JPH01309955A - Plasma apparatus - Google Patents

Abstract

PURPOSE:To efficiently form a thin film excellent in uniformity on a specimen by providing a plasma-producing means and also providing magnetic means generating a multopolar magnetic field to the position in the vicinity of a specimen to be treated in a plasma apparatus so as to generate a uniform and high- density plasma only in a part necessary for film formation. CONSTITUTION:At the time of forming a thin film of Al2O3 constituting a target 1 on the surface of a glass substrate 3 by means of sputtering in a plane- parallel plate-type sputtering device, the inside of a vacuum vessel 20 is evacuated and Ar gas is supplied, and a high-frequency voltage is impressed from a high-frequency electric power source 23 on a holder 2 of a target 1 to initiate electric discharge and produce plasma, by which Ar ls ionized and allowed to bombard the target 1 and a thin film of Al2O3 is formed on the surface of the glass substrate 3. At this time, by providing many permanent magnets or magnetic means 5 electrifying a superconductor in the vicinity of the target and the substrate, the plasma is localized only in a space enclosed with the target, the glass substrate, and the magnetic means, by which the thin film of Al2O3 excellent in uniformity can be formed on the glass substrate 3 at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in plasma devices, and particularly to plasma devices such as parallel plate sputtering devices that can perform uniform film formation and etching at high speed.

C. Prior Art] Parallel plate sputtering equipment and etching equipment are widely used in the manufacturing process of semiconductor devices or functional thin film elements such as thin film magnetic heads. Furthermore, in recent years, etching apparatuses using microwave discharge have also come into use.

Regarding a descending flat plate type etching device, it has been proposed to use a magnetic field in order to improve processing quality and processing speed. For example, in Japanese Patent Publication No. 60-58794,
A plasma processing apparatus equipped with a multipolar magnetic field generating means that generates a magnetic field only near the wall surface of a container is discussed. A similar device is disclosed in Japanese Unexamined Patent Publication No. 143330/1983. These devices are etching devices in which the region where ionized gas (plasma) used for processing is generated and the shape of the processing chamber are almost similar. These conventional techniques do not take into consideration the case where the plasma region required for processing and the shape of the processing chamber are significantly different, for example, in the case of a sputtering apparatus with a shutter.

Even in microwave etching equipment, the plasma area required for processing and the shape of the processing chamber differ greatly. In order to reduce power consumption in this device, a method has been devised in which a magnetic field is used to transport plasma from the plasma generating section to the workpiece.

For example, in Japanese Patent Publication No. 53-34463, a magnetic field is applied in a direction almost perpendicular to the workpiece using an electromagnet that causes magnetic field microwave discharge and a permanent magnet placed behind the workpiece. There is. On the other hand, JP-A-57-8295
In Publication No. 5, a magnetic field is applied in a direction substantially perpendicular to the workpiece by a part that introduces microwaves into the discharge space and a permanent magnet placed behind the substrate. Although these devices enable efficient plasma transport, it is difficult to realize large-scale devices due to the electromagnets and power supply required for the former.

Regarding the latter, there is a problem in that the permanent magnet that allows microwaves to pass through deteriorates after long-term use.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not sufficiently consider the plasma control method when the plasma area required for processing or film formation and the shape of the processing chamber or film formation chamber are significantly different. There was a problem that spatial uniformity was insufficient.

The purpose of the present invention is to generate high-density, uniform plasma only in parts of the processing chamber or film-forming chamber necessary for processing or film-forming, thereby enabling high-speed, highly uniform etching and film-forming. The purpose of the present invention is to provide a plasma device.

[Means to solve the problem]

The above purpose is to achieve the above objective in a plasma apparatus consisting of a vacuum vessel serving as a processing chamber or a film forming chamber, a plasma generating means disposed inside the chamber, and a sample to be processed. This is achieved by providing a magnetic means for generating a polar magnetic field and by making the magnetic means movable relative to the sample to be processed. That is, the plasma generated by this magnetic means is localized between the plasma generation means and the sample to be processed, and the plasma spreads throughout the vacuum container, resulting in a decrease in plasma density.
Moreover, deterioration of uniformity can be prevented.

As a result, it becomes possible to perform etching and film formation at high speed and with good uniformity.

[Effect]

A vacuum container equipped with a plasma generating means, a sample to be processed, and a magnetic means for localizing the plasma is evacuated. Plasma of the introduced gas is generated by the plasma generating means. The plasma tries to diffuse and spread throughout the vacuum vessel, but is confined by magnetic means, for example a magnetic vessel formed by a multipolar magnetic field. Therefore, the plasma generated by the discharge is localized in the space between the plasma generation means and the sample to be processed, resulting in high density and uniform plasma. Etching and film formation are performed using this plasma, and it is possible to perform etching and film formation at high speed and with good uniformity.6 Additionally, if it is necessary to use a shutter in the device, this magnetic means can be moved. Therefore, there is no problem in opening and closing the shutter. There is no problem at all with regard to the loading and unloading of the sample to be processed by providing a similar mechanism.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a perspective sectional view of this embodiment, and FIG. 2 is a longitudinal sectional view of this embodiment. This is a parallel plate type high frequency sputtering device. In the vacuum vessel 20, a target 1. attached to the target holder 2 is placed. Board 3 attached to board holder 4. A permanent magnet 6, an earth shield 5, and a shutter 8 are arranged to form a multipolar magnetic field.

The target holder 2 is electrically connected to an electrically insulated high-frequency terminal 10 via an insulator 10, and a high-frequency power of 13.56 MHX is supplied from a high-frequency power supply 23 through a matching box 22. applied. The high frequency terminal electrically connected to the substrate holder 4 is grounded. The vacuum container 20 and the earth shield 5 are also grounded.

The permanent magnet 6 has N poles and S poles arranged alternately in the circumferential direction, as shown in a cross-sectional view in FIG. 3(A). This creates a magnetic field such as 25. Each permanent magnet 6 is attached to an annular plate, and can be moved up and down in vacuum by a lifting mechanism 7 without changing the position of each permanent magnet 6. Although the permanent magnet 6 is not shown in the figure, it is housed in a stainless steel case. This is to prevent plasma from directly touching the permanent magnet 6. Further, instead of using such a case, the surface of the permanent magnet 6 may be coated with a metal having a lower sputtering rate than stainless steel, such as molybdenum. In this way, impurities in the vacuum vessel 20 can be further reduced than when the vacuum vessel 20 is placed in a stainless steel case. The shutter 8 is supported by a rail 9 and can be moved left and right by a mechanism not shown in the figure. The shutter 8 is at ground potential.

The vacuum container 20 is evacuated to a degree of vacuum of about 10'-4 Pa using an evacuation device (not shown). Argon gas is introduced into the vacuum container 20 at a pressure of 1 to 2 Pa.

When high frequency power of 13.56 MHz is applied to the target holder (referred to as target side electrode) from the high frequency 11@23, plasma is generated when discharge starts. A potential difference called an ion sheath is created near the target, and the ions in the plasma are accelerated by the electric field and impact the target, thereby sputtering target particles. A film is formed by depositing these sputtered particles on the opposing substrate 4. At this time, if the permanent magnet 6 were not present, the plasma would spread throughout the container, but in this example, the plasma could be localized only in the space surrounded by the target 1, the substrate 4, and the permanent magnet 6.

The results of experiments conducted by the inventors are shown. The target 1 used was made of 99.99% alumina, had a diameter of 200 m, and was water-cooled. The substrate is a 0.5 m thick glass substrate and is water cooled. 2K if permanent magnet 6 is not used
A high frequency power of W was applied to the target electrode to obtain a film forming rate of 1.5 μm/hour at the center of the electrode on the substrate side. The film forming rate was uniform within ±5% within the range of diameter 1201111+1 out of the electrode diameter of 200 mm. When the density distribution of the argon plasma generated by the discharge was examined at approximately the middle height of the picture electrode, it became as shown by the broken line in FIG. 3(B). For an electrode with a diameter of 200 nn+,
Although the density is uniform within the diameter 1100a, the density decreases as it approaches the periphery of the discharge space.

On the other hand, when a similar experiment was conducted with a permanent magnet 6 that generates a multipolar magnetic field, the plasma density distribution was
This is now shown by the solid line in Figure (B). The graphs with and without magnets in the figure are normalized by the maximum value. The deposition rate at the center of the electrode on the substrate side when a magnet is present is as follows:
When KW high frequency power was input, the alumina film formation rate was 1.8 μm/hour, and the film formation rate was uniform within ±5% within a diameter of 140 mm.

From this result, by attaching the permanent magnet 6 that generates a multipolar magnetic field, it is possible to achieve a faster and more uniform film deposition rate using a parallel plate type sputtering apparatus.

Although the operation of the shutter 8 has not been explained in the explanation so far, the shutter 8 is essential in the actual process. That is, prior to film formation, the permanent magnet 6 is lowered by the lifting mechanism 7, the shutter 8 is inserted between the target 1 and the substrate 3, and a high frequency discharge is generated between the target 1 and the shutter 8 to sputter the surface of the target 1. to clean the target surface. Thereafter, the discharge is stopped, the shutter 8 is pulled out from between the target 1 and the substrate 3, the permanent magnet 6 is pushed upward, and the high frequency discharge is performed again between the target side electrode and the substrate side electrode to perform the formation I simulation. When the formed film reaches a predetermined thickness, the high frequency discharge is stopped, the permanent magnet 6 is lowered, and the substrate 3 is taken out.

Whether the film formation rate has reached a predetermined thickness is determined by setting the sputtering time or monitoring the film thickness.

The operation of this device may be automatically controlled using a microcomputer.

According to this embodiment, by surrounding the discharge space formed by the target-side electrode and the substrate-side electrode with the permanent magnet 6 that generates a multipolar magnetic field, the plasma generated by the high-frequency discharge is confined, and the entire discharge space is By making the density almost uniform, it is possible to form a film with good uniformity at high speed, and by making the permanent magnet 6 that generates the multipolar magnetic field movable, there is no problem with the operation of the shutter. 6 A second embodiment of the present invention will be described using the longitudinal sectional view of FIG. 4. This embodiment is a high frequency sputtering apparatus, and its structure is almost the same as the embodiments shown in FIGS. 1 and 2. The point that high frequency is applied to the target holder 2 is the same in both cases, but the substrate holder shown in FIG.
The difference is that in the embodiment of FIG. 2, a ground potential is applied, whereas in the embodiment of FIG. 4, a high frequency is applied.

Specifically, the signal generated by the oscillator 24 is amplified by the amplifier 26 and then passed through the matching box 22.

The voltage is applied to the target holder 2. By passing the above-mentioned signal through the phase shifter 25, the phase is changed. The signal is amplified and applied to the substrate holder 4 via a matching box. Thereby, the phase and applied power applied to the target holder 2 and the wall plate holder 4 can be changed.

According to experiments conducted by the inventors, when high-frequency power is applied to the substrate side to apply a bias, the film formation rate increases and the adhesion of the film improves.

When the permanent magnet 6 that generates the multipolar magnetic field is not attached, the film formation speed is 3.2 μm/3 for a target input power of 2 KW.
It's time. When the permanent magnet 6 is attached, the film formation rate is 3.8 μm/hour for the same target input power.

Regarding the uniformity of the film formation rate, it was almost the same regardless of the presence or absence of the permanent magnet 6.

According to this embodiment, plasma confinement by a multipolar magnetic field provides the same effects as described for the embodiments of FIGS. 1 and 2.

A third embodiment of the present invention will be described using the perspective sectional view of FIG. This embodiment is also a high-frequency sputtering apparatus, and its structure is almost the same as the embodiments shown in FIGS. 1 and 2. The difference is that in the embodiments shown in FIGS. 1 and 2,
Although the permanent magnet 6 is used to generate a multipolar magnetic field, in this embodiment, current is passed through the conductor 3o. In order to efficiently confine the generated plasma,
Since a large current needs to flow, it is preferable to use a superconductor conductor 30 to reduce power consumption.

According to this embodiment, plasma confinement by a multipolar magnetic field provides the same effects as described for the embodiments of FIGS. 1 and 2.

A fourth embodiment (k) of the present invention will be described using the vertical cross-sectional view of FIG. This example is an in-line sputtering device,
This is a device that forms three different types of films. This apparatus consists of a substrate mounting chamber 51, three film forming chambers 52, and a substrate unloading chamber 53, and each chamber is evacuated by an exhaust device not shown in the figure. The gate valve 53 is closed during film formation. The substrate 3 is attached to a substrate tray 55, and the substrate tray 55 is moved between chambers using a tray moving mechanism 56.
During film formation, the substrate tray is at ground potential, and a discharge occurs between the target electrodes 54 to which high frequency waves are applied, generating plasma. Both? EwA54.55
Since permanent magnets that form a multipolar magnetic field are placed around the image electrodes 54 and 55, plasma is generated.
and a cylindrical area surrounded by permanent magnets 6. Note that when the substrate tray 55 moves, the permanent magnet 6 is moved upward by the lifting mechanism 7, so that the substrate tray 55
There is no obstacle to the horizontal movement of the

This embodiment also has the same effect as the embodiments shown in FIGS. 1 and 2 due to the plasma confinement by the multipolar magnetic field.

A fifth embodiment of the present invention will be described using FIG. 7. This example is a longitudinal section of a plasma etching apparatus. This device consists of a vacuum vessel 20 and an airtight discharge chamber 62. Microwaves (2.45 GHz) are introduced into the discharge chamber 62 through the waveguide 60, and a working gas is supplied. Permanent magnets 63 are arranged around the discharge chamber to generate an axial magnetic field near the wall. Inside the vacuum container 2o, a substrate holder 4 to which a substrate 3 is attached and a permanent magnet 6 for generating a multipolar magnetic field surrounding the substrate holder 4 are installed. Furthermore, the substrate holder 4 can be moved up and down by a lifting mechanism 7, making it easy to take out the substrate 3.

Plasma generated in the discharge chamber 62 due to magnetic field microwave discharge diffuses toward the vacuum vessel 20, but since the plasma is confined by the multipolar magnetic field created by the permanent magnet 6, other parts of the vacuum vessel Since there is almost no diffusion, not only is the efficiency of using the input microwave power improved, but also the plasma density near the substrate is almost the same everywhere, so uniform etching is possible.

FIG. 8 is a longitudinal sectional view of a conventional microwave plasma etching apparatus. It is the same as the embodiment shown in FIG. 7 in that the plasma is generated using microwave discharge and that the magnetic field created by the permanent magnet 80 is used to transport the plasma near the substrate. The difference is that the magnetic field is applied in a direction perpendicular to the substrate 3. Similarly to the embodiment shown in FIG. 7, a magnetic field applied in a direction perpendicular to the substrate 3 causes
This prevents plasma diffusion and improves the efficiency of using the input microwave power. However, in the embodiment shown in FIG. 8, the microwave is passed through the permanent magnet 80, but in the embodiment shown in FIG. Not a problem.

According to the example shown in Fig. 7, the plasma generated by microwave discharge is confined in a multipolar magnetic field created by a permanent magnet, so the density is almost constant in the confined area, and a uniform etching rate can be obtained. effective.

〔Effect of the invention〕

According to the present invention, the generated plasma is localized between the plasma generation means and the sample to be processed (substrate), and the plasma can be prevented from spreading throughout the vacuum chamber. , the etching speed, and their uniformity are improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective sectional view of an embodiment of the present invention, FIG. 2 is a vertical sectional view of the same embodiment, and FIG. 3 is an explanatory diagram showing the effects of the present invention.
4, 6, and 7 are longitudinal cross-sectional views of second, third, and fourth embodiments of the present invention; FIG. 5 is a perspective cross-sectional view of the fifth embodiment of the present invention; and FIG. The figure is a longitudinal sectional view of a conventional device. 1...Target, 3...Substrate, 6...Permanent magnet, 7...Figure 1, Figure 2, Figure 3 (,'1)

Claims (1)

[Scope of Claims] 1. A vacuum vessel, a plasma generating means disposed inside the vacuum vessel, or a plasma generating means disposed airtightly adjacent to the vacuum vessel, and a processing target disposed inside the vacuum vessel. A plasma apparatus comprising: a sample, further comprising magnetic means for generating a multipolar magnetic field from the vicinity of the plasma generation means to the vicinity of the sample to be processed. 2. The plasma apparatus according to claim 1, further comprising a mechanism that allows the magnetic means to be moved relative to the sample to be processed. 3. A plasma device according to claim 1, characterized in that a multipolar magnetic field generated by a plurality of permanent magnets is used. 4. A plasma device according to claim 1, characterized in that a parallel plate type direct current or high frequency discharge is used as the plasma generating means. 5. The plasma device according to claim 1, characterized in that microwave discharge is used as the plasma generating means. 6. A plasma device according to claim 1, characterized in that the magnetic means is a multipolar magnetic field generated by passing a current through a conductor. 7. The plasma device according to claim 6, wherein the conductor is a superconductor. 8. The plasma apparatus according to claim 3, wherein the permanent magnet is coated with a metal or alloy having a lower sputtering rate than stainless steel on the surface of the permanent magnet. 9. The plasma device according to claim 4, further comprising a shutter that can be inserted between the parallel plates. 10. The usage method according to claim 9, wherein the shutter is opened and closed while the magnetic means is moved to either the plasma generation side or the sample to be processed side. 11. A control method according to claim 9, wherein the magnetic means is moved to automatically open and close the shutter by automatically detecting an external command and the progress of processing. 12. When the method of claim 4 is used for film formation, a film formation method in which plasma of substantially equal density is generated anywhere near the parallel plate electrodes to form a film. 13. The plasma device according to claim 4, wherein high frequency power having mutually different phases is applied to the parallel plate electrodes.