JPH04160745A - Ion implantation device - Google Patents

Abstract

PURPOSE:To prevent local charge-up on a target by narrowing an arc chamber slit more at its central part than at both its ends and uniforming an ion density distribution CONSTITUTION:An arc chamber slit 3 is installed which is narrower at its central part than at both its ends. Plasma generates inside an arc chamber 1 and the plasma density is higher the more it goes toward the central part but lower the more it goes towarad the peripheral part. Positive ions thus pass the slit 3, which narrows only at the central part of high ion density to allow the same amount of the positive ions to pass through the central part as through the peripheral part. A drawn ion beam section 6 has an ion density distribution 7 uniform in the ion beam section. This eliminates local charge-up on a target.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an ion implantation method that uniformizes the ion density distribution in an ion beam on a target and prevents local charge-up of the target laser 1-. It is related to the device.

[Conventional technology]

FIG. 3 is a conventional view of the arc chamber where ions are generated, viewed from the downstream side of the ion beam.

In this figure, 1 is an arc chamber, 2 is a front surface of the arc chamber, and 3a is an arc chamber slit from which ions come out.

FIG. 4 is a diagram illustrating extraction of a conventional ion beam and ion density distribution inside the ion beam.

In FIG. 4, 4 is an extraction electrode for extracting the ion beam, 5 is an extraction electrode slit formed in this extraction electrode 4, 6 is a cross section of the extracted ion beam, and 7a is an ion beam of this ion beam 6 in the Y direction. density distribution,
Reference numeral 8 denotes an extraction power source used to extract ions from the arc chamber 1.

Ions generated inside the arc chamber 1 are extracted as an ion beam from the arc chamber slit 3a by a potential difference provided between the extraction electrode 4 and the extraction power source 8.

[Problem to be solved by the invention]

Since the conventional arc chamber slit 3a has a constant width, the ion density distribution 7a in the Y direction of the extracted ion beam cross section 6 is almost determined by the plasma density inside the arc chamber 1, and due to its nature, the center The ion density distribution 7a in the Y direction is higher than that in the surrounding area.
is the distribution of center elevation 9. In the ion implanter,
The beam transport path does not have a lens effect for convergence of the beam in the Y direction, and the beam is injected into the target with the central bulge distribution intact. Therefore, there is a problem that local charge-up of the target is promoted and problems such as electrostatic breakdown of the D1-oxide film of the MO3+- transistor occur.

This invention was made in order to solve the above-mentioned problems, and provides an ion implantation device that makes the ion density distribution in the Y direction uniform regardless of the position and prevents local charge-up of the target. The purpose is to

[Means to solve the problem]

In the ion implantation apparatus according to the present invention, the slit width of the arc chamber slit is narrower at the center than at both ends to make the ion density distribution uniform.

[Effect]

In this invention, since the slit width is narrowed at the center of the slit where the plasma density is high in the arc chamber, the central bulge in the ion density distribution in the Y direction of the extracted ion beam is alleviated, and the slit width is reduced within the ion beam cross section. The ion density distribution remains constant regardless of the position of the target, eliminating local charge-up of the target.

〔Example〕

An embodiment of the present invention will be described below.

FIG. 1 and FIG. 2 are diagrams showing one embodiment of this invention,
FIG. 1 is a front view of the arc chamber, and FIG. 2 is a perspective view of the configuration of the ion implantation apparatus. In this diagram, 1, 2, 4
, 5p8 are equivalent to those in the conventional examples shown in Figs. 3 and 4, 3 indicates an arc chamber slit whose central part is narrower than both ends, and 6 indicates an ion beam with a constant ion density distribution inside the ion beam. The beam cross section 7 is the ion density distribution in the Y direction of the cross section 6 of the ion beam.

In this operation, the density of plasma generated inside the arc chamber 1 is high at the center and low at the periphery, as in the conventional example. The plasma is extracted as a positive ion beam by the potential difference between the extraction electrode 4 and the extraction power supply 8, as in the conventional example.

At this time, positive ions pass through the arc chamber slits 1 and 3, but if the width of the slit is made small only in the center where the ion density is high, so that the amount passing through is the same as that in the periphery, the ions can be drawn out. The ion density distribution 7 in the cross section 6 of the ion beam becomes uniform within the ion beam cross section.

〔Effect of the invention〕

As explained above, in the present invention, the slit width of the arc chamber slit is made narrower at the center than at both ends to make the ion density distribution uniform, so that when ions are extracted from the arc chamber, the ions pass through. By freely determining the width of the arc chamber slit depending on the plasma density distribution within the arc chamber, regardless of the position,
Since the amount of ions passing through the arc chamber slit can be controlled at any position, a beam with a uniform ion density distribution can be obtained. As a result, charge-up can be prevented locally on the target, and since only the slit shape is changed, an inexpensive ion implantation device can be obtained.

[Brief explanation of drawings]

1 and 2 are a front view of an arc chamber and a perspective view of the configuration of an ion implantation device showing an embodiment of the present invention;
3 and 4 are a front view of a conventional arc chamber and a perspective view of the configuration of an ion implantation apparatus. In the figure, 1 is the arc chamber, 2 is the front surface of the arc chamber, 3 is the arc chamber slit, 4 is the extraction electrode,
5 is an extraction electrode slit, 6 is a cross section of the ion beam, and 7 is a cross section of the ion beam.
is the ion density distribution in the Y direction, and 8 is the extraction power source. In addition, the same reference numerals in each figure are the same. indicates a considerable portion. Agent Masuo Oiwa (2 others) Figure 1 Figure 2 Figure 3 Figure 4 Procedure correction band (voluntary)

Claims (1)

[Claims] In an ion implantation device in which ions generated inside the arc chamber are extracted as an ion beam from an arc chamber slit formed on one surface of the arc chamber, the slit width of the arc chamber slit is narrower at the center than at both ends. An ion implantation device characterized by having a shape that makes density distribution uniform.