JPS6332850A - Ion-implanting device - Google Patents

Abstract

PURPOSE:To prevent breakage of a semiconductor device and deterioration in implantation uniformity, which accompany electrification of the wafer surface, by capturing electrons by means of a high-frequency electric field in a space including an ion-beam way and by recombining ions with electrons so that ion beams are neutralized. CONSTITUTION:Ion beams 4 passing through a mask 5 are made to pass through slits of a flat plate electrode 15a and enter into a space interposed between a pair of parallel-flat plate electrodes 15a and 15b. A high-freguency electric field is generated in this space formed between both high-frequency sources comprising the flat plate electrodes 15a and 15b. When electrons generated in electron-generating sources 14a and 14b enter into this space, a large amount of them are captured there. when a change of the high-frequency electric field allows the ions to receive force in the same direction as the ion beams 4, these electrons are accelerated to become small in their speeds relatively to the ions in the ion beams 4 and to generate recombination of the electrons with the ions. These neutralized ion beams are radiated on the semiconductor, preventing breakage of the semiconductor device and deterioration of ion-implantation uniformity, which accompany electrification of the wafer surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion implantation device as a semiconductor manufacturing device.

[Conventional technology]

FIG. 2 shows an example of an ion beam neutralization mechanism of a conventional ion implanter.

In FIG. 2, 1 is a semiconductor wafer, 2 is a holder for fixing the wafer 1, and 3 is a disk. 4 is an ion beam,
5 is a mask that prevents the ion beam from hitting unnecessary parts;
6 is a suppressor that prevents electrons from escaping from the wafer 1 side to the outside of the mask 5, and 7 is a neutral cup that generates secondary electrons. 8 is an insulator with a yellow edge, 10 is a filament, and 9 is an extraction electrode for extracting electrons from the filament 10. 11 is a filament power source, 12 is a power source for the extraction electrode 9, and 13 is a current integrator.

Next, the operation will be explained.

The filament electric current R11 causes a current to flow through the filament 10 to heat the filament 10, and the extraction electrode 9 is positively biased with respect to the filament 10 to extract electrons from the filament 10. The extracted electrons are irradiated onto the neutral cup 7, and at this time, secondary electrons are generated.

The generated secondary electrons move in various directions, some of which wrap around the ion beam 4 and are absorbed by the wafer 1, and some of which directly impinge on the wafer 1. In this case, the wafer 1 is positively charged due to the ion beam 4 irradiation, but the charging is alleviated due to the above-mentioned secondary electrons.

[Problem that the invention seeks to solve]

Since the conventional ion implantation apparatus is configured as described above, it is almost impossible to directly neutralize the ions in the ion beam with electrons. Therefore, charging of the wafer surface is prevented by some of the secondary electrons and primary electrons that fly to the wafer, and there is a problem in that the ability to alleviate charging is low. Furthermore, with this method of preventing static electricity on the wafer surface, the amount of electrons generated from the filament must be controlled each time the ion beam current value is changed, and this has the problem of being difficult to control.

This invention was made to solve the above-mentioned problems, and provides an ion implantation device that can prevent damage to semiconductor devices due to charging on the wafer surface, and further prevent deterioration in implantation uniformity of ion implantation due to charging. The purpose is to obtain.

[Means for solving problems]

The ion implantation apparatus according to the present invention accelerates electrons emitted from a filament, their secondary electrons, etc. by a high-frequency electric field, and compares the electrons with ions in an ion beam that has been separately accelerated and flies. This method reduces the speed, increases the degree of recombination of ions and electrons, and brings the ion beam closer to a neutral particle beam before implanting it into the wafer.

[Effect]

The high-frequency electric field generated in this invention captures and accelerates electrons emitted from the filament and their secondary electrons, and increases the relative velocity of the ions in the ion beam that have been separately accelerated. By making the ion beam smaller and making it easier to recombine, the ion beam is turned into a neutral beam. This neutralized ion beam is irradiated onto the semiconductor,
This prevents the wafer surface from being charged and damaging the semiconductor device or reducing the uniformity of ion implantation.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 1 is a semiconductor wafer, 2 is a holder that fixes the semiconductor wafer, and 3 is a disk.

be. 4 is an ion beam, and 5 is a mask that cuts unnecessary spread of the ion beam 4. 6 is a suppressor biased to a negative potential, and 7 is a neutral cup located between the suppressor 6 and the disk 3. 1
Reference numerals 4a and 14b are electron generation sources, and the internal structure thereof is similar to the mechanism for generating electrons described in the related art. 11a and llb are the filament power supplies of the electron generating sources 14a and 14b, respectively, and 12a and 12b are the electron generating sources 14a and 14b, respectively.
This is the extraction electrode power supply. Reference numerals 15a and 15b are a pair of parallel plate electrodes, each having a slit in the center having a width through which the ion beam 4 passes. 16 is a high frequency power source.

In FIG. 1, the ion beam 4 is accelerated to high energy, and the ions that have spread unnecessarily hit the mask 5 and are cut off, passing through the mask 5.

Next, the ion beam 4 that has passed through the mask 5 passes through the slit of the flat plate electrode 15a, and passes through the pair of parallel plate electrodes til.
x 15 Enter the space between a and 15b.

The parallel plate electrodes 15a and 15b are connected to a high frequency power source 16 and generate a high frequency electric field between them, and when electrons generated from electron sources 14a and 14b enter this space, , a large number of electrons are captured in this space under the influence of this high-frequency electric field. At this time, the direction of the force received from the high-frequency electric field is parallel to the traveling direction of the ion beam 4, and when the high-frequency electric field changes and a force acts on the electrons in the same direction as the ion beam 4, these electrons The electrons are rapidly accelerated, the relative velocity with respect to the ions in the ion beam 4 becomes small, and recombination of electrons and ions occurs. The ion beam 4 thus neutralized is irradiated onto the wafer 1. As described above, the ion beam 4 is neutralized by the electrons accelerated by the high-frequency electric field, so the wafer surface is charged and the semiconductor device is destroyed.
The uniformity of ion implantation does not deteriorate. At this time, the wafer 1 is fixed by the holder 2 and placed on the disk 3, and the disk 3 is scanning from side to side while rotating.

Note that in the ion implanter shown in Figure 1, the mechanism for neutralizing the ion beam was installed just before the wafer, but it could also be installed before the mask if measures were taken to prevent errors in the implantation amount. In addition, the electrodes connected to a high frequency power source can be
Although it is provided in a high vacuum through which the ion beam travels, it may also be provided outside the vacuum chamber.

Further, in FIG. 1, the parallel plate electrodes are provided perpendicularly to the ion beam, but they may be provided parallel to the ion beam as long as the electrons are captured in space.

In addition, in Figure 1, the electrons obtained from the electron source are directly captured in space by a high-frequency electric field, but the electrons captured in this space are secondary electrons generated when the electrons obtained from the electron source hit the chamber wall. may be used.

〔Effect of the invention〕

As described above, according to the ion implantation apparatus according to the present invention, the high-frequency electric field traps electrons in the space including the ion beam path and reduces the relative velocity of the ions and electrons, thereby recombining the ions and electrons. This makes it possible to neutralize the ion beam, which is effective in preventing damage to semiconductor devices due to electrification on the wafer surface and deterioration of implantation uniformity, and also allows ion implantation even at large currents. , it also has the effect of improving throughput.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an ion implantation device according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional ion implantation device. In the figure, 1 is a wafer, 3 is a disk, 4 is an ion beam, 5 is a mask, 6 is a suppressor, 7 is a neutral cup, 13 is a current integrator, 14a and 14b are electron sources, and 15a and 15b are slits. Parallel plate electrodes, 1
6 is a high frequency power source. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) An ion implanter that performs ion implantation by irradiating an ion beam includes an extraction electrode that extracts electrons from a filament, and a high-frequency electric field that generates a high-frequency electric field to accelerate the electrons and combine them with the ions in the ion beam. An ion implantation device equipped with a high-frequency electric field generating means.