JPH0530276Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a sputter type negative ion source used in ion implantation equipment and the like.

(Prior Art) As is well known, a sputter type negative ion source is constructed to generate negative ions by sputtering a sputter target with cesium ions. FIG. 2 shows a conventional example.

In the figure, 1 is a sputter target (hereinafter simply referred to as target) that supplies elements extracted as negative ions, 2 is a cesium reservoir that supplies cesium vapor, 3 is an ionizer that hits target 1 and produces cesium positive ions, 4 is an ion source electrode that constitutes an electric field for extracting a negative ion beam, and 5 is an extraction electrode.

Further, 6 is a cooling shaft that supports and cools the target 1, 7 is an insulator that insulates between the target 1 and the ionizer 3, and 8 is an insulator between the ion source electrode 4 and the extraction electrode 5. The insulating flange 9 is a vacuum container.

A portion of the cesium vapor generated in the cesium reservoir 2 is ionized into positive ions by the ionizer 3, accelerated by an electric field applied between the ionizer 3 and the target 1, and spatters the target 1. Another part of the cesium vapor adheres to the surface of the target 1.

The sputtered particles sputtered by the positive cesium ions are supplied with electrons from the cesium adhering to the surface of the target 1, and negative ions are generated. Negative ions are extracted by an electric field generated by the ion source electrode 4 and extraction electrode 5. 10 indicates extracted negative ions. Note that 11 is a passage leading to a vacuum pump for evacuating the inside of the container 9.

(Problems to be Solved by the Invention) However, in a negative ion source having such a configuration, there is a problem when an element that consumes a large amount of cesium, such as boron or copper, is used as the target 1.

For example, when boron is used as a target, since boron has poor thermal conductivity, the surface of the target 1 becomes hot and the rate of cesium deposition becomes poor. Furthermore, when copper is used, the sputtering rate is high, so that cesium is also spattered.

For the above reasons, when boron, copper, etc. are used, the amount of cesium on the surface of target 1 tends to be insufficient, and the negative ion beam current is lower than when carbon, silicon, etc. are used, resulting in less cesium consumption. There are disadvantages as the amount increases.

The purpose of this invention is to make it possible to increase the size of the negative ion beam even when an element to which cesium is difficult to adhere is used as a target.

(Means for solving the problem) This idea provides a path for cesium vapor from the outlet of the cesium reservoir to near the surface of the target, so that the cesium vapor from the cesium reservoir is directly supplied to the surface of the target. It is characterized by what it did.

(Operation) Cesium vapor from the cesium reservoir is sprayed directly onto the surface of the target. This allows cesium vapor to be efficiently supplied to the surface of the target, making it possible to increase the negative ion beam even when using a target that tends to lack cesium.

(Example) An example of this invention will be described with reference to FIG.
Note that parts given the same reference numerals as in FIG. 2 indicate the same or corresponding parts. According to this idea, a pipe 13 is provided extending from the outlet 12 of the cesium reservoir 2 to the surface of the target 1. The pipe 13 supplies cesium vapor from the cesium reservoir 2 so as to spray it directly onto the surface of the target 1.

When the target 1 is boron, even if the cesium deposition rate is poor, a large amount of cesium is supplied to the surface, so there is no shortage of cesium on the surface. In the case of copper, even if cesium is sputtered together, a large amount of cesium is supplied to the surface as described above, so there is no shortage of cesium even in this case.

In this way, there will be no shortage of cesium, thereby increasing the negative ion beam current.

Next, the experimental results of this idea will be explained. In the conventional configuration shown in Figure 2, when attempting to obtain B ^- ion species using a negative ion source with a distance of 25 mm from the exit 12 to the surface of the target 1, the beam current was 58 μA. .

On the other hand, in the configuration shown in Fig. 1, when trying to obtain the same ion species by setting the distance between the tip of the pipe 13 and the surface of the target 1 to 10 mm, the beam current could be set to 80 μA. Ta.

(Effects of the invention) As detailed above, according to this invention, it is possible to supply a larger amount of cesium to the surface of the target than with the conventional configuration, and therefore it is possible to increase the negative ion beam. It has a great effect.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of this invention, Figure 2 is a sectional view showing an embodiment of this invention.
The figure is a sectional view of a conventional example. 1... Target, 2... Cesium reservoir, 3... Ionizer, 4... Ion source electrode, 5... Extraction electrode, 9... Container, 12... Outlet, 13... Pipe.

Claims (1)

[Claims for Utility Model Registration] An ionizer that ionizes a portion of cesium vapor generated by a cesium reservoir into positive ions; In a sputter type negative ion source equipped with a sputter target that generates negative ions, the cesium vapor from the cesium reservoir is directly supplied to the surface of the target from the outlet of the cesium reservoir to the vicinity of the surface of the target. A sputter-type negative ion source with a passageway for cesium vapor.