第9届表面工程国际会议 (ICSE 2024)

The high-current anode layer ion source, which can enhance gas ionization and output high-density ion beams, is used to enhance ion beam-assisted deposition, substrate cleaning, and ion implantation. However, under high-current conditions, the internal ion source is prone to discharge breakdown, and extensive ion bombardment of the inner and outer cathodes leads to significant erosion, potentially causing sample contamination. Traditional solutions mainly alleviate erosion by optimizing the discharge structure, but the parameter systems are too complex. This paper proposes to simplify the parameter system by abstracting the inner and outer cathodes into a magnetic mirror model. The simulation results reveal that magnetic mirror with R_m=2.50 and B₀=36 mT can constraint the plasma at the center between the inner and outer cathode. When the discharge center of the plasma is consistent with the magnetic mirror center, the anode layer ion source presents both high density output of ion beam current and significantly reduced cathode etching, suggesting the best balance obtained between the output and cathode etching. On this basis, two structures are designed, which are magnetic shielding around the anode and sputtering shielding on the top of the inner cathode and outer cathode, respectively. The results show that the magnetic shielding around the anode cuts off the magnetic induction line between the cathode and anode, eliminating the arcing condition in the ion source. The sputtering shielding for the cathode uses alumina ceramic because of its extremely low sputtering yield and high insulation performance. Therefore, the sputtering shields can not only resist the ion sputtering, but also shield the electric field on the outer surface of the cathode. The discharge experiments reveal that the modified ion source can eliminate the inside arcing and provide a clean and strong ion beam with a high efficiency. Compared with the original ion source, the output efficiency of the modified ion source is 36% higher, while the detected Fe content from the cathode sputtering is 2 orders of magnitude smaller.

Anode Layer Ion Source；magnetic mirror；electromagnetic shielding；high-power discharge