kinetic energy is determined as a function of the product Pd, where P is the background gas pressure and d is the distance from the cathode. Because of the effect of the finite cathode‐substrate separation on back diffusion, it was found that PD, where D is the cathode‐to‐substrate separation, is an important parameter in describing thermalization and, consequently, the average energy of sputt...

Monte Carlo calculation of the thermalization of atoms sputtered from the cathode of a sputtering discharge

Magnetron sputter deposition as visualized by Monte Carlo modeling

In the early days of microelectronics, physical vapor deposition was simply applied to the evaporation of Al to form the high conductivity connections to transistors. With the ever-increasing complexity of silicon integrated circuits and the development of GaAs circuits, a much wider range of materials must be deposited to fulfill special needs for patterning, electromigration, diffusion barriers, Schottky contacts, air bridges, etc. (Table 1); alloys and compounds must be deposited as well as elemental metals. Sputter deposition has been used increasingly and other specialized techniques have also been applied; reactive evaporation, activated reactive evaporation, ion plating, and cluster ion deposition have been developed to meet special needs. However, evaporative and sputter deposition techniques are still the primary physical vapor deposition methods used for microcircuit fabrication and this review chapter will focus on their similarities and differences as they apply to microcircuit fabrication in both Si and GaAs.

Physical Vapor Deposition

Practicality of the Monte Carlo (MC) method developed for the analysis of the particle transport process in sputter‐deposition was examined. Titanium film thickness distributions on both faces of a planar substrate facing and not facing a planar‐magnetron‐type target were compared with corresponding calculated profiles. The results show that sufficient performance of the MC method can be obtained in the usual sputtering condition up to the argon pressure beyond which the majority of particles are transported by the thermal diffusion process.

T. Motohiro

Papers

Applications of Monte Carlo simulation in the analysis of a sputter‐deposition process