JPH065221A - Ion implanting device - Google Patents

Abstract

PURPOSE:To prevent damage to a circuit formed on a wafer surface due to possitive charge in the case of implanting ions in a wafer covered with a film. CONSTITUTION:The latter stage of an analytic slit is provided with a low vacuum chamber 5, in which vacuum is controlled by an inert gas; a deflecting electromagnet 10 for separating a forcibly neutralized neutral molecule beam 16 by means of the low vacuum chamber 5 from an ion molecule beam 15; and a Faraday cup 17 for measuring the deflected ion molecule beam 15. This causes the implantation of impurities as the neutral molecule beam 16 in a wafer 7 to prevent charge on a surface and circuit damage in the wafer 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implantation apparatus for implanting ions into a semiconductor substrate, and more particularly, when ion implantation is performed on a wafer which is a semiconductor substrate, the ion beam irradiation direction is fixed and the wafer is mechanically moved. The present invention relates to an ion implantation device that scans an ion beam on a wafer to implant ions.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing a configuration of an example of a conventional ion implantation apparatus.

As shown in FIG. 2, the conventional ion implanter produces an ion source 1 for producing ions to be implanted as impurities on the wafer 7 and a necessary ion among the ions produced in the ion source 1. An analysis electromagnet 2 and an analysis slit 4 to be selected, a Faraday cup 6 which is a detector for detecting the amount of ions as a beam current value before implanting ions into the wafer 7, and a disk Faraday 18 which is a detector for detection during implantation. , A disk-shaped disk 8 on which the wafer 7 is placed and rotated, and the disk 8 is held by a rotating shaft and is included.
And the injection chamber 9 which reciprocates in the direction perpendicular to the disc rotation axis.
Then, it has the vacuum pumps 11 and 12 for maintaining the high vacuum in the vacuum chamber.

Next, the operation of this ion implanter will be described. First, the ion source 1 ionizes the impurities to be implanted in the wafer 7 and accelerates them to a predetermined energy. Next, only the necessary ions are analyzed by the analysis electromagnet 2 and the analysis slit 4, and the impurities injected into the wafer 7 by the Faraday cup 6 are detected as an ion beam current.
When the required amount of ions is set and the degree of vacuum in the implantation chamber reaches a predetermined degree of vacuum, the Faraday cup 6 deviates from the traveling direction of the ion beam 3 and the implantation on the wafer 7 is started.

[0005]

When ions are selectively implanted through a resist mask formed on a wafer by this conventional ion implantation apparatus, since the resist is an insulating film, positive charges that are ions are the resist surface. It can accumulate on top and reach a potential of hundreds of volts, destroying circuitry within the wafer. As a countermeasure, there is a method of neutralizing the positive potential on the surface by causing negative electrons to fall on the wafer to neutralize it. However, since the potential amount changes during the injection, it is difficult to control the amount of electrons to be dropped for complete neutralization, and this is not a reliable method.

It is an object of the present invention to provide an ion implantation apparatus which can perform ion implantation without being charged up even when an insulating film is applied.

[0007]

The ion implantation apparatus of the present invention is provided with a low vacuum chamber which is provided in the subsequent stage of an analysis slit for selecting necessary ions and whose vacuum degree can be controlled by the flow rate of an inert gas, and this low vacuum chamber. The neutral molecule beam generated by the ion beam passing through the chamber is separated from the ion molecule beam by a magnetic field, and a detector for detecting the deflected ion molecule beam is provided. It is characterized in that the implantation is performed by a beam, and the amount of the implanted impurities is calculated by a neutralization rate based on the total amount of the ion beam after the analysis slit and the amount of the ion molecule beam after the deflection.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the construction of an embodiment of the ion implantation apparatus of the present invention. As shown in FIG. 1, this ion implantation apparatus includes a low vacuum chamber 5 for generating a neutral molecular beam by passing an ion beam by introducing an inert gas in the middle of a column including an analysis slit 4 and a Faraday cup 6. The deflecting electromagnet 10 that bends the ion molecule beam by the lower stage of the low vacuum chamber 5 and the Faraday cup 17 that collects the bent ion molecule beam 15 are provided. Between the low vacuum chamber 5 and the gas cylinder 14, a part of the bent ion molecule beam 15 is expanded outward so as not to collide with the wall surface.

Next, the operation of this ion implanter will be described. First, as described in the conventional example, the total current value of the ion beam 3 after the analysis slit is designed. Next, when implanting on the wafer 7, it deviates from the beam path and then passes through the low vacuum chamber 5. Here, the low-vacuum chamber 5 is a chamber in which the opening is made as small as possible with respect to the analysis slit portion and the injection chamber 9 and has resistance in vacuum, and the inert gas is filled with the gas cylinder 14 and the leak valve 13. A low vacuum with a pressure of about 10 to the 5th power is used. The ion beam penetrating into the low vacuum chamber 5 is forcibly exchanged with the inert gas to generate a neutral ion beam. Next, the beam including the neutral ion molecular beam and the ion molecular beam is divided into a neutral molecular beam 16 and an ion molecular beam 15 by the deflection electromagnet 10 that applies a magnetic field perpendicular to the beam path.

The neutral molecular beam 16 is applied to the wafer 7
The ion molecular beam 15 injected as an impurity is measured by the Faraday cup 17 with the ion amount as a current value. The neutralization rate in the low vacuum chamber 5 is calculated from this current amount and the total current value of the ion beam 3 after the analysis slit described above, and the amount of impurities implanted as a neutral molecular beam on the wafer 7 is converted.

By injecting the neutral molecular beam having no electric charge in this way, electric charges are not accumulated in the insulating film, so that the film formed on the ground plane is not destroyed.

[0013]

As described above, according to the present invention, the low vacuum chamber of the inert gas atmosphere is provided immediately after the analysis slit to collide the ions with the inert gas molecules to forcibly neutralize the ion beam and generate the electric field. This neutral molecular beam is extracted by applying a pulse, and is injected as an impurity into the wafer, which has the effect of preventing circuit breakdown due to a potential rise on the surface of the wafer.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration in an embodiment of an ion implantation apparatus of the present invention.

FIG. 2 is a diagram showing a configuration of an example of a conventional ion implantation apparatus.

[Explanation of symbols]

 1 ion source 2 analysis electromagnet 3 ion beam 4 analysis slit 5 low vacuum chamber 6,17 Faraday cup 7 wafer 8 disk 9 injection chamber 10 deflection electromagnet 11,12 vacuum pump 13 leak valve 14 gas cylinder 15 ion molecular beam 16 neutral molecule Beam 18 Disc Faraday

Claims (1)

[Claims] 1. A low-vacuum chamber which is provided after an analysis slit for selecting necessary ions and whose degree of vacuum can be controlled by the flow rate of an inert gas, and a neutral molecule generated by an ion beam passing through this low-vacuum chamber. The semiconductor device is provided with a deflecting electromagnet for separating the ion beam and the ion molecule beam by a magnetic field, and a detector for detecting the deflected ion molecule beam. Is calculated by the neutralization rate based on the total amount of the ion beam after the analysis slit and the amount of the ion molecule beam after the deflection.