JPH01183123A - Al sputter etching 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 a sputter etching apparatus, and particularly to a sputter etching apparatus suitable for processing under low pressure.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 57-155384, a conventional device has a high-frequency electrode and a counter electrode arranged in parallel to each other in a vacuum chamber, and ionizes the gas introduced through the gas introduction hole to cover the sample surface. Some parallel plate type high frequency sputter etching apparatuses for sputter etching are provided with an inlet anode having a positive potential with respect to ground potential and having a gas inlet hole.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the case where plasma is generated under low pressure using the action of a magnetic field.
The problem is that the electrons during the discharge that occur between the high-frequency electrode and the counter electrode quickly flow to the positive electrode, and the magnetic field does not contribute much to the electrons during the discharge, making it impossible to generate strong plasma.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sputter etching apparatus which fully utilizes the effect of a magnetic field to increase plasma density and has a high processing speed.

[Means for Solving the Problems] The above object is achieved by providing a means for applying a repulsive force to electrons in plasma generated above a sample using the action of an electromagnetic field.

[For production]

By preventing electrons in the plasma space from flowing toward the anti-sample side and repelling and retaining the electrons in the plasma space, the magnetic field can fully contribute to the electrons, increasing plasma density. be able to. This makes it possible to increase the processing speed of plasma processing.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows a magnetic field type sputter etching apparatus which is a plasma etching apparatus.

The processing vessel 1 has a gas introduction lower and an exhaust port 8, and in this case, argon gas is introduced and exhausted at the same time to maintain a constant low pressure atmosphere.

The reaction vessel 1 is connected to ground in a direct current manner.

The cathode electrode 3 on which the wafer n is placed is a coupler, 3
.

Gukyabashita 4. It is connected via a matching box 5 to a high frequency power source 6 for plasma generation.

The cathode electrode 3 is attached to the reaction vessel l by a support 11 made of an insulating material. 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 l. The insulator 2 is insulated from the ground in terms of direct current. A magnet element 9 for introducing a magnetic field into the discharge space, that is, the space above the wafer ν, and a motor 10 for rotating the magnet element 9 are installed on the back surface (upper side in the figure) of the insulator 2.

With the device configured in this way, when a high frequency voltage is applied to the cathode 3 by the high frequency power supply 6, a discharge is started between the cathode 3 and the processing vessel l, the discharge spreads to the upper part of the sea urchin, and a magnet is placed in the upper space of the sea urchin. A strong plasma is formed by the action of the magnetic field generated by element 9. The generated plasma is held at a ground potential because the processing container 1 is connected to ground. On the other hand, cathode voltage 4
j3 is DC-driven by the coupling capacitor 4,
4.

The potential becomes negative, and an ion sheath is created between it and the plasma, generating 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 over-move the ion sheath, and becomes a negative potential with respect to the plasma, repelling the electrons in the plasma. Insulator 2
This prevents electrons from flowing to the sides, causes a large number of electrons to float in the plasma, and maintains the plasma at a high density under the action of a magnetic field.

For example, high frequency power 400W, argon pressure 5mTor
When a silicon oxide film is sputter etched at r (0.7 Pa), the etching rate is 100 n
m/min, and the self-bias voltage was -300V. However, when the insulator 2 is used as an anode electrode and connected to the ground as a conductor as in the past, the potential difference between the anode electrode and the plasma becomes as small as '/'to, and electrons flow from the plasma to the anode electrode. Since the density of electrons in the plasma decreases, in this case, if sputter etching is performed under the same conditions as above, the etching rate will be 4
0n m/min, and the processing speed decreases. Note that the self-bias voltage at this time was -600V.

Furthermore, when a conductor such as aluminum is sputter-etched, the aluminum of the wafer ν is sputtered and a disc-shaped aluminum film similar to the shape of the wafer is formed on the surface of the insulator 2, and the insulator 2 becomes electrically conductive. Even if the aluminum film is kept in a floating state, electrons are charged at the edge of the disc-shaped aluminum film, and the plasma density in the central space above the wafer L decreases, and the etching rate distribution with respect to the wafer changes to the peripheral region. A phenomenon occurred in which the value increased. In this case, an overhang is formed on the surface of the insulator 2 as shown in Figures 2 and 3 so that even if aluminum is attached, it will be discontinuous, and the electron charge will be High-density plasma can be maintained by holding the plasma in a certain portion.

The insulating plate 2 in this case is composed of a flat plate 21 made of alumina and a plurality of convex rings n made of alumina as well, and the convex rings n are pushed into the grooves of the flat plate B with the convex side facing the flat plate A. It is fixed.

Such grooving between the convex ring n and the flat plate 4 can be easily done by making it between the alumina material, and can be fixed by inserting the convex ring η into the groove provided in the flat plate B and then sintering it. Further, if adhesive strength is required, a contact agent mainly composed of alumina may be used. There is no problem with heat resistance against plasma, and heating to about 500°C is possible.

Furthermore, in this case, the flat plate 21 is grooved, but the convex ring n may be bonded and fixed without grooves.

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

Further, in this case, the insulating plate 2 is formed of an alumina flat plate and a convex ring 4, but the same effect can be obtained even if the insulating plate 2 is configured as shown in FIG. 4.

The insulating plate 2 shown in FIG. 4 is composed of a quartz plate and a resist (mask material) 25, and the quartz plate hollows out the bottom of the mask material 5 on the back side of the pattern grooves. Isodirectional wet etching. As a result, a shadow portion is formed in the etched groove n to which sputtered metal particles do not adhere.

In this embodiment, the entire insulating plate 2 is made of an insulating material, but a grounded conductor may be included inside. In this case, it is necessary that at least the surface of the conductor in contact with the discharge space is completely covered with an insulator.

Further, in the wood embodiment, there is a side wall of the processing container l that is grounded around the cathode and electrode 3, but a separately grounded earth electrode may be provided around the cathode electrode.

Next, another embodiment of the present invention will be described with reference to FIGS. 5 and 6.

In FIG. 5, the same reference numerals as in FIG. 1 indicate the same members. This figure differs from FIG.
Attach it to the anode section 14, 8.

The point is that it is connected to a DC power source that provides a negative potential.

With the apparatus configured in this way, in this case, the wafer ν
Using an aluminum film on a silicon oxide film, the cathode voltage is 8F! using a high frequency power supply 6. When a high frequency voltage is applied to the cathode electrode 3, a discharge starts between the cathode electrode 3 and the processing container 1, and the discharge spreads to the upper part of the sea urchin.
Strong plasma is formed between the wafer ν and the space above by the action of the magnetic field generated by the magnet element 9. The generated plasma is maintained at approximately the earth potential because the processing container 1 is connected to earth. On the other hand, the cathode electrode 3 has a negative DC potential due to the coupling capacitor 4, generates a large potential difference (self-bias voltage) with the plasma, and forms an ion sheath.

On the other hand, the anode 14 is kept at a negative potential by DC current #t15, and high-speed electrons from the plasma, ie.

Since the electrons that have jumped out in the direction perpendicular to the surface of the cathode electrode 3 and passed through the ion sheath are repelled and prevented from flowing into the anode 14 side, compared to the conventional case where the anode electrode 14 is connected to the ground. As a result, a large ion sheath is formed in the 1-node electrode 14 portion. Electrons are held in the discharge space by these two sheaths, and high-density plasma is formed under the action of the magnetic field.

Figure 6 shows high frequency power of 400W and argon pressure of 5mTor.
This figure shows the dependence of the etching rate and self-bias voltage on the DC voltage applied to the anode electrode when an aluminum film is etched at r (0,7 Pa). By increasing the absolute value of the DC applied voltage within the range of 100 V or less, the etching rate can be increased two to three times compared to the conventional method in which no DC applied voltage is applied. At this time, the self-bias voltage of the cathode electrode 3 is greatly reduced.

In any case, since the one-node section 14 is formed of a conductor, it is not necessary to form a groove as in the above-mentioned embodiment even when sputter etching the aluminum film.

According to the first embodiment described above, the same effects as those of the embodiment described in LFF are obtained. This is particularly suitable when the material to be etched is a metal material.

〔Effect of the invention〕

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

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing a plasma etching apparatus which is an embodiment of the present invention, Fig. 2 is a plan view of an insulating plate as seen from A-A in Fig. gJ1, and Fig. 3 is a plan view of Fig. Cross-sectional view,
FIG. 4 is a sectional view showing a different example from FIG. 3, FIG. 5 is a longitudinal sectional view showing a plasma etching apparatus according to another embodiment of the present invention, and FIG. FIG. 3 is a diagram showing the relationship between etching speed and voltage when an experiment was conducted. l...Processing container, 2...Insulator, 3.
... Cathode electrode, 6 ... High frequency power supply,
9...Magnetic element, 14...Anode electrode, b...DC power supply agent Patent attorney Katsuo Ogawa

Claims (1)

[Claims] 1. A method comprising means for generating plasma above a sample using the action of an electromagnetic field, and means provided on an opposing surface of the sample for imparting a repulsive force to electrons in the plasma. A plasma etching device characterized by: 2. A plasma etching apparatus that performs processing by generating plasma above a sample using the action of an electromagnetic field, characterized in that a member having an electrically negative potential is provided on the opposite surface of the sample. Etching equipment. 3. A cathode electrode on which a sample is placed, an electrically grounded electrode surrounding the cathode electrode, an insulator provided opposite the cathode electrode, and a magnetic field between the insulator and the cathode electrode. A plasma etching apparatus characterized by comprising a magnetic element that imparts. 4. A cathode electrode on which a sample is placed, an electrode that surrounds the cathode electrode and is electrically grounded, a negative electrode provided opposite to the cathode electrode and to which a negative potential is applied, and the negative electrode and the cathode. A plasma etching apparatus characterized by comprising a magnet element that applies a magnetic field between the electrode and the electrode. 5. A plasma etching apparatus that processes a sample by generating plasma above the sample using the action of an electromagnetic field, characterized in that an insulator is provided on the opposing surface of the sample with a groove having a wide interior. Al sputter etching equipment. 6. An insulating plate for a plasma etching device, characterized in that it is provided with a groove having a wide space inside.