JPH0719084Y2 - Ion implanter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ion implantation apparatus for implanting an ion beam into a target.

[Conventional technology]

A conventional, for example, electrostatic scan type ion implanter of this type will be described with reference to FIG.

This ion implanter, as shown in FIG.
11, an ion extraction electrode 12, and a mass analysis magnet 13 are provided. Then, an accelerating tube 15 'equipped with an analysis slit 14 and a plurality of accelerating electrodes 15 at the subsequent stage of the mass spectrometric magnet 13.
And a Q lens electrode 16 are provided. Further, a vertical scanning electrode 17 and a horizontal scanning electrode 18 are provided at the subsequent stage of the Q lens electrode 16, and a target is provided at the subsequent stage of the horizontal scanning electrode 18 via a mask 19.
20 are provided. A power source (not shown) is provided for each of the ion extraction electrode 12, the mass analysis magnet 13, the acceleration electrode 15, the vertical scanning electrode 17, and the horizontal scanning electrode 18.

In this ion implantation device, various ions generated in the ion source 11 are extracted into a beam by the ion extraction electrode 12. Then, from the various ions contained in the ion beam 21 extracted by the ion extraction electrode 12, only the necessary ions pass through the analysis slit 14, and the mass analysis magnet is used.
The ion beam 21 is deflected at 13. Next, the analysis slit
The ion beam 21 passing through 14 enters the accelerating tube 15 ′, is accelerated by the accelerating electrode 15, and is converged by the Q lens electrode 16. Further, the ion beam 21 focused by the Q lens electrode 16 is vertically and horizontally scanned by the vertical scanning electrode 17 and the horizontal scanning electrode 18, and is irradiated onto the target 20 via the mask 19.

When the ion beam 21 is horizontally and vertically scanned to inject ions into the target 20, this ion implantation apparatus overscans to a position where the target 20 is completely passed through. In order to reduce the loss of the ion beam 21 by reducing it as much as possible, the beam diameter of the ion beam 21 tends to be narrowed as much as possible.

However, if the beam diameter is narrowed, the uniformity of implantation will deteriorate,
In addition, as the ion beam current density increases, the area irradiated by the ion beam 21 is greatly charged up,
The target 20 may be destroyed due to electric discharge.

In order to solve the problem of the deterioration of the uniformity of the ion implantation and the destruction caused by the charge-up, the emission angle of the ion beam 21 emitted from the mass analysis magnet 13 is changed to shift the focal position of the ion beam 21. Also, by using a positive potential electrode, that is, an expander electrode, electrons contained in the plasma-like ion beam 21 are attracted to leave positively charged ions in the ion beam 21, and repulsion between the positively charged ions is caused. The beam diameter of the ion beam 21 was expanded by.

[Problems to be solved by the device]

However, any of these means has the following problems.

In the means for changing the emission angle of the ion beam 21 emitted from the mass analysis magnet 13, the mass analysis magnet 13
In order to attach the emission angle changing mechanism of the ion beam 21 to the above, the structure of the mass analysis magnet 13 must be changed, which causes a problem of significant increase in cost. Further, there is a problem that it is difficult to operate to change the emission angle of the ion beam 21.

Also, when using an expander electrode, the expander electrode must be attached to the ion implanter, and a power source for supplying power to the expander electrode is required, which increases the size of the device and greatly increases the cost. There was a problem that the sex became worse.

Further, these means have a problem that it is difficult to accurately control the diameter of the ion beam 21, and the diameter of the ion beam 21 varies.

Further, the above-mentioned two types of means substantially increase the beam diameter of the ion beam 21, so that there is no choice but to increase the range of overscan, and there is a problem that the loss of the ion beam 21 increases.

Therefore, an object of the present invention is to provide an ion implantation apparatus having a simple structure and capable of preventing deterioration of implantation uniformity and destruction due to charge-up without increasing ion beam loss.

[Means for Solving the Problems]

The ion implanter of the present invention has a high frequency that is sufficiently higher than the ion beam scanning frequency at the output of any one of the power sources of the ion extraction electrode, the mass analysis magnet, the acceleration electrode, the vertical scanning electrode and the horizontal scanning electrode. It is characterized in that a high frequency superimposing means for superimposing the components is provided.

[Action]

According to the configuration of the present invention, a high-frequency component having a frequency sufficiently higher than the ion beam scanning frequency is superimposed on the output of any one of the ion extraction electrode, the mass analysis magnet, the acceleration electrode, the scanning electrode, and each power source. As a result, the ion beam vibrates every minute and is scanned to irradiate the target. Therefore, the scanning range of the ion beam with which the target is irradiated per unit time is expanded.

〔Example〕

An example of the ion implantation apparatus of the present invention will be described with reference to FIGS. 1 and 2.

In this ion implanter, as shown in FIG. 1, the acceleration power source 6 is provided with a high frequency superimposing means 1. Other configurations are
This is the same as the conventional ion implanter shown in FIG.

The acceleration power supply 6 includes a control circuit 2, a voltage dividing circuit 3, and an error amplifier 4.
And a high-frequency superimposing means 1 composed of an oscillator and a reference voltage generating circuit 5, which inputs an input voltage E to convert it into a voltage E ₀ necessary for accelerating an ion beam and applies it to an accelerating electrode (not shown).

The operation of the acceleration power supply 6 will be described below.

The reference voltage generation circuit 5 sets a reference voltage v ₀ necessary for accelerating the ion beam and applies it to the high frequency superposition means 1. Then, the high-frequency superimposing means 1 superimposes a high-frequency component having a frequency sufficiently higher than the ion beam scanning frequency on the reference voltage v ₀ of the reference voltage generating circuit 5, and the small-amplified reference voltage v ₀ ′ is fed to the error amplifier 4. Add. The voltage dividing circuit 3 receives the output voltage E ₀ output from the control circuit 2 and outputs a voltage v corresponding to the output voltage E ₀ to the error amplifier 4
In addition to. The error amplifier 4 compares the reference voltage v ₀ ′ that has been oscillated in small steps from the high-frequency superimposing means 1 with the voltage v corresponding to the output voltage E _{0 that} has been input from the voltage dividing circuit 3, and the reference voltage v ₀ ′. And the difference between the output voltage E ₀ and
This difference signal is applied to the control circuit 2. The control circuit 2 is
The difference signal from the error amplifier 4 is input, and the output voltage E ₀ is controlled so as to be the voltage required for accelerating the ion beam corresponding to the reference voltage v ₀ ′. As a result, the acceleration voltage E ₀ output from the control circuit 2 becomes a voltage that oscillates in small steps. At this time, the frequency to be superposed by the high frequency superposing means 1 and the acceleration voltage E ₀ are set to oscillate within an allowable range of various conditions necessary for normal ion implantation.

This ion implanter, similar to a conventional ion implanter, extracts various ions generated in an ion source (not shown) with an ion extraction electrode (not shown) to extract various ions into an ion beam, and then extracts them from the ion extraction electrode. Only the necessary ions contained in the extracted ion beam deflect the ion beam by the mass analysis magnet so as to pass through the analysis slit (not shown). Next, the ion beam that has passed through the analysis slit enters an accelerating electrode (not shown). At this time, since the output voltage E ₀ oscillated in small increments is applied to the acceleration electrode from the acceleration power source 6, the velocity of the ion beam also changes in small increments. Then, the ion beam whose speed is changed in small steps enters the Q lens electrode (not shown). The ion beam entering the Q lens electrode is converged by the Q lens electrode, vertically and horizontally scanned by the vertical scanning electrode and the horizontal scanning electrode, and irradiated on a target (not shown) through a mask (not shown). . At this time, since the velocity of the ion beam is changing in small steps, the ion beam scanned by the vertical and horizontal scanning electrodes is oscillated in small steps. As a result, as shown in FIG. 2, the behavior of the ion beam 8 with which the target 7 is irradiated is oscillated in small steps, and the scanning range of the ion beam 8 with which the target 7 is irradiated per unit time is expanded. It will be. Further, the scanning of the ion beam 8 in the vertical and horizontal directions is the same as in the conventional ion implantation apparatus, but normally, scanning is performed at several tens Hz in the vertical direction and several hundred Hz in the horizontal direction. Then, in this case, the frequency at which the ion beam 8 is oscillated in small steps is
Frequencies that are sufficiently higher than the above scanning frequencies, eg, thousands
The frequency is set to Hz, which is one digit or more higher than the frequency of several tens to several hundreds Hz for scanning the ion beam 8 in the vertical and horizontal directions.

As described above, in this ion implantation apparatus, the acceleration power source 6 is provided with the high frequency superimposing means 1 so that the ion beam 8 is scanned while being oscillated in small steps to irradiate the target 7. Target 7 per hit
The scanning range can be expanded. As a result, the amount of ions implanted per unit time and unit area of the target 7 can be reduced without increasing the beam diameter of the ion beam 8, charge-up can be suppressed, and destruction of the target 7 can be prevented. In addition, it is possible to prevent deterioration of the uniformity of injection. Furthermore, since the beam diameter of the ion beam 8 is not expanded, the range of overscan can be narrowed and the loss of the ion beam 8 can be reduced.

Further, the acceleration electrode power source 6 is provided with the high-frequency superimposing means 1 including an oscillator, and the ion beam is oscillated in small steps to expand the scanning range of the ion beam. Control of enlargement can be performed accurately and easily, and there is no significant cost increase.

In the ion implantation apparatus of this embodiment, the high-frequency superimposing means 1 is provided in the acceleration power source 6 to change the acceleration speed of the ion beam 8 so that the ion beam 8 vibrates in small steps during beam scanning on the target 7. However, the high frequency superimposing means 1 is connected to the power source of any one of the ion extraction electrode, the mass analysis magnet, the vertical scanning electrode and the horizontal scanning electrode.
By providing the above, the ion beam 8 can be oscillated in small steps during beam scanning on the target 7.

[Effect of device]

In the ion implanter of the present invention, a high-frequency superimposing means is provided in any one of the power sources of the ion extraction electrode, the mass analysis magnet, the acceleration electrode, the vertical scanning electrode, and the horizontal scanning electrode to scan while oscillating the ion beam in small steps. However, since the target is irradiated, the scanning range of the ion beam to the target per unit time can be expanded. As a result, the amount of ions implanted per unit time and unit area can be reduced without increasing the ion beam diameter, charge-up can be suppressed, and target destruction can be prevented. Further, it is possible to prevent the deterioration of the uniformity of ion implantation. Furthermore, since the ion beam diameter is not expanded, the range of overscan can be narrowed,
It is possible to reduce the loss of the ion beam.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a first block diagram.
FIG. 3 is a waveform diagram showing the behavior of the ion beam with which the target shown in FIG. 3 is irradiated, and FIG. 3 is a schematic diagram showing the configuration of a conventional ion implantation apparatus. 1 ... High-frequency superimposing means, 6 ... Accelerating power supply, 7 ... Target,
8 ... Ion beam

Claims (1)

[Scope of utility model registration request] 1. An ion extraction electrode for extracting an ion beam from an ion source, a mass analysis magnet for selecting a necessary ion species from the ion beam extracted from the ion source, and a mass analysis magnet. In an ion implantation apparatus comprising an accelerating electrode for accelerating an ion beam of ion species, a vertical scanning electrode and a horizontal scanning electrode for scanning the accelerated ion beam on a target, the ion extracting electrode, the mass A high-frequency superimposing means for superimposing a high-frequency component having a frequency sufficiently higher than the ion beam scanning frequency on the output of one of the power sources of the analyzing magnet, the accelerating electrode, the vertical scanning electrode, and the horizontal scanning electrode. Ion implanter.