JPS62254352A - Ion implantation apparatus - Google Patents

Abstract

PURPOSE:To prevent foreign matter such as dust, which approach to a sample, from being attached to a surface of the sample, by arranging an electric field- formation means or a magnetic field-formation means on a sample board or in the vicinity of the front surface of the sample held on the board, in an ion implantation apparatus. CONSTITUTION:Ion beams 3 passing through a mass spectrographic part or the like are made to pass through secondary electron-capturing electrodes 5, 6 and a beam gate 4 and radiated on a sample 2 placed on a sample board 1, to perform ion implantation. Then, either an electric field-forming means 10 comprising a cylindrical conductor, which surrounds-the ion beams 3, or a magnetic field-forming means comprising magnetic poles, which have mutually opposite polarities and face to each other in the direction nearly parallel to the plane of the sample 2, is arranged between the secondary electron-capturing electrode 6 and the sample 2. Thus, dst or the like, which floats inside a processing chamber and gains electric charges from the ion beams, is prevented from approaching to the surface of the sample 2. Therefore, foreign matters attached to the sample 2 can be decreased to improve quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to ion implantation technology, particularly to a technology that is effective when applied to the introduction of impurities in a wafer processing step in the manufacture of semiconductor devices.

[Prior art] Regarding the introduction of impurities into semiconductor wafers by ion implantation, see "Electronic Materials J 1984 Special Issue, P62-P66" published by Kogyo Research Association Co., Ltd., November 20, 1984.
It is described in.

The outline is that ions of the selected target substance are accelerated to a predetermined speed after passing through a mass spectrometer, etc., and are made to collide with a semiconductor wafer located in a processing chamber that is evacuated to a predetermined degree of vacuum. The am impurity is accurately introduced into a predetermined portion of a semiconductor wafer.

[Problems to be Solved by the Invention] However, in the conventional ion implantation apparatus as described above, dust is thrown up when the processing chamber is evacuated, and metal is generated from the mechanical drive parts inside the processing chamber. The present invention has discovered that particles such as powder gain electric charge from the ion beam while floating in the processing chamber and adhere to the surface of the semiconductor wafer in a positively charged state, causing an increase in foreign particles adhering to the semiconductor wafer. found it.

This becomes an important problem in view of the fact that the size and quantity of foreign particles that are allowed are decreasing as the patterns constituting semiconductor integrated circuits become finer.

An object of the present invention is to provide an ion implantation technique that can reduce foreign matter adhering to a sample.

The above and other objects and novel features of the present invention include:
It will become clear from the description herein and the accompanying drawings.

[Means for Solving the Problems] A brief overview of typical inventions disclosed in this application is as follows.

In other words, it is an ion implantation device that implants a material into a sample by colliding an ion beam of a predetermined material with the sample, and an electric or magnetic field is applied to the sample stage on which the sample is placed or near the front of the sample held on the sample stage. The device is provided with an electric field forming means or a magnetic field forming means for forming the .

[Function] According to the above-mentioned means, for example, foreign matter such as dust floating in the processing chamber where the sample is placed, acquires an electric charge from the ion beam, and approaches the sample in a positively charged state, An electric field or a magnetic field formed near the front surface of the sample table or the sample held on the sample table prevents foreign substances from reaching the sample surface, thereby reducing the amount of foreign matter adhering to the sample.

[Example 1] FIG. 1 is an explanatory diagram showing the main parts of an ion implantation apparatus that is an example of the present invention.

A sample 2 such as a semiconductor wafer, for example, is removably fixed on a sample stage l, and an ion beam 3 of a predetermined substance is formed through an ion source, an extraction accelerator, and a mass spectrometer (not shown). The ion beam 3 is incident almost perpendicularly onto the surface of the sample 2, and is irradiated onto the sample 2 by a scanning unit (not shown) provided after the mass spectrometer.
The incident area is controlled.

Ion beam 3 at the latter stage of the scanning section (not shown)
A beam gate 4 having a through hole 4a formed in the center is provided in the path of the ion beam 3, and by being displaced in a direction that crosses the path of the ion beam 3, the ion beam 3 is incident on and blocked from the sample 2. The structure is controlled appropriately.

A cylindrical secondary electron capturing electrode 5 is provided before and after the beam gate 4.
and a secondary electron capturing electrode 6 are provided.

Secondary electron capture electrode 5 provided in front of beam gate 4
A negative potential of a predetermined value is applied to the beam gate 4 from a DC power supply 7, and secondary electrons generated from the beam gate 4 are captured when the beam gate 4 blocks the ion beam 3, and The secondary electron capturing electrode 6 captures secondary electrons generated from the sample 2 when the ion beam 3 is incident thereon.

Furthermore, the secondary electron capturing electrodes 5 and 6, as well as the beam gate 4, etc., are grounded via an ammeter 8, and from the current value detected by the ammeter 8, ions are ionized into the sample 2 per unit time. The structure is such that the amount of a predetermined substance incident as the beam 3 can be determined.

The sample stage 1, beam gate 4, secondary electron trapping electrodes 5 and 6, etc. are housed in a processing chamber (not shown) that is evacuated to a predetermined degree of vacuum, and the incident path of the ion beam 3 to the sample 2 is It is configured to be maintained at a predetermined degree of vacuum.

In this case, between the secondary electron capturing electrode 6 and the sample stage 1, a variable DC power source 9 is provided near the sample 2, which is composed of a cylindrical conductor that surrounds the ion beam 3 that is incident on the sample 2. An electric field forming means 10 to which a desired positive voltage is applied is provided, and the electric field forming means 10 is provided with an electric field forming means 10 to which a desired positive voltage is applied. During this time, a foreign object or the like that gains electric charge from the ion beam 4 and approaches the sample 2 in a positively charged state receives a repulsive force from the electric field forming means 10 having a positive potential, and is prevented from reaching the surface of the sample 2. It is configured to

The operation of this embodiment will be explained below.

First, a sample stage 1 holds a sample 2 such as a semiconductor wafer.
The inside of a processing chamber (not shown) in which the components are housed is evacuated to a predetermined degree of vacuum.

Thereafter, an ion beam 3 of a predetermined substance is formed by an ion source, an extraction accelerator, a mass spectrometer, etc. (not shown), and a secondary electron capturing electrode 5. Through hole 4a of beam gate 4, secondary electron capturing electrode 6. and the electric field forming means IO in order.
is incident on a predetermined area.

The ion beam 3 is then incident on a predetermined region of the sample 2 for a predetermined period of time based on the current value observed by the ammeter 8 connected to the secondary electron capturing electrodes 5 and 6 and further to the electric field forming means 10. After that, by moving the beam gate 4 to block the ion beam 3, a predetermined substance constituting the ion beam 3 is introduced into a predetermined region of the sample 2 at a predetermined concentration.

Here, dust scattered during the exhaustion of the processing chamber (not shown), metal powder generated when the beam gate 4 is activated, etc. obtain electric charge from the ion beam 3 and become positively charged, and the secondary electron capturing electrodes 5 and 6, etc. may be moved in the direction of the sample 2 due to the action of Since the electric field forming means 10 to which a positive voltage of a certain value is applied is provided in front of the sample 2, positively charged foreign matter etc. that approach the sample 2 are rejected by the electric field forming means 10 and removed. reaching the surface of 2 is reliably prevented.

As a result, foreign matter adhering to the surface of the sample 2 is reduced.

As described above, in this embodiment, the following effects can be obtained.

(1) Near the front surface of the sample 2, there is an electric field forming means lO, which is composed of a cylindrical conductor that surrounds the ion beam 3 that is incident on the sample 2, and to which a desired positive voltage is applied from a variable DC type a19. For example, beam gate 4
foreign objects, such as metal powder generated during the operation of the processing chamber and dust scattered during exhaustion of the processing chamber, and foreign objects that acquire electric charge from the ion beam 4 while floating in the processing chamber and approach the sample 2 in a positively charged state. is reliably prevented from reaching the surface of the sample 2 by receiving a repulsive force from the electric field forming means 10 having a positive potential, and the amount of foreign matter adhering to the surface of the sample 2 is reduced.

The occurrence of defects in semiconductor elements formed on a semiconductor wafer due to foreign matter adhering to the sample 2 is reduced, and the yield in manufacturing semiconductor devices is improved.

[Embodiment 2] FIG. 2 is an explanatory diagram showing the main parts of an ion implantation apparatus which is another embodiment of the present invention.

In the second embodiment, magnetic poles 11a having mutually different polarities are provided near the front surface of a sample 2 such as a semiconductor wafer held on a sample stage l, and are opposed in a direction substantially parallel to the plane of the sample 2.
A magnetic field forming means 11 composed of magnetic poles 11b and 11b is provided to form a magnetic field of a desired intensity in a direction substantially parallel to the plane of the sample 2. This embodiment differs from the first embodiment in that a positive potential is applied.

In other words, it is made up of metal powder generated when the beam gate 4 is activated, dust scattered during exhaust gas in the processing chamber, etc., and while it floats in the processing chamber, it acquires an electric charge from the ion beam 4 and the sample 2 becomes positively charged. Foreign objects that approach sample 2
Near the front surface of the sample 2, it is reliably removed by the magnetic field formed by the magnetic field forming means 11, and further receives a repulsive force from the sample stage 1 having a positive potential, so that it is surely prevented from reaching the surface of the sample 2.

In this way, in the second embodiment, the following effects can be obtained.

(l), a magnetic field formed by a magnetic pole ff1lla and a magnetic pole 11b having mutually different polarities and facing in a direction substantially parallel to the plane of the sample 2 near the front surface of a sample 2 such as a semiconductor wafer held on a sample stage l; A forming means 11 is provided to form a magnetic field of a desired intensity in a direction substantially parallel to the plane of the sample 2, and a positive potential of a predetermined value is applied to the sample stage 1 from a DC power source 12. Therefore, the sample is composed of metal powder generated when the beam gate 4 is activated and dust scattered during exhaustion of the processing chamber, and while floating in the processing chamber, it acquires an electric charge from the ion beam 4 and becomes positively charged. Foreign objects approaching the sample 2 are removed by the magnetic field generated by the magnetic field forming means 11 near the front of the sample 2, and are further repelled by the positive potential sample stage l, ensuring that they reach the surface of the sample 20. As a result, the amount of foreign matter adhering to the surface of the sample 2 is reduced.

(2) As a result of +11, the occurrence of defects in semiconductor elements formed on semiconductor wafers due to foreign matter adhering to sample 2 such as semiconductor wafers is reduced, and the yield in manufacturing semiconductor devices is improved. .

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, the structure may be a combination of electric field forming means and magnetic field forming means.

The above explanation has mainly been about the application of the invention made by the present inventor to the application of impurities during wafer processing in the manufacture of semiconductor devices, which is the background field of application, but the invention is not limited to this. This method can be widely applied to techniques that require ion beam irradiation while maintaining the cleanliness of the sample surface.

[Effects of the Invention] The effects obtained by typical inventions disclosed in this application are briefly described below.

That is, in an ion implantation device that implants a predetermined material into a sample by colliding an ion beam of the material with the sample, the sample is placed on a sample stand on which the sample is placed, or near the front part of the sample held on the sample stand. Since the sample is provided with an electric field forming means or a magnetic field forming means for forming an electric field or a magnetic field, for example, the sample is suspended in the processing chamber in which it is placed,
An electric or magnetic field is formed near the front surface of the sample table on which the sample is placed or the sample held on the sample table, when foreign objects such as dust gain electric charge from the ion beam and approach the sample in a positively charged state. This prevents foreign matter from reaching the sample surface, thereby reducing the amount of foreign matter adhering to the sample.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the main parts of an ion implantation device that is an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the main parts of an ion implantation device that is another embodiment of the invention. . DESCRIPTION OF SYMBOLS 1... Sample stage, 2... Sample, 3... Ion beam, 4... Beam gate, 4a... Through hole, 5, 6...
- Secondary electron capturing electrode, 7... DC power supply, 8... Ammeter, 9... Variable DC power supply, lO... Electric field forming means,
11...Magnetic field forming means, lla, llb...magnetic pole,
12...DC power supply.

Claims (1)

[Claims] 1. An ion implantation device for implanting a predetermined substance into a sample by colliding an ion beam of the substance into the sample, the apparatus comprising: a sample stand on which the sample is placed; or a sample stand on which the sample is placed; An ion implantation apparatus characterized in that an electric field forming means or a magnetic field forming means is provided for forming an electric field or a magnetic field near the front part of a sample to be held. 2. The electric field forming means is a cylindrical conductor that surrounds the incident path of the ion beam to the sample and is variable in the value of the applied positive potential. ion implantation device. 3. The ion implantation according to claim 1, wherein the magnetic field forming means is magnetic poles that are arranged near the front surface of the sample in a direction parallel to the surface of the sample and have mutually different polarities. Device. 4. The ion implantation apparatus according to claim 1, wherein a positive potential is applied to the sample or a sample stage that holds the sample. 5. The ion implantation apparatus according to claim 1, wherein the sample is a semiconductor wafer.