JPH08319588A - Plasma etching device - Google Patents

Abstract

PURPOSE: To obtain a sputter etching device of a high treating speed by imparting repulsive force to the electrons in the plasma generated in the upper part of a sample by utilizing the effect of an electromagnetic field to increase the plasma density. CONSTITUTION: The opposite surface of a cathode electrode 3 of this plasma etching device is provided with an insulator 2 to hermetically seal the upper aperture of a treating vessel 1. The discharge space on the rear surface of this insulator 2 is provided With a magnet element 9. An electric discharge is initiated between the cathode 3 and the treating vessel 1 when a high-frequency voltage is impressed on the cathode 3 from a high-frequency power source 6. This electric discharge spreads to the upper part of a wafer 12 and the strong plasma is formed by the effect of the magnetic field generated by the magnet element 9 in the upper space of the wafer 12. The generated plasma is held nearly at the grounding potential. As a result, the plasma density is increased by sufficiently utilizing the effect of the magnetic fields. The high- speed treatment is thus executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputter etching apparatus, and more particularly to a sputter etching apparatus which is suitable for processing under a low pressure.

[0002]

2. Description of the Related Art A conventional device is disclosed in Japanese Patent Application Laid-Open No. 57-15538.
As described in No. 4, a parallel plate type high frequency sputter etching apparatus in which a high frequency electrode and a counter electrode are arranged in parallel with each other in a vacuum chamber, and a gas introduced from a gas introduction hole is ionized to sputter-etch a sample surface. In some cases, an introduction positive electrode having a positive potential with respect to the ground potential and having a gas introduction hole is provided.

[0003]

The above-mentioned prior art does not take into consideration the case where plasma is generated under a low pressure by utilizing the action of a magnetic field, and during the discharge generated between the high frequency electrode and the counter electrode. However, there is a problem that the electrons of the above flow quickly to the introduction positive electrode, the action of the magnetic field does not contribute much to the electrons during the discharge, and strong plasma cannot be generated.

An object of the present invention is to provide a sputter etching apparatus which makes full use of the action of a magnetic field to increase the plasma density and has a high processing speed.

[0005]

The above object can be achieved by providing a means for imparting a repulsive force to the electrons in the plasma generated above the sample by utilizing the action of the electromagnetic field.

As a result, the electrons in the plasma space are prevented from flowing to the side opposite to the sample, and the electrons are repelled and held in the plasma space, thereby sufficiently contributing the action of the magnetic field to the electrons. Therefore, the plasma density can be increased. Thereby, the processing speed of the plasma processing can be increased.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a magnetic field combined type sputter etching apparatus which is a plasma etching apparatus. The processing container 1 has a gas introduction port 7 and an exhaust port 8, and in this case,
A steady low-pressure atmosphere is maintained by introducing argon gas and evacuating it at the same time.

The reaction vessel 1 is directly connected to the ground. The cathode electrode 3 on which the wafer 12 is placed is connected to a high frequency power source 6 for plasma generation via a coupling capacitor 4 and a matching box 5. The cathode electrode 3 is made up of a support material 11 made of an insulating material, and the reaction container 1
Attached to. An insulator 2 is provided on the opposite surface of the cathode electrode 3 and is attached so as to seal the upper opening of the processing container 1. The insulator 2 is galvanically isolated from the ground. On the back surface (upper side of the drawing) of the insulator 2, a magnet element 9 for introducing a magnetic field into the discharge space, that is, the upper space of the wafer 12, and a motor 10 for rotating the magnet element 9.
Is installed.

When a high-frequency voltage is applied to the cathode 3 by the high-frequency power source 6 by the apparatus configured as described above, the discharge is started between the cathode 3 and the processing container 1, and the discharge spreads on the upper part of the wafer 12 to cause the discharge of the wafer 12. A strong plasma is formed in the upper space by the action of the magnetic field generated by the magnet element 9. The generated plasma is kept substantially at the ground potential because the processing vessel 1 is connected to the ground. On the other hand, the cathode electrode 3 has a DC negative potential due to the coupling capacitor 4, and an ion sheath is formed between the cathode electrode 3 and the plasma to generate a large potential difference (self-bias voltage). The insulator 2 is charged up by high-speed electrons from the plasma, that is, electrons that fly out in a direction perpendicular to the surface of the cathode electrode 3 and are added through the ion sheath,
It has a negative potential with respect to plasma, prevents electrons in the plasma from repelling and flowing into the insulator 2 side, floating many electrons in the plasma, and keeping the plasma at a high density by the action of the magnetic field. .

For example, if the silicon oxide film is sputter-etched at a high-frequency power of 400 W and an argon pressure of 5 mTorr (0.7 Pa), the etching rate is 1 in this case.
The self bias voltage was 00 nm / min and -300V. However, when the insulator 2 is used as an anode electrode and is connected to the ground as a conductor as in the conventional case, the potential difference between the anode electrode and the plasma is reduced to about 1/10, and electrons flow from the plasma to the anode electrode to cause the plasma. Since the density of electrons in the inside decreases, in this case, if the sputter etching is performed under the same conditions as above, the etching rate becomes 40 nm / min, and the processing rate decreases. In addition,
The self-bias voltage at this time was -600V.

When a conductor such as aluminum is sputter-etched, aluminum of the wafer 12 is sputtered and a disk-shaped aluminum film similar to the shape of the wafer 12 is formed on the surface of the insulator 2. Are electrically kept in a floating state, electrons are charged at the end of the disk-shaped aluminum film, the plasma density in the space at the upper center of the wafer 12 is reduced, and the etching density distribution for the wafer 12 is reduced. Occurs in the peripheral area. In this case, the groove 2 having an overhang on the surface of the insulator 2 as shown in FIGS.
By forming 3 and making it discontinuous even if aluminum adheres, and by keeping the electron charge in each part, high density plasma can be held.

The insulating plate 2 in this case is a flat plate 21 of alumina.
And a plurality of convex rings 22 made of alumina, the convex ring 22 is fixed by being pushed into the groove of the flat plate 21 with the convex side facing the flat plate 21 side. The groove processing of the convex ring 22 and the flat plate 21 can be easily performed if it is performed between alumina materials, and it can be fixed by inserting the convex ring 22 into the groove provided in the flat plate 21 and then sintering. If adhesive strength is required, an alumina-based adhesive may be used. There is no problem in heat resistance to plasma, and heating at about 500 ° C. is possible.

In this case, the flat plate 21 is provided with the groove, but the convex ring 22 may be adhered and fixed without the groove.

According to this, when aluminum was sputter-etched under the same conditions as the previous conditions when the silicon oxide film was sputter-etched, both the sputter rate and the self-bias voltage were the same as those for the silicon oxide film.

In this case, the insulating plate 2 is formed of the alumina flat plate 21 and the convex ring 22. However, the same effect can be obtained by configuring the insulating plate 2 as shown in FIG.

The insulating plate 2 shown in FIG. 4 comprises a quartz plate 24 and a resist (mask material) 25.
The quartz plate 24 is isotropically wet-etched on the back side of the pattern groove 26 so as to engrave the bottom portion of the mask material 25. As a result, a shadow portion where the sputtered metal particles do not adhere is formed in the etch groove 27.

Although the insulating plate 2 is entirely made of an insulating material in this embodiment, a grounded conductor may be contained therein. At this time, at least the conductor on the surface in contact with the discharge space must be completely coated with an insulator.

Further, in the present embodiment, the side wall of the processing container 1 installed around the cathode electrode 3 is provided, but a separately installed earth electrode may be installed around the cathode electrode.

Next, another embodiment of the present invention will be described with reference to FIGS.

5, the same reference numerals as those in FIG. 1 indicate the same members. 1 is different from FIG. 1 in that the anode electrode 14 is attached to the processing container 1 via a support material 13 made of an insulator instead of the insulator 2, and a DC power supply 15 for giving a negative potential to the anode electrode 14 is provided. The point is that they are connected.

To the apparatus constructed as described above, in this case, a wafer 12 having a silicon oxide film coated with aluminum is used, and when a high frequency voltage is applied to the cathode electrode 3 by the high frequency power source 6, Electric discharge is started between the processing container 1 and the electric discharge, and the electric discharge spreads over the wafer 12, and strong plasma is formed in the wafer 12 and the upper space by the action of the magnetic field generated by the magnet element 9. The generated plasma is maintained at substantially the ground potential because the processing container 1 is connected to the ground. On the other hand, the cathode electrode 3
Becomes a DC negative potential due to the coupling capacitor 4 and generates a large potential difference (self-bias voltage) with the plasma to form an ion sheath.

On the other hand, the anode electrode 14 is kept at a negative potential by the DC power source 15 and repels high-speed electrons from the plasma, that is, electrons that fly out in the direction perpendicular to the surface of the cathode electrode 3 and pass through the ion sheath, and repel the anode electrode. 14
Since it is prevented from flowing into the side, the anode electrode 1 is compared with the conventional case in which the anode electrode 14 is connected to the ground.
A large ion sheath is formed on the 4th part. Electrons are held in the discharge space by these two sheaths, and a high-density plasma is formed under the action of a magnetic field.

FIG. 6 shows the dependence of the etching rate and the self-bias voltage on the DC voltage applied to the anode electrode when an aluminum film is etched at a high frequency power of 400 W and an argon pressure of 5 mTorr (0.7 Pa). is there. By increasing the absolute value of the DC applied voltage in the range of 100 V or less, the etching rate is increased by 2 to 3 times as compared with the conventional one in which the DC applied voltage is not applied. At this time, the self-bias voltage of the cathode electrode 3 has dropped significantly.

In this case, since the anode electrode 14 is formed of a conductor, it is not necessary to form a groove even when the aluminum film is sputter-etched as in the above-described embodiment.

As described above, according to this embodiment, the same effect as the above-mentioned one embodiment can be obtained. In particular, it is a good enemy when the material to be etched is a metal material.

[0027]

According to the present invention, since the plasma density can be increased by fully utilizing the action of the magnetic field, there is an effect that high speed processing can be performed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a plasma etching apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of the insulating plate viewed from AA in FIG.

3 is a sectional view of FIG. 2 viewed from B. FIG.

FIG. 4 is a cross-sectional view showing another example different from FIG.

FIG. 5 is a vertical sectional view showing a plasma etching apparatus according to another embodiment of the present invention.

6 is an explanatory diagram showing a relationship between an etching rate and a voltage when an experiment is performed using the apparatus of FIG.

[Explanation of Codes] 1 ... Processing container, 2 ... Insulator, 3 ... Cathode, 6 ... High frequency power source, 9 ... Magnet element, 14 ... Anode electrode, 15 ... DC power source.

Front page continued (72) Inventor Takeshi Oyamada 111 Nishiyokote-cho, Takasaki-shi, Gunma Hitachi Takasaki factory (72) Inventor Hikari Nishijima 111 Nishiyote-cho, Takasaki, Gunma Hitachi Takasaki factory

Claims (1)

[Claims] 1. A cathode electrode on which a sample is placed, an electrode which surrounds the cathode electrode and is electrically grounded, a negative electrode facing the cathode and to which a negative potential is applied, and the negative electrode. And a magnet element for applying a magnetic field between the cathode electrode and the cathode electrode, wherein plasma is generated on the upper portion of the sample by utilizing an action of an electromagnetic field generated by the magnet element to process the sample. And a plasma etching device.