An ion source that reduces the rate of electron escape

Abstract

The invention discloses an ion source capable of reducing an electron escape rate, including an anode ring, inner cathode and outer cathode, the anode ring, the inner cathode and the outer cathode areeach axisymmetric, a soft magnetic column is fixed in the middle of the yoke of the outer cathode, one end of the soft magnetic column passes through the center of the inn hole of the anode ring andis connected with the middle of the inner cathode, the longitudinal cross-sectional shape of the magnetic pole shoe of the inner cathode is mirror symmetrical with the longitudinal cross-sectional shape of the magnetic pole shoe of the outer cathode of the corresponding position, and an annular cathode gap is formed between the magnetic pole shoe of the inner cathode and the magnetic pole shoe ofthe outer cathode, the anode ring is directly opposite to the lower part of the cathode gap, two permanent magnets are arranged on the magnetic yoke of the outer cathode, the two permanent magnets aresymmetrical with respect to the soft magnetic column, and the two permanent magnets are respectively positioned directly below the opposite sides of the anode ring. By increasing the symmetrical magnetic field, the invention improves the uniformity of the magnetic field distribution on both sides of the cathode gap, can reduce the escape rate of electrons and effectively reduce the bombardment probability of the electrons on the cathode magnetic pole shoe.

Description

technical field [0001] The invention relates to the technical field of ion source equipment, in particular to an ion source capable of reducing the escape rate of electrons. Background technique [0002] An anode layer plasma source is usually used in the PECVD (Plasma Enhanced Chemical Vapor Deposition) reaction. In the DLC deposition process, it is used to ionize inert gases such as argon, or directly ionize acetylene, acetone, etc. The deposition gas makes it form an ion flow and injects it into the reaction vacuum chamber, and increases the ionization rate of the deposition reaction gas, thereby increasing the proportion of SP3 in the DLC coating and the deposition rate, so as to improve the quality of the deposited film and the deposition time shortening. [0003] The anode layer ion source was originally developed from a closed drift ion thruster used in space engines. An annular gap is opened on the cathode plate, an annular anode is set under the annular gap, and a ...

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Problems solved by technology

[0005] Existing ion sources are simply designed with permanent magnets or electromagnets on one side of the cathode magnetic circuit, which will lead to asymmetrical distribution of the magnetic field at the gap of the cathode magnetic pole piece, so that electrons are in the runway of the orthogonal electromagnetic field. When drifting upward, the constraints on the inner and outer sides are asymmetrical, and it is easy for most of the electrons to escape from the closed drifting runway. The escaped electrons are sputtered on the cathode pole piece, which increases the etching of the cathode pole piece. At the same time, the cathode The sputtered atoms of the material of the pole piece itself will pollute the deposited film, which not only affects the quality of the final coating, but also shortens the maintenance cycle of the cathode pole piece and increases the maintenance cost

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