JPH01225041A - Ion source device - Google Patents

Abstract

PURPOSE:To improve the generation efficiency of plasma by preventing the flow away of electrons to the outside of a plasma forming chamber with the cusp magnetic field coordination formed near a plasma outlet. CONSTITUTION:The voltage is applied across the first electrode 14 and the second electrode 15 so that the first electrode 14 is made positive and the second electrode 15 is made negative, the first electrode 14 and a plasma forming chamber 1 are set to the same potential, the second electrode 15 and a film forming chamber 9 are set to the same potential. Magnetic lines of force generated by a permanent magnet 13 draw a star shape extending branches to the above and below and the right and left near a plasma outlet to form the so called cusp magnetic field coordination. Electrons flowing out from the plasma forming chamber 1 are suppressed by the cusp magnetic field coordination near the plasma outlet 8 to prevent the divergence. The plasma generation efficiency is thereby improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion source device that generates plasma from a raw material using microwaves and a magnetic field and extracts ions.

[Conventional technology]

FIG. 4 is a cross-sectional view showing a conventional ion source device for thin film formation similar to the device disclosed in Japanese Patent Application Laid-Open No. 62-222074. In the figure, (υ is a plasma formation chamber, ( 2) is a waveguide located in the center of the earthen wall of the plasma formation chamber (υ), and (4) is an I quartz plate, (5
) is a tubular inlet provided in the plasma formation chamber (υ), (
6) is a cylindrical coil placed around the plasma formation chamber (1), and (7) is the plasma formation chamber (1).
A part of the partition plate (8), which forms the lower wall, is a part of the partition plate (
7) It is airtightly joined to the plasma formation chamber (1) and communicated through the plasma outlet (8). αG is the film formation chamber (
9) is an exhaust port provided in the center of the lower wall.

Next, I will explain the operational issues. The base material aυ to be deposited on the surface is placed below the plasma outlet (3) in the deposition chamber (9), and the exhaust port αO is opened using a true pump (not shown).
17, and enter the vapor deposition raw material gas from the inlet (5) into the plasma formation chamber (1), and from the waveguide (3) to the quartz plate (4).
When microwaves of 2.45 GH2 are incident through the coil (6) and the coil (6) is energized, plasma is generated in the plasma forming chamber (1). When the magnetic flux density of the magnetic field generated within the plasma formation chamber (υ) by the coil (6) is 875 Gauss, the electrons within the plasma formation chamber (υ undergo cyclotron movement due to electron cyclotron resonance, and their kinetic energy is increased by the microwave electric field. The quartz plate [4] prevents the plasma from flowing into the waveguide (3).The plasma near the outlet (8) generated by the coil (6) The magnetic field lines diverge downward.This divergent magnetic field and the plasma formation chamber (
Due to the pressure difference between 1) and the film forming chamber (9), ions, electrons,
Free radicals flow from the plasma outlet (8) into the film forming chamber (1).
), and a film is formed on the surface of the base metal circle.

[Problem to be solved by the invention]

Since the conventional ion source device is configured as described above, the magnetic field near the plasma outlet becomes a diverging magnetic field that diverges downward, which prevents energetic electrons from flowing out of the plasma formation chamber (1). However, there were problems such as a decrease in the number of electrons used for plasma generation and poor plasma generation efficiency.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain an ion source device with high plasma generation efficiency.

[Means to solve the problem]

The ion source device according to the present invention has a cusp magnetic field configuration formed near the plasma outlet.

[Effect]

The ion source device according to the present invention prevents electrons from flowing out of the plasma formation chamber (υ) by the cusp magnetic field configuration I formed near the plasma outlet.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a cross-sectional view showing an ion source device for forming a thin film according to Embodiment 1 of the present invention, which includes a plasma formation chamber (1), a waveguide connection port (2), a waveguide (3), and a quartz plate. (4), the inlet port (5), and the exhaust port αO are the same as those of the conventional ion source device shown in FIG. 4, so their explanation will be omitted. The cylindrical permanent magnet is placed around the plasma formation chamber (1), and has two magnetic poles at both ends of the cylinder. A4 is a part of the plasma formation chamber (1), that is, the bottom wall. (8) is a plasma outlet opening provided at the center of the first electrode side; (G) is a first electrode α;
4, US is the central part of the second electrode, that is, the opening provided below the plasma outlet (8), and αη is the first electrode α4. (9) is a cylindrical insulator provided between the second electrode head and airtightly joined to each of the picture electrodes 1141 and C15.
In the film forming chamber provided below the electrode μs of the second electrode (
(g), and communicates with the plasma formation chamber (1) through the opening QQ and the plasma outlet (8).

Next, the operation will be explained. A permanent magnet U generates a magnetic field in the plasma formation chamber (υ) shown in Figure 1.

The process of generating plasma in the plasma formation chamber (1) is the same as that of the conventional ion source device shown in FIG. 4, so the explanation will be omitted. Between the first electrode α4 and the second electrode head,
Voltage V at which the first electrode side is positive and the second electrode (G) is negative
is applied, and the first electrode σ4 and the plasma forming chamber (υ) are at the same potential, and the second electrode head and the film forming chamber (9) are at the same potential l.

Fig. 2(a) is a cross-sectional view of the same ion source device as Fig. 1;
Parts unnecessary for explanation have been omitted and shown as cylindrical. In the figure, the magnetic lines of force generated by the permanent magnet form a star shape with branches extending vertically and horizontally near the plasma outlet (8).
This forms a so-called cusp magnetic field configuration. The magnetic field strength increases from the center of the star in all directions around it, suppressing electron divergence from this point. FIG. 2(b) is a graph showing the potential corresponding to the position along the vertical central axis of the ion source device, and the position of the vertical axis is drawn corresponding to the cross-sectional view of FIG. 2(a). . The potential gradually decreases from the plasma outlet (8) toward the opening aQ. Therefore, in Fig. 1, the electrons flowing out from the plasma formation chamber (υ) are affected by the cusp magnetic field near the plasma outlet (8). The electrons are suppressed by the coordination and prevented from divergence.Furthermore, the electrons are pushed downwards from the plasma outlet (8) and then back upwards, where the potential is lower. Ions with a positive charge are pulled downward and accelerated by the above potential, and free radicals without a charge are forced into the opening aO by the momentum of flowing out from the plasma formation chamber (1). It passes through and flows into the film forming chamber (9).

These materials flowing into the film forming chamber (9) cause the film forming chamber (
9) A film is formed on the surface of the base metal layer.

In this embodiment, a permanent magnet is used to generate the magnetic field, so there is no need to run a current as in the case of using a coil, and the auxiliary equipment can be simplified and downsized.

FIG. 3 is a simplified cross-sectional view showing an ion source device for forming a thin film according to another embodiment of the present invention, in which a plurality of permanent magnets are used, and the other embodiments are the same as the embodiment of FIG. 1. Since they are similar, the explanation will be omitted.

In the figure, three cylindrical permanent magnets Q similar to those of the embodiment shown in FIG. 1 are arranged in the vertical direction. Adjacent permanent magnets U are arranged so that the N or S magnetic poles of the same polarity face each other. Since a single cusp magnetic field configuration is formed near the plasma outlet (8), electron divergence is prevented, and the same operation as the ion source device of the embodiment shown in FIG. 1 is performed.

Furthermore, although a plurality of permanent magnets are used in the embodiment shown in FIG. 3, a cylindrical coil may be used instead of the permanent magnets. In this case, the adjacent coils are arranged so that the directions of the lines of magnetic force generated on the central axis are opposite to each other, and polarities collide with each other. Plasma outlet (8)
Since a nearby cusp magnetic field configuration is formed, electron divergence is prevented, and the same operation as the ion source device of the embodiment shown in FIG. 2 is performed.

〔Effect of the invention〕

As described above, according to the present invention, since a cusp magnetic field is formed near the plasma outlet, it is possible to prevent electrons from dispersing from the plasma outlet, thereby providing an ion source device with high plasma generation efficiency. effective.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an ion source device according to an embodiment of the present invention, FIG. 2(a) is a simplified cross-sectional view of the ion source device of FIG. 1, and FIG. 2(b) shows the potential. In the diagram,
(1) is the plasma formation chamber, (8) is the plasma outlet, @
is the magnetic field line, and σ4 is the first electrode. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] In an ion source device having a plasma formation chamber that generates plasma using microwaves and a magnetic field, a cusp magnetic field configuration is formed in the vicinity of a plasma outlet provided in the plasma generation chamber to cause electrons to diverge from the plasma outlet. An ion source device characterized by preventing.