JPH0669163A - Etching device - Google Patents

Abstract

PURPOSE:To provide an etching device which achieves a high-speed etching uniformly without reducing anisotropy of an etching shape. CONSTITUTION:In an etching device in that a flat-plate shaped cathode electrode 2 where a high-frequency power is applied and a flat-plate shaped substrate electrode 3 are laid out opposingly in parallel in a vacuum vessel 1 and at the same time an anode electrode 4 is laid out around a space between these electrodes for etching a substrate 8 placed at the substrate electrode 3, a magnet 7 generating a magnetic field which is nearly vertical to the flat-plate shaped substrate electrode 3 is provided outside or inside the vacuum vessel 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching apparatus used for etching aluminum, aluminum alloys, refractory metals, compounds of refractory metals, insulators, gate electrode materials and the like.

[0002]

2. Description of the Related Art A conventional etching apparatus is shown in FIG. 5, in which a flat cathode electrode 2 and a flat substrate electrode 3 are arranged in parallel to each other in a vacuum chamber 1.
A grounded anode electrode 4 is arranged around the space sandwiched between the electrodes 2 and 3. A high frequency power source 5 is connected to the flat cathode electrode 2, a high frequency power source 6 is also connected to the flat substrate electrode 3, and high frequency power is applied to these electrodes 5, 6. A lattice-shaped multi-cusp type or annular cusp type magnet 7 is arranged behind the flat cathode electrode 2, and a cusp magnetic field is formed on the surface of the cathode electrode 2 by the magnet 7. A substrate 8 is placed on the substrate electrode 3.

In such an etching apparatus, first, the inside of the vacuum chamber 1 is evacuated, an etching gas is introduced, and high-frequency power is applied to the cathode electrode 2 from a high-frequency power source 5, so that the cathode electrode 2 and the anode electrode 4 are separated. Plasma is generated during the period, but the electrons in the plasma in the vicinity of the cathode electrode 2 undergo a cycloid motion due to the action of the magnet 7, so that the plasma has a high density and is diffused to the cathode electrode 2 by the cusp magnetic field. Suppressed. At this time, when high-frequency power is applied from the high-frequency power source 6 to the substrate electrode 3, when the potential of the substrate electrode 3 is negatively biased, the ions in the plasma are drawn toward the substrate electrode 3 and placed on the substrate electrode 3. The etched substrate 8 is etched. However, at this time, there is a magnetic field extending from the center of each magnet 7 substantially perpendicularly to the direction of the substrate 8, and the distribution of the magnetic field is not always uniform, so that the ions in the plasma may be biasedly incident on the surface of the substrate 8. become.

[0004]

In the conventional etching apparatus, the ions in the plasma are unevenly incident on the surface of the substrate 8 due to the influence of the magnetic field extending from the center of the magnet 7 substantially perpendicularly to the direction of the substrate 8 as described above. Therefore, there is a problem that the uniformity of etching is poor and it cannot be controlled to ± 10% or less. Therefore, in order to solve this problem, there is a means for widening the gap between the cathode electrode 2 and the substrate electrode 3 to weaken the vertical magnetic field on the substrate 8. In this means, plasma is generated in the anode electrode 4. Substrate 8
There is a problem that the density of the upper plasma is significantly reduced and the etching rate is reduced. Further, in order to solve the above problems, there is a means for increasing the pressure of the etching gas and diffusing ions by collision with gas molecules, thereby making the plasma uniform and making the etching uniform.
This means has a problem that the anisotropy of the etching shape is lowered by increasing the pressure of the etching gas, and an undercut in which the groove spreads in the lateral direction occurs.

The object of the present invention is to solve the above-mentioned problems of the prior art and to reduce the anisotropy of the etching shape,
An object is to provide an etching apparatus that enables uniform etching at high speed.

[0006]

To achieve the above object, according to the present invention, a flat cathode electrode to which high-frequency power is applied and a flat substrate electrode are arranged in parallel in a vacuum chamber while facing each other. , A grounded anode electrode is placed around the space sandwiched between these electrodes, and a cusp-shaped magnet is placed behind the flat cathode electrode to generate between the anode electrode and the cathode electrode. By the plasma
In an etching apparatus for etching a substrate placed on a substrate electrode, a magnet for generating a magnetic field substantially perpendicular to the flat substrate electrode is provided outside or inside the vacuum chamber. Is.

[0007]

In the present invention, a high density plasma is formed by the lattice-shaped multi-cusp type or annular cusp type magnet, and this plasma is affected by the magnetic field of the magnet extending in the direction substantially perpendicular to the substrate. While spreading.
However, at this time, since a magnet that generates a magnetic field almost perpendicular to the flat substrate electrode is provided outside or inside the vacuum chamber, the lateral spread of the plasma is shaped, and the ions in the plasma are The light is uniformly incident on the surface of the substrate, which enables uniform etching at high speed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. The etching apparatus of the embodiment of the present invention is an improvement of the conventional apparatus and is shown in FIG. 1, in which a flat cathode electrode 2 and a flat substrate electrode 3 are arranged in parallel in a vacuum chamber 1. An anode electrode 4 is disposed so as to face each other, and is grounded around a space sandwiched between the electrodes 2 and 3. A high-frequency power source 5 is connected to the flat cathode electrode 2, and a high-frequency power source 6 is connected to the flat substrate electrode 3 as well.
High frequency power is being applied to. Flat cathode electrode 2
A lattice-shaped multi-cusp-type or annular cusp-type magnet 7 is disposed behind the magnet, and a cusp magnetic field is formed on the surface of the cathode electrode 2 by the magnet 7. Substrate electrode 3
A substrate 8 is placed on the top. An electromagnet coil 9 is provided outside the vacuum chamber 1, and the electromagnet coil 9 generates a magnetic field almost perpendicular to the flat cathode electrode 2 and the flat substrate electrode 3. By changing the current flowing through the electromagnet coil 9, the magnetic field generated by the electromagnet coil 9 is controlled. In addition, these two high frequency power sources 5,
The same high-frequency power of 13.56 MHz may be used as 6, and the high-frequency power source 5 uses 13.56 MHz (V
_The high frequency power source 6 may use high frequency power (V _PP : 2 KV) of about 400 Hz. In the latter case, in the vicinity of the cathode electrode 2, -4 with respect to the plasma potential.
A sheath of about 00 to -500V is formed, and a sheath of about -200V is formed on the substrate electrode 3. However, the substrate electrode 3 is ± (500 to 1000) by the high frequency power source 6.
Since it is V-swing and this voltage is higher than the sheath voltage, the potential of the substrate electrode 3 is almost changed by the voltage of the high-frequency power source 6, and the frequency is as low as 400 Hz. Can be followed sufficiently, and when the potential of the substrate electrode 3 becomes negative, ions are drawn to the substrate electrode 3 side, and the substrate 8 is etched.

In such an embodiment, first, the inside of the vacuum chamber 1 is evacuated, an etching gas is introduced, and high-frequency power is applied from the high-frequency power source 5 to the cathode electrode 2. Plasma is generated between the cathode electrode 2 and the electrons in the plasma in the vicinity of the cathode electrode 2 undergoes a cycloid motion by the action of the magnet 7, and at the same time, the diffusion of the electrons to the cathode electrode 2 side is suppressed by the cusp magnetic field, The plasma near the electrode 2 has a high density. At this time, when high frequency power is applied to the substrate electrode 3 from the high frequency power source 6, when the substrate electrode 3 has a negative potential, the ions in the plasma are drawn toward the substrate electrode 3 and placed on the substrate electrode 3. The substrate 8 is etched. However, at this time, since a magnetic field almost perpendicular to the flat cathode electrode 2 and the flat substrate electrode 3 is generated by the electromagnet coil 9, the influence of this magnetic field limits the diffusion of plasma. The ions in the plasma are evenly incident on the surface of the substrate 8 on the surface, which enables uniform etching at high speed.

Next, FIG. 2 shows a magnetic field when an annular cusp type is used for the magnet 7 and a current of +10 [A] is applied to the electromagnet coil 9 in the embodiment, and FIG.
In the embodiment, an annular cusp type is used for the magnet 7 and the magnetic field when the electromagnet coil 9 is not provided is shown. FIG. 4 shows the etching rate and the etching rate distribution uniformity when an Al—Cu (1%) film on a 6-inch wafer is etched under the magnetic fields shown in FIGS. 2 and 3. The vertical axis represents the etching rate and the uniformity of the etching rate distribution, and the horizontal axis represents the current flowing through the electromagnet coil 9.

By the way, in the above embodiment, a permanent magnet is used as the magnet 7, but an electromagnet coil may be used instead. Further, in the above embodiment, the high frequency power source 5 is connected to the cathode electrode 2 and the anode electrode 4 is grounded. Instead of this, the cathode electrode 2 is grounded and the anode electrode 4 is grounded.
The high frequency power source 5 may be connected to the. Further, the electromagnet coil 9 may be provided in the vacuum chamber 1. The apparatus of the above embodiment may be used in a plasma CVD apparatus.

[0012]

According to the present invention, the diffusion of the high density plasma formed by the lattice-shaped multi-cusp type or annular cusp type magnets is suppressed from spreading to the cathode electrode side by the cusp magnetic field, and at the same time, by the electromagnet coil. Since the generated magnetic field almost perpendicular to the flat substrate electrode suppresses the lateral spread of plasma,
When the plasma density is increased, it is possible to prevent the plasma density from decreasing in the peripheral area of the substrate, so that the ions in the plasma are evenly incident on the surface of the substrate, and the anisotropy of the etching shape is not decreased. Uniform etching of 5% or less is possible at high speed. Further, compared to the conventional device, the plasma is less diffused in the lateral direction of the vacuum chamber, so that the plasma is less likely to be affected by the anode electrode and the side wall of the vacuum chamber, and the lateral dimension of the vacuum chamber can be reduced. it can.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a magnetic field when a current of +10 [A] is applied to the electromagnet coil 9 by using an annular cusp type magnet as an embodiment of the present invention.

FIG. 3 is an explanatory view showing a magnetic field when an annular cusp type is used for a magnet and an electromagnet coil is not provided in an embodiment of the present invention.

FIG. 4 is a graph showing etching rate and etching rate distribution uniformity when an Al—Cu (1%) film on a 6-inch wafer is etched under the magnetic fields shown in FIGS. 2 and 3.

FIG. 5 is an explanatory view showing a conventional etching apparatus.

[Explanation of symbols]

 1 ... Vacuum tank 2 ... Cathode electrode 3 ... Substrate electrode 4 ... Anode electrode 5 ... High frequency power supply 6 ... High frequency power supply 7 ... .... Magnet 8 ... Substrate 9 ... Electromagnetic coil

Front page continuation (72) Inventor Masahiro Ito 2500 Hagizono, Chigasaki City, Kanagawa Japan Vacuum Technology Co., Ltd.

Claims (2)

[Claims] 1. A flat cathode electrode to which high-frequency power is applied and a flat substrate electrode are arranged in parallel in a vacuum chamber so as to face each other, and are grounded around a space sandwiched between these electrodes. An anode electrode is arranged, and a cusp-type magnet is arranged behind the flat cathode electrode, and the substrate placed on the substrate electrode is etched by the plasma generated between the anode electrode and the cathode electrode. In the etching apparatus, a magnet that generates a magnetic field substantially perpendicular to the flat substrate electrode is provided outside or inside the vacuum chamber. 2. The etching apparatus according to claim 1, wherein the magnet for generating a magnetic field substantially perpendicular to the flat substrate electrode is an electromagnet coil whose magnetic field is controllable.