JPS6041820B2 - ion source device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion source device used in an ion accelerator or the like.

For example, ion implanters generate ions in a vacuum, accelerate, focus, and deflect them to implant (inject) them into a target, but an ion source is essential for these devices. belongs to.

The PIG type ion device, which is generally used as an ion source device, has an ion extraction part 2 in which an ion extraction port 1 is formed, an anode electrode 3, a cathode electrode 4, a reflection plate 5, etc., as shown in FIG. It is well known that the gas injection tube 6 is assembled in the housing and is connected to the cathode electrode 4 through the reflection plate 5 to inject gas. The ion extraction port 1 of the extraction section 2 is circular, and the internal shapes of the anode electrode 3 and cathode electrode 4 are generally circular. For this reason, the area of the ion extraction port 1 can be increased, and for this purpose, the diameter of the ion extraction port 1 can be increased. However, when this diameter is increased, the electric field for ion extraction is Since it becomes difficult to affect the J core, the ion current does not increase in proportion to the diameter, and therefore there is a limit to the increase in the ion current due to an increase in the diameter.To solve this, ion extraction It is conceivable to make the opening 1 a long hole.This is convenient because the electric field will be influenced near the center of the ion extraction port of the long hole. The ion beam has a high density at the center and a low density at the edges, resulting in a beam with non-uniform density.This is because the beam that passes through the cathode and anode electrodes has a circular cross section. This is natural considering that.The purpose of this invention is to increase the ion current and to make the ion beam density uniform.This invention aims at increasing the ion current and making the ion beam density uniform.This invention aims at making the ion extraction port of the ion extraction part a long hole. In addition, the beam passing through the anode electrode and heading toward the ion extraction port is characterized in that its cross section is elongated.

FIG. 1 shows an embodiment of the present invention, in which the ion extraction port 1 formed in the ion extraction section 2 is made elongated (for example, circular), and the inner surfaces of the anode electrode 3 and the cathode electrode 4 are shaped accordingly. The cross section is elongated (e.g. circular)
and arranged so that their long axes are parallel to each other.

A high DC voltage is applied between the anode electrode 3 and the cathode electrode 4 to cause a discharge, ionize the injected gas, and ionize it based on the electric field caused by the voltage applied between it and the external extraction electrode. A beam is extracted through an ion extraction port 1.

The above action is no different from the conventional one. However, in the illustrated configuration, since each of the electrodes 3 and 4 has an elongated inner surface shape, the cross section of the ion beam toward the ion extraction section 2 also has an elongated shape. That is, the ion extraction port 1 and the cross section of the ion beam have a similar relationship, and the long axis direction of the ion extraction port 1 and the long axis direction of the cross section of the ion beam are parallel to each other. Most of the ions that have passed through will pass through the ion extraction port 1 and be extracted to the outside. Therefore, ion attraction. The cross section of the ion beam that has passed through the outlet 1 has almost uniform density in all parts thereof, as shown in FIG. In Figure 2, the vertical axis shows the ion current density, and the horizontal axis shows the length (ion beam diameter) along the long axis of the ion beam cross section, from the edge to the center of the ion beam cross section. The density is almost constant. On the other hand, in the conventional configuration in which the ion beam has a circular cross section, as shown in Figure 3, the ion beam has only a high density at the center of the cross section, and an extremely low density at the ends, so that the cross section of the beam is It cannot be a uniform density. Since the ion extraction port 1 and the inner surface shape of each electrode are similar, most of the ion beam that has passed through the anode electrode 3 passes through the ion extraction port 1, resulting in high density and a large ion current. Become. In order to make the cross section of the ion beam toward the ion extracting section 2 elongated, the anode electrode 3 in the configuration shown in FIG.
, the cathode electrode 4 is formed so that its cross-sectional shape is elongated, but as shown in FIG. As shown in Figure 5, a rectangular hole 3 is used instead of a circular hole.
b may be arranged in a straight line. According to such a configuration, even if the cross section of the beam passing through each hole 3a, 3b is circular or rectangular, the areas near the adjacent ends of each beam cross section overlap, so that when viewed as a whole, It has an elongated shape and is almost similar to the ion extraction port 1, and exhibits the same effect as the case shown in FIG. FIG. 6 shows an example in which the inner surface of the anode electrode 3 has an elongated rectangular shape.
This has almost no difference from the configuration shown in FIG. It goes without saying that when an anode electrode having a shape as shown in FIGS. 4 to 6 is used, a cathode electrode having a corresponding shape is used. As described in detail above, according to the present invention, it is possible to make the density distribution of the ion beam uniform and to increase the density of the ion beam.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing an embodiment of the invention, Figures 2 and 3.
The figure is a characteristic diagram of an ion beam, and FIGS. 4 to 6 are front views of an anode electrode showing an embodiment. 1... Ion extraction port, 2... Ion extraction part, 3... Anode electrode, 4... Cathode electrode.

Claims (1)

[Scope of Claims] 1. An ion extraction portion having an anode electrode, a cathode electrode, and an ion extraction port through which ions ionized by the discharge between the two electrodes pass, and the ion extraction port has a long hole shape. The ion beam directed from the anode electrode to the ion extraction port is shaped so that its cross section is similar to the ion extraction port, and its long axis direction is parallel to the long axis direction of the ion extraction port. An ion source device comprising: forming an inner surface of the anode electrode. 2. The ion source device according to claim 1, wherein the anode electrode has an elongated inner surface. 3. The ion source device according to claim 1, wherein the anode electrode is configured in a shape having a plurality of holes arranged in a straight line. 4. The ion source device according to claim 3, wherein the hole is circular. 5. The ion source device according to claim 3, wherein the hole is rectangular.