JPS585985B2 - Ionization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses the structure of an electrode for drawing out electrons and a power application means to form a magnetic field and give spiral motion to the electrons, thereby efficiently ionizing a gaseous substance to be ionized. The present invention relates to an ionization method that prevents the gaseous substance from adhering to an electrode immersed in the atmosphere of the substance to be ionized.

Generally, in order to vaporize a solid or liquid substance at room temperature and ionize it by electron bombardment to form positive ions, or to form negative ions by adhesion of electrons, the electrons are actively given a spiral motion, and the vaporized substance particles are It is desirable to increase the probability of collision with

In this case, in order to efficiently ionize the gaseous gas, a method is used in which a magnetic coil or the like is provided externally to form an orthogonal electromagnetic field and give spiral motion to the electrons.

By the way, like the ion source used for ion implantation,
limited space.

That is, if electrons and vaporized substance particles are to interact only inside the ion generation chamber, it is easy to place a magnet coil outside.

However, in ion blating, in order to ionize the vaporous gaseous substance flowing out or spewing out into the vacuum region from one end of the crucible, an ionizing electrode is placed to surround the gaseous substance, and then It is practically inconvenient to place the magnet coil outside, in many cases outside the vacuum pelger.

Furthermore, even if a magnet coil is placed inside a vacuum pelger, it is necessary to prevent gaseous substances that are about to be ionized from being deposited on the surface of the magnet coil, and to prevent the temperature of the coil from increasing due to crucible heating power, etc.
A heat shield must be provided.

The present invention takes the above points into consideration and solves these drawbacks with a simple structure and power application means.
Next, the present invention will be explained in detail with reference to drawings showing embodiments thereof.

In Figure 1, substance 1 to be vaporized and ionized
is vaporized from, for example, a normal vacuum evaporation crucible 2 and introduced into the ionization electrode 3 according to the present invention.

Note that the gaseous substance 4 of the substance 1 to be ionized is
It may be injected from an injectable crucible or delivered in other ways.

The ionizing electrode 3 is installed in an atmosphere of a gaseous substance 4 or surrounding the gaseous substance 4, and includes a cathode 5 which generates electrons arranged in an annular manner, and a substantially annular or spiral cathode disposed inside the annular cathode 5. An annular shielding electrode 7 having a U-shaped cross section is provided to surround the cathode 5, if necessary.

The cathode 5 is heated to a temperature suitable for emitting electrons by a cathode heating power source 8 connected to both ends of the cathode 5, and an electron accelerator connected between one end of the cathode 5 and one end of an anode 6 The electric power source 9 forms an electric field for extracting electrons from the cathode 5.

The voltage of this electron acceleration power source 9 is an appropriate voltage, that is, when generating negative ions, it is a low voltage that is lower than the ionization voltage of the substance to be ionized, and when generating positive ions, it is a low voltage that is higher than the ionization voltage. voltage, mainly several tens of volts ~
The voltage is several thousand volts.

Electrons 10 emitted from the cathode 5 due to this voltage pass through the gap between the annular or helical electrode 6 and enter the working space 11 in which the gaseous substance 4 to be ionized is present.

The anode 6 is held at a positive potential with respect to the cathode 5 by the voltage of the electron acceleration power source 9, and at the same time, a current flows through the magnetic field forming power source 12 connected to both ends of the anode 6.
A magnetic field is formed in the working space 11 in the axial direction of the anode 6, that is, in a direction almost perpendicular to the movement of the incoming electrons. Due to this magnetic field, the electrons 10 cause spiral motion in the working space 11, and are efficiently combined with the gaseous substance 4. Collision causes ionization.

Next, the above-mentioned action is conceptually shown in a plan view as shown in FIG. 2.

That is, electrons 10 emitted from the cathode 5 pass between the anodes 6 and enter the working space 11 .

In this working space 11, a magnetic field B formed by the current flowing across the anode 6 is generated as shown in the figure, so that the electrons 10 cause a spiral motion as shown in the figure.

Further, the magnetic field forming power source 12 that supplies a current flowing to both ends of the anode 6 generally has a low voltage and a large current of 2 to IOV and 10 to 50 A.

Note that not only direct current but also alternating current may be applied as necessary.

The magnetic field B is generated in proportion to the product NI of the electric current flowing through the anode 6 and the number of spiral turns N (approximately 1 in the case of a circular ring), and is preferably selected to have a value of several tens of glass and several hundred Gauss. Appropriate.

Furthermore, the gaseous substance 4 that is intended to be ionized often collides with and adheres to the anode 6, and the anode 6 becomes practically unusable due to the deposition of the gaseous substance 4, or the anode 6 becomes unusable due to the deposition of the gaseous substance 4, or The particles may fly off and cause problems.

However, in this invention, the anode 6 is constantly heated to a high temperature by the electric current from the magnetic field forming power source 12, preventing the vapor deposition of the gaseous substance 4 on the anode 6, and occasionally heating the vaporized substance to re-heat it. Evaporated and removed.

Note that the shape of the cathode 5 is not limited to that shown in the drawings, and it goes without saying that the shape may be annular or spiral, and a magnetic field generated by a cathode heating power source may be used in combination.

Furthermore, the current applied to both ends of the anode 6 may be applied continuously, intermittently with a large current, or in a pulsed manner.

Further, the shape of the anode 6 is not particularly limited as long as the gist of the present invention is utilized; for example, an auxiliary mesh or rod-shaped part may be attached to hold the annular or spiral anode 6. In short, it is sufficient that the current flows in a circular or spiral shape to make the magnetic field effective.

As described above, according to the ionization method of the present invention, a magnetic field is formed using a special electrode structure and a power application means to give spiral motion to electrons, thereby efficiently ionizing the gaseous substance to be ionized. The gaseous substance is prevented from adhering to the anode, the substance adhering to the electrode is removed, and an annular cathode is placed outside the annular or spiral anode. Because of this, the surface area of the cathode required for electron emission can be set without disturbing the space for gaseous substance injection or ionization, and the temperature of the cathode can be adjusted to the temperature required for electron emission. The current passed through the cathode to maintain the magnetic field can be used directly to form the magnetic field, and the structure is extremely simple.
This provides an inexpensive ionization method.

[Brief explanation of the drawing]

FIG. 1 is a cutaway perspective view showing one embodiment of the ionization method of the present invention, and FIG. 2 is an explanatory plan view of FIG. 1. 4... Gaseous substance, 5... Cathode, 6... Anode, 8
... Power source for cathode heating, 9... Power source for electron acceleration, 12
...Power supply for magnetic field formation.

Claims (1)

[Claims] An anode formed in a hollow ring shape or a spiral shape is provided inside a cathode arranged in a ring shape that emits 1 electron, and a voltage is applied to the anode to extract electrons from the cathode.
．． Electrons emitted from the cathode are introduced inside the anode, and at the same time, a current for forming a magnetic field is passed between both ends of the anode, and the magnetic field formed by the current causes the electrons introduced inside the anode to A spiral motion is applied to efficiently ionize the gaseous substance to be ionized inside the anode, and the gaseous substance to be ionized is attached to the anode by heating the anode by the current flowing through the anode. An ionization method characterized by preventing or removing attached substances.