JPH06231711A - Matching method in microwave ion source device - Google Patents

Abstract

PURPOSE:To extend the range for matching the impedance between a microwave oscillator and a microwave ion source, and precisely conduct this matching in a short time. CONSTITUTION:A waveguide 8 for connecting a microwave oscillator 6 to a microwave ion source 2 is provided with a reflected power detector 10 for detecting the reflected power of a microwave from the microwave ion source 2 side and three stubs 21-23 which can be mutually independently put into and taken out from the waveguide 8. All the stubs 21-23 are simultaneously moved in the same direction and stopped in the position where the reflected power detected by the reflected power detector 10 is a minimum value, the respective stub 21-23 are successively moved one by one and stopped in the positions where the reflected power detected by the reflected power detector 10 is the minimum value, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave ion source device including a microwave ion source, a microwave oscillator and a waveguide, and obtains impedance matching between the microwave oscillator and the microwave ion source. Regarding the method.

[0002]

2. Description of the Related Art FIG. 5 is a schematic view showing an example of a conventional microwave ion source device. This microwave ion source device extracts a microwave ion source 2 for extracting an ion beam 4 from plasma generated by a microwave discharge, a microwave oscillator 6 for generating a microwave, and a microwave from the microwave oscillator 6. And a waveguide 8 that supplies the microwave ion source 2.

By simply supplying microwaves from the microwave oscillator 6 to the microwave ion source 2 via the waveguide 8, impedance matching between the microwave oscillator 6 and the microwave ion source 2 is normally obtained. However, since the reflected power of the microwave from the microwave ion source 2 side is large and the loss is large, the conventional matching is performed as follows.

That is, the microwave ion source 2 is provided in the waveguide 8.
Reflection power detector 10 for detecting the reflection power of microwaves from the side, and stub 12 that can be put in and taken out in waveguide 8.
Is provided, and the stub 12 is fixed by moving it manually or automatically at a position where the reflected power detected by the reflected power detector 10 becomes the minimum value. The reflected power detector 10 is, for example, a directional coupler, and the stub 12 is, for example, a metal rod.

[0005]

However, in the method of performing the matching by using one stub 12 as described above, the range in which the matching can be achieved is narrow, so that the variation of the load condition on the microwave ion source 2 side may occur. In some cases, it may not be possible to respond sufficiently.

Although there is a conventional idea that if a plurality of stubs are used, the range of matching can be widened. However, if this is done, the movements of the stubs affect each other, so that a plurality of stubs are simply provided. It is very difficult to make a match just by doing so, and it takes a long time to make a match.

Therefore, the main object of the present invention is to provide a matching method in which the impedance matching between the microwave oscillator and the microwave ion source is wide, and the matching can be performed accurately in a short time. And

[0008]

In order to achieve the above object, the matching method of the present invention provides a waveguide as described above,
A reflection power detector for detecting the reflection power of the microwave from the microwave ion source side and three or more stubs which can be independently put in and out of the waveguide are provided. All at the same time in the same direction to stop at the position where the reflection power detected by the reflection power detector becomes the minimum value, and then sequentially move each of the stubs one by one to detect the reflection power detector. It is characterized in that the reflection power is stopped at the position where the reflected power becomes the minimum value.

[0009]

According to the above method, relatively coarse alignment can be quickly achieved by first moving all the stubs at the same time. Then, by moving each stub one by one from that state, it is possible to quickly perform finer alignment. As described above, after the relatively coarse alignment is performed, the finer alignment is performed on the assumption that the alignment can be performed accurately in a short time while using three or more stubs. Moreover, since three or more stubs are used, the range of matching can be widened.

[0010]

1 is a schematic view showing an example of a microwave ion source apparatus for carrying out a matching method according to the present invention. The same or corresponding portions as those of the conventional example shown in FIG. 5 are designated by the same reference numerals, and the differences from the conventional example will be mainly described below.

In this embodiment, the waveguide 8 as described above is provided with the above-described reflection power detector 10 for detecting the reflection power of the microwave from the microwave ion source 2 side, and three stubs. 21 to 23, which can be put in and taken out of the waveguide 8 independently of each other. Each stub 21-23 is like a metal rod, for example.

Each stub 21-23 has a waveguide 8
The actuators 26 to 28 to be put in and taken out are respectively connected. Each of the actuators 26 to 28 is composed of, for example, a combination of a motor and gears.

Then, the reflected power detected by the reflected power detector 10 is taken into the control circuit 30, and the control circuit 30 controls the actuators 26 to 28,
The stubs 21 to 23 are controlled as follows.

That is, referring to FIG. 2, first, the stubs 21-
All three stubs 21 to 23 are stopped at the position where the reflection power detected by the reflection power detector 10 has a minimum value by moving three three in the same direction at the same time (step 40).

Then, the first stub, for example, the stub 21.
The stub 21 is stopped at a position where the reflected power detected by the reflected power detector 10 becomes the minimum value by moving only the stub 21 (step 41).

Similarly, the second stub, for example, the stub 22 is moved thereafter to stop the stub 22 at the position where the reflected power detected by the reflected power detector 10 becomes the minimum value (step 42). Further, only the third stub, for example, the stub 23 is moved to stop the stub 23 at the position where the reflection power detected by the reflection power detector 10 has the minimum value (step 43).

Next, at step 44, it is judged whether or not the reflection power detected by the reflection power detector 10 becomes smaller than a predetermined value (for example, about 5 W) by the above processing operation, and if it becomes smaller, the operation is performed. Is ended, and if not smaller, the process returns to step 40 and the above operation is repeated.

According to the above method, first, the stubs 21 to 23 are formed.
By moving all simultaneously, a relatively coarse match can be quickly achieved. Then, by moving each of the stubs 21 to 23 one by one from that state, it is possible to quickly perform finer alignment. As described above, after the relatively coarse alignment is performed, the finer alignment is performed on the premise that the alignment is performed, so that the three stubs 21 to 23 are aligned.
By using, it is possible to perform accurate matching in a short time.

Moreover, since the three stubs 21 to 23 are used, the range of matching can be widened. Therefore, since it is possible to sufficiently cope with the fluctuation of the load condition on the microwave ion source 2 side, for example, the efficiency of the ion beam 4 from the microwave ion source 2 over a wide beam current range can be improved. You will be able to pull out well.

According to the above method, accurate matching can be performed in a short time, but in order to achieve even more accurate matching, the method shown in FIGS. 3 and 4 can be adopted. good.

Since steps 50 to 54 in FIG. 3 are the same as steps 40 to 44 in FIG. 2, duplicate description will be omitted. Here, the difference from FIG. 2 will be described. In step 55 following step 54, It is determined whether or not a predetermined time has elapsed from the start of the operation of 50, and if not, the process returns to step 50 and the subsequent operations are repeated.

If the reflected power still does not fall within the predetermined value after the elapse of the certain time, the process proceeds to step 56 in FIG. 4 and the first and second stubs, for example, the stubs 21 and 22 are simultaneously moved in the same direction. The stubs 21 and 22 are moved and stopped at the position where the reflection power detected by the reflection power detector 10 becomes the minimum value.

Next, the second and third stubs, for example, the stubs 22 and 23 are simultaneously moved in the same direction, so that both stubs 22 and 23 are located at a position where the reflected power detected by the reflected power detector 10 has a minimum value. Stop (step 57).

Next, the third and first stubs, for example, the stubs 23 and 21 are simultaneously moved in the same direction, and both stubs 23 and 21 are placed at the position where the reflected power detected by the reflected power detector 10 becomes the minimum value. Stop (step 58).

Next, at step 59, it is judged whether or not the reflection power detected by the reflection power detector 10 has become smaller than a predetermined value by the above processing operation, and if it has become smaller, the operation is terminated and becomes smaller. If not, in step 60, it is determined whether or not a fixed time has elapsed from the start of the operation in step 56. If not, the process returns to step 56 and the subsequent operations are repeated.

If the reflected power does not fall within the predetermined value even after the lapse of the above-mentioned fixed time, the process returns to step 50 in FIG. 3 and the subsequent operations are repeated.

The method shown in FIGS. 3 and 4 is similar to that shown in FIG.
The two-step process of moving all three stubs and the process of moving one stub as shown in Fig. 3 is added to the process of moving two stubs, so a more accurate alignment can be achieved. Therefore, the reflection power can be more reliably made smaller than the predetermined value.

By the way, the stub has three parts as in this embodiment.
The provision of four stubs is usually sufficient, but four or more stubs may be provided if it is desired to widen the range of matching. In that case, step 40 of FIG. 2 and FIG.
All the stubs may be moved in the same direction at the same time in step 50. Further, as the process following step 55 in FIG. 3, (n-1) stubs, (n-2) stubs ...
It is sufficient to perform a process of moving (n is the total number of stubs) by one.

The reflected power detector 10 may be a device other than the directional coupler, for example, a power splitter or the like that separates an incident wave and a reflected wave like the directional coupler. Further, the reflected power detector 10 has the stub 2 as in this example.
It is better to provide the microwave ion source 2 side than 1 to 23
It is preferable because the reflected power can be detected closer to its source and therefore more accurately.

The microwave ion source 2 may or may not be of the ECR type.

[0031]

As described above, according to the present invention, a relatively coarse alignment is obtained by first moving all the stubs at the same time, and then a finer alignment is obtained by moving each stub one by one from that state. Because I chose
Accurate matching can be achieved in a short time while using three or more stubs. Moreover, since three or more stubs are used, the range of matching can be widened.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a microwave ion source device for carrying out a matching method according to the present invention.

FIG. 2 is a flowchart showing an example of a matching method according to the present invention.

FIG. 3 is a flowchart showing another example of the matching method according to the present invention.

FIG. 4 is a flowchart following the flowchart of FIG.

FIG. 5 is a schematic view showing an example of a conventional microwave ion source device.

[Explanation of symbols]

 2 microwave ion source 6 microwave oscillator 8 waveguide 10 reflection power detector 21-23 stub 26-28 actuator 30 control circuit

Claims (1)

[Claims] 1. A microwave ion source for extracting an ion beam from plasma generated by microwave discharge, a microwave oscillator for generating microwaves, and a microwave from the microwave oscillator is supplied to the microwave ion source. In the above-mentioned waveguide, a reflection power detector for detecting the reflection power of the microwave from the microwave ion source side and three or more stubs, which are independent of each other, Then, prepare something that can be put in and taken out in the waveguide, and first,
All the stubs are simultaneously moved in the same direction to stop at the position where the reflected power detected by the reflected power detector becomes the minimum value, and then each of the stubs is sequentially moved one by one so that the reflected power detector A matching method in a microwave ion source device, characterized in that the detection is stopped at each position where the detected reflected power becomes a minimum value.