JPS63250822A - plasma equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to thin film element manufacturing equipment such as semiconductor circuit elements and 8m magnetic heads, and particularly relates to LSI devices in the submicron region.
The present invention relates to a plasma apparatus suitable for dry etching.

[Conventional technology]

In LSI manufacturing programs, with the miniaturization of processing dimensions,
A wet process using a solution (etching solution) has been replaced by a dry process using Calaphrasma. It has recently come into widespread use. For example, a plasma device using microwaves is disclosed in Japanese Patent Application Laid-Open No. 56-152969.
The structure is as shown in the number. That is, in the conventional plasma apparatus, as shown in FIG. 9, a substrate holder 6 is provided in a vacuum container 5 equipped with a vacuum evacuation device 11, and a plasma chamber 1 is provided opposite the substrate holder 6. . The plasma chamber 1 has a configuration in which an excitation solenoid 2 is provided around its outer periphery, a waveguide 3 is provided coaxially with the excitation solenoid 2, and a microwave oscillator 10 is installed at the end of the waveguide 3.

When such a plasma device is used, the vacuum vessel 5 and the plasma chamber 1 are initially at a pressure of 10"-5
It is evacuated to an ultra-high vacuum below torr. Thereafter, an etching gas such as CF4 is introduced from the gas supply port 9 to a predetermined pressure. Next, the microwave oscillator 10 is operated to emit, for example, a 2.45 GHz microwave to the waveguide 3.
is supplied to the ion source via the ion source. On the other hand, excitation solenoid 2
Accordingly, a magnetic field of 875 Gauss is applied to the center of the ion source so that electrons undergo cyclotron resonance due to microwaves of 2.45 GHz. This results in
In plasma chamber 1, electron cyclotron resonance occurs,
Gas molecules are actively ionized and a dense plasma is generated. Ions are extracted as a beam from the dense plasma by the extraction electrode 4, and the substrate 7 is irradiated with the ions. As a result, the substrate 7 is etched.

[Problem that the invention seeks to solve]

In the prior art described above, the radial magnetic flux density distribution of the magnetic field generated by the excitation solenoid 2 is approximately equal as shown by a curve 32 in FIG. On the other hand, the electric field of the microwave becomes stronger in the center of the plasma chamber, resulting in the formation of dense plasma in the center of the plasma chamber. This plasma diffuses into the surroundings and recombines on the walls of the container. Therefore, as shown by curve 33 in FIG. 10, the plasma in the plasma container has a density distribution in which it is dense at the center and thin at the periphery, resulting in a problem of non-uniform ion beam intensity.

An object of the present invention is to provide a plasma apparatus that can obtain uniform ion beam intensity.

[Means for solving problems]

The plasma device of the present invention includes a vacuum container, an exhaust device, a gas introduction section, and a microwave introduction section each communicating with the vacuum container, and generates a magnetic field component in the same direction as the traveling direction of the microwave. In a plasma apparatus equipped with a magnetic field generating means, the magnetic field generating means is configured such that the generated magnetic field is stronger at the periphery than at the center of the vacuum vessel. A specific magnetic field generating means for generating a stronger magnetic field at the periphery than at the center of the plasma generation chamber (the center of the container) is achieved by arranging a permanent magnet outside the generation chamber.

A brief overview of typical inventions disclosed in the Hokkaido article is as follows.

[Effect]

In the plasma apparatus of the present invention, the dense plasma that was conventionally generated by electron cyclotron resonance at the center is generated at the periphery of the container and diffused into the center of the container. Therefore, since there is no object such as a container wall that promotes recombination in the center of the container, the plasma is averaged and a uniform ion beam intensity is generated in each part of the container. [Example] [First Example] Figure 1 is a sectional view showing an outline of a plasma device according to an embodiment of the present invention, Figure 2 is a graph showing the magnetic flux density distribution, and Figure 3 is a diagram showing another example. FIG. 3 is a plan view showing a permanent magnet structure.

In the plasma apparatus according to this embodiment, a substrate holder 6 is provided in a vacuum container 5 equipped with a vacuum evacuation device 11, and a plasma chamber 1 is provided opposite the substrate holder 6.

A hollow disk-shaped rare earth permanent magnet is arranged around the container wall 20 of the plasma chamber 1. These permanent magnets are arranged in two stages, with the upper permanent magnet 21-
As shown in FIG. 1, the permanent magnets a and the lower permanent magnets 21-b are arranged with different magnetic poles facing the container. A microwave transmission window 24 is provided on one end plate of the plasma chamber 1, and a waveguide 3 is attached to match the window, and a microwave oscillator 10 such as a magnetron is installed in the waveguide 3. It is provided.

On the other hand, at the other end of the plasma chamber 1, an extraction electrode 4 is provided which has a number of holes provided at the same positions. An appropriate potential is applied to the extraction electrode 4 from a DC power source 22,23. Here, permanent magnets 21-a, 21
-b are ring-shaped magnets that are magnetized in opposite radial directions, and their combination generates magnetic lines of force 25 having an axial component in a substantially axially symmetrical manner. The waveguide 3 that introduces the microwave is installed in a direction exactly along these lines of magnetic force. The vibration direction of the electromagnetic field of the microwave is perpendicular to the traveling direction of the microphone 80 waves, and is also perpendicular to the magnetic field lines.

Here, the frequency of the microwave is 2.45 GHz, and the axial component of the magnetic field generated by the permanent magnets 21-a and 21-b is 875 GHz at a part of the wall surface of the container of the plasma chamber 1.
Arrange so that it is equal to or higher than uss. According to the inventors' calculations, the inner diameter is 100 mm, the outer diameter is 150 mm, and the thickness is 8 m+a.
, if rare earth magnets with a residual magnetic flux density of about 9000 Gauss are arranged at intervals of about 30+ nm, the magnetic flux density will be 875 Gauss.
A magnetic flux density higher than that can be easily obtained.

The radial magnetic flux density distribution of the magnetic field created by the permanent magnet is shown in FIG. Although the numerical value of magnetic flux density is not shown in the same graph, as mentioned above, the magnetic flux density at the container wall is 87
It becomes 5 Gauss or more. As a result, a ring-shaped region of 875 Gauss where the electron cyclotron resonance frequency and the microwave frequency match is formed inside the container wall.

In such situations, an etch such as CF4 is supplied at an appropriate pressure (generally 10-5 to 1 O-3 torr). At this time, electrons are strongly accelerated by electron cyclotron resonance in the aforementioned ring-shaped electron cyclotron resonance region. These electrons collide with gas molecules,
As a result of the ionization, a dense plasma is generated near the vessel wall. Furthermore, since this plasma is diffused to the center of the plasma chamber, a uniform plasma state is formed.

Note that the permanent magnets are not limited to the hollow disk type, and as shown in FIG. 3, rectangular parallelepiped magnets 21 may be arranged in a polygonal shape.

[Second Embodiment] FIG. 4 is a sectional view showing a main part of a second embodiment of the plasma apparatus of the present invention. This embodiment has a structure in which a plurality of permanent magnets each having a different polarity arrangement are arranged on the outer wall of the container wall 20.

That is, the permanent magnets 31-a and 3 located at the top in the figure
1-b is arranged so that the N pole faces the plasma container side,
Permanent magnets 31-c and 31-d are arranged below the permanent magnets 31-a and 31-b.

It is arranged so that the south pole faces the container side.

By arranging the magnets in this manner, it is possible to create a magnetic field region that is long in the axial direction and generates electron cyclotron resonance within the plasma generation chamber using a relatively small magnet. Therefore, the coupling between microwaves and plasma is improved, and an economical and efficient plasma generation device with uniform ion beam intensity can be achieved.

[Third Embodiment] FIG. 5 is a sectional view showing a main part of a third embodiment of the plasma apparatus of the present invention. The plasma apparatus of this embodiment is the same as the embodiment shown in FIG. 4 in that it has a multi-stage structure with three or more stages of permanent magnets, but the arrangement of the poles of the magnets in each stage is different from that of the upper and lower stages. They differ in alternating ways. That is, in this embodiment, permanent magnets 70-a to 70- which are magnetic field generating means for causing electron cyclotron resonance
d are arranged in multiple stages so that adjacent magnetic poles in the axial direction have different polarities. As a result, magnetic fields 71-a to 71-C, called cusp magnetic fields, are formed near the container wall in the plasma chamber 1, and plasma is generated there by electron cyclotron resonance.

In a plasma device with such a magnet arrangement.

Since the magnetic field created by the magnet is limited to the vicinity of the magnet, the magnetic field for creating plasma can be designed independently of the electromagnetic field for extracting the ion beam, which makes device design easier.

[Fourth Embodiment] FIG. 6 is a sectional view showing a main part of a fourth embodiment of the plasma apparatus of the present invention. In the plasma apparatus of this embodiment, the plasma chamber 1 extends from the connection portion with the waveguide 3 with a tapered portion 83. Permanent magnets 81-a to 81-f are arranged around the outer periphery of the plasma chamber 80, including the tapered portion 83.

The microwave introduced from the waveguide 3 propagates while spreading in the tapered portion 83, and generates plasma along the way by electron cyclotron resonance with the magnetic fields 82-a to 82-e. In this embodiment, the taper part allows microwaves to be effectively guided into a large-diameter plasma chamber, and the area where plasma is generated by the interaction between the magnetic field and microwaves can be made long, so that plasma can be generated efficiently. be able to.

[Fifth Embodiment] FIG. 7 is a sectional view showing essential parts of a fifth embodiment of the plasma apparatus of the present invention. This embodiment has a plurality of microwave oscillators 10-a, 10-b.

And these microwave oscillators IQ-a.

Microwaves introduced from waveguides 3-a and 3-b connected to 10-b are transmitted to preliminary plasma chambers 91-a and 91-b.
The magnetic field 95-a created by the permanent magnets 92-a to 92-d,
The introduced gas is turned into plasma by interaction with 95-b. This plasma diffuses into the main plasma chamber 94 and the permanent magnet 9
It is confined in the main plasma chamber 94 by the cusp magnetic field 96 created by 3-a to 93-d. The magnetic field 96 further interacts with the microwaves leaking from the preliminary plasma chamber 91,
Plasma is created around the main plasma chamber 94.

This plasma also diffuses into the center of the main plasma chamber 94. In this way, a dense and uniform plasma is accumulated within the main plasma chamber 94. In this embodiment, the size of the main plasma chamber 94 can be easily increased in diameter by increasing the number of permanent magnets 93 arranged as shown in FIG. By arranging multiple microwave oscillators, a large amount of microwave power can be injected into the plasma, and an ion source with a large diameter and high power can be easily manufactured.

The above series of explanations is not limited to ion beam etching apparatuses; for example, as shown in FIG.
It can be used as a plasma etching apparatus in which the substrate 7 is placed in plasma in the plasma chamber 1, or as a plasma CVD apparatus by changing the introduced gas.

If there is a gap between the permanent magnet and the plasma generation chamber, it is possible to create a magnetic path by filling the gap with magnetic material or placing a magnetic material around the outer periphery of the permanent magnet. Needless to say, magnetic force can be used effectively and an economical magnet design can be achieved.

〔Effect of the invention〕

According to the present invention, since the plasma density in the plasma generation chamber can be made uniform, the ion beam intensity extracted from there becomes uniform, and uniform ion beam etching can be performed over the entire processing surface of the workpiece. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an outline of a plasma device according to an embodiment of the present invention, FIG. 2 is a graph showing the magnetic flux density distribution, FIG. 3 is a plan view showing another permanent magnet structure, and FIG.
The figure is a sectional view showing the main part of the second embodiment of the plasma device of the invention, FIG. 5 is a sectional view showing the main part of the third embodiment of the plasma device of the invention, and FIG. 4th part of the device
7 is a sectional view showing the main parts of a fifth embodiment of the plasma apparatus of the present invention; FIG. 8 is a main part of a plasma CVD apparatus according to another embodiment of the present invention. FIG. 9 is a cross-sectional view showing essential parts of a conventional plasma device, and FIG. 10 is a graph showing the magnetic flux density and plasma density distribution. 1.94...Plasma chamber, 2...Excitation solenoid,
3... Waveguide, 4... Extraction electrode, 5... Vacuum container, 6... Substrate holder, 7... Substrate, 10...
Microwave oscillator, 20... Container wall, 21... Magnet, 21-a, 21-b, 31-a to 31 d
, 70-a ~ 70 , 81-a ~ 81-f, 9
2-a ~ 92-d, 93-a ~ 93-d, 10
1-a, 101-b - permanent magnet, 25, 3
2-a, 32 b-magnetic field lines, 91-a. 91-b preliminary plasma chamber, 96...cusp magnetic field. 71-a to 71-c, 82-a to 82-e...magnetic field.

Claims (1)

[Claims] 1. It has a vacuum container, an exhaust device, a gas introduction part, and a microwave introduction part each communicating with the vacuum container, and generates a magnetic field component in the same direction as the traveling direction of the microwave. In the plasma apparatus, the magnetic field generating means is configured such that the generated magnetic field is stronger at the periphery than at the center of the vacuum vessel. Device. 2. A plasma device according to claim 1, wherein the magnetic field generating means is constituted by a permanent magnet placed outside the plasma generation chamber. 3. In claim 2, the permanent magnet is
A plasma device characterized in that one or more sets of magnetic poles with different polarities are arranged so as to face a plasma generation section. 4. In the plasma apparatus according to claims 1 to 3, the magnetic flux density formed in the plasma generation section by the magnetic field generation means is such that at least a part of the plasma generation section generates electrons at the frequency of the microwave. A plasma device characterized in that the magnetic flux density is selected to be higher than the magnetic flux density that produces cyclotron resonance.