Modeling and plasma characteristics of high-power direct current discharge

Abstract

To obtain both high ionization and high deposition rate, a modified global model for a continuous high-power DC magnetron sputtering (C-HPMS) is established by considering the continuous generation of the hot electrons and the high temperature caused by continuous high-power discharge. The results show that the plasma density is on the order of 1019 m−3 for power densities of only 183 W cm−2 (Al) and 117 W cm−2 (Cu). The ionization rate exceeds 90% of high-power impulse magnetron sputtering (HiPIMS) (peak power density of 564 W cm−2) for a DC power density of 180 W cm−2, and the total diffusion fluxes of the two targets are 26 (Al) and 30 (Cu) times that of conventional HiPIMS, leading to very high deposition rates. The work provides a theoretical basis for the realization of C-HPMS and gives an enlightenment to the development of deposition equipment for continuous high-power discharges.

High-precision modeling of dynamic etching in high-power magnetron sputtering

“…The physical processes in the plasma discharge and cathode etching in HPMS are analyzed and the influence of selfsputtering and high temperature on the plasma discharge and cathode etching is studied. Experimental results reveal a simulation error of only 0.8% that is much better that obtained by the traditional test-electron Monte Carlo (MC) method (10.1%) and static PIC/MCC method (4.0%) for continuous HPMS (C-HPMS) [28].…”

“…The software package used in our simulation is commercial software MATLAB R2019b. According to the detailed flowchart shown in figure A1, the codes of the models (including PIC/MCC model, test-particle MC model, CA model, dynamic etching model and ionization region model) are self-developed based on the function module of MATLAB [28,29]. During the simulation, the models invoke several built-in functions of MATLAB, including matrix operations, linear interpolation, ordinary differential equations, data reading and storage, post-processing, program loop and judgment.…”

“…The initial plasma density is set to 1 × 10 14 m −3 and each test particle (super-particle) represents 1 × 10 7 actual particles in the simulation. 34 320 electrons and Ar + are randomly generated in the simulation domain according to the grid quantity and their initial velocities are predicted by the Maxwellian distribution [28]. The initial average ion temperature is assumed equal to the background temperature, which is calculated by the plasma heat transfer model [33].…”

“…The initial average ion temperature is assumed equal to the background temperature, which is calculated by the plasma heat transfer model [33]. The initial average electron temperature is 2.5 eV in C-HPMS according to Chen et al [28]. The initial density of Cu is 0, and Cu atoms are generated by sputtering accompanied by secondary electron emission.…”

“…Discharge experiments were performed on a homemade vacuum chamber with a diameter of 1200 mm and height of 1350 mm. A custom high-power cathode was used for the C-HPMS [28] discharge in the constant current mode (I = 35 A) sustained by a 60 kW DC power supply (Ascent 60 K, Advanced Energy, US) with a maximum output voltage of 1000 V and maximum output current of 60 A. The cathode target was Cu (99.9% pure, 600 × 120 × 14 mm 3 ) and the background pressure was 5.0 × 10 -3 Pa.…”