Hall source for optical thin films

2019-10-18

Since the 1980s, more attention has been paid to the auxiliary role of ion energy transfer in the manufacture of high-quality optical films. It is of great benefit to improve the adhesion, density, absorption, refractive index and crystal structure of the films. At present, gate Kaufman source, RF ion source, gate free APS source and gate free Hall source are widely used in scientific research and production. Compared with other sources, the non grid Hall source is completely suitable for the requirements of the coating process, and its outstanding features are miniaturization, compact structure and easy disassembly.


The hall source does not need water cooling, and its structure is mainly divided into electrical connection and gas connection. In the electric connection part, the hall source has three connecting wires, one of which is anode positive high voltage, which is connected with the anode positive end of the ion source, one of the other two wires is connected with the anode negative end to become the common end, and the other wire is connected with the other end of the cathode filament fixed terminal to supply power to the cathode. The cathode is tungsten wire, which is located on the top of the ion source. In the air link part, the hall source enters the source through the air inlet at the bottom. When using, first connect the middle connecting air channel, then connect the air inlet with the air inlet of the vacuum system with the vacuum rubber pipe or polytetrafluoroethylene pipe, and connect with the mass flowmeter outside the vacuum system.


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The hall source uses the cathode filament to emit electrons in the divergent magnetic field to cause the discharge to form a plasma, the axial magnetic field to the radial current causes the circumferential Hall current, the circumferential current and the radial magnetic field produce the electromagnetic force to accelerate the electrons, and drive the ions to form a neutral plasma. The source uses the electromagnetic acceleration instead of the electrostatic acceleration, which is more convenient to obtain a large beam with low energy.


The system can be applied to any film deposition with low energy and large beam current (amperage) to prepare high quality films. Before the deposition of the film, the surface of the substrate was bombarded with ions to clean the surface contaminants, which increased the adhesion between the film and the substrate and reduced the membrane contamination. At the same time, it can increase the density of the film, increase the density of the film, eliminate the columnar crystal, refine the structure of the film, and significantly increase the adhesion between the film and the substrate.