JPS6388740A - Ion gun - Google Patents

Abstract

PURPOSE: To extend the service life and to improve the etching capability, by furnishing a means to radiate electrons, a means to repel the electrons radiated at the outer side of the above means (repeller), and an electron passable means of a mesh-form, a grid-form, or the like to absorb the electrons radiated at the inner side of the radiating means. CONSTITUTION:A neutralizer composed of three elements, a filament 5, a repeller 6, and a grid 7 is furnished at the periphery of ion beams, and the electrons are radiated toward the center of the ion beams by the neutralizer. As a result, as well as the number of electrons to strike the ion beams is increased and the neutralization efficiency of the ion beams is improve, a filament to be furnished on the passage of the ion beams can be removed, and the service life can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an ion gun used for etching the surface of a sample by ion bombardment.

In conventional surface analysis instruments, a Kauffman type ion gun for etching is used to remove dirt from a sample surface or to delete a sample surface in depth direction analysis of the sample surface. When performing etching with a large-diameter, high-current ion beam emitted from a Kauffman-type ion gun, etc., if the ion beam is not neutralized, the ion beam irradiated onto the sample surface will cause etching. Due to the space charge effect, the beam cannot be focused sufficiently, making it impossible to obtain the desired beam current density.Also, if the sample is an insulating material, the surface of the sample is charged by the charge of the irradiation beam, which causes the irradiation ions to This repulsion makes it difficult for the irradiation beam to reach the sample surface, reducing etching performance.

Conventionally, this neutralization has been carried out by placing a filament on the path of the ion beam, as shown in FIG. 4, and neutralizing the ion beam by thermionic electrons generated from the filament. However, since the filament is placed on the path of the ion beam, the filament itself is etched by the ion beam, resulting in a short service life.

Additionally, if the filament is placed outside the path of the ion beam, the electrons emitted from the filament collide with the ion beam less efficiently, reducing the neutralization ability and reducing the space charge effect of the ion beam. Problems to be Solved by the Invention The present invention attempts to suppress the space charge effect of an ion beam without reducing the neutralization efficiency as described above. The purpose of this invention is to solve the problem that the life of the filament becomes short and that the neutralizing effect is not sufficiently achieved when trying to lengthen the life of the filament 1.

22 Means for Solving Problems Within the vacuum outer casing of the ion gun, means for emitting electrons to the outer periphery of the ion beam, and means (rebeler) for repelling the electrons emitted to the outside of the emitting means; A mesh-like or lattice-like means through which electrons can pass is provided inside the emitting means to attract emitted electrons.

When performing ion etching as described above, if the ion beam is not neutralized to some extent, space charge effects and charging effects may occur depending on the sample. A neutralizer consisting of three elements: filament I, repeller, and grid.
By placing a neutralizer and emitting electrons toward the center of the ion beam, the number of electrons colliding with the ion beam is increased, thereby improving the neutralization efficiency of the ion beam. At the same time, the filament placed in the path of the ion beam will be removed to extend the life of the ion beam.

Embodiment FIG. 1 shows an embodiment of the present invention. In FIG. 1, W
is a vacuum outer casing, and 1 is an ionization chamber.

Inside the ionization chamber 1, a filament 2 and an ion accelerating electrode are arranged around the chamber, and the electrons emitted from the filament 2 are ion-accelerated into the argon gas (ArGas) sent into the ionization chamber 1. They are accelerated by the south pole and collided, ionizing gas molecules. The + ions generated by the ionization of gas molecules are accelerated because the pole is at a positive potential and the first grid 3 is at O or a negative potential.
It is drawn out of the ionization chamber 1 by the negative voltage on the grid 3 and accelerated in the second grid 4. The ions generated in the ionization chamber 1 have a tendency to converge toward the center due to the magnetic field, and are converged onto the sample surface. 5 is a filament for neutralization, 6 is a liberator for neutralization, and 7 is a grid for neutralization. These three elements constitute a neutralizer in the shape of a concentric cylinder as shown in Figure 2. are all,
It is located outside the radial extent of the ion beam passing through the center. A voltage as shown in Fig. 3 is applied to each element of this neutralizer, and the electrons emitted by the neutralizing filament 5 are placed outside the filament 5 at a negative potential when viewed from the filament 5. It is repelled by the neutralizing repeller 6, and is drawn out and concentrated at the center by the neutralizing grid 7 placed inside the filament 5 at a positive potential when viewed from the filament 5. The electrons concentrated at the center collide with ions in the ion beam extracted from the ionization chamber 1, neutralizing the ion beam. The atoms neutralized by the ions maintain their original speed and form a beam together with unneutralized ions, and the sample S is irradiated with this neutralized ion beam.

Since all the electrons emitted from the neutralizing filament 5 are accelerated toward the center, they collide with the ion beam extracted from the ionization chamber 1 without waste, resulting in a large neutralizing effect.

According to the present invention, ions can be efficiently neutralized without placing a neutralizer on the path of the ion beam, and since the neutralizer is not subjected to ion collisions, there are no consumable parts and the structure is simple. This allows for cost reduction, longer filament life, and improved etching ability.

[Brief Description of the Drawings] Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a detailed view of the neutralizer, Fig. 3 is a wiring diagram of the neutralizer, and Fig. 4 is a sectional view of a conventional example. S...sample, W...
・Vacuum outer casing, 1... Ionization chamber, 2... Filament, 3... First grid, 4... Second grid, 5
...Filament for neutralization, 6...Liberator for neutralization, 7...Grid for neutralization.

Claims (1)

[Claims] Inside the vacuum outer casing, on the outer periphery of the ion beam, a means for emitting electrons, a means for repelling electrons emitted to the outside of the emitting means, and a mesh shape for attracting electrons emitted to the inside of the emitting means are provided. Alternatively, an ion gun is characterized in that it is provided with a means through which electrons can pass, such as a grid.